Merge tag 'tty-4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty and serial updates from Greg KH:
"Here is the big tty and serial patch set for 4.9-rc1.

It also includes some drivers/dma/ changes, as those were needed by
some serial drivers, and they were all acked by the DMA maintainer.

Also in here is the long-suffering ACPI SPCR patchset, which was
passed around from maintainer to maintainer like a hot-potato. Seems I
was the sucker^Wlucky one. All of those patches have been acked by the
various subsystem maintainers as well.

All of this has been in linux-next with no reported issues"

* tag 'tty-4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (111 commits)
Revert "serial: pl011: add console matching function"
MAINTAINERS: update entry for atmel_serial driver
serial: pl011: add console matching function
ARM64: ACPI: enable ACPI_SPCR_TABLE
ACPI: parse SPCR and enable matching console
of/serial: move earlycon early_param handling to serial
Revert "drivers/tty: Explicitly pass current to show_stack"
tty: amba-pl011: Don't complain on -EPROBE_DEFER when no irq
nios2: dts: 10m50: Add tx-threshold parameter
serial: 8250: Set Altera 16550 TX FIFO Threshold
serial: 8250: of: Load TX FIFO Threshold from DT
Documentation: dt: serial: Add TX FIFO threshold parameter
drivers/tty: Explicitly pass current to show_stack
serial: imx: Fix DCD reading
serial: stm32: mark symbols static where possible
serial: xuartps: Add some register initialisation to cdns_early_console_setup()
serial: xuartps: Removed unwanted checks while reading the error conditions
serial: xuartps: Rewrite the interrupt handling logic
serial: stm32: use mapbase instead of membase for DMA
tty/serial: atmel: fix fractional baud rate computation
...

Documentation/devicetree/bindings/serial/8250.txt

···
 - auto-flow-control: one way to enable automatic flow control support. The
   driver is allowed to detect support for the capability even without this
   property.
+- tx-threshold: Specify the TX FIFO low water indication for parts with
+  programmable TX FIFO thresholds.
 
 Note:
 * fsl,ns16550:

Documentation/devicetree/bindings/serial/st,stm32-usart.txt

···
+* STMicroelectronics STM32 USART
+
+Required properties:
+- compatible: Can be either "st,stm32-usart", "st,stm32-uart",
+"st,stm32f7-usart" or "st,stm32f7-uart" depending on whether
+the device supports synchronous mode and is compatible with
+stm32(f4) or stm32f7.
+- reg: The address and length of the peripheral registers space
+- interrupts: The interrupt line of the USART instance
+- clocks: The input clock of the USART instance
+
+Optional properties:
+- pinctrl: The reference on the pins configuration
+- st,hw-flow-ctrl: bool flag to enable hardware flow control.
+- dmas: phandle(s) to DMA controller node(s). Refer to stm32-dma.txt
+- dma-names: "rx" and/or "tx"
+
+Examples:
+usart4: serial@40004c00 {
+	compatible = "st,stm32-uart";
+	reg = <0x40004c00 0x400>;
+	interrupts = <52>;
+	clocks = <&clk_pclk1>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_usart4>;
+};
+
+usart2: serial@40004400 {
+	compatible = "st,stm32-usart", "st,stm32-uart";
+	reg = <0x40004400 0x400>;
+	interrupts = <38>;
+	clocks = <&clk_pclk1>;
+	st,hw-flow-ctrl;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_usart2 &pinctrl_usart2_rtscts>;
+};
+
+usart1: serial@40011000 {
+	compatible = "st,stm32-usart", "st,stm32-uart";
+	reg = <0x40011000 0x400>;
+	interrupts = <37>;
+	clocks = <&rcc 0 164>;
+	dmas = <&dma2 2 4 0x414 0x0>,
+	       <&dma2 7 4 0x414 0x0>;
+	dma-names = "rx", "tx";
+};

Documentation/kernel-parameters.txt

···
 			determined by the stdout-path property in device
 			tree's chosen node.
 
-		cdns,<addr>
-			Start an early, polled-mode console on a cadence serial
-			port at the specified address. The cadence serial port
-			must already be setup and configured. Options are not
-			yet supported.
+		cdns,<addr>[,options]
+			Start an early, polled-mode console on a Cadence
+			(xuartps) serial port at the specified address. Only
+			supported option is baud rate. If baud rate is not
+			specified, the serial port must already be setup and
+			configured.
 
 		uart[8250],io,<addr>[,options]
 		uart[8250],mmio,<addr>[,options]

MAINTAINERS

···
 S:	Maintained
 F:	drivers/mmc/host/atmel-mci.c
 
-ATMEL AT91 / AT32 SERIAL DRIVER
-M:	Nicolas Ferre <[e-mail]>
-S:	Supported
-F:	drivers/tty/serial/atmel_serial.c
-
 ATMEL AT91 SAMA5D2-Compatible Shutdown Controller
 M:	Nicolas Ferre <[e-mail]>
 S:	Supported
···
 T:	git git://git.monstr.eu/linux-2.6-microblaze.git
 S:	Supported
 F:	arch/microblaze/
+
+MICROCHIP / ATMEL AT91 / AT32 SERIAL DRIVER
+M:	Richard Genoud <[e-mail]>
+S:	Maintained
+F:	drivers/tty/serial/atmel_serial.c
+F:	include/linux/atmel_serial.h
 
 MICROSOFT SURFACE PRO 3 BUTTON DRIVER
 M:	Chen Yu <[e-mail]>

arch/arm64/Kconfig

···
 	select ACPI_GENERIC_GSI if ACPI
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
 	select ACPI_MCFG if ACPI
+	select ACPI_SPCR_TABLE if ACPI
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI

arch/arm64/kernel/acpi.c

···
 #include <linux/memblock.h>
 #include <linux/of_fdt.h>
 #include <linux/smp.h>
+#include <linux/serial_core.h>
 
 #include <asm/cputype.h>
 #include <asm/cpu_ops.h>
···
 	if (param_acpi_off ||
 	    (!param_acpi_on && !param_acpi_force &&
 	     of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
-		return;
+		goto done;
 
 	/*
 	 * ACPI is disabled at this point. Enable it in order to parse
···
 		pr_err("Failed to init ACPI tables\n");
 		if (!param_acpi_force)
 			disable_acpi();
+	}
+
+done:
+	if (acpi_disabled) {
+		if (earlycon_init_is_deferred)
+			early_init_dt_scan_chosen_stdout();
+	} else {
+		parse_spcr(earlycon_init_is_deferred);
 	}
 }
 

arch/nios2/boot/dts/10m50_devboard.dts

···
 			fifo-size = <32>;
 			reg-io-width = <4>;
 			reg-shift = <2>;
+			tx-threshold = <16>;
 		};
 
 		sysid: sysid@18001528 {

drivers/acpi/Kconfig

···
 
 endif
 
+config ACPI_SPCR_TABLE
+	bool
+
 config ACPI_SLEEP
 	bool
 	depends on SUSPEND || HIBERNATION

drivers/acpi/Makefile

···
 obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o
 obj-$(CONFIG_ACPI_BGRT)		+= bgrt.o
 obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_acpi.o
+obj-$(CONFIG_ACPI_SPCR_TABLE)	+= spcr.o
 obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
 
 # processor has its own "processor." module_param namespace

drivers/acpi/spcr.c

···
+/*
+ * Copyright (c) 2012, Intel Corporation
+ * Copyright (c) 2015, Red Hat, Inc.
+ * Copyright (c) 2015, 2016 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) "ACPI: SPCR: " fmt
+
+#include <linux/acpi.h>
+#include <linux/console.h>
+#include <linux/kernel.h>
+#include <linux/serial_core.h>
+
+/**
+ * parse_spcr() - parse ACPI SPCR table and add preferred console
+ *
+ * @earlycon: set up earlycon for the console specified by the table
+ *
+ * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
+ * defined to parse ACPI SPCR table.  As a result of the parsing preferred
+ * console is registered and if @earlycon is true, earlycon is set up.
+ *
+ * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
+ * from arch inintialization code as soon as the DT/ACPI decision is made.
+ *
+ */
+int __init parse_spcr(bool earlycon)
+{
+	static char opts[64];
+	struct acpi_table_spcr *table;
+	acpi_size table_size;
+	acpi_status status;
+	char *uart;
+	char *iotype;
+	int baud_rate;
+	int err;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	status = acpi_get_table_with_size(ACPI_SIG_SPCR, 0,
+					  (struct acpi_table_header **)&table,
+					  &table_size);
+
+	if (ACPI_FAILURE(status))
+		return -ENOENT;
+
+	if (table->header.revision < 2) {
+		err = -ENOENT;
+		pr_err("wrong table version\n");
+		goto done;
+	}
+
+	iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
+			"mmio" : "io";
+
+	switch (table->interface_type) {
+	case ACPI_DBG2_ARM_SBSA_32BIT:
+		iotype = "mmio32";
+		/* fall through */
+	case ACPI_DBG2_ARM_PL011:
+	case ACPI_DBG2_ARM_SBSA_GENERIC:
+	case ACPI_DBG2_BCM2835:
+		uart = "pl011";
+		break;
+	case ACPI_DBG2_16550_COMPATIBLE:
+	case ACPI_DBG2_16550_SUBSET:
+		uart = "uart";
+		break;
+	default:
+		err = -ENOENT;
+		goto done;
+	}
+
+	switch (table->baud_rate) {
+	case 3:
+		baud_rate = 9600;
+		break;
+	case 4:
+		baud_rate = 19200;
+		break;
+	case 6:
+		baud_rate = 57600;
+		break;
+	case 7:
+		baud_rate = 115200;
+		break;
+	default:
+		err = -ENOENT;
+		goto done;
+	}
+
+	snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
+		 table->serial_port.address, baud_rate);
+
+	pr_info("console: %s\n", opts);
+
+	if (earlycon)
+		setup_earlycon(opts);
+
+	err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
+
+done:
+	early_acpi_os_unmap_memory((void __iomem *)table, table_size);
+	return err;
+}

drivers/dma/dw/core.c

···
 		u8 _dmsize = _is_slave ? _sconfig->dst_maxburst :	\
 			DW_DMA_MSIZE_16;			\
 		u8 _dms = (_dwc->direction == DMA_MEM_TO_DEV) ?		\
-			_dwc->p_master : _dwc->m_master;		\
+			_dwc->dws.p_master : _dwc->dws.m_master;	\
 		u8 _sms = (_dwc->direction == DMA_DEV_TO_MEM) ?		\
-			_dwc->p_master : _dwc->m_master;		\
+			_dwc->dws.p_master : _dwc->dws.m_master;	\
 								\
 		(DWC_CTLL_DST_MSIZE(_dmsize)			\
 		 | DWC_CTLL_SRC_MSIZE(_smsize)			\
···
 	struct dw_dma *dw = to_dw_dma(dwc->chan.device);
 	u32 cfghi = DWC_CFGH_FIFO_MODE;
 	u32 cfglo = DWC_CFGL_CH_PRIOR(dwc->priority);
+	bool hs_polarity = dwc->dws.hs_polarity;
 
 	if (test_bit(DW_DMA_IS_INITIALIZED, &dwc->flags))
 		return;
 
-	cfghi |= DWC_CFGH_DST_PER(dwc->dst_id);
-	cfghi |= DWC_CFGH_SRC_PER(dwc->src_id);
+	cfghi |= DWC_CFGH_DST_PER(dwc->dws.dst_id);
+	cfghi |= DWC_CFGH_SRC_PER(dwc->dws.src_id);
+
+	/* Set polarity of handshake interface */
+	cfglo |= hs_polarity ? DWC_CFGL_HS_DST_POL | DWC_CFGL_HS_SRC_POL : 0;
 
 	channel_writel(dwc, CFG_LO, cfglo);
 	channel_writel(dwc, CFG_HI, cfghi);
···
 static void dwc_dostart(struct dw_dma_chan *dwc, struct dw_desc *first)
 {
 	struct dw_dma	*dw = to_dw_dma(dwc->chan.device);
-	u8		lms = DWC_LLP_LMS(dwc->m_master);
+	u8		lms = DWC_LLP_LMS(dwc->dws.m_master);
 	unsigned long	was_soft_llp;
 
 	/* ASSERT:  channel is idle */
···
 	struct dw_desc		*prev;
 	size_t			xfer_count;
 	size_t			offset;
-	u8			m_master = dwc->m_master;
+	u8			m_master = dwc->dws.m_master;
 	unsigned int		src_width;
 	unsigned int		dst_width;
 	unsigned int		data_width = dw->pdata->data_width[m_master];
···
 	struct dw_desc		*prev;
 	struct dw_desc		*first;
 	u32			ctllo;
-	u8			m_master = dwc->m_master;
+	u8			m_master = dwc->dws.m_master;
 	u8			lms = DWC_LLP_LMS(m_master);
 	dma_addr_t		reg;
 	unsigned int		reg_width;
···
 		return false;
 
 	/* We have to copy data since dws can be temporary storage */
-
-	dwc->src_id = dws->src_id;
-	dwc->dst_id = dws->dst_id;
-
-	dwc->m_master = dws->m_master;
-	dwc->p_master = dws->p_master;
+	memcpy(&dwc->dws, dws, sizeof(struct dw_dma_slave));
 
 	return true;
 }
···
 	spin_lock_irqsave(&dwc->lock, flags);
 
 	/* Clear custom channel configuration */
-	dwc->src_id = 0;
-	dwc->dst_id = 0;
-
-	dwc->m_master = 0;
-	dwc->p_master = 0;
+	memset(&dwc->dws, 0, sizeof(struct dw_dma_slave));
 
 	clear_bit(DW_DMA_IS_INITIALIZED, &dwc->flags);
 
···
 	struct dw_cyclic_desc		*retval = NULL;
 	struct dw_desc			*desc;
 	struct dw_desc			*last = NULL;
-	u8				lms = DWC_LLP_LMS(dwc->m_master);
+	u8				lms = DWC_LLP_LMS(dwc->dws.m_master);
 	unsigned long			was_cyclic;
 	unsigned int			reg_width;
 	unsigned int			periods;
···
 				(dwc_params >> DWC_PARAMS_MBLK_EN & 0x1) == 0;
 		} else {
 			dwc->block_size = pdata->block_size;
-
-			/* Check if channel supports multi block transfer */
-			channel_writel(dwc, LLP, DWC_LLP_LOC(0xffffffff));
-			dwc->nollp = DWC_LLP_LOC(channel_readl(dwc, LLP)) == 0;
-			channel_writel(dwc, LLP, 0);
+			dwc->nollp = pdata->is_nollp;
 		}
 	}
 

drivers/dma/dw/regs.h

···
 	bool			nollp;
 
 	/* custom slave configuration */
-	u8			src_id;
-	u8			dst_id;
-	u8			m_master;
-	u8			p_master;
+	struct dw_dma_slave	dws;
 
 	/* configuration passed via .device_config */
 	struct dma_slave_config dma_sconfig;

drivers/dma/hsu/hsu.c

···
  *      is not a normal timeout interrupt, ie. hsu_dma_get_status() returned 0.
  *
  *      Return:
- *      IRQ_NONE for invalid channel number, IRQ_HANDLED otherwise.
+ *      0 for invalid channel number, 1 otherwise.
  */
-irqreturn_t hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr,
-			   u32 status)
+int hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr, u32 status)
 {
 	struct hsu_dma_chan *hsuc;
 	struct hsu_dma_desc *desc;
···
 
 	/* Sanity check */
 	if (nr >= chip->hsu->nr_channels)
-		return IRQ_NONE;
+		return 0;
 
 	hsuc = &chip->hsu->chan[nr];
 
···
 	}
 	spin_unlock_irqrestore(&hsuc->vchan.lock, flags);
 
-	return IRQ_HANDLED;
+	return 1;
 }
 EXPORT_SYMBOL_GPL(hsu_dma_do_irq);
 

drivers/dma/hsu/pci.c

···
 	u32 dmaisr;
 	u32 status;
 	unsigned short i;
-	irqreturn_t ret = IRQ_NONE;
+	int ret = 0;
 	int err;
 
 	dmaisr = readl(chip->regs + HSU_PCI_DMAISR);
···
 		if (dmaisr & 0x1) {
 			err = hsu_dma_get_status(chip, i, &status);
 			if (err > 0)
-				ret |= IRQ_HANDLED;
+				ret |= 1;
 			else if (err == 0)
 				ret |= hsu_dma_do_irq(chip, i, status);
 		}
 		dmaisr >>= 1;
 	}
 
-	return ret;
+	return IRQ_RETVAL(ret);
 }
 
 static int hsu_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)

drivers/dma/imx-sdma.c

···
 	writel_relaxed(val, sdma->regs + chnenbl);
 }
 
-static void sdma_handle_channel_loop(struct sdma_channel *sdmac)
-{
-	if (sdmac->desc.callback)
-		sdmac->desc.callback(sdmac->desc.callback_param);
-}
-
 static void sdma_update_channel_loop(struct sdma_channel *sdmac)
 {
 	struct sdma_buffer_descriptor *bd;
+	int error = 0;
+	enum dma_status	old_status = sdmac->status;
 
 	/*
 	 * loop mode. Iterate over descriptors, re-setup them and
···
 		if (bd->mode.status & BD_DONE)
 			break;
 
-		if (bd->mode.status & BD_RROR)
+		if (bd->mode.status & BD_RROR) {
+			bd->mode.status &= ~BD_RROR;
 			sdmac->status = DMA_ERROR;
+			error = -EIO;
+		}
 
+	       /*
+		* We use bd->mode.count to calculate the residue, since contains
+		* the number of bytes present in the current buffer descriptor.
+		*/
+
+		sdmac->chn_real_count = bd->mode.count;
 		bd->mode.status |= BD_DONE;
+		bd->mode.count = sdmac->period_len;
+
+		/*
+		 * The callback is called from the interrupt context in order
+		 * to reduce latency and to avoid the risk of altering the
+		 * SDMA transaction status by the time the client tasklet is
+		 * executed.
+		 */
+
+		if (sdmac->desc.callback)
+			sdmac->desc.callback(sdmac->desc.callback_param);
+
 		sdmac->buf_tail++;
 		sdmac->buf_tail %= sdmac->num_bd;
+
+		if (error)
+			sdmac->status = old_status;
 	}
 }
 
-static void mxc_sdma_handle_channel_normal(struct sdma_channel *sdmac)
+static void mxc_sdma_handle_channel_normal(unsigned long data)
 {
+	struct sdma_channel *sdmac = (struct sdma_channel *) data;
 	struct sdma_buffer_descriptor *bd;
 	int i, error = 0;
 
···
 		sdmac->desc.callback(sdmac->desc.callback_param);
 }
 
-static void sdma_tasklet(unsigned long data)
-{
-	struct sdma_channel *sdmac = (struct sdma_channel *) data;
-
-	if (sdmac->flags & IMX_DMA_SG_LOOP)
-		sdma_handle_channel_loop(sdmac);
-	else
-		mxc_sdma_handle_channel_normal(sdmac);
-}
-
 static irqreturn_t sdma_int_handler(int irq, void *dev_id)
 {
 	struct sdma_engine *sdma = dev_id;
···
 
 		if (sdmac->flags & IMX_DMA_SG_LOOP)
 			sdma_update_channel_loop(sdmac);
-
-		tasklet_schedule(&sdmac->tasklet);
+		else
+			tasklet_schedule(&sdmac->tasklet);
 
 		__clear_bit(channel, &stat);
 	}
···
 	u32 residue;
 
 	if (sdmac->flags & IMX_DMA_SG_LOOP)
-		residue = (sdmac->num_bd - sdmac->buf_tail) * sdmac->period_len;
+		residue = (sdmac->num_bd - sdmac->buf_tail) *
+			   sdmac->period_len - sdmac->chn_real_count;
 	else
 		residue = sdmac->chn_count - sdmac->chn_real_count;
 
···
 		dma_cookie_init(&sdmac->chan);
 		sdmac->channel = i;
 
-		tasklet_init(&sdmac->tasklet, sdma_tasklet,
+		tasklet_init(&sdmac->tasklet, mxc_sdma_handle_channel_normal,
 			     (unsigned long) sdmac);
 		/*
 		 * Add the channel to the DMAC list. Do not add channel 0 though

drivers/of/fdt.c

···
 
 #ifdef CONFIG_SERIAL_EARLYCON
 
-static int __init early_init_dt_scan_chosen_serial(void)
+int __init early_init_dt_scan_chosen_stdout(void)
 {
 	int offset;
 	const char *p, *q, *options = NULL;
···
 	}
 	return -ENODEV;
 }
-
-static int __init setup_of_earlycon(char *buf)
-{
-	if (buf)
-		return 0;
-
-	return early_init_dt_scan_chosen_serial();
-}
-early_param("earlycon", setup_of_earlycon);
 #endif
 
 /**

drivers/tty/pty.c

···
 	return retval;
 }
 
-static struct file_operations ptmx_fops;
+static struct file_operations ptmx_fops __ro_after_init;
 
 static void __init unix98_pty_init(void)
 {

drivers/tty/serial/8250/8250.h

···
 	struct dma_chan		*rxchan;
 	struct dma_chan		*txchan;
 
+	/* Device address base for DMA operations */
+	phys_addr_t		rx_dma_addr;
+	phys_addr_t		tx_dma_addr;
+
+	/* DMA address of the buffer in memory */
 	dma_addr_t		rx_addr;
 	dma_addr_t		tx_addr;
 

drivers/tty/serial/8250/8250_core.c

···
 {
 	char match[] = "uart";	/* 8250-specific earlycon name */
 	unsigned char iotype;
-	unsigned long addr;
+	resource_size_t addr;
 	int i;
 
 	if (strncmp(name, match, 4) != 0)

drivers/tty/serial/8250/8250_dma.c

···
 	if (dma->rx_running) {
 		dmaengine_pause(dma->rxchan);
 		__dma_rx_complete(p);
-		dmaengine_terminate_all(dma->rxchan);
+		dmaengine_terminate_async(dma->rxchan);
 	}
 }
 EXPORT_SYMBOL_GPL(serial8250_rx_dma_flush);
···
 int serial8250_request_dma(struct uart_8250_port *p)
 {
 	struct uart_8250_dma	*dma = p->dma;
+	phys_addr_t rx_dma_addr = dma->rx_dma_addr ?
+				  dma->rx_dma_addr : p->port.mapbase;
+	phys_addr_t tx_dma_addr = dma->tx_dma_addr ?
+				  dma->tx_dma_addr : p->port.mapbase;
 	dma_cap_mask_t		mask;
 	struct dma_slave_caps	caps;
 	int			ret;
···
 	/* Default slave configuration parameters */
 	dma->rxconf.direction		= DMA_DEV_TO_MEM;
 	dma->rxconf.src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
-	dma->rxconf.src_addr		= p->port.mapbase + UART_RX;
+	dma->rxconf.src_addr		= rx_dma_addr + UART_RX;
 
 	dma->txconf.direction		= DMA_MEM_TO_DEV;
 	dma->txconf.dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
-	dma->txconf.dst_addr		= p->port.mapbase + UART_TX;
+	dma->txconf.dst_addr		= tx_dma_addr + UART_TX;
 
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
···
 		return;
 
 	/* Release RX resources */
-	dmaengine_terminate_all(dma->rxchan);
+	dmaengine_terminate_sync(dma->rxchan);
 	dma_free_coherent(dma->rxchan->device->dev, dma->rx_size, dma->rx_buf,
 			  dma->rx_addr);
 	dma_release_channel(dma->rxchan);
 	dma->rxchan = NULL;
 
 	/* Release TX resources */
-	dmaengine_terminate_all(dma->txchan);
+	dmaengine_terminate_sync(dma->txchan);
 	dma_unmap_single(dma->txchan->device->dev, dma->tx_addr,
 			 UART_XMIT_SIZE, DMA_TO_DEVICE);
 	dma_release_channel(dma->txchan);

drivers/tty/serial/8250/8250_dw.c

···
 	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	int irq = platform_get_irq(pdev, 0);
 	struct uart_port *p = &uart.port;
+	struct device *dev = &pdev->dev;
 	struct dw8250_data *data;
 	int err;
 	u32 val;
 
 	if (!regs) {
-		dev_err(&pdev->dev, "no registers defined\n");
+		dev_err(dev, "no registers defined\n");
 		return -EINVAL;
 	}
 
 	if (irq < 0) {
 		if (irq != -EPROBE_DEFER)
-			dev_err(&pdev->dev, "cannot get irq\n");
+			dev_err(dev, "cannot get irq\n");
 		return irq;
 	}
 
···
 	p->pm		= dw8250_do_pm;
 	p->type		= PORT_8250;
 	p->flags	= UPF_SHARE_IRQ | UPF_FIXED_PORT;
-	p->dev		= &pdev->dev;
+	p->dev		= dev;
 	p->iotype	= UPIO_MEM;
 	p->serial_in	= dw8250_serial_in;
 	p->serial_out	= dw8250_serial_out;
 
-	p->membase = devm_ioremap(&pdev->dev, regs->start, resource_size(regs));
+	p->membase = devm_ioremap(dev, regs->start, resource_size(regs));
 	if (!p->membase)
 		return -ENOMEM;
 
-	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
···
 	data->usr_reg = DW_UART_USR;
 	p->private_data = data;
 
-	data->uart_16550_compatible = device_property_read_bool(p->dev,
+	data->uart_16550_compatible = device_property_read_bool(dev,
 						"snps,uart-16550-compatible");
 
-	err = device_property_read_u32(p->dev, "reg-shift", &val);
+	err = device_property_read_u32(dev, "reg-shift", &val);
 	if (!err)
 		p->regshift = val;
 
-	err = device_property_read_u32(p->dev, "reg-io-width", &val);
+	err = device_property_read_u32(dev, "reg-io-width", &val);
 	if (!err && val == 4) {
 		p->iotype = UPIO_MEM32;
 		p->serial_in = dw8250_serial_in32;
 		p->serial_out = dw8250_serial_out32;
 	}
 
-	if (device_property_read_bool(p->dev, "dcd-override")) {
+	if (device_property_read_bool(dev, "dcd-override")) {
 		/* Always report DCD as active */
 		data->msr_mask_on |= UART_MSR_DCD;
 		data->msr_mask_off |= UART_MSR_DDCD;
 	}
 
-	if (device_property_read_bool(p->dev, "dsr-override")) {
+	if (device_property_read_bool(dev, "dsr-override")) {
 		/* Always report DSR as active */
 		data->msr_mask_on |= UART_MSR_DSR;
 		data->msr_mask_off |= UART_MSR_DDSR;
 	}
 
-	if (device_property_read_bool(p->dev, "cts-override")) {
+	if (device_property_read_bool(dev, "cts-override")) {
 		/* Always report CTS as active */
 		data->msr_mask_on |= UART_MSR_CTS;
 		data->msr_mask_off |= UART_MSR_DCTS;
 	}
 
-	if (device_property_read_bool(p->dev, "ri-override")) {
+	if (device_property_read_bool(dev, "ri-override")) {
 		/* Always report Ring indicator as inactive */
 		data->msr_mask_off |= UART_MSR_RI;
 		data->msr_mask_off |= UART_MSR_TERI;
 	}
 
 	/* Always ask for fixed clock rate from a property. */
-	device_property_read_u32(p->dev, "clock-frequency", &p->uartclk);
+	device_property_read_u32(dev, "clock-frequency", &p->uartclk);
 
 	/* If there is separate baudclk, get the rate from it. */
-	data->clk = devm_clk_get(&pdev->dev, "baudclk");
+	data->clk = devm_clk_get(dev, "baudclk");
 	if (IS_ERR(data->clk) && PTR_ERR(data->clk) != -EPROBE_DEFER)
-		data->clk = devm_clk_get(&pdev->dev, NULL);
+		data->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(data->clk) && PTR_ERR(data->clk) == -EPROBE_DEFER)
 		return -EPROBE_DEFER;
 	if (!IS_ERR_OR_NULL(data->clk)) {
 		err = clk_prepare_enable(data->clk);
 		if (err)
-			dev_warn(&pdev->dev, "could not enable optional baudclk: %d\n",
+			dev_warn(dev, "could not enable optional baudclk: %d\n",
 				 err);
 		else
 			p->uartclk = clk_get_rate(data->clk);
···
 
 	/* If no clock rate is defined, fail. */
 	if (!p->uartclk) {
-		dev_err(&pdev->dev, "clock rate not defined\n");
+		dev_err(dev, "clock rate not defined\n");
 		return -EINVAL;
 	}
 
-	data->pclk = devm_clk_get(&pdev->dev, "apb_pclk");
-	if (IS_ERR(data->clk) && PTR_ERR(data->clk) == -EPROBE_DEFER) {
+	data->pclk = devm_clk_get(dev, "apb_pclk");
+	if (IS_ERR(data->pclk) && PTR_ERR(data->pclk) == -EPROBE_DEFER) {
 		err = -EPROBE_DEFER;
 		goto err_clk;
 	}
 	if (!IS_ERR(data->pclk)) {
 		err = clk_prepare_enable(data->pclk);
 		if (err) {
-			dev_err(&pdev->dev, "could not enable apb_pclk\n");
+			dev_err(dev, "could not enable apb_pclk\n");
 			goto err_clk;
 		}
 	}
 
-	data->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
+	data->rst = devm_reset_control_get_optional(dev, NULL);
 	if (IS_ERR(data->rst) && PTR_ERR(data->rst) == -EPROBE_DEFER) {
 		err = -EPROBE_DEFER;
 		goto err_pclk;
···
 
 	platform_set_drvdata(pdev, data);
 
-	pm_runtime_set_active(&pdev->dev);
-	pm_runtime_enable(&pdev->dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
 
 	return 0;
 
···
 	{ "APMC0D08", 0},
 	{ "AMD0020", 0 },
 	{ "AMDI0020", 0 },
+	{ "HISI0031", 0 },
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);

drivers/tty/serial/8250/8250_lpss.c

···
+/*
+ * 8250_lpss.c - Driver for UART on Intel Braswell and various other Intel SoCs
+ *
+ * Copyright (C) 2016 Intel Corporation
+ * Author: Andy Shevchenko <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/rational.h>
+
+#include <linux/dmaengine.h>
+#include <linux/dma/dw.h>
+
+#include "8250.h"
+
+#define PCI_DEVICE_ID_INTEL_QRK_UARTx	0x0936
+
+#define PCI_DEVICE_ID_INTEL_BYT_UART1	0x0f0a
+#define PCI_DEVICE_ID_INTEL_BYT_UART2	0x0f0c
+
+#define PCI_DEVICE_ID_INTEL_BSW_UART1	0x228a
+#define PCI_DEVICE_ID_INTEL_BSW_UART2	0x228c
+
+#define PCI_DEVICE_ID_INTEL_BDW_UART1	0x9ce3
+#define PCI_DEVICE_ID_INTEL_BDW_UART2	0x9ce4
+
+/* Intel LPSS specific registers */
+
+#define BYT_PRV_CLK			0x800
+#define BYT_PRV_CLK_EN			BIT(0)
+#define BYT_PRV_CLK_M_VAL_SHIFT		1
+#define BYT_PRV_CLK_N_VAL_SHIFT		16
+#define BYT_PRV_CLK_UPDATE		BIT(31)
+
+#define BYT_TX_OVF_INT			0x820
+#define BYT_TX_OVF_INT_MASK		BIT(1)
+
+struct lpss8250;
+
+struct lpss8250_board {
+	unsigned long freq;
+	unsigned int base_baud;
+	int (*setup)(struct lpss8250 *, struct uart_port *p);
+	void (*exit)(struct lpss8250 *);
+};
+
+struct lpss8250 {
+	int line;
+	struct lpss8250_board *board;
+
+	/* DMA parameters */
+	struct uart_8250_dma dma;
+	struct dw_dma_chip dma_chip;
+	struct dw_dma_slave dma_param;
+	u8 dma_maxburst;
+};
+
+static void byt_set_termios(struct uart_port *p, struct ktermios *termios,
+			    struct ktermios *old)
+{
+	unsigned int baud = tty_termios_baud_rate(termios);
+	struct lpss8250 *lpss = p->private_data;
+	unsigned long fref = lpss->board->freq, fuart = baud * 16;
+	unsigned long w = BIT(15) - 1;
+	unsigned long m, n;
+	u32 reg;
+
+	/* Gracefully handle the B0 case: fall back to B9600 */
+	fuart = fuart ? fuart : 9600 * 16;
+
+	/* Get Fuart closer to Fref */
+	fuart *= rounddown_pow_of_two(fref / fuart);
+
+	/*
+	 * For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M the
+	 * dividers must be adjusted.
+	 *
+	 * uartclk = (m / n) * 100 MHz, where m <= n
+	 */
+	rational_best_approximation(fuart, fref, w, w, &m, &n);
+	p->uartclk = fuart;
+
+	/* Reset the clock */
+	reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT);
+	writel(reg, p->membase + BYT_PRV_CLK);
+	reg |= BYT_PRV_CLK_EN | BYT_PRV_CLK_UPDATE;
+	writel(reg, p->membase + BYT_PRV_CLK);
+
+	p->status &= ~UPSTAT_AUTOCTS;
+	if (termios->c_cflag & CRTSCTS)
+		p->status |= UPSTAT_AUTOCTS;
+
+	serial8250_do_set_termios(p, termios, old);
+}
+
+static unsigned int byt_get_mctrl(struct uart_port *port)
+{
+	unsigned int ret = serial8250_do_get_mctrl(port);
+
+	/* Force DCD and DSR signals to permanently be reported as active */
+	ret |= TIOCM_CAR | TIOCM_DSR;
+
+	return ret;
+}
+
+static int byt_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
+{
+	struct dw_dma_slave *param = &lpss->dma_param;
+	struct uart_8250_port *up = up_to_u8250p(port);
+	struct pci_dev *pdev = to_pci_dev(port->dev);
+	unsigned int dma_devfn = PCI_DEVFN(PCI_SLOT(pdev->devfn), 0);
+	struct pci_dev *dma_dev = pci_get_slot(pdev->bus, dma_devfn);
+
+	switch (pdev->device) {
+	case PCI_DEVICE_ID_INTEL_BYT_UART1:
+	case PCI_DEVICE_ID_INTEL_BSW_UART1:
+	case PCI_DEVICE_ID_INTEL_BDW_UART1:
+		param->src_id = 3;
+		param->dst_id = 2;
+		break;
+	case PCI_DEVICE_ID_INTEL_BYT_UART2:
+	case PCI_DEVICE_ID_INTEL_BSW_UART2:
+	case PCI_DEVICE_ID_INTEL_BDW_UART2:
+		param->src_id = 5;
+		param->dst_id = 4;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	param->dma_dev = &dma_dev->dev;
+	param->m_master = 0;
+	param->p_master = 1;
+
+	/* TODO: Detect FIFO size automaticaly for DesignWare 8250 */
+	port->fifosize = 64;
+	up->tx_loadsz = 64;
+
+	lpss->dma_maxburst = 16;
+
+	port->set_termios = byt_set_termios;
+	port->get_mctrl = byt_get_mctrl;
+
+	/* Disable TX counter interrupts */
+	writel(BYT_TX_OVF_INT_MASK, port->membase + BYT_TX_OVF_INT);
+
+	return 0;
+}
+
+#ifdef CONFIG_SERIAL_8250_DMA
+static const struct dw_dma_platform_data qrk_serial_dma_pdata = {
+	.nr_channels = 2,
+	.is_private = true,
+	.is_nollp = true,
+	.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
+	.chan_priority = CHAN_PRIORITY_ASCENDING,
+	.block_size = 4095,
+	.nr_masters = 1,
+	.data_width = {4},
+};
+
+static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
+{
+	struct uart_8250_dma *dma = &lpss->dma;
+	struct dw_dma_chip *chip = &lpss->dma_chip;
+	struct dw_dma_slave *param = &lpss->dma_param;
+	struct pci_dev *pdev = to_pci_dev(port->dev);
+	int ret;
+
+	chip->dev = &pdev->dev;
+	chip->irq = pdev->irq;
+	chip->regs = pci_ioremap_bar(pdev, 1);
+	chip->pdata = &qrk_serial_dma_pdata;
+
+	/* Falling back to PIO mode if DMA probing fails */
+	ret = dw_dma_probe(chip);
+	if (ret)
+		return;
+
+	/* Special DMA address for UART */
+	dma->rx_dma_addr = 0xfffff000;
+	dma->tx_dma_addr = 0xfffff000;
+
+	param->dma_dev = &pdev->dev;
+	param->src_id = 0;
+	param->dst_id = 1;
+	param->hs_polarity = true;
+
+	lpss->dma_maxburst = 8;
+}
+
+static void qrk_serial_exit_dma(struct lpss8250 *lpss)
+{
+	struct dw_dma_slave *param = &lpss->dma_param;
+
+	if (!param->dma_dev)
+		return;
+	dw_dma_remove(&lpss->dma_chip);
+}
+#else	/* CONFIG_SERIAL_8250_DMA */
+static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port) {}
+static void qrk_serial_exit_dma(struct lpss8250 *lpss) {}
+#endif	/* !CONFIG_SERIAL_8250_DMA */
+
+static int qrk_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
+{
+	struct pci_dev *pdev = to_pci_dev(port->dev);
+	int ret;
+
+	ret = pci_alloc_irq_vectors(pdev, 1, 1, 0);
+	if (ret < 0)
+		return ret;
+
+	port->irq = pci_irq_vector(pdev, 0);
+
+	qrk_serial_setup_dma(lpss, port);
+	return 0;
+}
+
+static void qrk_serial_exit(struct lpss8250 *lpss)
+{
+	qrk_serial_exit_dma(lpss);
+}
+
+static bool lpss8250_dma_filter(struct dma_chan *chan, void *param)
+{
+	struct dw_dma_slave *dws = param;
+
+	if (dws->dma_dev != chan->device->dev)
+		return false;
+
+	chan->private = dws;
+	return true;
+}
+
+static int lpss8250_dma_setup(struct lpss8250 *lpss, struct uart_8250_port *port)
+{
+	struct uart_8250_dma *dma = &lpss->dma;
+	struct dw_dma_slave *rx_param, *tx_param;
+	struct device *dev = port->port.dev;
+
+	if (!lpss->dma_param.dma_dev)
+		return 0;
+
+	rx_param = devm_kzalloc(dev, sizeof(*rx_param), GFP_KERNEL);
+	if (!rx_param)
+		return -ENOMEM;
+
+	tx_param = devm_kzalloc(dev, sizeof(*tx_param), GFP_KERNEL);
+	if (!tx_param)
+		return -ENOMEM;
+
+	*rx_param = lpss->dma_param;
+	dma->rxconf.src_maxburst = lpss->dma_maxburst;
+
+	*tx_param = lpss->dma_param;
+	dma->txconf.dst_maxburst = lpss->dma_maxburst;
+
+	dma->fn = lpss8250_dma_filter;
+	dma->rx_param = rx_param;
+	dma->tx_param = tx_param;
+
+	port->dma = dma;
+	return 0;
+}
+
+static int lpss8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+	struct uart_8250_port uart;
+	struct lpss8250 *lpss;
+	int ret;
+
+	ret = pcim_enable_device(pdev);
+	if (ret)
+		return ret;
+
+	pci_set_master(pdev);
+
+	lpss = devm_kzalloc(&pdev->dev, sizeof(*lpss), GFP_KERNEL);
+	if (!lpss)
+		return -ENOMEM;
+
+	lpss->board = (struct lpss8250_board *)id->driver_data;
+
+	memset(&uart, 0, sizeof(struct uart_8250_port));
+
+	uart.port.dev = &pdev->dev;
+	uart.port.irq = pdev->irq;
+	uart.port.private_data = lpss;
+	uart.port.type = PORT_16550A;
+	uart.port.iotype = UPIO_MEM;
+	uart.port.regshift = 2;
+	uart.port.uartclk = lpss->board->base_baud * 16;
+	uart.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE;
+	uart.capabilities = UART_CAP_FIFO | UART_CAP_AFE;
+	uart.port.mapbase = pci_resource_start(pdev, 0);
+	uart.port.membase = pcim_iomap(pdev, 0, 0);
+	if (!uart.port.membase)
+		return -ENOMEM;
+
+	ret = lpss->board->setup(lpss, &uart.port);
+	if (ret)
+		return ret;
+
+	ret = lpss8250_dma_setup(lpss, &uart);
+	if (ret)
+		goto err_exit;
+
+	ret = serial8250_register_8250_port(&uart);
+	if (ret < 0)
+		goto err_exit;
+
+	lpss->line = ret;
+
+	pci_set_drvdata(pdev, lpss);
+	return 0;
+
+err_exit:
+	if (lpss->board->exit)
+		lpss->board->exit(lpss);
+	return ret;
+}
+
+static void lpss8250_remove(struct pci_dev *pdev)
+{
+	struct lpss8250 *lpss = pci_get_drvdata(pdev);
+
+	if (lpss->board->exit)
+		lpss->board->exit(lpss);
+
+	serial8250_unregister_port(lpss->line);
+}
+
+static const struct lpss8250_board byt_board = {
+	.freq = 100000000,
+	.base_baud = 2764800,
+	.setup = byt_serial_setup,
+};
+
+static const struct lpss8250_board qrk_board = {
+	.freq = 44236800,
+	.base_baud = 2764800,
+	.setup = qrk_serial_setup,
+	.exit = qrk_serial_exit,
+};
+
+#define LPSS_DEVICE(id, board) { PCI_VDEVICE(INTEL, id), (kernel_ulong_t)&board }
+
+static const struct pci_device_id pci_ids[] = {
+	LPSS_DEVICE(PCI_DEVICE_ID_INTEL_QRK_UARTx, qrk_board),
+	LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BYT_UART1, byt_board),
+	LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BYT_UART2, byt_board),
+	LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BSW_UART1, byt_board),
+	LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BSW_UART2, byt_board),
+	LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BDW_UART1, byt_board),
+	LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BDW_UART2, byt_board),
+	{ },
+};
+MODULE_DEVICE_TABLE(pci, pci_ids);
+
+static struct pci_driver lpss8250_pci_driver = {
+	.name           = "8250_lpss",
+	.id_table       = pci_ids,
+	.probe          = lpss8250_probe,
+	.remove         = lpss8250_remove,
+};
+
+module_pci_driver(lpss8250_pci_driver);
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Intel LPSS UART driver");

drivers/tty/serial/8250/8250_mid.c

···
 	struct uart_8250_port *up = up_to_u8250p(p);
 	unsigned int fisr = serial_port_in(p, INTEL_MID_UART_DNV_FISR);
 	u32 status;
-	int ret = IRQ_NONE;
+	int ret = 0;
 	int err;
 
 	if (fisr & BIT(2)) {
 		err = hsu_dma_get_status(&mid->dma_chip, 1, &status);
 		if (err > 0) {
 			serial8250_rx_dma_flush(up);
-			ret |= IRQ_HANDLED;
+			ret |= 1;
 		} else if (err == 0)
 			ret |= hsu_dma_do_irq(&mid->dma_chip, 1, status);
 	}
 	if (fisr & BIT(1)) {
 		err = hsu_dma_get_status(&mid->dma_chip, 0, &status);
 		if (err > 0)
-			ret |= IRQ_HANDLED;
+			ret |= 1;
 		else if (err == 0)
 			ret |= hsu_dma_do_irq(&mid->dma_chip, 0, status);
 	}
 	if (fisr & BIT(0))
 		ret |= serial8250_handle_irq(p, serial_port_in(p, UART_IIR));
-	return ret;
+	return IRQ_RETVAL(ret);
 }
 
 #define DNV_DMA_CHAN_OFFSET 0x80

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

···
 	 */
 	baud = uart_get_baud_rate(port, termios, old,
 				  port->uartclk / 16 / 0xffff,
-				  port->uartclk / 16);
+				  port->uartclk);
 
 	if (baud <= 115200) {
 		serial_port_out(port, UART_MTK_HIGHS, 0x0);
···
 		quot = DIV_ROUND_UP(port->uartclk, 4 * baud);
 	} else {
 		serial_port_out(port, UART_MTK_HIