Merge tag 'tty-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial updates from Greg KH:
"Here is the "big" set of tty/serial driver patches for 5.2-rc1.

It's really pretty small, not much happening in this portion of the
kernel at the moment. When the "highlight" is the movement of the
documentation from .txt to .rst files, it's a good merge window.

There's a number of small fixes and updates over the various serial
drivers, and a new "tty null" driver for those embedded systems that
like to make things even smaller and not break things.

All of these have been in linux-next for a while with no reported
issues"

* tag 'tty-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (45 commits)
tty: serial: add driver for the SiFive UART
dt-bindings: serial: add documentation for the SiFive UART driver
serial: uartps: Add support for cts-override
dt-bindings: xilinx-uartps: Add support for cts-override
serial: milbeaut_usio: Fix error handling in probe and remove
tty: rocket: deprecate the rp_ioctl
tty: rocket: Remove RCPK_GET_STRUCT ioctl
tty: update obsolete termios comment
tty: serial_core: fix error code returned by uart_register_driver()
serial: 8250-mtk: modify baudrate setting
serial: 8250-mtk: add follow control
docs: serial: convert docs to ReST and rename to *.rst
serial: 8250_exar: Adjust IOT2000 matching
TTY: serial_core, add ->install
serial: Fix using plain integer instead of Null pointer
tty:serial_core: Spelling mistake
tty: Add NULL TTY driver
tty: vt: keyboard: Allow Unicode compose base char
Revert "tty: fix NULL pointer issue when tty_port ops is not set"
serial: Add Milbeaut serial control
...

Documentation/devicetree/bindings/serial/cdns,uart.txt

···
   See ../clocks/clock-bindings.txt for details.
 
 
+Optional properties:
+- cts-override : Override the CTS modem status signal. This signal will
+  always be reported as active instead of being obtained from the modem status
+  register. Define this if your serial port does not use this pin
+
 Example:
 	uart@e0000000 {
 		compatible = "cdns,uart-r1p8";

Documentation/devicetree/bindings/serial/nxp,sc16is7xx.txt

···
 - reg: I2C address of the SC16IS7xx device.
 - interrupts: Should contain the UART interrupt
 - clocks: Reference to the IC source clock.
+	OR (when there is no clock provider visible to the platform)
+- clock-frequency: The source clock frequency for the IC.
 
 Optional properties:
 - gpio-controller: Marks the device node as a GPIO controller.

Documentation/devicetree/bindings/serial/sifive-serial.txt

···
+SiFive asynchronous serial interface (UART)
+
+Required properties:
+
+- compatible: should be something similar to
+	      "sifive,<chip>-uart" for the UART as integrated
+	      on a particular chip, and "sifive,uart<version>" for the
+	      general UART IP block programming model.	Supported
+	      compatible strings as of the date of this writing are:
+	      "sifive,fu540-c000-uart" for the SiFive UART v0 as
+	      integrated onto the SiFive FU540 chip, or "sifive,uart0"
+	      for the SiFive UART v0 IP block with no chip integration
+	      tweaks (if any)
+- reg: address and length of the register space
+- interrupts: Should contain the UART interrupt identifier
+- clocks: Should contain a clock identifier for the UART's parent clock
+
+
+UART HDL that corresponds to the IP block version numbers can be found
+here:
+
+https://github.com/sifive/sifive-blocks/tree/master/src/main/scala/devices/uart
+
+
+Example:
+
+uart0: serial@10010000 {
+	compatible = "sifive,fu540-c000-uart", "sifive,uart0";
+	interrupt-parent = <&plic0>;
+	interrupts = <80>;
+	reg = <0x0 0x10010000 0x0 0x1000>;
+	clocks = <&prci PRCI_CLK_TLCLK>;
+};

Documentation/devicetree/bindings/serial/sprd-uart.txt

···
 
 - reg: offset and length of the register set for the device
 - interrupts: exactly one interrupt specifier
-- clocks: phandles to input clocks.
+- clock-names: Should contain following entries:
+  "enable" for UART module enable clock,
+  "uart" for UART clock,
+  "source" for UART source (parent) clock.
+- clocks: Should contain a clock specifier for each entry in clock-names.
+  UART clock and source clock are optional properties, but enable clock
+  is required.
+
+Optional properties:
+- dma-names: Should contain "rx" for receive and "tx" for transmit channels.
+- dmas: A list of dma specifiers, one for each entry in dma-names.
 
 Example:
 	uart0: serial@0 {
···
 			     "sprd,sc9836-uart";
 		reg = <0x0 0x100>;
 		interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
-		clocks = <&ext_26m>;
+		dma-names = "rx", "tx";
+		dmas = <&ap_dma 19>, <&ap_dma 20>;
+		clock-names = "enable", "uart", "source";
+		clocks = <&clk_ap_apb_gates 9>, <&clk_uart0>, <&ext_26m>;
 	};

Documentation/serial/README.cycladesZ Documentation/serial/cyclades_z.rst

···
+================
+Cyclades-Z notes
+================
 
 The Cyclades-Z must have firmware loaded onto the card before it will
 operate.  This operation should be performed during system startup,
 
 The firmware, loader program and the latest device driver code are
 available from Cyclades at
-    ftp://ftp.cyclades.com/pub/cyclades/cyclades-z/linux/
 
+    ftp://ftp.cyclades.com/pub/cyclades/cyclades-z/linux/

Documentation/serial/driver Documentation/serial/driver.rst

···
-
-			Low Level Serial API
-			--------------------
+====================
+Low Level Serial API
+====================
 
 
 This document is meant as a brief overview of some aspects of the new serial
···
 There are two locks.  A per-port spinlock, and an overall semaphore.
 
 From the core driver perspective, the port->lock locks the following
-data:
+data::
 
 	port->mctrl
 	port->icount
···
 	return TIOCSER_TEMT.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
+
 	This call must not sleep
 
   set_mctrl(port, mctrl)
 	This function sets the modem control lines for port described
 	by 'port' to the state described by mctrl.  The relevant bits
 	of mctrl are:
+
 		- TIOCM_RTS	RTS signal.
 		- TIOCM_DTR	DTR signal.
 		- TIOCM_OUT1	OUT1 signal.
 		- TIOCM_OUT2	OUT2 signal.
 		- TIOCM_LOOP	Set the port into loopback mode.
+
 	If the appropriate bit is set, the signal should be driven
 	active.  If the bit is clear, the signal should be driven
 	inactive.
 
 	Locking: port->lock taken.
+
 	Interrupts: locally disabled.
+
 	This call must not sleep
 
   get_mctrl(port)
 	Returns the current state of modem control inputs.  The state
 	of the outputs should not be returned, since the core keeps
 	track of their state.  The state information should include:
+
 		- TIOCM_CAR	state of DCD signal
 		- TIOCM_CTS	state of CTS signal
 		- TIOCM_DSR	state of DSR signal
 		- TIOCM_RI	state of RI signal
+
 	The bit is set if the signal is currently driven active.  If
 	the port does not support CTS, DCD or DSR, the driver should
 	indicate that the signal is permanently active.  If RI is
 	not available, the signal should not be indicated as active.
 
 	Locking: port->lock taken.
+
 	Interrupts: locally disabled.
+
 	This call must not sleep
 
   stop_tx(port)
···
 	possible.
 
 	Locking: port->lock taken.
+
 	Interrupts: locally disabled.
+
 	This call must not sleep
 
   start_tx(port)
 	Start transmitting characters.
 
 	Locking: port->lock taken.
+
 	Interrupts: locally disabled.
+
 	This call must not sleep
 
   throttle(port)
···
 	This will be called only if hardware assisted flow control is enabled.
 
 	Locking: serialized with .unthrottle() and termios modification by the
-		 tty layer.
+	tty layer.
 
   unthrottle(port)
 	Notify the serial driver that characters can now be sent to the serial
 	port without fear of overrunning the input buffers of the line
 	disciplines.
+
 	This will be called only if hardware assisted flow control is enabled.
 
 	Locking: serialized with .throttle() and termios modification by the
-		 tty layer.
+	tty layer.
 
   send_xchar(port,ch)
 	Transmit a high priority character, even if the port is stopped.
···
 	Do not transmit if ch == '\0' (__DISABLED_CHAR).
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   stop_rx(port)
···
 	being closed.
 
 	Locking: port->lock taken.
+
 	Interrupts: locally disabled.
+
 	This call must not sleep
 
   enable_ms(port)
···
 	called.
 
 	Locking: port->lock taken.
+
 	Interrupts: locally disabled.
+
 	This call must not sleep
 
   break_ctl(port,ctl)
···
 	This method will only be called when the port is initially opened.
 
 	Locking: port_sem taken.
+
 	Interrupts: globally disabled.
 
   shutdown(port)
···
 	this port.
 
 	Locking: port_sem taken.
+
 	Interrupts: caller dependent.
 
   flush_buffer(port)
···
 	buffer is cleared.
 
 	Locking: port->lock taken.
+
 	Interrupts: locally disabled.
+
 	This call must not sleep
 
   set_termios(port,termios,oldtermios)
···
 	bits.  Update read_status_mask and ignore_status_mask to indicate
 	the types of events we are interested in receiving.  Relevant
 	termios->c_cflag bits are:
-		CSIZE	- word size
-		CSTOPB	- 2 stop bits
-		PARENB	- parity enable
-		PARODD	- odd parity (when PARENB is in force)
-		CREAD	- enable reception of characters (if not set,
+
+		CSIZE
+			- word size
+		CSTOPB
+			- 2 stop bits
+		PARENB
+			- parity enable
+		PARODD
+			- odd parity (when PARENB is in force)
+		CREAD
+			- enable reception of characters (if not set,
 			  still receive characters from the port, but
 			  throw them away.
-		CRTSCTS	- if set, enable CTS status change reporting
-		CLOCAL	- if not set, enable modem status change
+		CRTSCTS
+			- if set, enable CTS status change reporting
+		CLOCAL
+			- if not set, enable modem status change
 			  reporting.
+
 	Relevant termios->c_iflag bits are:
-		INPCK	- enable frame and parity error events to be
+
+		INPCK
+			- enable frame and parity error events to be
 			  passed to the TTY layer.
-		BRKINT
-		PARMRK	- both of these enable break events to be
+		BRKINT / PARMRK
+			- both of these enable break events to be
 			  passed to the TTY layer.
 
-		IGNPAR	- ignore parity and framing errors
-		IGNBRK	- ignore break errors,  If IGNPAR is also
+		IGNPAR
+			- ignore parity and framing errors
+		IGNBRK
+			- ignore break errors,  If IGNPAR is also
 			  set, ignore overrun errors as well.
+
 	The interaction of the iflag bits is as follows (parity error
 	given as an example):
+
+	=============== ======= ======  =============================
 	Parity error	INPCK	IGNPAR
+	=============== ======= ======  =============================
 	n/a		0	n/a	character received, marked as
 					TTY_NORMAL
 	None		1	n/a	character received, marked as
···
 	Yes		1	0	character received, marked as
 					TTY_PARITY
 	Yes		1	1	character discarded
+	=============== ======= ======  =============================
 
 	Other flags may be used (eg, xon/xoff characters) if your
 	hardware supports hardware "soft" flow control.
 
 	Locking: caller holds tty_port->mutex
+
 	Interrupts: caller dependent.
+
 	This call must not sleep
 
   set_ldisc(port,termios)
-	Notifier for discipline change. See Documentation/serial/tty.txt.
+	Notifier for discipline change. See Documentation/serial/tty.rst.
 
 	Locking: caller holds tty_port->mutex
 
···
 	will occur even if CONFIG_PM is not set.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   type(port)
···
 	substituted.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   release_port(port)
···
 	the port.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   request_port(port)
···
 	returns, and it should return -EBUSY on failure.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   config_port(port,type)
···
 	internally hard wired (eg, system on a chip implementations).
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   verify_port(port,serinfo)
···
 	suitable for this port type.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   ioctl(port,cmd,arg)
···
 	using the standard numbering system found in <asm/ioctl.h>
 
 	Locking: none.
+
 	Interrupts: caller dependent.
 
   poll_init(port)
···
 	this should not request interrupts.
 
 	Locking: tty_mutex and tty_port->mutex taken.
+
 	Interrupts: n/a.
 
   poll_put_char(port,ch)
···
 	port.  It can and should block until there is space in the TX FIFO.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
+
 	This call must not sleep
 
   poll_get_char(port)
···
 	the function should return NO_POLL_CHAR immediately.
 
 	Locking: none.
+
 	Interrupts: caller dependent.
+
 	This call must not sleep
 
 Other functions
···
 	number of bits, parity, stop bits and baud rate.
 
 	Locking: caller is expected to take port->lock
+
 	Interrupts: n/a
 
 uart_get_baud_rate(port,termios,old,min,max)
···
 	Note: min..max must always allow 9600 baud to be selected.
 
 	Locking: caller dependent.
+
 	Interrupts: n/a
 
 uart_get_divisor(port,baud)
···
 	custom divisor instead.
 
 	Locking: caller dependent.
+
 	Interrupts: n/a
 
 uart_match_port(port1,port2)
···
 	uart_port structures describe the same port.
 
 	Locking: n/a
+
 	Interrupts: n/a
 
 uart_write_wakeup(port)
···
 	characters in the transmit buffer have dropped below a threshold.
 
 	Locking: port->lock should be held.
+
 	Interrupts: n/a
 
 uart_register_driver(drv)
···
 	registered using uart_add_one_port after this call has succeeded.
 
 	Locking: none
+
 	Interrupts: enabled
 
 uart_unregister_driver()
···
 	uart_remove_one_port() if it registered them with uart_add_one_port().
 
 	Locking: none
+
 	Interrupts: enabled
 
-uart_suspend_port()
+**uart_suspend_port()**
 
-uart_resume_port()
+**uart_resume_port()**
 
-uart_add_one_port()
+**uart_add_one_port()**
 
-uart_remove_one_port()
+**uart_remove_one_port()**
 
 Other notes
 -----------
···
 allow low level drivers to register their own individual uart_port's with
 the core.  This will allow drivers to use uart_port as a pointer to a
 structure containing both the uart_port entry with their own extensions,
-thus:
+thus::
 
 	struct my_port {
 		struct uart_port	port;
···
 mctrl_gpio_init(port, idx):
 	This will get the {cts,rts,...}-gpios from device tree if they are
 	present and request them, set direction etc, and return an
-	allocated structure. devm_* functions are used, so there's no need
+	allocated structure. `devm_*` functions are used, so there's no need
 	to call mctrl_gpio_free().
 	As this sets up the irq handling make sure to not handle changes to the
 	gpio input lines in your driver, too.
 
 mctrl_gpio_free(dev, gpios):
 	This will free the requested gpios in mctrl_gpio_init().
-	As devm_* functions are used, there's generally no need to call
+	As `devm_*` functions are used, there's generally no need to call
 	this function.
 
 mctrl_gpio_to_gpiod(gpios, gidx)

Documentation/serial/index.rst

···
+:orphan:
+
+==========================
+Support for Serial devices
+==========================
+
+.. toctree::
+    :maxdepth: 1
+
+
+    driver
+    tty
+
+Serial drivers
+==============
+
+.. toctree::
+    :maxdepth: 1
+
+    cyclades_z
+    moxa-smartio
+    n_gsm
+    rocket
+    serial-iso7816
+    serial-rs485
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`

Documentation/serial/moxa-smartio

···
-=============================================================================
-          MOXA Smartio/Industio Family Device Driver Installation Guide
-		    for Linux Kernel 2.4.x, 2.6.x
-	       Copyright (C) 2008, Moxa Inc.
-=============================================================================
-Date: 01/21/2008
-
-Content
-
-1. Introduction
-2. System Requirement
-3. Installation
-   3.1 Hardware installation
-   3.2 Driver files
-   3.3 Device naming convention
-   3.4 Module driver configuration
-   3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x.
-   3.6 Custom configuration
-   3.7 Verify driver installation
-4. Utilities
-5. Setserial
-6. Troubleshooting
-
------------------------------------------------------------------------------
-1. Introduction
-
-   The Smartio/Industio/UPCI family Linux driver supports following multiport
-   boards.
-
-    - 2 ports multiport board
-	CP-102U, CP-102UL, CP-102UF
-	CP-132U-I, CP-132UL,
-	CP-132, CP-132I, CP132S, CP-132IS,
-	CI-132, CI-132I, CI-132IS,
-	(C102H, C102HI, C102HIS, C102P, CP-102, CP-102S)
-
-    - 4 ports multiport board
-	CP-104EL,
-	CP-104UL, CP-104JU,
-	CP-134U, CP-134U-I,
-	C104H/PCI, C104HS/PCI,
-	CP-114, CP-114I, CP-114S, CP-114IS, CP-114UL,
-	C104H, C104HS,
-	CI-104J, CI-104JS,
-	CI-134, CI-134I, CI-134IS,
-	(C114HI, CT-114I, C104P)
-	POS-104UL,
-	CB-114,
-	CB-134I
-
-    - 8 ports multiport board
-	CP-118EL, CP-168EL,
-	CP-118U, CP-168U,
-	C168H/PCI,
-	C168H, C168HS,
-	(C168P),
-	CB-108
-
-   This driver and installation procedure have been developed upon Linux Kernel
-   2.4.x and 2.6.x. This driver supports Intel x86 hardware platform. In order
-   to maintain compatibility, this version has also been properly tested with
-   RedHat, Mandrake, Fedora and S.u.S.E Linux. However, if compatibility problem
-   occurs, please contact Moxa at [e-mail].
-
-   In addition to device driver, useful utilities are also provided in this
-   version. They are
-    - msdiag     Diagnostic program for displaying installed Moxa
-                 Smartio/Industio boards.
-    - msmon      Monitor program to observe data count and line status signals.
-    - msterm     A simple terminal program which is useful in testing serial
-	         ports.
-    - io-irq.exe Configuration program to setup ISA boards. Please note that
-                 this program can only be executed under DOS.
-
-   All the drivers and utilities are published in form of source code under
-   GNU General Public License in this version. Please refer to GNU General
-   Public License announcement in each source code file for more detail.
-
-   In Moxa's Web sites, you may always find latest driver at http://www.moxa.com/.
-
-   This version of driver can be installed as Loadable Module (Module driver)
-   or built-in into kernel (Static driver). You may refer to following
-   installation procedure for suitable one. Before you install the driver,
-   please refer to hardware installation procedure in the User's Manual.
-
-   We assume the user should be familiar with following documents.
-   - Serial-HOWTO
-   - Kernel-HOWTO
-
------------------------------------------------------------------------------
-2. System Requirement
-   - Hardware platform: Intel x86 machine
-   - Kernel version: 2.4.x or 2.6.x
-   - gcc version 2.72 or later
-   - Maximum 4 boards can be installed in combination
-
------------------------------------------------------------------------------
-3. Installation
-
-   3.1 Hardware installation
-   3.2 Driver files
-   3.3 Device naming convention
-   3.4 Module driver configuration
-   3.5 Static driver configuration for Linux kernel 2.4.x, 2.6.x.
-   3.6 Custom configuration
-   3.7 Verify driver installation
-
-
-   3.1 Hardware installation
-
-       There are two types of buses, ISA and PCI, for Smartio/Industio
-       family multiport board.
-
-       ISA board
-       ---------
-       You'll have to configure CAP address, I/O address, Interrupt Vector
-       as well as IRQ before installing this driver. Please refer to hardware
-       installation procedure in User's Manual before proceed any further.
-       Please make sure the JP1 is open after the ISA board is set properly.
-
-       PCI/UPCI board
-       --------------
-       You may need to adjust IRQ usage in BIOS to avoid from IRQ conflict
-       with other ISA devices. Please refer to hardware installation
-       procedure in User's Manual in advance.
-
-       PCI IRQ Sharing
-       -----------
-       Each port within the same multiport board shares the same IRQ. Up to
-       4 Moxa Smartio/Industio PCI Family multiport boards can be installed
-       together on one system and they can share the same IRQ.
-
-
-   3.2 Driver files
-
-       The driver file may be obtained from ftp, CD-ROM or floppy disk. The
-       first step, anyway, is to copy driver file "mxser.tgz" into specified
-       directory. e.g. /moxa. The execute commands as below.
-
-       # cd /
-       # mkdir moxa
-       # cd /moxa
-       # tar xvf /dev/fd0
-
-       or
-
-       # cd /
-       # mkdir moxa
-       # cd /moxa
-       # cp /mnt/cdrom/<driver directory>/mxser.tgz .
-       # tar xvfz mxser.tgz
-
-
-   3.3 Device naming convention
-
-       You may find all the driver and utilities files in /moxa/mxser.
-       Following installation procedure depends on the model you'd like to
-       run the driver. If you prefer module driver, please refer to 3.4.
-       If static driver is required, please refer to 3.5.
-
-       Dialin and callout port
-       -----------------------
-       This driver remains traditional serial device properties. There are
-       two special file name for each serial port. One is dial-in port
-       which is named "ttyMxx". For callout port, the naming convention
-       is "cumxx".
-
-       Device naming when more than 2 boards installed
-       -----------------------------------------------
-       Naming convention for each Smartio/Industio multiport board is
-       pre-defined as below.
-
-       Board Num.	 Dial-in Port	      Callout port
-       1st board	ttyM0  - ttyM7	      cum0  - cum7
-       2nd board	ttyM8  - ttyM15       cum8  - cum15
-       3rd board	ttyM16 - ttyM23       cum16 - cum23
-       4th board	ttyM24 - ttym31       cum24 - cum31
-
-
-       !!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-       Under Kernel 2.6 the cum Device is Obsolete. So use ttyM*
-       device instead.
-       !!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-       Board sequence
-       --------------
-       This driver will activate ISA boards according to the parameter set
-       in the driver. After all specified ISA board activated, PCI board
-       will be installed in the system automatically driven.
-       Therefore the board number is sorted by the CAP address of ISA boards.
-       For PCI boards, their sequence will be after ISA boards and C168H/PCI
-       has higher priority than C104H/PCI boards.
-
-   3.4 Module driver configuration
-       Module driver is easiest way to install. If you prefer static driver
-       installation, please skip this paragraph.
-
-
-       ------------- Prepare to use the MOXA driver--------------------
-       3.4.1 Create tty device with correct major number
-          Before using MOXA driver, your system must have the tty devices
-          which are created with driver's major number. We offer one shell
-          script "msmknod" to simplify the procedure.
-          This step is only needed to be executed once. But you still
-          need to do this procedure when:
-          a. You change the driver's major number. Please refer the "3.7"
-             section.
-          b. Your total installed MOXA boards number is changed. Maybe you
-             add/delete one MOXA board.
-          c. You want to change the tty name. This needs to modify the
-             shell script "msmknod"
-
-          The procedure is:
-	  # cd /moxa/mxser/driver
-	  # ./msmknod
-
-          This shell script will require the major number for dial-in
-          device and callout device to create tty device. You also need
-          to specify the total installed MOXA board number. Default major
-          numbers for dial-in device and callout device are 30, 35. If
-          you need to change to other number, please refer section "3.7"
-          for more detailed procedure.
-          Msmknod will delete any special files occupying the same device
-          naming.
-
-       3.4.2 Build the MOXA driver and utilities
-          Before using the MOXA driver and utilities, you need compile the
-          all the source code. This step is only need to be executed once.
-          But you still re-compile the source code if you modify the source
-          code. For example, if you change the driver's major number (see
-          "3.7" section), then you need to do this step again.
-
-          Find "Makefile" in /moxa/mxser, then run
-
-	  # make clean; make install
-
-          !!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!
-	  For Red Hat 9, Red Hat Enterprise Linux AS3/ES3/WS3 & Fedora Core1:
-	  # make clean; make installsp1
-
-	  For Red Hat Enterprise Linux AS4/ES4/WS4:
-	  # make clean; make installsp2
-          !!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!
-
-	  The driver files "mxser.o" and utilities will be properly compiled
-	  and copied to system directories respectively.
-
-       ------------- Load MOXA driver--------------------
-       3.4.3 Load the MOXA driver
-
-	  # modprobe mxser <argument>
-
-	  will activate the module driver. You may run "lsmod" to check
-	  if "mxser" is activated. If the MOXA board is ISA board, the
-          <argument> is needed. Please refer to section "3.4.5" for more
-          information.
-
-
-       ------------- Load MOXA driver on boot --------------------
-       3.4.4 For the above description, you may manually execute
-          "modprobe mxser" to activate this driver and run
-	  "rmmod mxser" to remove it.
-          However, it's better to have a boot time configuration to
-          eliminate manual operation. Boot time configuration can be
-          achieved by rc file. We offer one "rc.mxser" file to simplify
-          the procedure under "moxa/mxser/driver".
-
-          But if you use ISA board, please modify the "modprobe ..." command
-          to add the argument (see "3.4.5" section). After modifying the
-          rc.mxser, please try to execute "/moxa/mxser/driver/rc.mxser"
-          manually to make sure the modification is ok. If any error
-          encountered, please try to modify again. If the modification is
-          completed, follow the below step.
-
-	  Run following command for setting rc files.
-
-	  # cd /moxa/mxser/driver
-	  # cp ./rc.mxser /etc/rc.d
-	  # cd /etc/rc.d
-
-	  Check "rc.serial" is existed or not. If "rc.serial" doesn't exist,
-	  create it by vi, run "chmod 755 rc.serial" to change the permission.
-	  Add "/etc/rc.d/rc.mxser" in last line,
-
-          Reboot and check if moxa.o activated by "lsmod" command.
-
-       3.4.5. If you'd like to drive Smartio/Industio ISA boards in the system,
-          you'll have to add parameter to specify CAP address of given
-	  board while activating "mxser.o". The format for parameters are
-	  as follows.
-
-	  modprobe mxser ioaddr=0x???,0x???,0x???,0x???
-				|      |     |	  |
-				|      |     |	  +- 4th ISA board
-				|      |     +------ 3rd ISA board
-				|      +------------ 2nd ISA board
-				+------------------- 1st ISA board
-
-   3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x
-
-       Note: To use static driver, you must install the linux kernel
-             source package.
-
-       3.5.1 Backup the built-in driver in the kernel.
-          # cd /usr/src/linux/drivers/char
-          # mv mxser.c mxser.c.old
-
-          For Red Hat 7.x user, you need to create link:
-          # cd /usr/src
-          # ln -s linux-2.4 linux
-
-       3.5.2 Create link
-	  # cd /usr/src/linux/drivers/char
-	  # ln -s /moxa/mxser/driver/mxser.c mxser.c
-
-       3.5.3 Add CAP address list for ISA boards. For PCI boards user,
-          please skip this step.
-
-	  In module mode, the CAP address for ISA board is given by
-	  parameter. In static driver configuration, you'll have to
-	  assign it within driver's source code. If you will not
-	  install any ISA boards, you may skip to next portion.
-	  The instructions to modify driver source code are as
-	  below.
-	  a. # cd /moxa/mxser/driver
-	     # vi mxser.c
-	  b. Find the array mxserBoardCAP[] as below.
-
-	     static int mxserBoardCAP[]
-	     = {0x00, 0x00, 0x00, 0x00};
-
-	  c. Change the address within this array using vi. For
-	     example, to driver 2 ISA boards with CAP address
-	     0x280 and 0x180 as 1st and 2nd board. Just to change
-	     the source code as follows.
-
-	     static int mxserBoardCAP[]
-	     = {0x280, 0x180, 0x00, 0x00};
-
-       3.5.4 Setup kernel configuration
-
-          Configure the kernel:
-
-            # cd /usr/src/linux
-            # make menuconfig
-
-          You will go into a menu-driven system. Please select [Character
-          devices][Non-standard serial port support], enable the [Moxa
-          SmartIO support] driver with "[*]" for built-in (not "[M]"), then
-          select [Exit] to exit this program.
-
-       3.5.5 Rebuild kernel
-	  The following are for Linux kernel rebuilding, for your
-          reference only.
-	  For appropriate details, please refer to the Linux document.
-
-	   a. cd /usr/src/linux
-	   b. make clean	     /* take a few minutes */
-	   c. make dep		     /* take a few minutes */
-	   d. make bzImage	     /* take probably 10-20 minutes */
-	   e. make install	     /* copy boot image to correct position */
-	   f. Please make sure the boot kernel (vmlinuz) is in the
-	      correct position.
-	   g. If you use 'lilo' utility, you should check /etc/lilo.conf
-	      'image' item specified the path which is the 'vmlinuz' path,
-	      or you will load wrong (or old) boot kernel image (vmlinuz).
-	      After checking /etc/lilo.conf, please run "lilo".
-
-	  Note that if the result of "make bzImage" is ERROR, then you have to
-	  go back to Linux configuration Setup. Type "make menuconfig" in
-          directory /usr/src/linux.
-
-
-       3.5.6 Make tty device and special file
-          # cd /moxa/mxser/driver
-          # ./msmknod
-
-       3.5.7 Make utility
-	  # cd /moxa/mxser/utility
-	  # make clean; make install
-
-       3.5.8 Reboot
-
-
-
-   3.6 Custom configuration
-       Although this driver already provides you default configuration, you
-       still can change the device name and major number. The instruction to
-       change these parameters are shown as below.
-
-       Change Device name
-       ------------------
-       If you'd like to use other device names instead of default naming
-       convention, all you have to do is to modify the internal code
-       within the shell script "msmknod". First, you have to open "msmknod"
-       by vi. Locate each line contains "ttyM" and "cum" and change them
-       to the device name you desired. "msmknod" creates the device names
-       you need next time executed.
-
-       Change Major number
-       -------------------
-       If major number 30 and 35 had been occupied, you may have to select
-       2 free major numbers for this driver. There are 3 steps to change
-       major numbers.
-
-       3.6.1 Find free major numbers
-	  In /proc/devices, you may find all the major numbers occupied
-	  in the system. Please select 2 major numbers that are available.
-	  e.g. 40, 45.
-       3.6.2 Create special files
-	  Run /moxa/mxser/driver/msmknod to create special files with
-	  specified major numbers.
-       3.6.3 Modify driver with new major number
-	  Run vi to open /moxa/mxser/driver/mxser.c. Locate the line
-	  contains "MXSERMAJOR". Change the content as below.
-	  #define	  MXSERMAJOR		  40
-	  #define	  MXSERCUMAJOR		  45
-       3.6.4 Run "make clean; make install" in /moxa/mxser/driver.
-
-   3.7 Verify driver installation
-       You may refer to /var/log/messages to check the latest status
-       log reported by this driver whenever it's activated.
-
------------------------------------------------------------------------------
-4. Utilities
-   There are 3 utilities contained in this driver. They are msdiag, msmon and
-   msterm. These 3 utilities are released in form of source code. They should
-   be compiled into executable file and copied into /usr/bin.
-
-   Before using these utilities, please load driver (refer 3.4 & 3.5) and
-   make sure you had run the "msmknod" utility.
-
-   msdiag - Diagnostic
-   --------------------
-   This utility provides the function to display what Moxa Smartio/Industio
-   board found by driver in the system.
-
-   msmon - Port Monitoring
-   -----------------------
-   This utility gives the user a quick view about all the MOXA ports'
-   activities. One can easily learn each port's total received/transmitted
-   (Rx/Tx) character count since the time when the monitoring is started.
-   Rx/Tx throughputs per second are also reported in interval basis (e.g.
-   the last 5 seconds) and in average basis (since the time the monitoring
-   is started). You can reset all ports' count by <HOME> key. <+> <->
-   (plus/minus) keys to change the displaying time interval. Press <ENTER>
-   on the port, that cursor stay, to view the port's communication
-   parameters, signal status, and input/output queue.
-
-   msterm - Terminal Emulation
-   ---------------------------
-   This utility provides data sending and receiving ability of all tty ports,
-   especially for MOXA ports. It is quite useful for testing simple
-   application, for example, sending AT command to a modem connected to the
-   port or used as a terminal for login purpose. Note that this is only a
-   dumb terminal emulation without handling full screen operation.
-
------------------------------------------------------------------------------
-5. Setserial
-
-   Supported Setserial parameters are listed as below.
-
-   uart		  set UART type(16450-->disable FIFO, 16550A-->enable FIFO)
-   close_delay	  set the amount of time(in 1/100 of a second) that DTR
-		  should be kept low while being closed.
-   closing_wait   set the amount of time(in 1/100 of a second) that the
-		  serial port should wait for data to be drained while
-		  being closed, before the receiver is disable.
-   spd_hi	  Use  57.6kb  when  the application requests 38.4kb.
-   spd_vhi	  Use  115.2kb	when  the application requests 38.4kb.
-   spd_shi	  Use  230.4kb	when  the application requests 38.4kb.
-   spd_warp	  Use  460.8kb	when  the application requests 38.4kb.
-   spd_normal	  Use  38.4kb  when  the application requests 38.4kb.
-   spd_cust	  Use  the custom divisor to set the speed when  the
-		  application requests 38.4kb.
-   divisor	  This option set the custom division.
-   baud_base	  This option set the base baud rate.
-
------------------------------------------------------------------------------
-6. Troubleshooting
-
-   The boot time error messages and solutions are stated as clearly as
-   possible. If all the possible solutions fail, please contact our technical
-   support team to get more help.
-
-
-   Error msg: More than 4 Moxa Smartio/Industio family boards found. Fifth board
-              and after are ignored.
-   Solution:
-   To avoid this problem, please unplug fifth and after board, because Moxa
-   driver supports up to 4 boards.
-
-   Error msg: Request_irq fail, IRQ(?) may be conflict with another device.
-   Solution:
-   Other PCI or ISA devices occupy the assigned IRQ. If you are not sure
-   which device causes the situation, please check /proc/interrupts to find
-   free IRQ and simply change another free IRQ for Moxa board.
-
-   Error msg: Board #: C1xx Series(CAP=xxx) interrupt number invalid.
-   Solution:
-   Each port within the same multiport board shares the same IRQ. Please set
-   one IRQ (IRQ doesn't equal to zero) for one Moxa board.
-
-   Error msg: No interrupt vector be set for Moxa ISA board(CAP=xxx).
-   Solution:
-   Moxa ISA board needs an interrupt vector.Please refer to user's manual
-   "Hardware Installation" chapter to set interrupt vector.
-
-   Error msg: Couldn't install MOXA Smartio/Industio family driver!
-   Solution:
-   Load Moxa driver fail, the major number may conflict with other devices.
-   Please refer to previous section 3.7 to change a free major number for
-   Moxa driver.
-
-   Error msg: Couldn't install MOXA Smartio/Industio family callout driver!
-   Solution:
-   Load Moxa callout driver fail, the callout device major number may
-   conflict with other devices. Please refer to previous section 3.7 to
-   change a free callout device major number for Moxa driver.
-
-
------------------------------------------------------------------------------
-

Documentation/serial/moxa-smartio.rst

···
+=============================================================
+MOXA Smartio/Industio Family Device Driver Installation Guide
+=============================================================
+
+.. note::
+
+   This file is outdated. It needs some care in order to make it
+   updated to Kernel 5.0 and upper
+
+Copyright (C) 2008, Moxa Inc.
+
+Date: 01/21/2008
+
+.. Content
+
+   1. Introduction
+   2. System Requirement
+   3. Installation
+      3.1 Hardware installation
+      3.2 Driver files
+      3.3 Device naming convention
+      3.4 Module driver configuration
+      3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x.
+      3.6 Custom configuration
+      3.7 Verify driver installation
+   4. Utilities
+   5. Setserial
+   6. Troubleshooting
+
+1. Introduction
+^^^^^^^^^^^^^^^
+
+   The Smartio/Industio/UPCI family Linux driver supports following multiport
+   boards.
+
+    - 2 ports multiport board
+	CP-102U, CP-102UL, CP-102UF
+	CP-132U-I, CP-132UL,
+	CP-132, CP-132I, CP132S, CP-132IS,
+	CI-132, CI-132I, CI-132IS,
+	(C102H, C102HI, C102HIS, C102P, CP-102, CP-102S)
+
+    - 4 ports multiport board
+	CP-104EL,
+	CP-104UL, CP-104JU,
+	CP-134U, CP-134U-I,
+	C104H/PCI, C104HS/PCI,
+	CP-114, CP-114I, CP-114S, CP-114IS, CP-114UL,
+	C104H, C104HS,
+	CI-104J, CI-104JS,
+	CI-134, CI-134I, CI-134IS,
+	(C114HI, CT-114I, C104P),
+	POS-104UL,
+	CB-114,
+	CB-134I
+
+    - 8 ports multiport board
+	CP-118EL, CP-168EL,
+	CP-118U, CP-168U,
+	C168H/PCI,
+	C168H, C168HS,
+	(C168P),
+	CB-108
+
+   This driver and installation procedure have been developed upon Linux Kernel
+   2.4.x and 2.6.x. This driver supports Intel x86 hardware platform. In order
+   to maintain compatibility, this version has also been properly tested with
+   RedHat, Mandrake, Fedora and S.u.S.E Linux. However, if compatibility problem
+   occurs, please contact Moxa at [e-mail].
+
+   In addition to device driver, useful utilities are also provided in this
+   version. They are:
+
+    - msdiag
+		 Diagnostic program for displaying installed Moxa
+                 Smartio/Industio boards.
+    - msmon
+		 Monitor program to observe data count and line status signals.
+    - msterm     A simple terminal program which is useful in testing serial
+	         ports.
+    - io-irq.exe
+		 Configuration program to setup ISA boards. Please note that
+                 this program can only be executed under DOS.
+
+   All the drivers and utilities are published in form of source code under
+   GNU General Public License in this version. Please refer to GNU General
+   Public License announcement in each source code file for more detail.
+
+   In Moxa's Web sites, you may always find latest driver at http://www.moxa.com/.
+
+   This version of driver can be installed as Loadable Module (Module driver)
+   or built-in into kernel (Static driver). You may refer to following
+   installation procedure for suitable one. Before you install the driver,
+   please refer to hardware installation procedure in the User's Manual.
+
+   We assume the user should be familiar with following documents.
+
+   - Serial-HOWTO
+   - Kernel-HOWTO
+
+2. System Requirement
+^^^^^^^^^^^^^^^^^^^^^
+
+   - Hardware platform: Intel x86 machine
+   - Kernel version: 2.4.x or 2.6.x
+   - gcc version 2.72 or later
+   - Maximum 4 boards can be installed in combination
+
+3. Installation
+^^^^^^^^^^^^^^^
+
+3.1 Hardware installation
+=========================
+
+   There are two types of buses, ISA and PCI, for Smartio/Industio
+   family multiport board.
+
+ISA board
+---------
+
+   You'll have to configure CAP address, I/O address, Interrupt Vector
+   as well as IRQ before installing this driver. Please refer to hardware
+   installation procedure in User's Manual before proceed any further.
+   Please make sure the JP1 is open after the ISA board is set properly.
+
+PCI/UPCI board
+--------------
+
+   You may need to adjust IRQ usage in BIOS to avoid from IRQ conflict
+   with other ISA devices. Please refer to hardware installation
+   procedure in User's Manual in advance.
+
+PCI IRQ Sharing
+---------------
+
+   Each port within the same multiport board shares the same IRQ. Up to
+   4 Moxa Smartio/Industio PCI Family multiport boards can be installed
+   together on one system and they can share the same IRQ.
+
+
+3.2 Driver files
+================
+
+   The driver file may be obtained from ftp, CD-ROM or floppy disk. The
+   first step, anyway, is to copy driver file "mxser.tgz" into specified
+   directory. e.g. /moxa. The execute commands as below::
+
+       # cd /
+       # mkdir moxa
+       # cd /moxa
+       # tar xvf /dev/fd0
+
+or::
+
+       # cd /
+       # mkdir moxa
+       # cd /moxa
+       # cp /mnt/cdrom/<driver directory>/mxser.tgz .
+       # tar xvfz mxser.tgz
+
+
+3.3 Device naming convention
+============================
+
+   You may find all the driver and utilities files in /moxa/mxser.
+   Following installation procedure depends on the model you'd like to
+   run the driver. If you prefer module driver, please refer to 3.4.
+   If static driver is required, please refer to 3.5.
+
+Dialin and callout port
+-----------------------
+
+   This driver remains traditional serial device properties. There are
+   two special file name for each serial port. One is dial-in port
+   which is named "ttyMxx". For callout port, the naming convention
+   is "cumxx".
+
+Device naming when more than 2 boards installed
+-----------------------------------------------
+
+   Naming convention for each Smartio/Industio multiport board is
+   pre-defined as below.
+
+   ============ ===============       ==============
+   Board Num.	 Dial-in Port	      Callout port
+   1st board	ttyM0  - ttyM7	      cum0  - cum7
+   2nd board	ttyM8  - ttyM15       cum8  - cum15
+   3rd board	ttyM16 - ttyM23       cum16 - cum23
+   4th board	ttyM24 - ttym31       cum24 - cum31
+   ============ ===============       ==============
+
+.. note::
+
+   Under Kernel 2.6 and upper, the cum Device is Obsolete. So use ttyM*
+   device instead.
+
+Board sequence
+--------------
+
+   This driver will activate ISA boards according to the parameter set
+   in the driver. After all specified ISA board activated, PCI board
+   will be installed in the system automatically driven.
+   Therefore the board number is sorted by the CAP address of ISA boards.
+   For PCI boards, their sequence will be after ISA boards and C168H/PCI
+   has higher priority than C104H/PCI boards.
+
+3.4 Module driver configuration
+===============================
+
+   Module driver is easiest way to install. If you prefer static driver
+   installation, please skip this paragraph.
+
+
+   ------------- Prepare to use the MOXA driver --------------------
+
+3.4.1 Create tty device with correct major number
+-------------------------------------------------
+
+   Before using MOXA driver, your system must have the tty devices
+   which are created with driver's major number. We offer one shell
+   script "msmknod" to simplify the procedure.
+   This step is only needed to be executed once. But you still
+   need to do this procedure when:
+
+   a. You change the driver's major number. Please refer the "3.7"
+      section.
+   b. Your total installed MOXA boards number is changed. Maybe you
+      add/delete one MOXA board.
+   c. You want to change the tty name. This needs to modify the
+      shell script "msmknod"
+
+   The procedure is::
+
+	 # cd /moxa/mxser/driver
+	 # ./msmknod
+
+   This shell script will require the major number for dial-in
+   device and callout device to create tty device. You also need
+   to specify the total installed MOXA board number. Default major
+   numbers for dial-in device and callout device are 30, 35. If
+   you need to change to other number, please refer section "3.7"
+   for more detailed procedure.
+   Msmknod will delete any special files occupying the same device
+   naming.
+
+3.4.2 Build the MOXA driver and utilities
+-----------------------------------------
+
+   Before using the MOXA driver and utilities, you need compile the
+   all the source code. This step is only need to be executed once.
+   But you still re-compile the source code if you modify the source
+   code. For example, if you change the driver's major number (see
+   "3.7" section), then you need to do this step again.
+
+   Find "Makefile" in /moxa/mxser, then run
+
+	 # make clean; make install
+
+   ..note::
+
+	 For Red Hat 9, Red Hat Enterprise Linux AS3/ES3/WS3 & Fedora Core1:
+	 # make clean; make installsp1
+
+	 For Red Hat Enterprise Linux AS4/ES4/WS4:
+	 # make clean; make installsp2
+
+   The driver files "mxser.o" and utilities will be properly compiled
+   and copied to system directories respectively.
+
+------------- Load MOXA driver--------------------
+
+3.4.3 Load the MOXA driver
+--------------------------
+
+   ::
+
+	 # modprobe mxser <argument>
+
+   will activate the module driver. You may run "lsmod" to check
+   if "mxser" is activated. If the MOXA board is ISA board, the
+   <argument> is needed. Please refer to section "3.4.5" for more
+   information.
+
+------------- Load MOXA driver on boot --------------------
+
+3.4.4 Load the mxser driver
+---------------------------
+
+
+   For the above description, you may manually execute
+   "modprobe mxser" to activate this driver and run
+   "rmmod mxser" to remove it.
+
+   However, it's better to have a boot time configuration to
+   eliminate manual operation. Boot time configuration can be
+   achieved by rc file. We offer one "rc.mxser" file to simplify
+   the procedure under "moxa/mxser/driver".
+
+   But if you use ISA board, please modify the "modprobe ..." command
+   to add the argument (see "3.4.5" section). After modifying the
+   rc.mxser, please try to execute "/moxa/mxser/driver/rc.mxser"
+   manually to make sure the modification is ok. If any error
+   encountered, please try to modify again. If the modification is
+   completed, follow the below step.
+
+   Run following command for setting rc files::
+
+	 # cd /moxa/mxser/driver
+	 # cp ./rc.mxser /etc/rc.d
+	 # cd /etc/rc.d
+
+   Check "rc.serial" is existed or not. If "rc.serial" doesn't exist,
+   create it by vi, run "chmod 755 rc.serial" to change the permission.
+
+   Add "/etc/rc.d/rc.mxser" in last line.
+
+   Reboot and check if moxa.o activated by "lsmod" command.
+
+3.4.5. specify CAP address
+--------------------------
+
+   If you'd like to drive Smartio/Industio ISA boards in the system,
+   you'll have to add parameter to specify CAP address of given
+   board while activating "mxser.o". The format for parameters are
+   as follows.::
+
+	   modprobe mxser ioaddr=0x???,0x???,0x???,0x???
+				  |  |  |    |
+				  |  |  |    +- 4th ISA board
+				  |  |  +------ 3rd ISA board
+				  |  +------------ 2nd ISA board
+				  +-------------------1st ISA board
+
+3.5 Static driver configuration for Linux kernel 2.4.x and 2.6.x
+================================================================
+
+    Note:
+          To use static driver, you must install the linux kernel
+          source package.
+
+3.5.1 Backup the built-in driver in the kernel
+----------------------------------------------
+
+    ::
+
+       # cd /usr/src/linux/drivers/char
+       # mv mxser.c mxser.c.old
+
+       For Red Hat 7.x user, you need to create link:
+       # cd /usr/src
+       # ln -s linux-2.4 linux
+
+3.5.2 Create link
+-----------------
+    ::
+
+	  # cd /usr/src/linux/drivers/char
+	  # ln -s /moxa/mxser/driver/mxser.c mxser.c
+
+3.5.3 Add CAP address list for ISA boards.
+------------------------------------------
+
+    For PCI boards user, please skip this step.
+
+    In module mode, the CAP address for ISA board is given by
+    parameter. In static driver configuration, you'll have to
+    assign it within driver's source code. If you will not
+    install any ISA boards, you may skip to next portion.
+    The instructions to modify driver source code are as
+    below.
+
+    a. run::
+
+	# cd /moxa/mxser/driver
+	# vi mxser.c
+
+    b. Find the array mxserBoardCAP[] as below::
+
+	  static int mxserBoardCAP[] = {0x00, 0x00, 0x00, 0x00};
+
+    c. Change the address within this array using vi. For
+       example, to driver 2 ISA boards with CAP address
+       0x280 and 0x180 as 1st and 2nd board. Just to change
+       the source code as follows::
+
+	  static int mxserBoardCAP[] = {0x280, 0x180, 0x00, 0x00};
+
+3.5.4 Setup kernel configuration
+--------------------------------
+
+    Configure the kernel::
+
+      # cd /usr/src/linux
+      # make menuconfig
+
+    You will go into a menu-driven system. Please select [Character
+    devices][Non-standard serial port support], enable the [Moxa
+    SmartIO support] driver with "[*]" for built-in (not "[M]"), then
+    select [Exit] to exit this program.
+
+3.5.5 Rebuild kernel
+--------------------
+
+    The following are for Linux kernel rebuilding, for your
+    reference only.
+
+    For appropriate details, please refer to the Linux document:
+
+        a. Run the following commands::
+
+	     cd /usr/src/linux
+	     make clean		     # take a few minutes
+	     make dep		     # take a few minutes
+	     make bzImage	     # take probably 10-20 minutes
+	     make install	     # copy boot image to correct position
+
+	f. Please make sure the boot kernel (vmlinuz) is in the
+	   correct position.
+	g. If you use 'lilo' utility, you should check /etc/lilo.conf
+	   'image' item specified the path which is the 'vmlinuz' path,
+	   or you will load wrong (or old) boot kernel image (vmlinuz).
+	   After checking /etc/lilo.conf, please run "lilo".
+
+	  Note that if the result of "make bzImage" is ERROR, then you have to
+	  go back to Linux configuration Setup. Type "make menuconfig" in
+          directory /usr/src/linux.
+
+
+3.5.6 Make tty device and special file
+--------------------------------------
+
+    ::
+       # cd /moxa/mxser/driver
+       # ./msmknod
+
+3.5.7 Make utility
+------------------
+
+    ::
+
+	  # cd /moxa/mxser/utility
+	  # make clean; make install
+
+3.5.8 Reboot
+------------
+
+
+
+3.6 Custom configuration
+========================
+
+    Although this driver already provides you default configuration, you
+    still can change the device name and major number. The instruction to
+    change these parameters are shown as below.
+
+a. Change Device name
+
+    If you'd like to use other device names instead of default naming
+    convention, all you have to do is to modify the internal code
+    within the shell script "msmknod". First, you have to open "msmknod"
+    by vi. Locate each line contains "ttyM" and "cum" and change them
+    to the device name you desired. "msmknod" creates the device names
+    you need next time executed.
+
+b. Change Major number
+
+    If major number 30 and 35 had been occupied, you may have to select
+    2 free major numbers for this driver. There are 3 steps to change
+    major numbers.
+
+3.6.1 Find free major numbers
+-----------------------------
+
+    In /proc/devices, you may find all the major numbers occupied
+    in the system. Please select 2 major numbers that are available.
+    e.g. 40, 45.
+
+3.6.2 Create special files
+--------------------------
+
+   Run /moxa/mxser/driver/msmknod to create special files with
+   specified major numbers.
+
+3.6.3 Modify driver with new major number
+-----------------------------------------
+
+   Run vi to open /moxa/mxser/driver/mxser.c. Locate the line
+   contains "MXSERMAJOR". Change the content as below::
+
+	  #define	  MXSERMAJOR		  40
+	  #define	  MXSERCUMAJOR		  45
+
+    3.6.4 Run "make clean; make install" in /moxa/mxser/driver.
+
+3.7 Verify driver installation
+==============================
+
+    You may refer to /var/log/messages to check the latest status
+    log reported by this driver whenever it's activated.
+
+4. Utilities
+^^^^^^^^^^^^
+
+   There are 3 utilities contained in this driver. They are msdiag, msmon and
+   msterm. These 3 utilities are released in form of source code. They should
+   be compiled into executable file and copied into /usr/bin.
+
+   Before using these utilities, please load driver (refer 3.4 & 3.5) and
+   make sure you had run the "msmknod" utility.
+
+msdiag - Diagnostic
+===================
+
+   This utility provides the function to display what Moxa Smartio/Industio
+   board found by driver in the system.
+
+msmon - Port Monitoring
+=======================
+
+   This utility gives the user a quick view about all the MOXA ports'
+   activities. One can easily learn each port's total received/transmitted
+   (Rx/Tx) character count since the time when the monitoring is started.
+
+   Rx/Tx throughputs per second are also reported in interval basis (e.g.
+   the last 5 seconds) and in average basis (since the time the monitoring
+   is started). You can reset all ports' count by <HOME> key. <+> <->
+   (plus/minus) keys to change the displaying time interval. Press <ENTER>
+   on the port, that cursor stay, to view the port's communication
+   parameters, signal status, and input/output queue.
+
+msterm - Terminal Emulation
+===========================
+
+   This utility provides data sending and receiving ability of all tty ports,
+   especially for MOXA ports. It is quite useful for testing simple
+   application, for example, sending AT command to a modem connected to the
+   port or used as a terminal for login purpose. Note that this is only a
+   dumb terminal emulation without handling full screen operation.
+
+5. Setserial
+^^^^^^^^^^^^
+
+   Supported Setserial parameters are listed as below.
+
+   ============== =========================================================
+   uart		  set UART type(16450-->disable FIFO, 16550A-->enable FIFO)
+   close_delay	  set the amount of time(in 1/100 of a second) that DTR
+		  should be kept low while being closed.
+   closing_wait   set the amount of time(in 1/100 of a second) that the
+		  serial port should wait for data to be drained while
+		  being closed, before the receiver is disable.
+   spd_hi	  Use  57.6kb  when  the application requests 38.4kb.
+   spd_vhi	  Use  115.2kb	when  the application requests 38.4kb.
+   spd_shi	  Use  230.4kb	when  the application requests 38.4kb.
+   spd_warp	  Use  460.8kb	when  the application requests 38.4kb.
+   spd_normal	  Use  38.4kb  when  the application requests 38.4kb.
+   spd_cust	  Use  the custom divisor to set the speed when  the
+		  application requests 38.4kb.
+   divisor	  This option set the custom division.
+   baud_base	  This option set the base baud rate.
+   ============== =========================================================
+
+6. Troubleshooting
+^^^^^^^^^^^^^^^^^^
+
+   The boot time error messages and solutions are stated as clearly as
+   possible. If all the possible solutions fail, please contact our technical
+   support team to get more help.
+
+
+   Error msg:
+	      More than 4 Moxa Smartio/Industio family boards found. Fifth board
+              and after are ignored.
+
+   Solution:
+   To avoid this problem, please unplug fifth and after board, because Moxa
+   driver supports up to 4 boards.
+
+   Error msg:
+	      Request_irq fail, IRQ(?) may be conflict with another device.
+
+   Solution:
+   Other PCI or ISA devices occupy the assigned IRQ. If you are not sure
+   which device causes the situation, please check /proc/interrupts to find
+   free IRQ and simply change another free IRQ for Moxa board.
+
+   Error msg:
+	      Board #: C1xx Series(CAP=xxx) interrupt number invalid.
+
+   Solution:
+   Each port within the same multiport board shares the same IRQ. Please set
+   one IRQ (IRQ doesn't equal to zero) for one Moxa board.
+
+   Error msg:
+	      No interrupt vector be set for Moxa ISA board(CAP=xxx).
+
+   Solution:
+   Moxa ISA board needs an interrupt vector.Please refer to user's manual
+   "Hardware Installation" chapter to set interrupt vector.
+
+   Error msg:
+              Couldn't install MOXA Smartio/Industio family driver!
+
+   Solution:
+   Load Moxa driver fail, the major number may conflict with other devices.
+   Please refer to previous section 3.7 to change a free major number for
+   Moxa driver.
+
+   Error msg:
+              Couldn't install MOXA Smartio/Industio family callout driver!
+
+   Solution:
+   Load Moxa callout driver fail, the callout device major number may
+   conflict with other devices. Please refer to previous section 3.7 to
+   change a free callout device major number for Moxa driver.

Documentation/serial/n_gsm.rst

···
+==============================
+GSM 0710 tty multiplexor HOWTO
+==============================
+
+This line discipline implements the GSM 07.10 multiplexing protocol
+detailed in the following 3GPP document:
+
+	http://www.3gpp.org/ftp/Specs/archive/07_series/07.10/0710-720.zip
+
+This document give some hints on how to use this driver with GPRS and 3G
+modems connected to a physical serial port.
+
+How to use it
+-------------
+1. initialize the modem in 0710 mux mode (usually AT+CMUX= command) through
+   its serial port. Depending on the modem used, you can pass more or less
+   parameters to this command,
+2. switch the serial line to using the n_gsm line discipline by using
+   TIOCSETD ioctl,
+3. configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl,
+
+Major parts of the initialization program :
+(a good starting point is util-linux-ng/sys-utils/ldattach.c)::
+
+  #include <linux/gsmmux.h>
+  #define N_GSM0710	21	/* GSM 0710 Mux */
+  #define DEFAULT_SPEED	B115200
+  #define SERIAL_PORT	/dev/ttyS0
+
+	int ldisc = N_GSM0710;
+	struct gsm_config c;
+	struct termios configuration;
+
+	/* open the serial port connected to the modem */
+	fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
+
+	/* configure the serial port : speed, flow control ... */
+
+	/* send the AT commands to switch the modem to CMUX mode
+	   and check that it's successful (should return OK) */
+	write(fd, "AT+CMUX=0\r", 10);
+
+	/* experience showed that some modems need some time before
+	   being able to answer to the first MUX packet so a delay
+	   may be needed here in some case */
+	sleep(3);
+
+	/* use n_gsm line discipline */
+	ioctl(fd, TIOCSETD, &ldisc);
+
+	/* get n_gsm configuration */
+	ioctl(fd, GSMIOC_GETCONF, &c);
+	/* we are initiator and need encoding 0 (basic) */
+	c.initiator = 1;
+	c.encapsulation = 0;
+	/* our modem defaults to a maximum size of 127 bytes */
+	c.mru = 127;
+	c.mtu = 127;
+	/* set the new configuration */
+	ioctl(fd, GSMIOC_SETCONF, &c);
+
+	/* and wait for ever to keep the line discipline enabled */
+	daemon(0,0);
+	pause();
+
+4. create the devices corresponding to the "virtual" serial ports (take care,
+   each modem has its configuration and some DLC have dedicated functions,
+   for example GPS), starting with minor 1 (DLC0 is reserved for the management
+   of the mux)::
+
+     MAJOR=`cat /proc/devices |grep gsmtty | awk '{print $1}`
+     for i in `seq 1 4`; do
+	mknod /dev/ttygsm$i c $MAJOR $i
+     done
+
+5. use these devices as plain serial ports.
+
+   for example, it's possible:
+
+   - and to use gnokii to send / receive SMS on ttygsm1
+   - to use ppp to establish a datalink on ttygsm2
+
+6. first close all virtual ports before closing the physical port.
+
+   Note that after closing the physical port the modem is still in multiplexing
+   mode. This may prevent a successful re-opening of the port later. To avoid
+   this situation either reset the modem if your hardware allows that or send
+   a disconnect command frame manually before initializing the multiplexing mode
+   for the second time. The byte sequence for the disconnect command frame is::
+
+      0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9.
+
+Additional Documentation
+------------------------
+More practical details on the protocol and how it's supported by industrial
+modems can be found in the following documents :
+
+- http://www.telit.com/module/infopool/download.php?id=616
+- http://www.u-blox.com/images/downloads/Product_Docs/LEON-G100-G200-MuxImplementation_ApplicationNote_%28GSM%20G1-CS-10002%29.pdf
+- http://www.sierrawireless.com/Support/Downloads/AirPrime/WMP_Series/~/media/Support_Downloads/AirPrime/Application_notes/CMUX_Feature_Application_Note-Rev004.ashx
+- http://wm.sim.com/sim/News/photo/2010721161442.pdf
+
+11-03-08 - Eric Bénard - <[e-mail]>

Documentation/serial/n_gsm.txt

···
-n_gsm.c GSM 0710 tty multiplexor HOWTO
-===================================================
-
-This line discipline implements the GSM 07.10 multiplexing protocol
-detailed in the following 3GPP document :
-http://www.3gpp.org/ftp/Specs/archive/07_series/07.10/0710-720.zip
-
-This document give some hints on how to use this driver with GPRS and 3G
-modems connected to a physical serial port.
-
-How to use it
--------------
-1- initialize the modem in 0710 mux mode (usually AT+CMUX= command) through
-its serial port. Depending on the modem used, you can pass more or less
-parameters to this command,
-2- switch the serial line to using the n_gsm line discipline by using
-TIOCSETD ioctl,
-3- configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl,
-
-Major parts of the initialization program :
-(a good starting point is util-linux-ng/sys-utils/ldattach.c)
-#include <linux/gsmmux.h>
-#define N_GSM0710	21	/* GSM 0710 Mux */
-#define DEFAULT_SPEED	B115200
-#define SERIAL_PORT	/dev/ttyS0
-
-	int ldisc = N_GSM0710;
-	struct gsm_config c;
-	struct termios configuration;
-
-	/* open the serial port connected to the modem */
-	fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
-
-	/* configure the serial port : speed, flow control ... */
-
-	/* send the AT commands to switch the modem to CMUX mode
-	   and check that it's successful (should return OK) */
-	write(fd, "AT+CMUX=0\r", 10);
-
-	/* experience showed that some modems need some time before
-	   being able to answer to the first MUX packet so a delay
-	   may be needed here in some case */
-	sleep(3);
-
-	/* use n_gsm line discipline */
-	ioctl(fd, TIOCSETD, &ldisc);
-
-	/* get n_gsm configuration */
-	ioctl(fd, GSMIOC_GETCONF, &c);
-	/* we are initiator and need encoding 0 (basic) */
-	c.initiator = 1;
-	c.encapsulation = 0;
-	/* our modem defaults to a maximum size of 127 bytes */
-	c.mru = 127;
-	c.mtu = 127;
-	/* set the new configuration */
-	ioctl(fd, GSMIOC_SETCONF, &c);
-
-	/* and wait for ever to keep the line discipline enabled */
-	daemon(0,0);
-	pause();
-
-4- create the devices corresponding to the "virtual" serial ports (take care,
-each modem has its configuration and some DLC have dedicated functions,
-for example GPS), starting with minor 1 (DLC0 is reserved for the management
-of the mux)
-
-MAJOR=`cat /proc/devices |grep gsmtty | awk '{print $1}`
-for i in `seq 1 4`; do
-	mknod /dev/ttygsm$i c $MAJOR $i
-done
-
-5- use these devices as plain serial ports.
-for example, it's possible :
-- and to use gnokii to send / receive SMS on ttygsm1
-- to use ppp to establish a datalink on ttygsm2
-
-6- first close all virtual ports before closing the physical port.
-
-Note that after closing the physical port the modem is still in multiplexing
-mode. This may prevent a successful re-opening of the port later. To avoid
-this situation either reset the modem if your hardware allows that or send
-a disconnect command frame manually before initializing the multiplexing mode
-for the second time. The byte sequence for the disconnect command frame is:
-0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9.
-
-Additional Documentation
-------------------------
-More practical details on the protocol and how it's supported by industrial
-modems can be found in the following documents :
-http://www.telit.com/module/infopool/download.php?id=616
-http://www.u-blox.com/images/downloads/Product_Docs/LEON-G100-G200-MuxImplementation_ApplicationNote_%28GSM%20G1-CS-10002%29.pdf
-http://www.sierrawireless.com/Support/Downloads/AirPrime/WMP_Series/~/media/Support_Downloads/AirPrime/Application_notes/CMUX_Feature_Application_Note-Rev004.ashx
-http://wm.sim.com/sim/News/photo/2010721161442.pdf
-
-11-03-08 - Eric Bénard - <[e-mail]>

Documentation/serial/rocket.txt Documentation/serial/rocket.rst

···
-Comtrol(tm) RocketPort(R)/RocketModem(TM) Series 
+================================================
+Comtrol(tm) RocketPort(R)/RocketModem(TM) Series
+================================================
+
 Device Driver for the Linux Operating System
+============================================
 
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-
-PRODUCT OVERVIEW
+Product overview
 ----------------
 
 This driver provides a loadable kernel driver for the Comtrol RocketPort
-and RocketModem PCI boards. These boards provide, 2, 4, 8, 16, or 32 
+and RocketModem PCI boards. These boards provide, 2, 4, 8, 16, or 32
 high-speed serial ports or modems.  This driver supports up to a combination
 of four RocketPort or RocketModems boards in one machine simultaneously.
 This file assumes that you are using the RocketPort driver which is
-integrated into the kernel sources.  
+integrated into the kernel sources.
 
-The driver can also be installed as an external module using the usual 
-"make;make install" routine.  This external module driver, obtainable 
+The driver can also be installed as an external module using the usual
+"make;make install" routine.  This external module driver, obtainable
 from the Comtrol website listed below, is useful for updating the driver
 or installing it into kernels which do not have the driver configured
 into them.  Installations instructions for the external module
···
 
 You pass the I/O port to the driver using the following module parameters:
 
-board1 :	I/O port for the first ISA board
-board2 :	I/O port for the second ISA board
-board3 :	I/O port for the third ISA board
-board4 :	I/O port for the fourth ISA board
+board1:
+	I/O port for the first ISA board
+board2:
+	I/O port for the second ISA board
+board3:
+	I/O port for the third ISA board
+board4:
+	I/O port for the fourth ISA board
 
 There is a set of utilities and scripts provided with the external driver
-( downloadable from http://www.comtrol.com ) that ease the configuration and
+(downloadable from http://www.comtrol.com) that ease the configuration and
 setup of the ISA cards.
 
 The RocketModem II PCI boards require firmware to be loaded into the card
 before it will function.  The driver has only been tested as a module for this
 board.
 
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-
-INSTALLATION PROCEDURES
+Installation Procedures
 -----------------------
 
-RocketPort/RocketModem PCI cards require no driver configuration, they are 
+RocketPort/RocketModem PCI cards require no driver configuration, they are
 automatically detected and configured.
 
-The RocketPort driver can be installed as a module (recommended) or built 
+The RocketPort driver can be installed as a module (recommended) or built
 into the kernel. This is selected, as for other drivers, through the `make config`
-command from the root of the Linux source tree during the kernel build process. 
+command from the root of the Linux source tree during the kernel build process.
 
 The RocketPort/RocketModem serial ports installed by this driver are assigned
-device major number 46, and will be named /dev/ttyRx, where x is the port number 
+device major number 46, and will be named /dev/ttyRx, where x is the port number
 starting at zero (ex. /dev/ttyR0, /devttyR1, ...).  If you have multiple cards
 installed in the system, the mapping of port names to serial ports is displayed
 in the system log at /var/log/messages.
 
 If installed as a module, the module must be loaded.  This can be done
 manually by entering "modprobe rocket".  To have the module loaded automatically
-upon system boot, edit a /etc/modprobe.d/*.conf file and add the line
+upon system boot, edit a `/etc/modprobe.d/*.conf` file and add the line
 "alias char-major-46 rocket".
 
 In order to use the ports, their device names (nodes) must be created with mknod.
-This is only required once, the system will retain the names once created.  To 
-create the RocketPort/RocketModem device names, use the command 
-"mknod /dev/ttyRx c 46 x" where x is the port number starting at zero.  For example:
+This is only required once, the system will retain the names once created.  To
+create the RocketPort/RocketModem device names, use the command
+"mknod /dev/ttyRx c 46 x" where x is the port number starting at zero.
 
->mknod /dev/ttyR0 c 46 0
->mknod /dev/ttyR1 c 46 1
->mknod /dev/ttyR2 c 46 2  
+For example::
+
+	> mknod /dev/ttyR0 c 46 0
+	> mknod /dev/ttyR1 c 46 1
+	> mknod /dev/ttyR2 c 46 2
 
 The Linux script MAKEDEV will create the first 16 ttyRx device names (nodes)
-for you:
+for you::
 
->/dev/MAKEDEV ttyR
-
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+	>/dev/MAKEDEV ttyR
 
 ISA Rocketport Boards
 ---------------------
···
 switches on the Rocketport board.
 
 
-SETTING THE I/O ADDRESS
+Setting the I/O address
 -----------------------
 
 Before installing RocketPort(R) or RocketPort RA boards, you must find
···
 need to set the second, third, or fourth board to one of the next available
 blocks such as 0x180.
 
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+RocketPort and RocketPort RA SW1 Settings::
 
-RocketPort and RocketPort RA SW1 Settings:
+            +-------------------------------+
+            | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |
+            +-------+-------+---------------+
+            | Unused| Card  | I/O Port Block|
+            +-------------------------------+
 
-          +-------------------------------+
-          | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |
-          +-------+-------+---------------+
-          | Unused| Card  | I/O Port Block|
-          +-------------------------------+
+  DIP Switches                             DIP Switches
+  7    8                                   6    5
+  ===================                      ===================
+  On   On   UNUSED, MUST BE ON.            On   On   First Card    <==== Default
+                                           On   Off  Second Card
+                                           Off  On   Third Card
+                                           Off  Off  Fourth Card
 
-DIP Switches                             DIP Switches
-7    8                                   6    5
-===================                      ===================
-On   On   UNUSED, MUST BE ON.            On   On   First Card    <==== Default
-                                         On   Off  Second Card
-                                         Off  On   Third Card
-                                         Off  Off  Fourth Card
+  DIP Switches         I/O Address Range
+  4    3    2    1     Used by the First Card
+  =====================================
+  On   Off  On   Off   100-143
+  On   Off  Off  On    140-183
+  On   Off  Off  Off   180-1C3       <==== Default
+  Off  On   On   Off   200-243
+  Off  On   Off  On    240-283
+  Off  On   Off  Off   280-2C3
+  Off  Off  On   Off   300-343
+  Off  Off  Off  On    340-383
+  Off  Off  Off  Off   380-3C3
 
-DIP Switches         I/O Address Range
-4    3    2    1     Used by the First Card
-=====================================
-On   Off  On   Off   100-143
-On   Off  Off  On    140-183
-On   Off  Off  Off   180-1C3       <==== Default
-Off  On   On   Off   200-243
-Off  On   Off  On    240-283
-Off  On   Off  Off   280-2C3
-Off  Off  On   Off   300-343
-Off  Off  Off  On    340-383
-Off  Off  Off  Off   380-3C3
-
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-
-REPORTING BUGS
+Reporting Bugs
 --------------
 
 For technical support, please provide the following
···
 kernel, and type of board you are using. Error messages and log
 printouts port configuration details are especially helpful.
 
-USA
-    Phone: [phone]
-      FAX: [phone]
-    email: [e-mail]
+USA:
+    :Phone: [phone]
+    :FAX: [phone]
+    :email: [e-mail]
 
-Comtrol Europe
-    Phone: [phone]
-      FAX: [phone]
-    email: [e-mail]
+Comtrol Europe:
+    :Phone: [phone]
+    :FAX: [phone]
+    :email: [e-mail]
 
 Web:	http://www.comtrol.com
 FTP:	ftp.comtrol.com
-
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-
-

Documentation/serial/serial-iso7816.txt Documentation/serial/serial-iso7816.rst

···
-                        ISO7816 SERIAL COMMUNICATIONS
+=============================
+ISO7816 Serial Communications
+=============================
 
-1. INTRODUCTION
+1. Introduction
+===============
 
   ISO/IEC7816 is a series of standards specifying integrated circuit cards (ICC)
   also known as smart cards.
 
-2. HARDWARE-RELATED CONSIDERATIONS
+2. Hardware-related considerations
+==================================
 
   Some CPUs/UARTs (e.g., Microchip AT91) contain a built-in mode capable of
   handling communication with a smart card.
···
   available at user-level to allow switching from one mode to the other, and
   vice versa.
 
-3. DATA STRUCTURES ALREADY AVAILABLE IN THE KERNEL
+3. Data Structures Already Available in the Kernel
+==================================================
 
   The Linux kernel provides the serial_iso7816 structure (see [1]) to handle
   ISO7816 communications. This data structure is used to set and configure
···
   to TIOCGISO7816 and TIOCSISO7816 ioctls (see below). The iso7816_config
   callback receives a pointer to struct serial_iso7816.
 
-4. USAGE FROM USER-LEVEL
+4. Usage from user-level
+========================
 
   From user-level, ISO7816 configuration can be get/set using the previous
-  ioctls. For instance, to set ISO7816 you can use the following code:
+  ioctls. For instance, to set ISO7816 you can use the following code::
 
 	#include <linux/serial.h>
 
···
 		/* Error handling. See errno. */
 	}
 
-5. REFERENCES
+5. References
+=============
 
  [1]    include/uapi/linux/serial.h

Documentation/serial/serial-rs485.txt Documentation/serial/serial-rs485.rst

···
-                        RS485 SERIAL COMMUNICATIONS
+===========================
+RS485 Serial Communications
+===========================
 
-1. INTRODUCTION
+1. Introduction
+===============
 
    EIA-485, also known as TIA/EIA-485 or RS-485, is a standard defining the
    electrical characteristics of drivers and receivers for use in balanced
···
    because it can be used effectively over long distances and in electrically
    noisy environments.
 
-2. HARDWARE-RELATED CONSIDERATIONS
+2. Hardware-related Considerations
+==================================
 
    Some CPUs/UARTs (e.g., Atmel AT91 or 16C950 UART) contain a built-in
    half-duplex mode capable of automatically controlling line direction by
···
    available at user-level to allow switching from one mode to the other, and
    vice versa.
 
-3. DATA STRUCTURES ALREADY AVAILABLE IN THE KERNEL
+3. Data Structures Already Available in the Kernel
+==================================================
 
    The Linux kernel provides the serial_rs485 structure (see [1]) to handle
    RS485 communications. This data structure is used to set and configure RS485
···
    to TIOCSRS485 and TIOCGRS485 ioctls (see below). The rs485_config callback
    receives a pointer to struct serial_rs485.
 
-4. USAGE FROM USER-LEVEL
+4. Usage from user-level
+========================
 
    From user-level, RS485 configuration can be get/set using the previous
-   ioctls. For instance, to set RS485 you can use the following code:
+   ioctls. For instance, to set RS485 you can use the following code::
 
 	#include <linux/serial.h>
 
···
 		/* Error handling. See errno. */
 	}
 
-5. REFERENCES
+5. References
+=============
 
  [1]	include/uapi/linux/serial.h
+
  [2]	Documentation/devicetree/bindings/serial/rs485.txt

Documentation/serial/tty.txt Documentation/serial/tty.rst

···
-
-			The Lockronomicon
+=================
+The Lockronomicon
+=================
 
 Your guide to the ancient and twisted locking policies of the tty layer and
 the warped logic behind them. Beware all ye who read on.
···
 ---------------
 
 Line disciplines are registered with tty_register_ldisc() passing the
-discipline number and the ldisc structure. At the point of registration the 
+discipline number and the ldisc structure. At the point of registration the
 discipline must be ready to use and it is possible it will get used before
 the call returns success. If the call returns an error then it won't get
 called. Do not re-use ldisc numbers as they are part of the userspace ABI
 and writing over an existing ldisc will cause demons to eat your computer.
-After the return the ldisc data has been copied so you may free your own 
+After the return the ldisc data has been copied so you may free your own
 copy of the structure. You must not re-register over the top of the line
 discipline even with the same data or your computer again will be eaten by
 demons.
···
 
 Heed this warning: the reference count field of the registered copies of the
 tty_ldisc structure in the ldisc table counts the number of lines using this
-discipline. The reference count of the tty_ldisc structure within a tty 
+discipline. The reference count of the tty_ldisc structure within a tty
 counts the number of active users of the ldisc at this instant. In effect it
 counts the number of threads of execution within an ldisc method (plus those
 about to enter and exit although this detail matters not).
···
 Line Discipline Methods
 -----------------------
 
-TTY side interfaces:
+TTY side interfaces
+^^^^^^^^^^^^^^^^^^^
 
-open()		-	Called when the line discipline is attached to
+======================= =======================================================
+open()			Called when the line discipline is attached to
 			the terminal. No other call into the line
 			discipline for this tty will occur until it
 			completes successfully. Should initialize any
···
 			Returning an error will prevent the ldisc from
 			being attached. Can sleep.
 
-close()		-	This is called on a terminal when the line
+close()			This is called on a terminal when the line
 			discipline is being unplugged. At the point of
 			execution no further users will enter the
 			ldisc code for this tty. Can sleep.
 
-hangup()	-	Called when the tty line is hung up.
+hangup()		Called when the tty line is hung up.
 			The line discipline should cease I/O to the tty.
 			No further calls into the ldisc code will occur.
 			The return value is ignored. Can sleep.
 
-read()		-	(optional) A process requests reading data from
+read()			(optional) A process requests reading data from
 			the line. Multiple read calls may occur in parallel
 			and the ldisc must deal with serialization issues.
 			If not defined, the process will receive an EIO
 			error. May sleep.
 
-write()		-	(optional) A process requests writing data to the
+write()			(optional) A process requests writing data to the
 			line. Multiple write calls are serialized by the
 			tty layer for the ldisc. If not defined, the
 			process will receive an EIO error. May sleep.
 
-flush_buffer()	-	(optional) May be called at any point between
+flush_buffer()		(optional) May be called at any point between
 			open and close, and instructs the line discipline
 			to empty its input buffer.
 
-set_termios()	-	(optional) Called on termios structure changes.
+set_termios()		(optional) Called on termios structure changes.
 			The caller passes the old termios data and the
 			current data is in the tty. Called under the
 			termios semaphore so allowed to sleep. Serialized
 			against itself only.
 
-poll()		-	(optional) Check the status for the poll/select
+poll()			(optional) Check the status for the poll/select
 			calls. Multiple poll calls may occur in parallel.
 			May sleep.
 
-ioctl()		-	(optional) Called when an ioctl is handed to the
+ioctl()			(optional) Called when an ioctl is handed to the
 			tty layer that might be for the ldisc. Multiple
 			ioctl calls may occur in parallel. May sleep.
 
-compat_ioctl()	-	(optional) Called when a 32 bit ioctl is handed
+compat_ioctl()		(optional) Called when a 32 bit ioctl is handed
 			to the tty layer that might be for the ldisc.
 			Multiple ioctl calls may occur in parallel.
 			May sleep.
+======================= =======================================================
 
-Driver Side Interfaces:
+Driver Side Interfaces
+^^^^^^^^^^^^^^^^^^^^^^
 
-receive_buf()	-	(optional) Called by the low-level driver to hand
+======================= =======================================================
+receive_buf()		(optional) Called by the low-level driver to hand
 			a buffer of received bytes to the ldisc for
 			processing. The number of bytes is guaranteed not
 			to exceed the current value of tty->receive_room.
 			All bytes must be processed.
 
-receive_buf2()	-	(optional) Called by the low-level driver to hand
+receive_buf2()		(optional) Called by the low-level driver to hand
 			a buffer of received bytes to the ldisc for
 			processing. Returns the number of bytes processed.
 
 			If both receive_buf() and receive_buf2() are
 			defined, receive_buf2() should be preferred.
 
-write_wakeup()	-	May be called at any point between open and close.
+write_wakeup()		May be called at any point between open and close.
 			The TTY_DO_WRITE_WAKEUP flag indicates if a call
 			is needed but always races versus calls. Thus the
 			ldisc must be careful about setting order and to
···
 			is permitted to call the driver write method from
 			this function. In such a situation defer it.
 
-dcd_change()	-	Report to the tty line the current DCD pin status
+dcd_change()		Report to the tty line the current DCD pin status
 			changes and the relative timestamp. The timestamp
 			cannot be NULL.
+======================= =======================================================
 
 
 Driver Access
+^^^^^^^^^^^^^
 
 Line discipline methods can call the following methods of the underlying
 hardware driver through the function pointers within the tty->driver
 structure:
 
+======================= =======================================================
 write()			Write a block of characters to the tty device.
 			Returns the number of characters accepted. The
 			character buffer passed to this method is already
···
 			characters in its transmitter FIFO.
 
 send_xchar()		Send a high-priority XON/XOFF character to the device.
+======================= =======================================================
 
 
 Flags
+^^^^^
 
 Line discipline methods have access to tty->flags field containing the
 following interesting flags:
 
+======================= =======================================================
 TTY_THROTTLED		Driver input is throttled. The ldisc should call
 			tty->driver->unthrottle() in order to resume
 			reception when it is ready to process more data.
···
 
 TTY_NO_WRITE_SPLIT	Prevent driver from splitting up writes into
 			smaller chunks.
+======================= =======================================================
 
 
 Locking
+^^^^^^^
 
 Callers to the line discipline functions from the tty layer are required to
 take line discipline locks. The same is true of calls from the driver side
 but not yet enforced.
 
-Three calls are now provided
+Three calls are now provided::
 
 	ldisc = tty_ldisc_ref(tty);
 
 takes a handle to the line discipline in the tty and returns it. If no ldisc
 is currently attached or the ldisc is being closed and re-opened at this
 point then NULL is returned. While this handle is held the ldisc will not
-change or go away.
+change or go away::
 
 	tty_ldisc_deref(ldisc)
 
 Returns the ldisc reference and allows the ldisc to be closed. Returning the
 reference takes away your right to call the ldisc functions until you take
-a new reference.
+a new reference::
 
 	ldisc = tty_ldisc_ref_wait(tty);
 
 Performs the same function as tty_ldisc_ref except that it will wait for an
-ldisc change to complete and then return a reference to the new ldisc. 
+ldisc change to complete and then return a reference to the new ldisc.
 
 While these functions are slightly slower than the old code they should have
 minimal impact as most receive logic uses the flip buffers and they only
 need to take a reference when they push bits up through the driver.
 
-A caution: The ldisc->open(), ldisc->close() and driver->set_ldisc 
+A caution: The ldisc->open(), ldisc->close() and driver->set_ldisc
 functions are called with the ldisc unavailable. Thus tty_ldisc_ref will
 fail in this situation if used within these functions. Ldisc and driver
-code calling its own functions must be careful in this case. 
+code calling its own functions must be careful in this case.
 
 
 Driver Interface
 ----------------
 
-open()		-	Called when a device is opened. May sleep
+======================= =======================================================
+open()			Called when a device is opened. May sleep
 
-close()		-	Called when a device is closed. At the point of
-			return from this call the driver must make no 
+close()			Called when a device is closed. At the point of
+			return from this call the driver must make no
 			further ldisc calls of any kind. May sleep
 
-write()		-	Called to write bytes to the device. May not
-			sleep. May occur in parallel in special cases. 
+write()			Called to write bytes to the device. May not
+			sleep. May occur in parallel in special cases.
 			Because this includes panic paths drivers generally
 			shouldn't try and do clever locking here.
 
-put_char()	-	Stuff a single character onto the queue. The
+put_char()		Stuff a single character onto the queue. The
 			driver is guaranteed following up calls to
 			flush_chars.
 
-flush_chars()	-	Ask the kernel to write put_char queue
+flush_chars()		Ask the kernel to write put_char queue
 
-write_room()	-	Return the number of characters that can be stuffed
+write_room()		Return the number of characters that can be stuffed
 			into the port buffers without overflow (or less).
 			The ldisc is responsible for being intelligent
- 			about multi-threading of write_room/write calls
+			about multi-threading of write_room/write calls
 
-ioctl()		-	Called when an ioctl may be for the driver
+ioctl()			Called when an ioctl may be for the driver
 
-set_termios()	-	Called on termios change, serialized against
+set_termios()		Called on termios change, serialized against
 			itself by a semaphore. May sleep.
 
-set_ldisc()	-	Notifier for discipline change. At the point this 
+set_ldisc()		Notifier for discipline change. At the point this
 			is done the discipline is not yet usable. Can now
 			sleep (I think)
 
-throttle()	-	Called by the ldisc to ask the driver to do flow
+throttle()		Called by the ldisc to ask the driver to do flow
 			control.  Serialization including with unthrottle
 			is the job of the ldisc layer.
 
-unthrottle()	-	Called by the ldisc to ask the driver to stop flow
+unthrottle()		Called by the ldisc to ask the driver to stop flow
 			control.
 
-stop()		-	Ldisc notifier to the driver to stop output. As with
+stop()			Ldisc notifier to the driver to stop output. As with
 			throttle the serializations with start() are down
 			to the ldisc layer.
 
-start()		-	Ldisc notifier to the driver to start output.
+start()			Ldisc notifier to the driver to start output.
 
-hangup()	-	Ask the tty driver to cause a hangup initiated
+hangup()		Ask the tty driver to cause a hangup initiated
 			from the host side. [Can sleep ??]
 
-break_ctl()	-	Send RS232 break. Can sleep. Can get called in
+break_ctl()		Send RS232 break. Can sleep. Can get called in
 			parallel, driver must serialize (for now), and
 			with write calls.
 
-wait_until_sent() -	Wait for characters to exit the hardware queue
+wait_until_sent()	Wait for characters to exit the hardware queue
 			of the driver. Can sleep
 
-send_xchar()	  -	Send XON/XOFF and if possible jump the queue with
+send_xchar()	  	Send XON/XOFF and if possible jump the queue with
 			it in order to get fast flow control responses.
 			Cannot sleep ??
-
+======================= =======================================================

MAINTAINERS

···
 MOXA SMARTIO/INDUSTIO/INTELLIO SERIAL CARD
 M:	Jiri Slaby <[e-mail]>
 S:	Maintained
-F:	Documentation/serial/moxa-smartio
+F:	Documentation/serial/moxa-smartio.rst
 F:	drivers/tty/mxser.*
 
 MR800 AVERMEDIA USB FM RADIO DRIVER
···
 P:	Comtrol Corp.
 W:	http://www.comtrol.com
 S:	Maintained
-F:	Documentation/serial/rocket.txt
+F:	Documentation/serial/rocket.rst
 F:	drivers/tty/rocket*
 
 ROCKETPORT EXPRESS/INFINITY DRIVER

drivers/char/virtio_console.c

···
 	/* All the console devices handled by this driver */
 	struct list_head consoles;
 };
-static struct ports_driver_data pdrvdata;
+static struct ports_driver_data pdrvdata = { .next_vtermno = 1};
 
 static DEFINE_SPINLOCK(pdrvdata_lock);
 static DECLARE_COMPLETION(early_console_added);
···
 	port->async_queue = NULL;
 
 	port->cons.ws.ws_row = port->cons.ws.ws_col = 0;
+	port->cons.vtermno = 0;
 
 	port->host_connected = port->guest_connected = false;
 	port->stats = (struct port_stats) { 0 };

drivers/tty/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0
 config TTY
 	bool "Enable TTY" if EXPERT
 	default y
···
 config VT_HW_CONSOLE_BINDING
        bool "Support for binding and unbinding console drivers"
        depends on HW_CONSOLE
-       default n
        ---help---
          The virtual terminal is the device that interacts with the physical
          terminal through console drivers. On these systems, at least one
···
 	  This driver supports Comtrol RocketPort and RocketModem PCI boards.   
           These boards provide 2, 4, 8, 16, or 32 high-speed serial ports or
           modems.  For information about the RocketPort/RocketModem  boards
-          and this driver read <file:Documentation/serial/rocket.txt>.
+          and this driver read <file:Documentation/serial/rocket.rst>.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called rocket.
···
 	  your Linux box, for instance in order to become a dial-in server.
 
 	  For information about the Cyclades-Z card, read
-	  <file:Documentation/serial/README.cycladesZ>.
+	  <file:Documentation/serial/cyclades_z.rst>.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called cyclades.
···
 config TRACE_ROUTER
 	tristate "Trace data router for MIPI P1149.7 cJTAG standard"
 	depends on TRACE_SINK
-	default n
 	help
 	  The trace router uses the Linux tty line discipline framework to
 	  route trace data coming from a tty port (say UART for example) to
···
 
 config TRACE_SINK
 	tristate "Trace data sink for MIPI P1149.7 cJTAG standard"
-	default n
 	help
 	  The trace sink uses the Linux line discipline framework to receive
 	  trace data coming from the trace router line discipline driver
···
 	  If the number you specify is not a valid byte channel handle, then
 	  there simply will be no early console output.  This is true also
 	  if you don't boot under a hypervisor at all.
+
+config NULL_TTY
+	tristate "NULL TTY driver"
+	help
+	  Say Y here if you want a NULL TTY which simply discards messages.
+
+	  This is useful to allow userspace applications which expect a console
+	  device to work without modifications even when no console is
+	  available or desired.
+
+	  In order to use this driver, you should redirect the console to this
+	  TTY, or boot the kernel with console=ttynull.
+
+	  If unsure, say N.
 
 config GOLDFISH_TTY
 	tristate "Goldfish TTY Driver"

drivers/tty/Makefile

···
 obj-$(CONFIG_MOXA_INTELLIO)	+= moxa.o
 obj-$(CONFIG_MOXA_SMARTIO)	+= mxser.o
 obj-$(CONFIG_NOZOMI)		+= nozomi.o
+obj-$(CONFIG_NULL_TTY)	        += ttynull.o
 obj-$(CONFIG_ROCKETPORT)	+= rocket.o
 obj-$(CONFIG_SYNCLINK_GT)	+= synclink_gt.o
 obj-$(CONFIG_SYNCLINKMP)	+= synclinkmp.o

drivers/tty/hvc/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0
 if TTY
 
 config HVC_DRIVER
···
 config HVC_OLD_HVSI
 	bool "Old driver for pSeries serial port (/dev/hvsi*)"
 	depends on HVC_CONSOLE
-	default n
 
 config HVC_OPAL
 	bool "OPAL Console support"
···
        bool "udbg based fake hypervisor console"
        depends on PPC
        select HVC_DRIVER
-       default n
        help
          This is meant to be used during HW bring up or debugging when
 	 no other console mechanism exist but udbg, to get you a quick

drivers/tty/ipwireless/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for the IPWireless driver
 #

drivers/tty/ipwireless/main.c

···
 
 	ipw->common_memory = ioremap(p_dev->resource[2]->start,
 				resource_size(p_dev->resource[2]));
+	if (!ipw->common_memory) {
+		ret = -ENOMEM;
+		goto exit1;
+	}
 	if (!request_mem_region(p_dev->resource[2]->start,
 				resource_size(p_dev->resource[2]),
 				IPWIRELESS_PCCARD_NAME)) {
···
 
 	ipw->attr_memory = ioremap(p_dev->resource[3]->start,
 				resource_size(p_dev->resource[3]));
+	if (!ipw->attr_memory) {
+		ret = -ENOMEM;
+		goto exit3;
+	}
 	if (!request_mem_region(p_dev->resource[3]->start,
 				resource_size(p_dev->resource[3]),
 				IPWIRELESS_PCCARD_NAME)) {

drivers/tty/n_tty.c

···
 	mutex_lock(&ldata->output_lock);
 
 	space = tty_write_room(tty);
-	if (!space) {
+	if (space <= 0) {
 		mutex_unlock(&ldata->output_lock);
-		return 0;
+		return space;
 	}
 	if (nr > space)
 		nr = space;

drivers/tty/rocket.c

···
 		return -ENXIO;
 
 	switch (cmd) {
-	case RCKP_GET_STRUCT:
-		if (copy_to_user(argp, info, sizeof (struct r_port)))
-			ret = -EFAULT;
-		break;
 	case RCKP_GET_CONFIG:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_GET_CONFIG option is deprecated\n");
 		ret = get_config(info, argp);
 		break;
 	case RCKP_SET_CONFIG:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_SET_CONFIG option is deprecated\n");
 		ret = set_config(tty, info, argp);
 		break;
 	case RCKP_GET_PORTS:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_GET_PORTS option is deprecated\n");
 		ret = get_ports(info, argp);
 		break;
 	case RCKP_RESET_RM2:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_RESET_RM2 option is deprecated\n");
 		ret = reset_rm2(info, argp);
 		break;
 	case RCKP_GET_VERSION:
+		dev_warn_ratelimited(tty->dev,
+					"RCKP_GET_VERSION option is deprecated\n");
 		ret = get_version(info, argp);
 		break;
 	default:

drivers/tty/rocket.h

···
 /*
  * Rocketport ioctls -- "RP"
  */
-#define RCKP_GET_STRUCT		0x00525001
 #define RCKP_GET_CONFIG		0x00525002
 #define RCKP_SET_CONFIG		0x00525003
 #define RCKP_GET_PORTS		0x00525004

drivers/tty/serdev/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # Serial bus device driver configuration
 #

drivers/tty/serdev/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
 serdev-objs := core.o
 
 obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o

drivers/tty/serial/8250/8250_exar.c

···
 	.register_gpio = iot2040_register_gpio,
 };
 
+/*
+ * For SIMATIC IOT2000, only IOT2040 and its variants have the Exar device,
+ * IOT2020 doesn't have. Therefore it is sufficient to match on the common
+ * board name after the device was found.
+ */
 static const struct dmi_system_id exar_platforms[] = {
 	{
 		.matches = {
 			DMI_EXACT_MATCH(DMI_BOARD_NAME, "SIMATIC IOT2000"),
-			DMI_EXACT_MATCH(DMI_BOARD_ASSET_TAG,
-					"6ES7647-0AA00-1YA2"),
 		},
 		.driver_data = (void *)&iot2040_platform,
 	},

drivers/tty/serial/8250/8250_fintek.c

···
 	}
 }
 
-void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios,
-			struct ktermios *old)
+static void fintek_8250_set_termios(struct uart_port *port,
+				    struct ktermios *termios,
+				    struct ktermios *old)
 {
 	struct fintek_8250 *pdata = port->private_data;
 	unsigned int baud = tty_termios_baud_rate(termios);

drivers/tty/serial/8250/8250_men_mcb.c

···
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/module.h>

drivers/tty/serial/8250/8250_mtk.c

···
 
 #include "8250.h"
 
-#define UART_MTK_HIGHS		0x09	/* Highspeed register */
-#define UART_MTK_SAMPLE_COUNT	0x0a	/* Sample count register */
-#define UART_MTK_SAMPLE_POINT	0x0b	/* Sample point register */
+#define MTK_UART_HIGHS		0x09	/* Highspeed register */
+#define MTK_UART_SAMPLE_COUNT	0x0a	/* Sample count register */
+#define MTK_UART_SAMPLE_POINT	0x0b	/* Sample point register */
 #define MTK_UART_RATE_FIX	0x0d	/* UART Rate Fix Register */
-
+#define MTK_UART_ESCAPE_DAT	0x10	/* Escape Character register */
+#define MTK_UART_ESCAPE_EN	0x11	/* Escape Enable register */
 #define MTK_UART_DMA_EN		0x13	/* DMA Enable register */
+#define MTK_UART_RXTRI_AD	0x14	/* RX Trigger address */
+#define MTK_UART_FRACDIV_L	0x15	/* Fractional divider LSB address */
+#define MTK_UART_FRACDIV_M	0x16	/* Fractional divider MSB address */
+#define MTK_UART_IER_XOFFI	0x20	/* Enable XOFF character interrupt */
+#define MTK_UART_IER_RTSI	0x40	/* Enable RTS Modem status interrupt */
+#define MTK_UART_IER_CTSI	0x80	/* Enable CTS Modem status interrupt */
+
+#define MTK_UART_EFR_EN		0x10	/* Enable enhancement feature */
+#define MTK_UART_EFR_RTS	0x40	/* Enable hardware rx flow control */
+#define MTK_UART_EFR_CTS	0x80	/* Enable hardware tx flow control */
+#define MTK_UART_EFR_NO_SW_FC	0x0	/* no sw flow control */
+#define MTK_UART_EFR_XON1_XOFF1	0xa	/* XON1/XOFF1 as sw flow control */
+#define MTK_UART_EFR_XON2_XOFF2	0x5	/* XON2/XOFF2 as sw flow control */
+#define MTK_UART_EFR_SW_FC_MASK	0xf	/* Enable CTS Modem status interrupt */
+#define MTK_UART_EFR_HW_FC	(MTK_UART_EFR_RTS | MTK_UART_EFR_CTS)
 #define MTK_UART_DMA_EN_TX	0x2
 #define MTK_UART_DMA_EN_RX	0x5
 
+#define MTK_UART_ESCAPE_CHAR	0x77	/* Escape char added under sw fc */
 #define MTK_UART_TX_SIZE	UART_XMIT_SIZE
 #define MTK_UART_RX_SIZE	0x8000
 #define MTK_UART_TX_TRIGGER	1
···
 struct mtk8250_data {
 	int			line;
 	unsigned int		rx_pos;
+	unsigned int		clk_count;
 	struct clk		*uart_clk;
 	struct clk		*bus_clk;
 	struct uart_8250_dma	*dma;
 #ifdef CONFIG_SERIAL_8250_DMA
 	enum dma_rx_status	rx_status;
 #endif
+};
+
+/* flow control mode */
+enum {
+	MTK_UART_FC_NONE,
+	MTK_UART_FC_SW,
+	MTK_UART_FC_HW,
 };
 
 #ifdef CONFIG_SERIAL_8250_DMA
···
 	return serial8250_do_shutdown(port);
 }
 
+static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask)
+{
+	serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask));
+}
+
+static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask)
+{
+	serial_out(up, UART_IER, serial_in(up, UART_IER) | mask);
+}
+
+static void mtk8250_set_flow_ctrl(struct uart_8250_port *up, int mode)
+{
+	struct uart_port *port = &up->port;
+	int lcr = serial_in(up, UART_LCR);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, UART_EFR_ECB);
+	serial_out(up, UART_LCR, lcr);
+	lcr = serial_in(up, UART_LCR);
+
+	switch (mode) {
+	case MTK_UART_FC_NONE:
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+		serial_out(up, UART_EFR, serial_in(up, UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK)));
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI |
+			MTK_UART_IER_RTSI | MTK_UART_IER_CTSI);
+		break;
+
+	case MTK_UART_FC_HW:
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x00);
+		serial_out(up, UART_MCR, UART_MCR_RTS);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+		/*enable hw flow control*/
+		serial_out(up, UART_EFR, MTK_UART_EFR_HW_FC |
+			(serial_in(up, UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));
+
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_XOFFI);
+		mtk8250_enable_intrs(up, MTK_UART_IER_CTSI | MTK_UART_IER_RTSI);
+		break;
+
+	case MTK_UART_FC_SW:	/*MTK software flow control */
+		serial_out(up, MTK_UART_ESCAPE_DAT, MTK_UART_ESCAPE_CHAR);
+		serial_out(up, MTK_UART_ESCAPE_EN, 0x01);
+		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+		/*enable sw flow control */
+		serial_out(up, UART_EFR, MTK_UART_EFR_XON1_XOFF1 |
+			(serial_in(up, UART_EFR) &
+			(~(MTK_UART_EFR_HW_FC | MTK_UART_EFR_SW_FC_MASK))));
+
+		serial_out(up, UART_XON1, START_CHAR(port->state->port.tty));
+		serial_out(up, UART_XOFF1, STOP_CHAR(port->state->port.tty));
+		serial_out(up, UART_LCR, lcr);
+		mtk8250_disable_intrs(up, MTK_UART_IER_CTSI|MTK_UART_IER_RTSI);
+		mtk8250_enable_intrs(up, MTK_UART_IER_XOFFI);
+		break;
+	default:
+		break;
+	}
+}
+
 static void
 mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
 			struct ktermios *old)
 {
+	unsigned short fraction_L_mapping[] = {
+		0, 1, 0x5, 0x15, 0x55, 0x57, 0x57, 0x77, 0x7F, 0xFF, 0xFF
+	};
+	unsigned short fraction_M_mapping[] = {
+		0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3
+	};
 	struct uart_8250_port *up = up_to_u8250p(port);
+	unsigned int baud, quot, fraction;
 	unsigned long flags;
-	unsigned int baud, quot;
+	int mode;
 
 #ifdef CONFIG_SERIAL_8250_DMA
 	if (up->dma) {
···
 	serial8250_do_set_termios(port, termios, old);
 
 	/*
-	 * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS)
+	 * Mediatek UARTs use an extra highspeed register (MTK_UART_HIGHS)
 	 *
 	 * We need to recalcualte the quot register, as the claculation depends
 	 * on the vaule in the highspeed register.
···
 				  port->uartclk / 16 / UART_DIV_MAX,
 				  port->uartclk);
 
-	if (baud <= 115200) {
-		serial_port_out(port, UART_MTK_HIGHS, 0x0);
+	if (baud < 115200) {
+		serial_port_out(port, MTK_UART_HIGHS, 0x0);
 		quot = uart_get_divisor(port, baud);
-	} else if (baud <= 576000) {
-		serial_port_out(port, UART_MTK_HIGHS, 0x2);
-
-		/* Set to next lower baudrate supported */
-		if ((baud == 500000) || (baud == 576000))
-			baud = 460800;
-		quot = DIV_ROUND_UP(port->uartclk, 4 * baud);
 	} else {
-		serial_port_out(port, UART_MTK_HIGHS, 0x3);
+		serial_port_out(port, MTK_UART_HIGHS, 0x3);
 		quot = DIV_ROUND_UP(port->uartclk, 256 * baud);
 	}
 
···
 	/* reset DLAB */
 	serial_port_out(port, UART_LCR, up->lcr);
 
-	if (baud > 460800) {
+	if (baud >= 115200) {
 		unsigned int tmp;
 
-		tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud);
-		serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1);
-		serial_port_out(port, UART_MTK_SAMPLE_POINT,
-					(tmp - 2) >> 1);
+		tmp = (port->uartclk / (baud *  quot)) - 1;
+		serial_port_out(port, MTK_UART_SAMPLE_COUNT, tmp);
+		serial_port_out(port, MTK_UART_SAMPLE_POINT,
+					(tmp >> 1) - 1);
+
+		/*count fraction to set fractoin register */
+		fraction = ((port->uartclk  * 100) / baud / quot) % 100;
+		fraction = DIV_ROUND_CLOSEST(fraction, 10);
+		serial_port_out(port, MTK_UART_FRACDIV_L,
+						fraction_L_mapping[fraction]);
+		serial_port_out(port, MTK_UART_FRACDIV_M,
+						fraction_M_mapping[fraction]);
 	} else {
-		serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00);
-		serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff);
+		serial_port_out(port, MTK_UART_SAMPLE_COUNT, 0x00);
+		serial_port_out(port, MTK_UART_SAMPLE_POINT, 0xff);
+		serial_port_out(port, MTK_UART_FRACDIV_L, 0x00);
+		serial_port_out(port, MTK_UART_FRACDIV_M, 0x00);
 	}
+
+	if ((termios->c_cflag & CRTSCTS) && (!(termios->c_iflag & CRTSCTS)))
+		mode = MTK_UART_FC_HW;
+	else if (termios->c_iflag & CRTSCTS)
+		mode = MTK_UART_FC_SW;
+	else
+		mode = MTK_UART_FC_NONE;
+
+	mtk8250_set_flow_ctrl(up, mode);
+
+	if (uart_console(port))
+		up->port.cons->cflag = termios->c_cflag;
 
 	spin_unlock_irqrestore(&port->lock, flags);
 	/* Don't rewrite B0 */

drivers/tty/serial/8250/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # The 8250/16550 serial drivers.  You shouldn't be in this list unless
 # you somehow have an implicit or explicit dependency on SERIAL_8250.

drivers/tty/serial/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # Serial device configuration
 #
···
 	depends on SPI_MASTER
 	select SERIAL_CORE
 	select REGMAP_SPI if SPI_MASTER
-	default n
 	help
 	  This selects support for an advanced UART from Maxim (Dallas).
 	  Supported ICs are MAX3107, MAX3108, MAX3109, MAX14830.
···
 config PDC_CONSOLE
 	bool "PDC software console support"
 	depends on PARISC && !SERIAL_MUX && VT
-	default n
 	help
 	  Saying Y here will enable the software based PDC console to be 
 	  used as the system console.  This is useful for machines in 
···
 	  your boot loader about how to pass options to the kernel at
 	  boot time.)
 
+config SERIAL_SIFIVE
+	tristate "SiFive UART support"
+	depends on OF
+	select SERIAL_CORE
+	help
+	  Select this option if you are building a kernel for a device that
+	  contains a SiFive UART IP block.  This type of UART is present on
+	  SiFive FU540 SoCs, among others.
+
+config SERIAL_SIFIVE_CONSOLE
+	bool "Console on SiFive UART"
+	depends on SERIAL_SIFIVE=y
+	select SERIAL_CORE_CONSOLE
+	help
+	  Select this option if you would like to use a SiFive UART as the
+	  system console.
+
+	  Even if you say Y here, the currently visible virtual console
+	  (/dev/tty0) will still be used as the system console by default, but
+	  you can alter that using a kernel command line option such as
+	  "console=ttySIFx". (Try "man bootparam" or see the documentation of
+	  your boot loader about how to pass options to the kernel at
+	  boot time.)
+
 config SERIAL_LANTIQ
 	bool "Lantiq serial driver"
 	depends on LANTIQ
···
 	depends on QUICC_ENGINE
 	select SERIAL_CORE
 	select FW_LOADER
-	default n
 	help
 	  This driver supports the QE serial ports on Freescale embedded
 	  PowerPC that contain a QUICC Engine.
···
 	help
 	  Say 'Y' here if you wish to use the RDA8810PL UART as the system
 	  console. Only earlycon is implemented currently.
+
+config SERIAL_MILBEAUT_USIO
+	tristate "Milbeaut USIO/UART serial port support"
+	depends on ARCH_MILBEAUT || (COMPILE_TEST && OF)
+	default ARCH_MILBEAUT
+	select SERIAL_CORE
+	help
+	  This selects the USIO/UART IP found in Socionext Milbeaut SoCs.
+
+config SERIAL_MILBEAUT_USIO_PORTS
+	int "Maximum number of CSIO/UART ports (1-8)"
+	range 1 8
+	depends on SERIAL_MILBEAUT_USIO
+	default "4"
+
+config SERIAL_MILBEAUT_USIO_CONSOLE
+	bool "Support for console on MILBEAUT USIO/UART serial port"
+	depends on SERIAL_MILBEAUT_USIO=y
+	default y
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	help
+	  Say 'Y' here if you wish to use a USIO/UART of Socionext Milbeaut
+	  SoCs as the system console (the system console is the device which
+	  receives all kernel messages and warnings and which allows logins in
+	  single user mode).
 
 endmenu
 

drivers/tty/serial/Makefile

···
 obj-$(CONFIG_SERIAL_MPS2_UART)	+= mps2-uart.o
 obj-$(CONFIG_SERIAL_OWL)	+= owl-uart.o
 obj-$(CONFIG_SERIAL_RDA)	+= rda-uart.o
+obj-$(CONFIG_SERIAL_MILBEAUT_USIO) += milbeaut_usio.o
+obj-$(CONFIG_SERIAL_SIFIVE)	+= sifive.o
 
 # GPIOLIB helpers for modem control lines
 obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o

drivers/tty/serial/cpm_uart/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for the Motorola 8xx FEC ethernet controller
 #

drivers/tty/serial/jsm/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for Jasmine adapter
 #

drivers/tty/serial/milbeaut_usio.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Socionext Inc.
+ */
+
+#if defined(CONFIG_SERIAL_MILBEAUT_USIO_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#define USIO_NAME		"mlb-usio-uart"
+#define USIO_UART_DEV_NAME	"ttyUSI"
+
+static struct uart_port mlb_usio_ports[CONFIG_SERIAL_MILBEAUT_USIO_PORTS];
+
+#define RX	0
+#define TX	1
+static int mlb_usio_irq[CONFIG_SERIAL_MILBEAUT_USIO_PORTS][2];
+
+#define MLB_USIO_REG_SMR		0
+#define MLB_USIO_REG_SCR		1
+#define MLB_USIO_REG_ESCR		2
+#define MLB_USIO_REG_SSR		3
+#define MLB_USIO_REG_DR			4
+#define MLB_USIO_REG_BGR		6
+#define MLB_USIO_REG_FCR		12
+#define MLB_USIO_REG_FBYTE		14
+
+#define MLB_USIO_SMR_SOE		BIT(0)
+#define MLB_USIO_SMR_SBL		BIT(3)
+#define MLB_USIO_SCR_TXE		BIT(0)
+#define MLB_USIO_SCR_RXE		BIT(1)
+#define MLB_USIO_SCR_TBIE		BIT(2)
+#define MLB_USIO_SCR_TIE		BIT(3)
+#define MLB_USIO_SCR_RIE		BIT(4)
+#define MLB_USIO_SCR_UPCL		BIT(7)
+#define MLB_USIO_ESCR_L_8BIT		0
+#define MLB_USIO_ESCR_L_5BIT		1
+#define MLB_USIO_ESCR_L_6BIT		2
+#define MLB_USIO_ESCR_L_7BIT		3
+#define MLB_USIO_ESCR_P			BIT(3)
+#define MLB_USIO_ESCR_PEN		BIT(4)
+#define MLB_USIO_ESCR_FLWEN		BIT(7)
+#define MLB_USIO_SSR_TBI		BIT(0)
+#define MLB_USIO_SSR_TDRE		BIT(1)
+#define MLB_USIO_SSR_RDRF		BIT(2)
+#define MLB_USIO_SSR_ORE		BIT(3)
+#define MLB_USIO_SSR_FRE		BIT(4)
+#define MLB_USIO_SSR_PE			BIT(5)
+#define MLB_USIO_SSR_REC		BIT(7)
+#define MLB_USIO_SSR_BRK		BIT(8)
+#define MLB_USIO_FCR_FE1		BIT(0)
+#define MLB_USIO_FCR_FE2		BIT(1)
+#define MLB_USIO_FCR_FCL1		BIT(2)
+#define MLB_USIO_FCR_FCL2		BIT(3)
+#define MLB_USIO_FCR_FSET		BIT(4)
+#define MLB_USIO_FCR_FTIE		BIT(9)
+#define MLB_USIO_FCR_FDRQ		BIT(10)
+#define MLB_USIO_FCR_FRIIE		BIT(11)
+
+static void mlb_usio_stop_tx(struct uart_port *port)
+{
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FTIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) & ~MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_tx_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	int count;
+
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FTIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) &
+	       ~(MLB_USIO_SCR_TIE | MLB_USIO_SCR_TBIE),
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (port->x_char) {
+		writew(port->x_char, port->membase + MLB_USIO_REG_DR);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		mlb_usio_stop_tx(port);
+		return;
+	}
+
+	count = port->fifosize -
+		(readw(port->membase + MLB_USIO_REG_FBYTE) & 0xff);
+
+	do {
+		writew(xmit->buf[xmit->tail], port->membase + MLB_USIO_REG_DR);
+
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+
+	} while (--count > 0);
+
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FDRQ,
+	       port->membase + MLB_USIO_REG_FCR);
+
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) | MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit))
+		mlb_usio_stop_tx(port);
+}
+
+static void mlb_usio_start_tx(struct uart_port *port)
+{
+	u16 fcr = readw(port->membase + MLB_USIO_REG_FCR);
+
+	writew(fcr | MLB_USIO_FCR_FTIE, port->membase + MLB_USIO_REG_FCR);
+	if (!(fcr & MLB_USIO_FCR_FDRQ))
+		return;
+
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) | MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI)
+		mlb_usio_tx_chars(port);
+}
+
+static void mlb_usio_stop_rx(struct uart_port *port)
+{
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) & ~MLB_USIO_SCR_RIE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_enable_ms(struct uart_port *port)
+{
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) |
+	       MLB_USIO_SCR_RIE | MLB_USIO_SCR_RXE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_rx_chars(struct uart_port *port)
+{
+	struct tty_port *ttyport = &port->state->port;
+	unsigned long flag = 0;
+	char ch = 0;
+	u8 status;
+	int max_count = 2;
+
+	while (max_count--) {
+		status = readb(port->membase + MLB_USIO_REG_SSR);
+
+		if (!(status & MLB_USIO_SSR_RDRF))
+			break;
+
+		if (!(status & (MLB_USIO_SSR_ORE | MLB_USIO_SSR_FRE |
+				MLB_USIO_SSR_PE))) {
+			ch = readw(port->membase + MLB_USIO_REG_DR);
+			flag = TTY_NORMAL;
+			port->icount.rx++;
+			if (uart_handle_sysrq_char(port, ch))
+				continue;
+			uart_insert_char(port, status, MLB_USIO_SSR_ORE,
+					 ch, flag);
+			continue;
+		}
+		if (status & MLB_USIO_SSR_PE)
+			port->icount.parity++;
+		if (status & MLB_USIO_SSR_ORE)
+			port->icount.overrun++;
+		status &= port->read_status_mask;
+		if (status & MLB_USIO_SSR_BRK) {
+			flag = TTY_BREAK;
+			ch = 0;
+		} else
+			if (status & MLB_USIO_SSR_PE) {
+				flag = TTY_PARITY;
+				ch = 0;
+			} else
+				if (status & MLB_USIO_SSR_FRE) {
+					flag = TTY_FRAME;
+					ch = 0;
+				}
+		if (flag)
+			uart_insert_char(port, status, MLB_USIO_SSR_ORE,
+					 ch, flag);
+
+		writeb(readb(port->membase + MLB_USIO_REG_SSR) |
+				MLB_USIO_SSR_REC,
+				port->membase + MLB_USIO_REG_SSR);
+
+		max_count = readw(port->membase + MLB_USIO_REG_FBYTE) >> 8;
+		writew(readw(port->membase + MLB_USIO_REG_FCR) |
+		       MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+		port->membase + MLB_USIO_REG_FCR);
+	}
+
+	tty_flip_buffer_push(ttyport);
+}
+
+static irqreturn_t mlb_usio_rx_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+
+	spin_lock(&port->lock);
+	mlb_usio_rx_chars(port);
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t mlb_usio_tx_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+
+	spin_lock(&port->lock);
+	if (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI)
+		mlb_usio_tx_chars(port);
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int mlb_usio_tx_empty(struct uart_port *port)
+{
+	return (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI) ?
+		TIOCSER_TEMT : 0;
+}
+
+static void mlb_usio_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static unsigned int mlb_usio_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+
+}
+
+static void mlb_usio_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+static int mlb_usio_startup(struct uart_port *port)
+{
+	const char *portname = to_platform_device(port->dev)->name;
+	unsigned long flags;
+	int ret, index = port->line;
+	unsigned char  escr;
+
+	ret = request_irq(mlb_usio_irq[index][RX], mlb_usio_rx_irq,
+				0, portname, port);
+	if (ret)
+		return ret;
+	ret = request_irq(mlb_usio_irq[index][TX], mlb_usio_tx_irq,
+				0, portname, port);
+	if (ret) {
+		free_irq(mlb_usio_irq[index][RX], port);
+		return ret;
+	}
+
+	escr = readb(port->membase + MLB_USIO_REG_ESCR);
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control"))
+		escr |= MLB_USIO_ESCR_FLWEN;
+	spin_lock_irqsave(&port->lock, flags);
+	writeb(0, port->membase + MLB_USIO_REG_SCR);
+	writeb(escr, port->membase + MLB_USIO_REG_ESCR);
+	writeb(MLB_USIO_SCR_UPCL, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SSR_REC, port->membase + MLB_USIO_REG_SSR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FCL1 | MLB_USIO_FCR_FCL2,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FE1 | MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(0, port->membase + MLB_USIO_REG_FBYTE);
+	writew(BIT(12), port->membase + MLB_USIO_REG_FBYTE);
+
+	writeb(MLB_USIO_SCR_TXE  | MLB_USIO_SCR_RIE | MLB_USIO_SCR_TBIE |
+	       MLB_USIO_SCR_RXE, port->membase + MLB_USIO_REG_SCR);
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return 0;
+}
+
+static void mlb_usio_shutdown(struct uart_port *port)
+{
+	int index = port->line;
+
+	free_irq(mlb_usio_irq[index][RX], port);
+	free_irq(mlb_usio_irq[index][TX], port);
+}
+
+static void mlb_usio_set_termios(struct uart_port *port,
+			struct ktermios *termios, struct ktermios *old)
+{
+	unsigned int escr, smr = MLB_USIO_SMR_SOE;
+	unsigned long flags, baud, quot;
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		escr = MLB_USIO_ESCR_L_5BIT;
+		break;
+	case CS6:
+		escr = MLB_USIO_ESCR_L_6BIT;
+		break;
+	case CS7:
+		escr = MLB_USIO_ESCR_L_7BIT;
+		break;
+	case CS8:
+	default:
+		escr = MLB_USIO_ESCR_L_8BIT;
+		break;
+	}
+
+	if (termios->c_cflag & CSTOPB)
+		smr |= MLB_USIO_SMR_SBL;
+
+	if (termios->c_cflag & PARENB) {
+		escr |= MLB_USIO_ESCR_PEN;
+		if (termios->c_cflag & PARODD)
+			escr |= MLB_USIO_ESCR_P;
+	}
+	/* Set hard flow control */
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control") ||
+			(termios->c_cflag & CRTSCTS))
+		escr |= MLB_USIO_ESCR_FLWEN;
+
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk);
+	if (baud > 1)
+		quot = port->uartclk / baud - 1;
+	else
+		quot = 0;
+
+	spin_lock_irqsave(&port->lock, flags);
+	uart_update_timeout(port, termios->c_cflag, baud);
+	port->read_status_mask = MLB_USIO_SSR_ORE | MLB_USIO_SSR_RDRF |
+				 MLB_USIO_SSR_TDRE;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= MLB_USIO_SSR_FRE | MLB_USIO_SSR_PE;
+
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask |= MLB_USIO_SSR_FRE | MLB_USIO_SSR_PE;
+	if ((termios->c_iflag & IGNBRK) && (termios->c_iflag & IGNPAR))
+		port->ignore_status_mask |= MLB_USIO_SSR_ORE;
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= MLB_USIO_SSR_RDRF;
+
+	writeb(0, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SCR_UPCL, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SSR_REC, port->membase + MLB_USIO_REG_SSR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writeb(smr, port->membase + MLB_USIO_REG_SMR);
+	writeb(escr, port->membase + MLB_USIO_REG_ESCR);
+	writew(quot, port->membase + MLB_USIO_REG_BGR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FCL1 | MLB_USIO_FCR_FCL2 | MLB_USIO_FCR_FE1 |
+	       MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(0, port->membase + MLB_USIO_REG_FBYTE);
+	writew(BIT(12), port->membase + MLB_USIO_REG_FBYTE);
+	writeb(MLB_USIO_SCR_RIE | MLB_USIO_SCR_RXE | MLB_USIO_SCR_TBIE |
+	       MLB_USIO_SCR_TXE, port->membase + MLB_USIO_REG_SCR);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *mlb_usio_type(struct uart_port *port)
+{
+	return ((port->type == PORT_MLB_USIO) ? USIO_NAME : NULL);
+}
+
+static void mlb_usio_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_MLB_USIO;
+}
+
+static const struct uart_ops mlb_usio_ops = {
+	.tx_empty	= mlb_usio_tx_empty,
+	.set_mctrl	= mlb_usio_set_mctrl,
+	.get_mctrl	= mlb_usio_get_mctrl,
+	.stop_tx	= mlb_usio_stop_tx,
+	.start_tx	= mlb_usio_start_tx,
+	.stop_rx	= mlb_usio_stop_rx,
+	.enable_ms	= mlb_usio_enable_ms,
+	.break_ctl	= mlb_usio_break_ctl,
+	.startup	= mlb_usio_startup,
+	.shutdown	= mlb_usio_shutdown,
+	.set_termios	= mlb_usio_set_termios,
+	.type		= mlb_usio_type,
+	.config_port	= mlb_usio_config_port,
+};
+
+#ifdef CONFIG_SERIAL_MILBEAUT_USIO_CONSOLE
+
+static void mlb_usio_console_putchar(struct uart_port *port, int c)
+{
+	while (!(readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TDRE))
+		cpu_relax();
+
+	writew(c, port->membase + MLB_USIO_REG_DR);
+}
+
+static void mlb_usio_console_write(struct console *co, const char *s,
+			       unsigned int count)
+{
+	struct uart_port *port = &mlb_usio_ports[co->index];
+
+	uart_console_write(port, s, count, mlb_usio_console_putchar);
+}
+
+static int __init mlb_usio_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port;
+	int baud = 115200;
+	int parity = 'n';
+	int flow = 'n';
+	int bits = 8;
+
+	if (co->index >= CONFIG_SERIAL_MILBEAUT_USIO_PORTS)
+		return -ENODEV;
+
+	port = &mlb_usio_ports[co->index];
+	if (!port->membase)
+		return -ENODEV;
+
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control"))
+		flow = 'r';
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+
+static struct uart_driver mlb_usio_uart_driver;
+static struct console mlb_usio_console = {
+	.name   = USIO_UART_DEV_NAME,
+	.write  = mlb_usio_console_write,
+	.device = uart_console_device,
+	.setup  = mlb_usio_console_setup,
+	.flags  = CON_PRINTBUFFER,
+	.index  = -1,
+	.data   = &mlb_usio_uart_driver,
+};
+
+static int __init mlb_usio_console_init(void)
+{
+	register_console(&mlb_usio_console);
+	return 0;
+}
+console_initcall(mlb_usio_console_init);
+
+
+static void mlb_usio_early_console_write(struct console *co, const char *s,
+					u_int count)
+{
+	struct earlycon_device *dev = co->data;
+
+	uart_console_write(&dev->port, s, count, mlb_usio_console_putchar);
+}
+
+static int __init mlb_usio_early_console_setup(struct earlycon_device *device,
+						const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+	device->con->write = mlb_usio_early_console_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(mlb_usio, "socionext,milbeaut-usio-uart",
+			mlb_usio_early_console_setup);
+
+#define USIO_CONSOLE	(&mlb_usio_console)
+#else
+#define USIO_CONSOLE	NULL
+#endif
+
+static struct  uart_driver mlb_usio_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= USIO_NAME,
+	.dev_name	= USIO_UART_DEV_NAME,
+	.cons           = USIO_CONSOLE,
+	.nr		= CONFIG_SERIAL_MILBEAUT_USIO_PORTS,
+};
+
+static int mlb_usio_probe(struct platform_device *pdev)
+{
+	struct clk *clk = devm_clk_get(&pdev->dev, NULL);
+	struct uart_port *port;
+	struct resource *res;
+	int index = 0;
+	int ret;
+
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "Missing clock\n");
+		return PTR_ERR(clk);
+	}
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Clock enable failed: %d\n", ret);
+		return ret;
+	}
+	of_property_read_u32(pdev->dev.of_node, "index", &index);
+	port = &mlb_usio_ports[index];
+
+	port->private_data = (void *)clk;
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "Missing regs\n");
+		ret = -ENODEV;
+		goto failed;
+	}
+	port->membase = devm_ioremap(&pdev->dev, res->start,
+				resource_size(res));
+
+	ret = platform_get_irq_byname(pdev, "rx");
+	mlb_usio_irq[index][RX] = ret;
+
+	ret = platform_get_irq_byname(pdev, "tx");
+	mlb_usio_irq[index][TX] = ret;
+
+	port->irq = mlb_usio_irq[index][RX];
+	port->uartclk = clk_get_rate(clk);
+	port->fifosize = 128;
+	port->iotype = UPIO_MEM32;
+	port->flags = UPF_BOOT_AUTOCONF | UPF_SPD_VHI;
+	port->line = index;
+	port->ops = &mlb_usio_ops;
+	port->dev = &pdev->dev;
+
+	ret = uart_add_one_port(&mlb_usio_uart_driver, port);
+	if (ret) {
+		dev_err(&pdev->dev, "Adding port failed: %d\n", ret);
+		goto failed;
+	}
+	return 0;
+
+failed:
+	clk_disable_unprepare(clk);
+
+	return ret;
+}
+
+static int mlb_usio_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = &mlb_usio_ports[pdev->id];
+	struct clk *clk = port->private_data;
+
+	uart_remove_one_port(&mlb_usio_uart_driver, port);
+	clk_disable_unprepare(clk);
+
+	return 0;
+}
+
+static const struct of_device_id mlb_usio_dt_ids[] = {
+	{ .compatible = "socionext,milbeaut-usio-uart" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mlb_usio_dt_ids);
+
+static struct platform_driver mlb_usio_driver = {
+	.probe          = mlb_usio_probe,
+	.remove         = mlb_usio_remove,
+	.driver         = {
+		.name   = USIO_NAME,
+		.of_match_table = mlb_usio_dt_ids,
+	},
+};
+
+static int __init mlb_usio_init(void)
+{
+	int ret = uart_register_driver(&mlb_usio_uart_driver);
+
+	if (ret) {
+		pr_err("%s: uart registration failed: %d\n", __func__, ret);
+		return ret;
+	}
+	ret = platform_driver_register(&mlb_usio_driver);
+	if (ret) {
+		uart_unregister_driver(&mlb_usio_uart_driver);
+		pr_err("%s: drv registration failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit mlb_usio_exit(void)
+{
+	platform_driver_unregister(&mlb_usio_driver);
+	uart_unregister_driver(&mlb_usio_uart_driver);
+}
+
+module_init(mlb_usio_init);
+module_exit(mlb_usio_exit);
+
+MODULE_AUTHOR("SOCIONEXT");
+MODULE_DESCRIPTION("MILBEAUT_USIO/UART Driver");
+MODULE_LICENSE("GPL");

drivers/tty/serial/sc16is7xx.c

···
 #include <linux/device.h>
 #include <linux/gpio/driver.h>
 #include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
-#include <linux/of.h>
-#include <linux/of_device.h>
+#include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
···
 			   struct regmap *regmap, int irq, unsigned long flags)
 {
 	struct sched_param sched_param = { .sched_priority = MAX_RT_PRIO / 2 };
-	unsigned long freq, *pfreq = dev_get_platdata(dev);
+	unsigned long freq = 0, *pfreq = dev_get_platdata(dev);
+	u32 uartclk = 0;
 	int i, ret;
 	struct sc16is7xx_port *s;
 
···
 		return -ENOMEM;
 	}
 
+	/* Always ask for fixed clock rate from a property. */
+	device_property_read_u32(dev, "clock-frequency", &uartclk);
+
 	s->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(s->clk)) {
+		if (uartclk)
+			freq = uartclk;
 		if (pfreq)
 			freq = *pfreq;
+		if (freq)
+			dev_dbg(dev, "Clock frequency: %luHz\n", freq);
 		else
 			return PTR_ERR(s->clk);
 	} else {
···
 		return ret;
 
 	if (spi->dev.of_node) {
-		const struct of_device_id *of_id =
-			of_match_device(sc16is7xx_dt_ids, &spi->dev);
-
-		if (!of_id)
+		devtype = device_get_match_data(&spi->dev);
+		if (!devtype)
 			return -ENODEV;
-
-		devtype = (struct sc16is7xx_devtype *)of_id->data;
 	} else {
 		const struct spi_device_id *id_entry = spi_get_device_id(spi);
 
···
 static struct spi_driver sc16is7xx_spi_uart_driver = {
 	.driver = {
 		.name		= SC16IS7XX_NAME,
-		.of_match_table	= of_match_ptr(sc16is7xx_dt_ids),
+		.of_match_table	= sc16is7xx_dt_ids,
 	},
 	.probe		= sc16is7xx_spi_probe,
 	.remove		= sc16is7xx_spi_remove,
···
 	struct regmap *regmap;
 
 	if (i2c->dev.of_node) {
-		const struct of_device_id *of_id =
-				of_match_device(sc16is7xx_dt_ids, &i2c->dev);
-
-		if (!of_id)
+		devtype = device_get_match_data(&i2c->dev);
+		if (!devtype)
 			return -ENODEV;
-
-		devtype = (struct sc16is7xx_devtype *)of_id->data;
 	} else {
 		devtype = (struct sc16is7xx_devtype *)id->driver_data;
 		flags = IRQF_TRIGGER_FALLING;
···
 static struct i2c_driver sc16is7xx_i2c_uart_driver = {
 	.driver = {
 		.name		= SC16IS7XX_NAME,
-		.of_match_table	= of_match_ptr(sc16is7xx_dt_ids),
+		.of_match_table	= sc16is7xx_dt_ids,
 	},
 	.probe		= sc16is7xx_i2c_probe,
 	.remove		= sc16is7xx_i2c_remove,

drivers/tty/serial/serial_core.c

···
 	struct uart_port *port;
 	unsigned long flags;
 
-	if (!state)
-		return;
-
 	port = uart_port_lock(state, flags);
 	__uart_start(tty);
 	uart_port_unlock(port, flags);
···
 	struct uart_state *state = tty->driver_data;
 	upstat_t mask = UPSTAT_SYNC_FIFO;
 	struct uart_port *port;
-
-	if (!state)
-		return;
 
 	port = uart_port_ref(state);
 	if (!port)
···
 	}
 
 	uart_change_speed(tty, state, old_termios);
-	/* reload cflag from termios; port driver may have overriden flags */
+	/* reload cflag from termios; port driver may have overridden flags */
 	cflag = tty->termios.c_cflag;
 
 	/* Handle transition to B0 status */
···
 	uart_port_deref(uport);
 }
 
+static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+	struct uart_driver *drv = driver->driver_state;
+	struct uart_state *state = drv->state + tty->index;
+
+	tty->driver_data = state;
+
+	return tty_standard_install(driver, tty);
+}
+
 /*
  * Calls to uart_open are serialised by the tty_lock in
  *   drivers/tty/tty_io.c:tty_open()
···
  */
 static int uart_open(struct tty_struct *tty, struct file *filp)
 {
-	struct uart_driver *drv = tty->driver->driver_state;
-	int retval, line = tty->index;
-	struct uart_state *state = drv->state + line;
-
-	tty->driver_data = state;
+	struct uart_state *state = tty->driver_data;
+	int retval;
 
 	retval = tty_port_open(&state->port, tty, filp);
 	if (retval > 0)
···
 #endif
 
 static const struct tty_operations uart_ops = {
+	.install	= uart_install,
 	.open		= uart_open,
 	.close		= uart_close,
 	.write		= uart_write,
···
 int uart_register_driver(struct uart_driver *drv)
 {
 	struct tty_driver *normal;
-	int i, retval;
+	int i, retval = -ENOMEM;
 
 	BUG_ON(drv->state);
 
···
 out_kfree:
 	kfree(drv->state);
 out:
-	return -ENOMEM;
+	return retval;
 }
 
 /**

drivers/tty/serial/sifive.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * SiFive UART driver
+ * Copyright (C) 2018 Paul Walmsley <[e-mail]>
+ * Copyright (C) 2018-2019 SiFive
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Based partially on:
+ * - drivers/tty/serial/pxa.c
+ * - drivers/tty/serial/amba-pl011.c
+ * - drivers/tty/serial/uartlite.c
+ * - drivers/tty/serial/omap-serial.c
+ * - drivers/pwm/pwm-sifive.c
+ *
+ * See the following sources for further documentation:
+ * - Chapter 19 "Universal Asynchronous Receiver/Transmitter (UART)" of
+ *   SiFive FE310-G000 v2p3
+ * - The tree/master/src/main/scala/devices/uart directory of
+ *   https://github.com/sifive/sifive-blocks/
+ *
+ * The SiFive UART design is not 8250-compatible.  The following common
+ * features are not supported:
+ * - Word lengths other than 8 bits
+ * - Break handling
+ * - Parity
+ * - Flow control
+ * - Modem signals (DSR, RI, etc.)
+ * On the other hand, the design is free from the baggage of the 8250
+ * programming model.
+ */
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+/*
+ * Register offsets
+ */
+
+/* TXDATA */
+#define SIFIVE_SERIAL_TXDATA_OFFS		0x0
+#define SIFIVE_SERIAL_TXDATA_FULL_SHIFT		31
+#define SIFIVE_SERIAL_TXDATA_FULL_MASK		(1 << SIFIVE_SERIAL_TXDATA_FULL_SHIFT)
+#define SIFIVE_SERIAL_TXDATA_DATA_SHIFT		0
+#define SIFIVE_SERIAL_TXDATA_DATA_MASK		(0xff << SIFIVE_SERIAL_TXDATA_DATA_SHIFT)
+
+/* RXDATA */
+#define SIFIVE_SERIAL_RXDATA_OFFS		0x4
+#define SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT	31
+#define SIFIVE_SERIAL_RXDATA_EMPTY_MASK		(1 << SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT)
+#define SIFIVE_SERIAL_RXDATA_DATA_SHIFT		0
+#define SIFIVE_SERIAL_RXDATA_DATA_MASK		(0xff << SIFIVE_SERIAL_RXDATA_DATA_SHIFT)
+
+/* TXCTRL */
+#define SIFIVE_SERIAL_TXCTRL_OFFS		0x8
+#define SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT	16
+#define SIFIVE_SERIAL_TXCTRL_TXCNT_MASK		(0x7 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT)
+#define SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT	1
+#define SIFIVE_SERIAL_TXCTRL_NSTOP_MASK		(1 << SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT)
+#define SIFIVE_SERIAL_TXCTRL_TXEN_SHIFT		0
+#define SIFIVE_SERIAL_TXCTRL_TXEN_MASK		(1 << SIFIVE_SERIAL_TXCTRL_TXEN_SHIFT)
+
+/* RXCTRL */
+#define SIFIVE_SERIAL_RXCTRL_OFFS		0xC
+#define SIFIVE_SERIAL_RXCTRL_RXCNT_SHIFT	16
+#define SIFIVE_SERIAL_RXCTRL_RXCNT_MASK		(0x7 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT)
+#define SIFIVE_SERIAL_RXCTRL_RXEN_SHIFT		0
+#define SIFIVE_SERIAL_RXCTRL_RXEN_MASK		(1 << SIFIVE_SERIAL_RXCTRL_RXEN_SHIFT)
+
+/* IE */
+#define SIFIVE_SERIAL_IE_OFFS			0x10
+#define SIFIVE_SERIAL_IE_RXWM_SHIFT		1
+#define SIFIVE_SERIAL_IE_RXWM_MASK		(1 << SIFIVE_SERIAL_IE_RXWM_SHIFT)
+#define SIFIVE_SERIAL_IE_TXWM_SHIFT		0
+#define SIFIVE_SERIAL_IE_TXWM_MASK		(1 << SIFIVE_SERIAL_IE_TXWM_SHIFT)
+
+/* IP */
+#define SIFIVE_SERIAL_IP_OFFS			0x14
+#define SIFIVE_SERIAL_IP_RXWM_SHIFT		1
+#define SIFIVE_SERIAL_IP_RXWM_MASK		(1 << SIFIVE_SERIAL_IP_RXWM_SHIFT)
+#define SIFIVE_SERIAL_IP_TXWM_SHIFT		0
+#define SIFIVE_SERIAL_IP_TXWM_MASK		(1 << SIFIVE_SERIAL_IP_TXWM_SHIFT)
+
+/* DIV */
+#define SIFIVE_SERIAL_DIV_OFFS			0x18
+#define SIFIVE_SERIAL_DIV_DIV_SHIFT		0
+#define SIFIVE_SERIAL_DIV_DIV_MASK		(0xffff << SIFIVE_SERIAL_IP_DIV_SHIFT)
+
+/*
+ * Config macros
+ */
+
+/*
+ * SIFIVE_SERIAL_MAX_PORTS: maximum number of UARTs on a device that can
+ *                          host a serial console
+ */
+#define SIFIVE_SERIAL_MAX_PORTS			8
+
+/*
+ * SIFIVE_DEFAULT_BAUD_RATE: default baud rate that the driver should
+ *                           configure itself to use
+ */
+#define SIFIVE_DEFAULT_BAUD_RATE		115200
+
+/* SIFIVE_SERIAL_NAME: our driver's name that we pass to the operating system */
+#define SIFIVE_SERIAL_NAME			"sifive-serial"
+
+/* SIFIVE_TTY_PREFIX: tty name prefix for SiFive serial ports */
+#define SIFIVE_TTY_PREFIX			"ttySIF"
+
+/* SIFIVE_TX_FIFO_DEPTH: depth of the TX FIFO (in bytes) */
+#define SIFIVE_TX_FIFO_DEPTH			8
+
+/* SIFIVE_RX_FIFO_DEPTH: depth of the TX FIFO (in bytes) */
+#define SIFIVE_RX_FIFO_DEPTH			8
+
+#if (SIFIVE_TX_FIFO_DEPTH != SIFIVE_RX_FIFO_DEPTH)
+#error Driver does not support configurations with different TX, RX FIFO sizes
+#endif
+
+/*
+ *
+ */
+
+/**
+ * sifive_serial_port - driver-specific data extension to struct uart_port
+ * @port: struct uart_port embedded in this struct
+ * @dev: struct device *
+ * @ier: shadowed copy of the interrupt enable register
+ * @clkin_rate: input clock to the UART IP block.
+ * @baud_rate: UART serial line rate (e.g., 115200 baud)
+ * @clk_notifier: clock rate change notifier for upstream clock changes
+ *
+ * Configuration data specific to this SiFive UART.
+ */
+struct sifive_serial_port {
+	struct uart_port	port;
+	struct device		*dev;
+	unsigned char		ier;
+	unsigned long		clkin_rate;
+	unsigned long		baud_rate;
+	struct clk		*clk;
+	struct notifier_block	clk_notifier;
+};
+
+/*
+ * Structure container-of macros
+ */
+
+#define port_to_sifive_serial_port(p) (container_of((p), \
+						    struct sifive_serial_port, \
+						    port))
+
+#define notifier_to_sifive_serial_port(nb) (container_of((nb), \
+							 struct sifive_serial_port, \
+							 clk_notifier))
+
+/*
+ * Forward declarations
+ */
+static void sifive_serial_stop_tx(struct uart_port *port);
+
+/*
+ * Internal functions
+ */
+
+/**
+ * __ssp_early_writel() - write to a SiFive serial port register (early)
+ * @port: pointer to a struct uart_port record
+ * @offs: register address offset from the IP block base address
+ * @v: value to write to the register
+ *
+ * Given a pointer @port to a struct uart_port record, write the value
+ * @v to the IP block register address offset @offs.  This function is
+ * intended for early console use.
+ *
+ * Context: Intended to be used only by the earlyconsole code.
+ */
+static void __ssp_early_writel(u32 v, u16 offs, struct uart_port *port)
+{
+	writel_relaxed(v, port->membase + offs);
+}
+
+/**
+ * __ssp_early_readl() - read from a SiFive serial port register (early)
+ * @port: pointer to a struct uart_port record
+ * @offs: register address offset from the IP block base address
+ *
+ * Given a pointer @port to a struct uart_port record, read the
+ * contents of the IP block register located at offset @offs from the
+ * IP block base and return it.  This function is intended for early
+ * console use.
+ *
+ * Context: Intended to be called only by the earlyconsole code or by
+ *          __ssp_readl() or __ssp_writel() (in this driver)
+ *
+ * Returns: the register value read from the UART.
+ */
+static u32 __ssp_early_readl(struct uart_port *port, u16 offs)
+{
+	return readl_relaxed(port->membase + offs);
+}
+
+/**
+ * __ssp_writel() - write to a SiFive serial port register
+ * @v: value to write to the register
+ * @offs: register address offset from the IP block base address
+ * @ssp: pointer to a struct sifive_serial_port record
+ *
+ * Write the value @v to the IP block register located at offset @offs from the
+ * IP block base, given a pointer @ssp to a struct sifive_serial_port record.
+ *
+ * Context: Any context.
+ */
+static void __ssp_writel(u32 v, u16 offs, struct sifive_serial_port *ssp)
+{
+	__ssp_early_writel(v, offs, &ssp->port);
+}
+
+/**
+ * __ssp_readl() - read from a SiFive serial port register
+ * @ssp: pointer to a struct sifive_serial_port record
+ * @offs: register address offset from the IP block base address
+ *
+ * Read the contents of the IP block register located at offset @offs from the
+ * IP block base, given a pointer @ssp to a struct sifive_serial_port record.
+ *
+ * Context: Any context.
+ *
+ * Returns: the value of the UART register
+ */
+static u32 __ssp_readl(struct sifive_serial_port *ssp, u16 offs)
+{
+	return __ssp_early_readl(&ssp->port, offs);
+}
+
+/**
+ * sifive_serial_is_txfifo_full() - is the TXFIFO full?
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Read the transmit FIFO "full" bit, returning a non-zero value if the
+ * TX FIFO is full, or zero if space remains.  Intended to be used to prevent
+ * writes to the TX FIFO when it's full.
+ *
+ * Returns: SIFIVE_SERIAL_TXDATA_FULL_MASK (non-zero) if the transmit FIFO
+ * is full, or 0 if space remains.
+ */
+static int sifive_serial_is_txfifo_full(struct sifive_serial_port *ssp)
+{
+	return __ssp_readl(ssp, SIFIVE_SERIAL_TXDATA_OFFS) &
+		SIFIVE_SERIAL_TXDATA_FULL_MASK;
+}
+
+/**
+ * __ssp_transmit_char() - enqueue a byte to transmit onto the TX FIFO
+ * @ssp: pointer to a struct sifive_serial_port
+ * @ch: character to transmit
+ *
+ * Enqueue a byte @ch onto the transmit FIFO, given a pointer @ssp to the
+ * struct sifive_serial_port * to transmit on.  Caller should first check to
+ * ensure that the TXFIFO has space; see sifive_serial_is_txfifo_full().
+ *
+ * Context: Any context.
+ */
+static void __ssp_transmit_char(struct sifive_serial_port *ssp, int ch)
+{
+	__ssp_writel(ch, SIFIVE_SERIAL_TXDATA_OFFS, ssp);
+}
+
+/**
+ * __ssp_transmit_chars() - enqueue multiple bytes onto the TX FIFO
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Transfer up to a TX FIFO size's worth of characters from the Linux serial
+ * transmit buffer to the SiFive UART TX FIFO.
+ *
+ * Context: Any context.  Expects @ssp->port.lock to be held by caller.
+ */
+static void __ssp_transmit_chars(struct sifive_serial_port *ssp)
+{
+	struct circ_buf *xmit = &ssp->port.state->xmit;
+	int count;
+
+	if (ssp->port.x_char) {
+		__ssp_transmit_char(ssp, ssp->port.x_char);
+		ssp->port.icount.tx++;
+		ssp->port.x_char = 0;
+		return;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&ssp->port)) {
+		sifive_serial_stop_tx(&ssp->port);
+		return;
+	}
+	count = SIFIVE_TX_FIFO_DEPTH;
+	do {
+		__ssp_transmit_char(ssp, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		ssp->port.icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+	} while (--count > 0);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&ssp->port);
+
+	if (uart_circ_empty(xmit))
+		sifive_serial_stop_tx(&ssp->port);
+}
+
+/**
+ * __ssp_enable_txwm() - enable transmit watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Enable interrupt generation when the transmit FIFO watermark is reached
+ * on the SiFive UART referred to by @ssp.
+ */
+static void __ssp_enable_txwm(struct sifive_serial_port *ssp)
+{
+	if (ssp->ier & SIFIVE_SERIAL_IE_TXWM_MASK)
+		return;
+
+	ssp->ier |= SIFIVE_SERIAL_IE_TXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_enable_rxwm() - enable receive watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Enable interrupt generation when the receive FIFO watermark is reached
+ * on the SiFive UART referred to by @ssp.
+ */
+static void __ssp_enable_rxwm(struct sifive_serial_port *ssp)
+{
+	if (ssp->ier & SIFIVE_SERIAL_IE_RXWM_MASK)
+		return;
+
+	ssp->ier |= SIFIVE_SERIAL_IE_RXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_disable_txwm() - disable transmit watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Disable interrupt generation when the transmit FIFO watermark is reached
+ * on the UART referred to by @ssp.
+ */
+static void __ssp_disable_txwm(struct sifive_serial_port *ssp)
+{
+	if (!(ssp->ier & SIFIVE_SERIAL_IE_TXWM_MASK))
+		return;
+
+	ssp->ier &= ~SIFIVE_SERIAL_IE_TXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_disable_rxwm() - disable receive watermark interrupts
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Disable interrupt generation when the receive FIFO watermark is reached
+ * on the UART referred to by @ssp.
+ */
+static void __ssp_disable_rxwm(struct sifive_serial_port *ssp)
+{
+	if (!(ssp->ier & SIFIVE_SERIAL_IE_RXWM_MASK))
+		return;
+
+	ssp->ier &= ~SIFIVE_SERIAL_IE_RXWM_MASK;
+	__ssp_writel(ssp->ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+}
+
+/**
+ * __ssp_receive_char() - receive a byte from the UART
+ * @ssp: pointer to a struct sifive_serial_port
+ * @is_empty: char pointer to return whether the RX FIFO is empty
+ *
+ * Try to read a byte from the SiFive UART RX FIFO, referenced by
+ * @ssp, and to return it.  Also returns the RX FIFO empty bit in
+ * the char pointed to by @ch.  The caller must pass the byte back to the
+ * Linux serial layer if needed.
+ *
+ * Returns: the byte read from the UART RX FIFO.
+ */
+static char __ssp_receive_char(struct sifive_serial_port *ssp, char *is_empty)
+{
+	u32 v;
+	u8 ch;
+
+	v = __ssp_readl(ssp, SIFIVE_SERIAL_RXDATA_OFFS);
+
+	if (!is_empty)
+		WARN_ON(1);
+	else
+		*is_empty = (v & SIFIVE_SERIAL_RXDATA_EMPTY_MASK) >>
+			SIFIVE_SERIAL_RXDATA_EMPTY_SHIFT;
+
+	ch = (v & SIFIVE_SERIAL_RXDATA_DATA_MASK) >>
+		SIFIVE_SERIAL_RXDATA_DATA_SHIFT;
+
+	return ch;
+}
+
+/**
+ * __ssp_receive_chars() - receive multiple bytes from the UART
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Receive up to an RX FIFO's worth of bytes from the SiFive UART referred
+ * to by @ssp and pass them up to the Linux serial layer.
+ *
+ * Context: Expects ssp->port.lock to be held by caller.
+ */
+static void __ssp_receive_chars(struct sifive_serial_port *ssp)
+{
+	unsigned char ch;
+	char is_empty;
+	int c;
+
+	for (c = SIFIVE_RX_FIFO_DEPTH; c > 0; --c) {
+		ch = __ssp_receive_char(ssp, &is_empty);
+		if (is_empty)
+			break;
+
+		ssp->port.icount.rx++;
+		uart_insert_char(&ssp->port, 0, 0, ch, TTY_NORMAL);
+	}
+
+	spin_unlock(&ssp->port.lock);
+	tty_flip_buffer_push(&ssp->port.state->port);
+	spin_lock(&ssp->port.lock);
+}
+
+/**
+ * __ssp_update_div() - calculate the divisor setting by the line rate
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Calculate the appropriate value of the clock divisor for the UART
+ * and target line rate referred to by @ssp and write it into the
+ * hardware.
+ */
+static void __ssp_update_div(struct sifive_serial_port *ssp)
+{
+	u16 div;
+
+	div = DIV_ROUND_UP(ssp->clkin_rate, ssp->baud_rate) - 1;
+
+	__ssp_writel(div, SIFIVE_SERIAL_DIV_OFFS, ssp);
+}
+
+/**
+ * __ssp_update_baud_rate() - set the UART "baud rate"
+ * @ssp: pointer to a struct sifive_serial_port
+ * @rate: new target bit rate
+ *
+ * Calculate the UART divisor value for the target bit rate @rate for the
+ * SiFive UART described by @ssp and program it into the UART.  There may
+ * be some error between the target bit rate and the actual bit rate implemented
+ * by the UART due to clock ratio granularity.
+ */
+static void __ssp_update_baud_rate(struct sifive_serial_port *ssp,
+				   unsigned int rate)
+{
+	if (ssp->baud_rate == rate)
+		return;
+
+	ssp->baud_rate = rate;
+	__ssp_update_div(ssp);
+}
+
+/**
+ * __ssp_set_stop_bits() - set the number of stop bits
+ * @ssp: pointer to a struct sifive_serial_port
+ * @nstop: 1 or 2 (stop bits)
+ *
+ * Program the SiFive UART referred to by @ssp to use @nstop stop bits.
+ */
+static void __ssp_set_stop_bits(struct sifive_serial_port *ssp, char nstop)
+{
+	u32 v;
+
+	if (nstop < 1 || nstop > 2) {
+		WARN_ON(1);
+		return;
+	}
+
+	v = __ssp_readl(ssp, SIFIVE_SERIAL_TXCTRL_OFFS);
+	v &= ~SIFIVE_SERIAL_TXCTRL_NSTOP_MASK;
+	v |= (nstop - 1) << SIFIVE_SERIAL_TXCTRL_NSTOP_SHIFT;
+	__ssp_writel(v, SIFIVE_SERIAL_TXCTRL_OFFS, ssp);
+}
+
+/**
+ * __ssp_wait_for_xmitr() - wait for an empty slot on the TX FIFO
+ * @ssp: pointer to a struct sifive_serial_port
+ *
+ * Delay while the UART TX FIFO referred to by @ssp is marked as full.
+ *
+ * Context: Any context.
+ */
+static void __maybe_unused __ssp_wait_for_xmitr(struct sifive_serial_port *ssp)
+{
+	while (sifive_serial_is_txfifo_full(ssp))
+		udelay(1); /* XXX Could probably be more intelligent here */
+}
+
+/*
+ * Linux serial API functions
+ */
+
+static void sifive_serial_stop_tx(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_disable_txwm(ssp);
+}
+
+static void sifive_serial_stop_rx(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_disable_rxwm(ssp);
+}
+
+static void sifive_serial_start_tx(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_enable_txwm(ssp);
+}
+
+static irqreturn_t sifive_serial_irq(int irq, void *dev_id)
+{
+	struct sifive_serial_port *ssp = dev_id;
+	u32 ip;
+
+	spin_lock(&ssp->port.lock);
+
+	ip = __ssp_readl(ssp, SIFIVE_SERIAL_IP_OFFS);
+	if (!ip) {
+		spin_unlock(&ssp->port.lock);
+		return IRQ_NONE;
+	}
+
+	if (ip & SIFIVE_SERIAL_IP_RXWM_MASK)
+		__ssp_receive_chars(ssp);
+	if (ip & SIFIVE_SERIAL_IP_TXWM_MASK)
+		__ssp_transmit_chars(ssp);
+
+	spin_unlock(&ssp->port.lock);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int sifive_serial_tx_empty(struct uart_port *port)
+{
+	return TIOCSER_TEMT;
+}
+
+static unsigned int sifive_serial_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;
+}
+
+static void sifive_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	/* IP block does not support these signals */
+}
+
+static void sifive_serial_break_ctl(struct uart_port *port, int break_state)
+{
+	/* IP block does not support sending a break */
+}
+
+static int sifive_serial_startup(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_enable_rxwm(ssp);
+
+	return 0;
+}
+
+static void sifive_serial_shutdown(struct uart_port *port)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_disable_rxwm(ssp);
+	__ssp_disable_txwm(ssp);
+}
+
+/**
+ * sifive_serial_clk_notifier() - clock post-rate-change notifier
+ * @nb: pointer to the struct notifier_block, from the notifier code
+ * @event: event mask from the notifier code
+ * @data: pointer to the struct clk_notifier_data from the notifier code
+ *
+ * On the V0 SoC, the UART IP block is derived from the CPU clock source
+ * after a synchronous divide-by-two divider, so any CPU clock rate change
+ * requires the UART baud rate to be updated.  This presumably could corrupt any
+ * serial word currently being transmitted or received.  It would probably
+ * be better to stop receives and transmits, then complete the baud rate
+ * change, then re-enable them.
+ */
+static int sifive_serial_clk_notifier(struct notifier_block *nb,
+				      unsigned long event, void *data)
+{
+	struct clk_notifier_data *cnd = data;
+	struct sifive_serial_port *ssp = notifier_to_sifive_serial_port(nb);
+
+	if (event == POST_RATE_CHANGE && ssp->clkin_rate != cnd->new_rate) {
+		ssp->clkin_rate = cnd->new_rate;
+		__ssp_update_div(ssp);
+	}
+
+	return NOTIFY_OK;
+}
+
+static void sifive_serial_set_termios(struct uart_port *port,
+				      struct ktermios *termios,
+				      struct ktermios *old)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+	unsigned long flags;
+	u32 v, old_v;
+	int rate;
+	char nstop;
+
+	if ((termios->c_cflag & CSIZE) != CS8)
+		dev_err_once(ssp->port.dev, "only 8-bit words supported\n");
+	if (termios->c_iflag & (INPCK | PARMRK))
+		dev_err_once(ssp->port.dev, "parity checking not supported\n");
+	if (termios->c_iflag & BRKINT)
+		dev_err_once(ssp->port.dev, "BREAK detection not supported\n");
+
+	/* Set number of stop bits */
+	nstop = (termios->c_cflag & CSTOPB) ? 2 : 1;
+	__ssp_set_stop_bits(ssp, nstop);
+
+	/* Set line rate */
+	rate = uart_get_baud_rate(port, termios, old, 0, ssp->clkin_rate / 16);
+	__ssp_update_baud_rate(ssp, rate);
+
+	spin_lock_irqsave(&ssp->port.lock, flags);
+
+	/* Update the per-port timeout */
+	uart_update_timeout(port, termios->c_cflag, rate);
+
+	ssp->port.read_status_mask = 0;
+
+	/* Ignore all characters if CREAD is not set */
+	v = __ssp_readl(ssp, SIFIVE_SERIAL_RXCTRL_OFFS);
+	old_v = v;
+	if ((termios->c_cflag & CREAD) == 0)
+		v &= SIFIVE_SERIAL_RXCTRL_RXEN_MASK;
+	else
+		v |= SIFIVE_SERIAL_RXCTRL_RXEN_MASK;
+	if (v != old_v)
+		__ssp_writel(v, SIFIVE_SERIAL_RXCTRL_OFFS, ssp);
+
+	spin_unlock_irqrestore(&ssp->port.lock, flags);
+}
+
+static void sifive_serial_release_port(struct uart_port *port)
+{
+}
+
+static int sifive_serial_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void sifive_serial_config_port(struct uart_port *port, int flags)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	ssp->port.type = PORT_SIFIVE_V0;
+}
+
+static int sifive_serial_verify_port(struct uart_port *port,
+				     struct serial_struct *ser)
+{
+	return -EINVAL;
+}
+
+static const char *sifive_serial_type(struct uart_port *port)
+{
+	return port->type == PORT_SIFIVE_V0 ? "SiFive UART v0" : NULL;
+}
+
+/*
+ * Early console support
+ */
+
+#ifdef CONFIG_SERIAL_EARLYCON
+static void early_sifive_serial_putc(struct uart_port *port, int c)
+{
+	while (__ssp_early_readl(port, SIFIVE_SERIAL_TXDATA_OFFS) &
+	       SIFIVE_SERIAL_TXDATA_FULL_MASK)
+		cpu_relax();
+
+	__ssp_early_writel(c, SIFIVE_SERIAL_TXDATA_OFFS, port);
+}
+
+static void early_sifive_serial_write(struct console *con, const char *s,
+				      unsigned int n)
+{
+	struct earlycon_device *dev = con->data;
+	struct uart_port *port = &dev->port;
+
+	uart_console_write(port, s, n, early_sifive_serial_putc);
+}
+
+static int __init early_sifive_serial_setup(struct earlycon_device *dev,
+					    const char *options)
+{
+	struct uart_port *port = &dev->port;
+
+	if (!port->membase)
+		return -ENODEV;
+
+	dev->con->write = early_sifive_serial_write;
+
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(sifive, "sifive,uart0", early_sifive_serial_setup);
+OF_EARLYCON_DECLARE(sifive, "sifive,fu540-c000-uart0",
+		    early_sifive_serial_setup);
+#endif /* CONFIG_SERIAL_EARLYCON */
+
+/*
+ * Linux console interface
+ */
+
+#ifdef CONFIG_SERIAL_SIFIVE_CONSOLE
+
+static struct sifive_serial_port *sifive_serial_console_ports[SIFIVE_SERIAL_MAX_PORTS];
+
+static void sifive_serial_console_putchar(struct uart_port *port, int ch)
+{
+	struct sifive_serial_port *ssp = port_to_sifive_serial_port(port);
+
+	__ssp_wait_for_xmitr(ssp);
+	__ssp_transmit_char(ssp, ch);
+}
+
+static void sifive_serial_console_write(struct console *co, const char *s,
+					unsigned int count)
+{
+	struct sifive_serial_port *ssp = sifive_serial_console_ports[co->index];
+	unsigned long flags;
+	unsigned int ier;
+	int locked = 1;
+
+	if (!ssp)
+		return;
+
+	local_irq_save(flags);
+	if (ssp->port.sysrq)
+		locked = 0;
+	else if (oops_in_progress)
+		locked = spin_trylock(&ssp->port.lock);
+	else
+		spin_lock(&ssp->port.lock);
+
+	ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
+	__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	uart_console_write(&ssp->port, s, count, sifive_serial_console_putchar);
+
+	__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	if (locked)
+		spin_unlock(&ssp->port.lock);
+	local_irq_restore(flags);
+}
+
+static int __init sifive_serial_console_setup(struct console *co, char *options)
+{
+	struct sifive_serial_port *ssp;
+	int baud = SIFIVE_DEFAULT_BAUD_RATE;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index < 0 || co->index >= SIFIVE_SERIAL_MAX_PORTS)
+		return -ENODEV;
+
+	ssp = sifive_serial_console_ports[co->index];
+	if (!ssp)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(&ssp->port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver sifive_serial_uart_driver;
+
+static struct console sifive_serial_console = {
+	.name		= SIFIVE_TTY_PREFIX,
+	.write		= sifive_serial_console_write,
+	.device		= uart_console_device,
+	.setup		= sifive_serial_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &sifive_serial_uart_driver,
+};
+
+static int __init sifive_console_init(void)
+{
+	register_console(&sifive_serial_console);
+	return 0;
+}
+
+console_initcall(sifive_console_init);
+
+static void __ssp_add_console_port(struct sifive_serial_port *ssp)
+{
+	sifive_serial_console_ports[ssp->port.line] = ssp;
+}
+
+static void __ssp_remove_console_port(struct sifive_serial_port *ssp)
+{
+	sifive_serial_console_ports[ssp->port.line] = 0;
+}
+
+#define SIFIVE_SERIAL_CONSOLE	(&sifive_serial_console)
+
+#else
+
+#define SIFIVE_SERIAL_CONSOLE	NULL
+
+static void __ssp_add_console_port(struct sifive_serial_port *ssp)
+{}
+static void __ssp_remove_console_port(struct sifive_serial_port *ssp)
+{}
+
+#endif
+
+static const struct uart_ops sifive_serial_uops = {
+	.tx_empty	= sifive_serial_tx_empty,
+	.set_mctrl	= sifive_serial_set_mctrl,
+	.get_mctrl	= sifive_serial_get_mctrl,
+	.stop_tx	= sifive_serial_stop_tx,
+	.start_tx	= sifive_serial_start_tx,
+	.stop_rx	= sifive_serial_stop_rx,
+	.break_ctl	= sifive_serial_break_ctl,
+	.startup	= sifive_serial_startup,
+	.shutdown	= sifive_serial_shutdown,
+	.set_termios	= sifive_serial_set_termios,
+	.type		= sifive_serial_type,
+	.release_port	= sifive_serial_release_port,
+	.request_port	= sifive_serial_request_port,
+	.config_port	= sifive_serial_config_port,
+	.verify_port	= sifive_serial_verify_port,
+};
+
+static struct uart_driver sifive_serial_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= SIFIVE_SERIAL_NAME,
+	.dev_name	= SIFIVE_TTY_PREFIX,
+	.nr		= SIFIVE_SERIAL_MAX_PORTS,
+	.cons		= SIFIVE_SERIAL_CONSOLE,
+};
+
+static int sifive_serial_probe(struct platform_device *pdev)
+{
+	struct sifive_serial_port *ssp;
+	struct resource *mem;
+	struct clk *clk;
+	void __iomem *base;
+	int irq, id, r;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "could not acquire interrupt\n");
+		return -EPROBE_DEFER;
+	}
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(base)) {
+		dev_err(&pdev->dev, "could not acquire device memory\n");
+		return PTR_ERR(base);
+	}
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "unable to find controller clock\n");
+		return PTR_ERR(clk);
+	}
+
+	id = of_alias_get_id(pdev->dev.of_node, "serial");
+	if (id < 0) {
+		dev_err(&pdev->dev, "missing aliases entry\n");
+		return id;
+	}
+
+#ifdef CONFIG_SERIAL_SIFIVE_CONSOLE
+	if (id > SIFIVE_SERIAL_MAX_PORTS) {
+		dev_err(&pdev->dev, "too many UARTs (%d)\n", id);
+		return -EINVAL;
+	}
+#endif
+
+	ssp = devm_kzalloc(&pdev->dev, sizeof(*ssp), GFP_KERNEL);
+	if (!ssp)
+		return -ENOMEM;
+
+	ssp->port.dev = &pdev->dev;
+	ssp->port.type = PORT_SIFIVE_V0;
+	ssp->port.iotype = UPIO_MEM;
+	ssp->port.irq = irq;
+	ssp->port.fifosize = SIFIVE_TX_FIFO_DEPTH;
+	ssp->port.ops = &sifive_serial_uops;
+	ssp->port.line = id;
+	ssp->port.mapbase = mem->start;
+	ssp->port.membase = base;
+	ssp->dev = &pdev->dev;
+	ssp->clk = clk;
+	ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
+
+	r = clk_notifier_register(ssp->clk, &ssp->clk_notifier);
+	if (r) {
+		dev_err(&pdev->dev, "could not register clock notifier: %d\n",
+			r);
+		goto probe_out1;
+	}
+
+	/* Set up clock divider */
+	ssp->clkin_rate = clk_get_rate(ssp->clk);
+	ssp->baud_rate = SIFIVE_DEFAULT_BAUD_RATE;
+	__ssp_update_div(ssp);
+
+	platform_set_drvdata(pdev, ssp);
+
+	/* Enable transmits and set the watermark level to 1 */
+	__ssp_writel((1 << SIFIVE_SERIAL_TXCTRL_TXCNT_SHIFT) |
+		     SIFIVE_SERIAL_TXCTRL_TXEN_MASK,
+		     SIFIVE_SERIAL_TXCTRL_OFFS, ssp);
+
+	/* Enable receives and set the watermark level to 0 */
+	__ssp_writel((0 << SIFIVE_SERIAL_RXCTRL_RXCNT_SHIFT) |
+		     SIFIVE_SERIAL_RXCTRL_RXEN_MASK,
+		     SIFIVE_SERIAL_RXCTRL_OFFS, ssp);
+
+	r = request_irq(ssp->port.irq, sifive_serial_irq, ssp->port.irqflags,
+			dev_name(&pdev->dev), ssp);
+	if (r) {
+		dev_err(&pdev->dev, "could not attach interrupt: %d\n", r);
+		goto probe_out2;
+	}
+
+	__ssp_add_console_port(ssp);
+
+	r = uart_add_one_port(&sifive_serial_uart_driver, &ssp->port);
+	if (r != 0) {
+		dev_err(&pdev->dev, "could not add uart: %d\n", r);
+		goto probe_out3;
+	}
+
+	return 0;
+
+probe_out3:
+	__ssp_remove_console_port(ssp);
+	free_irq(ssp->port.irq, ssp);
+probe_out2:
+	clk_notifier_unregister(ssp->clk, &ssp->clk_notifier);
+probe_out1:
+	return r;
+}
+
+static int sifive_serial_remove(struct platform_device *dev)
+{
+	struct sifive_serial_port *ssp = platform_get_drvdata(dev);
+
+	__ssp_remove_console_port(ssp);
+	uart_remove_one_port(&sifive_serial_uart_driver, &ssp->port);
+	free_irq(ssp->port.irq, ssp);
+	clk_notifier_unregister(ssp->clk, &ssp->clk_notifier);
+
+	return 0;
+}
+
+static const struct of_device_id sifive_serial_of_match[] = {
+	{ .compatible = "sifive,fu540-c000-uart0" },
+	{ .compatible = "sifive,uart0" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sifive_serial_of_match);
+
+static struct platform_driver sifive_serial_platform_driver = {
+	.probe		= sifive_serial_probe,
+	.remove		= sifive_serial_remove,
+	.driver		= {
+		.name	= SIFIVE_SERIAL_NAME,
+		.of_match_table = of_match_ptr(sifive_serial_of_match),
+	},
+};
+
+static int __init sifive_serial_init(void)
+{
+	int r;
+
+	r = uart_register_driver(&sifive_serial_uart_driver);
+	if (r)
+		goto init_out1;
+
+	r = platform_driver_register(&sifive_serial_platform_driver);
+	if (r)
+		goto init_out2;
+
+	return 0;
+
+init_out2:
+	uart_unregister_driver(&sifive_serial_uart_driver);
+init_out1:
+	return r;
+}
+
+static void __exit sifive_serial_exit(void)
+{
+	platform_driver_unregister(&sifive_serial_platform_driver);
+	uart_unregister_driver(&sifive_serial_uart_driver);
+}
+
+module_init(sifive_serial_init);
+module_exit(sifive_serial_exit);
+
+MODULE_DESCRIPTION("SiFive UART serial driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Paul Walmsley <[e-mail]>");

drivers/tty/serial/sn_console.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * C-Brick Serial Port (and console) driver for SGI Altix machines.
  *

drivers/tty/serial/sprd_serial.c

···
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma/sprd-dma.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
···
 
 /* control register 1 */
 #define SPRD_CTL1		0x001C
+#define SPRD_DMA_EN		BIT(15)
 #define RX_HW_FLOW_CTL_THLD	BIT(6)
 #define RX_HW_FLOW_CTL_EN	BIT(7)
 #define TX_HW_FLOW_CTL_EN	BIT(8)
···
 #define THLD_TX_EMPTY		0x40
 #define THLD_TX_EMPTY_SHIFT	8
 #define THLD_RX_FULL		0x40
+#define THLD_RX_FULL_MASK	GENMASK(6, 0)
 
 /* config baud rate register */
 #define SPRD_CLKD0		0x0024
···
 #define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
 #define SPRD_IMSR_BREAK_DETECT	BIT(7)
 #define SPRD_IMSR_TIMEOUT	BIT(13)
+#define SPRD_DEFAULT_SOURCE_CLK	26000000
+
+#define SPRD_RX_DMA_STEP	1
+#define SPRD_RX_FIFO_FULL	1
+#define SPRD_TX_FIFO_FULL	0x20
+#define SPRD_UART_RX_SIZE	(UART_XMIT_SIZE / 4)
+
+struct sprd_uart_dma {
+	struct dma_chan *chn;
+	unsigned char *virt;
+	dma_addr_t phys_addr;
+	dma_cookie_t cookie;
+	u32 trans_len;
+	bool enable;
+};
 
 struct sprd_uart_port {
 	struct uart_port port;
 	char name[16];
+	struct clk *clk;
+	struct sprd_uart_dma tx_dma;
+	struct sprd_uart_dma rx_dma;
+	dma_addr_t pos;
+	unsigned char *rx_buf_tail;
 };
 
 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
 static int sprd_ports_num;
+
+static int sprd_start_dma_rx(struct uart_port *port);
+static int sprd_tx_dma_config(struct uart_port *port);
 
 static inline unsigned int serial_in(struct uart_port *port,
 				     unsigned int offset)
···
 	/* nothing to do */
 }
 
-static void sprd_stop_tx(struct uart_port *port)
-{
-	unsigned int ien, iclr;
-
-	iclr = serial_in(port, SPRD_ICLR);
-	ien = serial_in(port, SPRD_IEN);
-
-	iclr |= SPRD_IEN_TX_EMPTY;
-	ien &= ~SPRD_IEN_TX_EMPTY;
-
-	serial_out(port, SPRD_ICLR, iclr);
-	serial_out(port, SPRD_IEN, ien);
-}
-
-static void sprd_start_tx(struct uart_port *port)
-{
-	unsigned int ien;
-
-	ien = serial_in(port, SPRD_IEN);
-	if (!(ien & SPRD_IEN_TX_EMPTY)) {
-		ien |= SPRD_IEN_TX_EMPTY;
-		serial_out(port, SPRD_IEN, ien);
-	}
-}
-
 static void sprd_stop_rx(struct uart_port *port)
 {
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
 	unsigned int ien, iclr;
+
+	if (sp->rx_dma.enable)
+		dmaengine_terminate_all(sp->rx_dma.chn);
 
 	iclr = serial_in(port, SPRD_ICLR);
 	ien = serial_in(port, SPRD_IEN);
···
 
 	serial_out(port, SPRD_IEN, ien);
 	serial_out(port, SPRD_ICLR, iclr);
+}
+
+static void sprd_uart_dma_enable(struct uart_port *port, bool enable)
+{
+	u32 val = serial_in(port, SPRD_CTL1);
+
+	if (enable)
+		val |= SPRD_DMA_EN;
+	else
+		val &= ~SPRD_DMA_EN;
+
+	serial_out(port, SPRD_CTL1, val);
+}
+
+static void sprd_stop_tx_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+	struct dma_tx_state state;
+	u32 trans_len;
+
+	dmaengine_pause(sp->tx_dma.chn);
+
+	dmaengine_tx_status(sp->tx_dma.chn, sp->tx_dma.cookie, &state);
+	if (state.residue) {
+		trans_len = state.residue - sp->tx_dma.phys_addr;
+		xmit->tail = (xmit->tail + trans_len) & (UART_XMIT_SIZE - 1);
+		port->icount.tx += trans_len;
+		dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
+				 sp->tx_dma.trans_len, DMA_TO_DEVICE);
+	}
+
+	dmaengine_terminate_all(sp->tx_dma.chn);
+	sp->tx_dma.trans_len = 0;
+}
+
+static int sprd_tx_buf_remap(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+
+	sp->tx_dma.trans_len =
+		CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+	sp->tx_dma.phys_addr = dma_map_single(port->dev,
+					      (void *)&(xmit->buf[xmit->tail]),
+					      sp->tx_dma.trans_len,
+					      DMA_TO_DEVICE);
+	return dma_mapping_error(port->dev, sp->tx_dma.phys_addr);
+}
+
+static void sprd_complete_tx_dma(void *data)
+{
+	struct uart_port *port = (struct uart_port *)data;
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
+			 sp->tx_dma.trans_len, DMA_TO_DEVICE);
+
+	xmit->tail = (xmit->tail + sp->tx_dma.trans_len) & (UART_XMIT_SIZE - 1);
+	port->icount.tx += sp->tx_dma.trans_len;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit) || sprd_tx_buf_remap(port) ||
+	    sprd_tx_dma_config(port))
+		sp->tx_dma.trans_len = 0;
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int sprd_uart_dma_submit(struct uart_port *port,
+				struct sprd_uart_dma *ud, u32 trans_len,
+				enum dma_transfer_direction direction,
+				dma_async_tx_callback callback)
+{
+	struct dma_async_tx_descriptor *dma_des;
+	unsigned long flags;
+
+	flags = SPRD_DMA_FLAGS(SPRD_DMA_CHN_MODE_NONE,
+			       SPRD_DMA_NO_TRG,
+			       SPRD_DMA_FRAG_REQ,
+			       SPRD_DMA_TRANS_INT);
+
+	dma_des = dmaengine_prep_slave_single(ud->chn, ud->phys_addr, trans_len,
+					      direction, flags);
+	if (!dma_des)
+		return -ENODEV;
+
+	dma_des->callback = callback;
+	dma_des->callback_param = port;
+
+	ud->cookie = dmaengine_submit(dma_des);
+	if (dma_submit_error(ud->cookie))
+		return dma_submit_error(ud->cookie);
+
+	dma_async_issue_pending(ud->chn);
+
+	return 0;
+}
+
+static int sprd_tx_dma_config(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	u32 burst = sp->tx_dma.trans_len > SPRD_TX_FIFO_FULL ?
+		SPRD_TX_FIFO_FULL : sp->tx_dma.trans_len;
+	int ret;
+	struct dma_slave_config cfg = {
+		.dst_addr = port->mapbase + SPRD_TXD,
+		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.src_maxburst = burst,
+	};
+
+	ret = dmaengine_slave_config(sp->tx_dma.chn, &cfg);
+	if (ret < 0)
+		return ret;
+
+	return sprd_uart_dma_submit(port, &sp->tx_dma, sp->tx_dma.trans_len,
+				    DMA_MEM_TO_DEV, sprd_complete_tx_dma);
+}
+
+static void sprd_start_tx_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct circ_buf *xmit = &port->state->xmit;
+
+	if (port->x_char) {
+		serial_out(port, SPRD_TXD, port->x_char);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		sprd_stop_tx_dma(port);
+		return;
+	}
+
+	if (sp->tx_dma.trans_len)
+		return;
+
+	if (sprd_tx_buf_remap(port) || sprd_tx_dma_config(port))
+		sp->tx_dma.trans_len = 0;
+}
+
+static void sprd_rx_full_thld(struct uart_port *port, u32 thld)
+{
+	u32 val = serial_in(port, SPRD_CTL2);
+
+	val &= ~THLD_RX_FULL_MASK;
+	val |= thld & THLD_RX_FULL_MASK;
+	serial_out(port, SPRD_CTL2, val);
+}
+
+static int sprd_rx_alloc_buf(struct sprd_uart_port *sp)
+{
+	sp->rx_dma.virt = dma_alloc_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
+					     &sp->rx_dma.phys_addr, GFP_KERNEL);
+	if (!sp->rx_dma.virt)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void sprd_rx_free_buf(struct sprd_uart_port *sp)
+{
+	if (sp->rx_dma.virt)
+		dma_free_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
+				  sp->rx_dma.virt, sp->rx_dma.phys_addr);
+
+}
+
+static int sprd_rx_dma_config(struct uart_port *port, u32 burst)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_slave_config cfg = {
+		.src_addr = port->mapbase + SPRD_RXD,
+		.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.src_maxburst = burst,
+	};
+
+	return dmaengine_slave_config(sp->rx_dma.chn, &cfg);
+}
+
+static void sprd_uart_dma_rx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct tty_port *tty = &port->state->port;
+
+	port->icount.rx += sp->rx_dma.trans_len;
+	tty_insert_flip_string(tty, sp->rx_buf_tail, sp->rx_dma.trans_len);
+	tty_flip_buffer_push(tty);
+}
+
+static void sprd_uart_dma_irq(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_tx_state state;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(sp->rx_dma.chn,
+				     sp->rx_dma.cookie, &state);
+	if (status == DMA_ERROR)
+		sprd_stop_rx(port);
+
+	if (!state.residue && sp->pos == sp->rx_dma.phys_addr)
+		return;
+
+	if (!state.residue) {
+		sp->rx_dma.trans_len = SPRD_UART_RX_SIZE +
+			sp->rx_dma.phys_addr - sp->pos;
+		sp->pos = sp->rx_dma.phys_addr;
+	} else {
+		sp->rx_dma.trans_len = state.residue - sp->pos;
+		sp->pos = state.residue;
+	}
+
+	sprd_uart_dma_rx(port);
+	sp->rx_buf_tail += sp->rx_dma.trans_len;
+}
+
+static void sprd_complete_rx_dma(void *data)
+{
+	struct uart_port *port = (struct uart_port *)data;
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	struct dma_tx_state state;
+	enum dma_status status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	status = dmaengine_tx_status(sp->rx_dma.chn,
+				     sp->rx_dma.cookie, &state);
+	if (status != DMA_COMPLETE) {
+		sprd_stop_rx(port);
+		spin_unlock_irqrestore(&port->lock, flags);
+		return;
+	}
+
+	if (sp->pos != sp->rx_dma.phys_addr) {
+		sp->rx_dma.trans_len =  SPRD_UART_RX_SIZE +
+			sp->rx_dma.phys_addr - sp->pos;
+		sprd_uart_dma_rx(port);
+		sp->rx_buf_tail += sp->rx_dma.trans_len;
+	}
+
+	if (sprd_start_dma_rx(port))
+		sprd_stop_rx(port);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int sprd_start_dma_rx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+	int ret;
+
+	if (!sp->rx_dma.enable)
+		return 0;
+
+	sp->pos = sp->rx_dma.phys_addr;
+	sp->rx_buf_tail = sp->rx_dma.virt;
+	sprd_rx_full_thld(port, SPRD_RX_FIFO_FULL);
+	ret = sprd_rx_dma_config(port, SPRD_RX_DMA_STEP);
+	if (ret)
+		return ret;
+
+	return sprd_uart_dma_submit(port, &sp->rx_dma, SPRD_UART_RX_SIZE,
+				    DMA_DEV_TO_MEM, sprd_complete_rx_dma);
+}
+
+static void sprd_release_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+
+	sprd_uart_dma_enable(port, false);
+
+	if (sp->rx_dma.enable)
+		dma_release_channel(sp->rx_dma.chn);
+
+	if (sp->tx_dma.enable)
+		dma_release_channel(sp->tx_dma.chn);
+
+	sp->tx_dma.enable = false;
+	sp->rx_dma.enable = false;
+}
+
+static void sprd_request_dma(struct uart_port *port)
+{
+	struct sprd_uart_port *sp =
+		container_of(port, struct sprd_uart_port, port);
+
+	sp->tx_dma.enable = true;
+	sp->rx_dma.enable = true;
+
+	sp->tx_dma.chn = dma_request_chan(port->dev, "tx");
+	if (IS_ERR(sp->tx_dma.chn)) {
+		dev_err(port->dev, "request TX DMA channel failed, ret = %ld\n",
+			PTR_ERR(sp->tx_dma.chn));
+		sp->tx_dma.enable = false;
+	}
+
+	sp->rx_dma.chn = dma_request_chan(port->dev, "rx");
+	if (IS_ERR(sp->rx_dma.chn)) {
+		dev_err(port->dev, "request RX DMA channel failed, ret = %ld\n",
+			PTR_ERR(sp->rx_dma.chn));
+		sp->rx_dma.enable = false;
+	}
+}
+
+static void sprd_stop_tx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
+	unsigned int ien, iclr;
+
+	if (sp->tx_dma.enable) {
+		sprd_stop_tx_dma(port);
+		return;
+	}
+
+	iclr = serial_in(port, SPRD_ICLR);
+	ien = serial_in(port, SPRD_IEN);
+
+	iclr |= SPRD_IEN_TX_EMPTY;
+	ien &= ~SPRD_IEN_TX_EMPTY;
+
+	serial_out(port, SPRD_IEN, ien);
+	serial_out(port, SPRD_ICLR, iclr);
+}
+
+static void sprd_start_tx(struct uart_port *port)
+{
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
+	unsigned int ien;
+
+	if (sp->tx_dma.enable) {
+		sprd_start_tx_dma(port);
+		return;
+	}
+
+	ien = serial_in(port, SPRD_IEN);
+	if (!(ien & SPRD_IEN_TX_EMPTY)) {
+		ien |= SPRD_IEN_TX_EMPTY;
+		serial_out(port, SPRD_IEN, ien);
+	}
 }
 
 /* The Sprd serial does not support this function. */
···
 
 static inline void sprd_rx(struct uart_port *port)
 {
+	struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
+						 port);
 	struct tty_port *tty = &port->state->port;
 	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
+
+	if (sp->rx_dma.enable) {
+		sprd_uart_dma_irq(port);
+		return;
+	}
 
 	while ((serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK) &&
 	       max_count--) {
···
 	return IRQ_HANDLED;
 }
 
+static void sprd_uart_dma_startup(struct uart_port *port,
+				  struct sprd_uart_port *sp)
+{
+	int ret;
+
+	sprd_request_dma(port);
+	if (!(sp->rx_dma.enable || sp->tx_dma.enable))
+		return;
+
+	ret = sprd_start_dma_rx(port);
+	if (ret) {
+		sp->rx_dma.enable = false;
+		dma_release_channel(sp->rx_dma.chn);
+		dev_warn(port->dev, "fail to start RX dma mode\n");
+	}
+
+	sprd_uart_dma_enable(port, true);
+}
+
 static int sprd_startup(struct uart_port *port)
 {
 	int ret = 0;
···
 	/* allocate irq */
 	sp = container_of(port, struct sprd_uart_port, port);
 	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
+
+	sprd_uart_dma_startup(port, sp);
+
 	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
 			       IRQF_SHARED, sp->name, port);
 	if (ret) {
···
 	/* enable interrupt */
 	spin_lock_irqsave(&port->lock, flags);
 	ien = serial_in(port, SPRD_IEN);
-	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
+	ien |= SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
+	if (!sp->rx_dma.enable)
+		ien |= SPRD_IEN_RX_FULL;
 	serial_out(port, SPRD_IEN, ien);
 	spin_unlock_irqrestore(&port->lock, flags);
 
···
 
 static void sprd_shutdown(struct uart_port *port)
 {
+	sprd_release_dma(port);
 	serial_out(port, SPRD_IEN, 0);
 	serial_out(port, SPRD_ICLR, ~0);
 	devm_free_irq(port->dev, port->irq, port);
···
 	return 0;
 }
 
+static void sprd_pm(struct uart_port *port, unsigned int state,
+		unsigned int oldstate)
+{
+	struct sprd_uart_port *sup =
+		container_of(port, struct sprd_uart_port, port);
+
+	switch (state) {
+	case UART_PM_STATE_ON:
+		clk_prepare_enable(sup->clk);
+		break;
+	case UART_PM_STATE_OFF:
+		clk_disable_unprepare(sup->clk);
+		break;
+	}
+}
+
 static const struct uart_ops serial_sprd_ops = {
 	.tx_empty = sprd_tx_empty,
 	.get_mctrl = sprd_get_mctrl,
···
 	.request_port = sprd_request_port,
 	.config_port = sprd_config_port,
 	.verify_port = sprd_verify_port,
+	.pm = sprd_pm,
 };
 
 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
···
 	if (!sprd_ports_num)
 		uart_unregister_driver(&sprd_uart_driver);
 
+	sprd_rx_free_buf(sup);
+
+	return 0;
+}
+
+static int sprd_clk_init(struct uart_port *uport)
+{
+	struct clk *clk_uart, *clk_parent;
+	struct sprd_uart_port *u = sprd_port[uport->line];
+
+	clk_uart = devm_clk_get(uport->dev, "uart");
+	if (IS_ERR(clk_uart)) {
+		dev_warn(uport->dev, "uart%d can't get uart clock\n",
+			 uport->line);
+		clk_uart = NULL;
+	}
+
+	clk_parent = devm_clk_get(uport->dev, "source");
+	if (IS_ERR(clk_parent)) {
+		dev_warn(uport->dev, "uart%d can't get source clock\n",
+			 uport->line);
+		clk_parent = NULL;
+	}
+
+	if (!clk_uart || clk_set_parent(clk_uart, clk_parent))
+		uport->uartclk = SPRD_DEFAULT_SOURCE_CLK;
+	else
+		uport->uartclk = clk_get_rate(clk_uart);
+
+	u->clk = devm_clk_get(uport->dev, "enable");
+	if (IS_ERR(u->clk)) {
+		if (PTR_ERR(u->clk) != -EPROBE_DEFER)
+			dev_err(uport->dev, "uart%d can't get enable clock\n",
+				uport->line);
+		return PTR_ERR(u->clk);
+	}
+
 	return 0;
 }
 
···
 {
 	struct resource *res;
 	struct uart_port *up;
-	struct clk *clk;
 	int irq;
 	int index;
 	int ret;
···
 	up->ops = &serial_sprd_ops;
 	up->flags = UPF_BOOT_AUTOCONF;
 
-	clk = devm_clk_get(&pdev->dev, NULL);
-	if (!IS_ERR_OR_NULL(clk))
-		up->uartclk = clk_get_rate(clk);
+	ret = sprd_clk_init(up);
+	if (ret)
+		return ret;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	up->membase = devm_ioremap_resource(&pdev->dev, res);
···
 		return irq;
 	}
 	up->irq = irq;
+
+	/*
+	 * Allocate one dma buffer to prepare for receive transfer, in case
+	 * memory allocation failure at runtime.
+	 */
+	ret = sprd_rx_alloc_buf(sprd_port[index]);
+	if (ret)
+		return ret;
 
 	if (!sprd_ports_num) {
 		ret = uart_register_driver(&sprd_uart_driver);

drivers/tty/serial/ucc_uart.c

···
 }
 /* UART operations
  *
- * Details on these functions can be found in Documentation/serial/driver
+ * Details on these functions can be found in Documentation/serial/driver.rst
  */
 static const struct uart_ops qe_uart_pops = {
 	.tx_empty       = qe_uart_tx_empty,

drivers/tty/serial/xilinx_uartps.c

···
 	int			id;
 	struct notifier_block	clk_rate_change_nb;
 	u32			quirks;
+	bool cts_override;
 };
 struct cdns_platform_data {
 	u32 quirks;
···
  */
 static unsigned int cdns_uart_get_mctrl(struct uart_port *port)
 {
+	struct cdns_uart *cdns_uart_data = port->private_data;
+
+	if (cdns_uart_data->cts_override)
+		return 0;
+
 	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 }
 
···
 {
 	u32 val;
 	u32 mode_reg;
+	struct cdns_uart *cdns_uart_data = port->private_data;
+
+	if (cdns_uart_data->cts_override)
+		return;
 
 	val = readl(port->membase + CDNS_UART_MODEMCR);
 	mode_reg = readl(port->membase + CDNS_UART_MR);
···
 		console_port = NULL;
 #endif
 
+	cdns_uart_data->cts_override = of_property_read_bool(pdev->dev.of_node,
+							     "cts-override");
 	return 0;
 
 err_out_pm_disable:

drivers/tty/sysrq.c

···
 #endif
 
 #ifdef CONFIG_SMP
-static DEFINE_SPINLOCK(show_lock);
+static DEFINE_RAW_SPINLOCK(show_lock);
 
 static void showacpu(void *dummy)
 {
···
 	if (idle_cpu(smp_processor_id()))
 		return;
 
-	spin_lock_irqsave(&show_lock, flags);
+	raw_spin_lock_irqsave(&show_lock, flags);
 	pr_info("CPU%d:\n", smp_processor_id());
 	show_stack(NULL, NULL);
-	spin_unlock_irqrestore(&show_lock, flags);
+	raw_spin_unlock_irqrestore(&show_lock, flags);
 }
 
 static void sysrq_showregs_othercpus(struct work_struct *dummy)

drivers/tty/tty_io.c

···
  *	tty_init_termios	-  helper for termios setup
  *	@tty: the tty to set up
  *
- *	Initialise the termios structures for this tty. Thus runs under
+ *	Initialise the termios structure for this tty. This runs under
  *	the tty_mutex currently so we can be relaxed about ordering.
  */
 

drivers/tty/tty_jobctrl.c

···
 	tty_pgrp = tty->pgrp;
 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
-	if (tty_pgrp && pgrp != tty->pgrp) {
+	if (tty_pgrp && pgrp != tty_pgrp) {
 		if (is_ignored(sig)) {
 			if (sig == SIGTTIN)
 				ret = -EIO;
···
 	read_unlock(&tasklist_lock);
 }
 
-/**
+/*
  *
  *	no_tty	- Ensure the current process does not have a controlling tty
  */

drivers/tty/tty_port.c

···
 		if (tty && C_HUPCL(tty))
 			tty_port_lower_dtr_rts(port);
 
-		if (port->ops && port->ops->shutdown)
+		if (port->ops->shutdown)
 			port->ops->shutdown(port);
 	}
 out:
···
  */
 int tty_port_carrier_raised(struct tty_port *port)
 {
-	if (!port->ops || !port->ops->carrier_raised)
+	if (port->ops->carrier_raised == NULL)
 		return 1;
 	return port->ops->carrier_raised(port);
 }
···
  */
 void tty_port_raise_dtr_rts(struct tty_port *port)
 {
-	if (port->ops && port->ops->dtr_rts)
+	if (port->ops->dtr_rts)
 		port->ops->dtr_rts(port, 1);
 }
 EXPORT_SYMBOL(tty_port_raise_dtr_rts);
···
  */
 void tty_port_lower_dtr_rts(struct tty_port *port)
 {
-	if (port->ops && port->ops->dtr_rts)
+	if (port->ops->dtr_rts)
 		port->ops->dtr_rts(port, 0);
 }
 EXPORT_SYMBOL(tty_port_lower_dtr_rts);
···
 
 	if (!tty_port_initialized(port)) {
 		clear_bit(TTY_IO_ERROR, &tty->flags);
-		if (port->ops && port->ops->activate) {
+		if (port->ops->activate) {
 			int retval = port->ops->activate(port, tty);
 			if (retval) {
 				mutex_unlock(&port->mutex);

drivers/tty/ttynull.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Axis Communications AB
+ *
+ * Based on ttyprintk.c:
+ *  Copyright (C) 2010 Samo Pogacnik
+ */
+
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+
+static const struct tty_port_operations ttynull_port_ops;
+static struct tty_driver *ttynull_driver;
+static struct tty_port ttynull_port;
+
+static int ttynull_open(struct tty_struct *tty, struct file *filp)
+{
+	return tty_port_open(&ttynull_port, tty, filp);
+}
+
+static void ttynull_close(struct tty_struct *tty, struct file *filp)
+{
+	tty_port_close(&ttynull_port, tty, filp);
+}
+
+static void ttynull_hangup(struct tty_struct *tty)
+{
+	tty_port_hangup(&ttynull_port);
+}
+
+static int ttynull_write(struct tty_struct *tty, const unsigned char *buf,
+			 int count)
+{
+	return count;
+}
+
+static int ttynull_write_room(struct tty_struct *tty)
+{
+	return 65536;
+}
+
+static const struct tty_operations ttynull_ops = {
+	.open = ttynull_open,
+	.close = ttynull_close,
+	.hangup = ttynull_hangup,
+	.write = ttynull_write,
+	.write_room = ttynull_write_room,
+};
+
+static struct tty_driver *ttynull_device(struct console *c, int *index)
+{
+	*index = 0;
+	return ttynull_driver;
+}
+
+static struct console ttynull_console = {
+	.name = "ttynull",
+	.device = ttynull_device,
+};
+
+static int __init ttynull_init(void)
+{
+	struct tty_driver *driver;
+	int ret;
+
+	driver = tty_alloc_driver(1,
+		TTY_DRIVER_RESET_TERMIOS |
+		TTY_DRIVER_REAL_RAW |
+		TTY_DRIVER_UNNUMBERED_NODE);
+	if (IS_ERR(driver))
+		return PTR_ERR(driver);
+
+	tty_port_init(&ttynull_port);
+	ttynull_port.ops = &ttynull_port_ops;
+
+	driver->driver_name = "ttynull";
+	driver->name = "ttynull";
+	driver->type = TTY_DRIVER_TYPE_CONSOLE;
+	driver->init_termios = tty_std_termios;
+	driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
+	tty_set_operations(driver, &ttynull_ops);
+	tty_port_link_device(&ttynull_port, driver, 0);
+
+	ret = tty_register_driver(driver);
+	if (ret < 0) {
+		put_tty_driver(driver);
+		tty_port_destroy(&ttynull_port);
+		return ret;
+	}
+
+	ttynull_driver = driver;
+	register_console(&ttynull_console);
+
+	return 0;
+}
+
+static void __exit ttynull_exit(void)
+{
+	unregister_console(&ttynull_console);
+	tty_unregister_driver(ttynull_driver);
+	put_tty_driver(ttynull_driver);
+	tty_port_destroy(&ttynull_port);
+}
+
+module_init(ttynull_init);
+module_exit(ttynull_exit);
+
+MODULE_LICENSE("GPL v2");

drivers/tty/vcc.c

···
+// SPDX-License-Identifier: GPL-2.0
 /* vcc.c: sun4v virtual channel concentrator
  *
  * Copyright (C) 2017 Oracle. All rights reserved.

drivers/tty/vt/.gitignore

···
+# SPDX-License-Identifier: GPL-2.0
 consolemap_deftbl.c
 defkeymap.c

drivers/tty/vt/consolemap.c

···
 	if (!ct)
 		return 0;
 
-	unilist = memdup_user(list, ct * sizeof(struct unipair));
+	unilist = vmemdup_user(list, ct * sizeof(struct unipair));
 	if (IS_ERR(unilist))
 		return PTR_ERR(unilist);
 
···
 
 out_unlock:
 	console_unlock();
-	kfree(unilist);
+	kvfree(unilist);
 	return err;
 }
 
···
 	struct uni_pagedir *p;
 	struct unipair *unilist;
 
-	unilist = kmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
+	unilist = kvmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
 	if (!unilist)
 		return -ENOMEM;
 
···
 	if (copy_to_user(list, unilist, min(ect, ct) * sizeof(struct unipair)))
 		ret = -EFAULT;
 	put_user(ect, uct);
-	kfree(unilist);
+	kvfree(unilist);
 	return ret ? ret : (ect <= ct) ? 0 : -ENOMEM;
 }
 

drivers/tty/vt/cp437.uni

···
+# SPDX-License-Identifier: GPL-2.0
 #
 # Unicode table for IBM Codepage 437.  Note that there are many more
 # substitutions that could be conceived (for example, thick-line

drivers/tty/vt/defkeymap.c_shipped

···
+// SPDX-License-Identifier: GPL-2.0
 /* Do not edit this file! It was automatically generated by   */
 /*    loadkeys --mktable defkeymap.map > defkeymap.c          */
 

drivers/tty/vt/defkeymap.map

···
+# SPDX-License-Identifier: GPL-2.0
 # Default kernel keymap. This uses 7 modifier combinations.
 keymaps 0-2,4-5,8,12
 # Change the above line into

drivers/tty/vt/keyboard.c

···
 static struct input_handler kbd_handler;
 static DEFINE_SPINLOCK(kbd_event_lock);
 static DEFINE_SPINLOCK(led_lock);
+static DEFINE_SPINLOCK(func_buf_lock); /* guard 'func_buf'  and friends */
 static unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];	/* keyboard key bitmap */
 static unsigned char shift_down[NR_SHIFT];		/* shift state counters.. */
 static bool dead_key_next;
···
 						KBD_UNICODE, &param);
 		if (rc != NOTIFY_STOP)
 			if (down && !raw_mode)
-				to_utf8(vc, keysym);
+				k_unicode(vc, keysym, !down);
 		return;
 	}
 
···
 	char *p;
 	u_char *q;
 	u_char __user *up;
-	int sz;
+	int sz, fnw_sz;
 	int delta;
 	char *first_free, *fj, *fnw;
 	int i, j, k;
 	int ret;
+	unsigned long flags;
 
 	if (!capable(CAP_SYS_TTY_CONFIG))
 		perm = 0;
···
 			goto reterr;
 		}
 
+		fnw = NULL;
+		fnw_sz = 0;
+		/* race aginst other writers */
+		again:
+		spin_lock_irqsave(&func_buf_lock, flags);
 		q = func_table[i];
+
+		/* fj pointer to next entry after 'q' */
 		first_free = funcbufptr + (funcbufsize - funcbufleft);
 		for (j = i+1; j < MAX_NR_FUNC && !func_table[j]; j++)
 			;
···
 			fj = func_table[j];
 		else
 			fj = first_free;
-
+		/* buffer usage increase by new entry */
 		delta = (q ? -strlen(q) : 1) + strlen(kbs->kb_string);
+
 		if (delta <= funcbufleft) { 	/* it fits in current buf */
 		    if (j < MAX_NR_FUNC) {
+			/* make enough space for new entry at 'fj' */
 			memmove(fj + delta, fj, first_free - fj);
 			for (k = j; k < MAX_NR_FUNC; k++)
 			    if (func_table[k])
···
 		    sz = 256;
 		    while (sz < funcbufsize - funcbufleft + delta)
 		      sz <<= 1;
-		    fnw = kmalloc(sz, GFP_KERNEL);
-		    if(!fnw) {
-		      ret = -ENOMEM;
-		      goto reterr;
+		    if (fnw_sz != sz) {
+		      spin_unlock_irqrestore(&func_buf_lock, flags);
+		      kfree(fnw);
+		      fnw = kmalloc(sz, GFP_KERNEL);
+		      fnw_sz = sz;
+		      if (!fnw) {
+			ret = -ENOMEM;
+			goto reterr;
+		      }
+		      goto again;
 		    }
 
 		    if (!q)
 		      func_table[i] = fj;
+		    /* copy data before insertion point to new location */
 		    if (fj > funcbufptr)
 			memmove(fnw, funcbufptr, fj - funcbufptr);
 		    for (k = 0; k < j; k++)
 		      if (func_table[k])
 			func_table[k] = fnw + (func_table[k] - funcbufptr);
 
+		    /* copy data after insertion point to new location */
 		    if (first_free > fj) {
 			memmove(fnw + (fj - funcbufptr) + delta, fj, first_free - fj);
 			for (k = j; k < MAX_NR_FUNC; k++)
···
 		    funcbufleft = funcbufleft - delta + sz - funcbufsize;
 		    funcbufsize = sz;
 		}
+		/* finally insert item itself */
 		strcpy(func_table[i], kbs->kb_string);
+		spin_unlock_irqrestore(&func_buf_lock, flags);
 		break;
 	}
 	ret = 0;

drivers/tty/vt/vc_screen.c

···
 // SPDX-License-Identifier: GPL-2.0
 /*
  * Provide access to virtual console memory.
- * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
+ * /dev/vcs: the screen as it is being viewed right now (possibly scrolled)
  * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
  *            [minor: N]
  *

drivers/tty/vt/vt.c

···
 		return;
 	}
 
-	if (blank_state != blank_normal_wait)
-		return;
 	blank_state = blank_off;
 
 	/* don't blank graphics */

include/linux/serial_core.h

···
 
 /*
  * This structure describes all the operations that can be done on the
- * physical hardware.  See Documentation/serial/driver for details.
+ * physical hardware.  See Documentation/serial/driver.rst for details.
  */
 struct uart_ops {
 	unsigned int	(*tx_empty)(struct uart_port *);

include/uapi/linux/serial_core.h

···
 /* RDA UART */
 #define PORT_RDA	118
 
+/* Socionext Milbeaut UART */
+#define PORT_MLB_USIO	119
+
+/* SiFive UART */
+#define PORT_SIFIVE_V0	120
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */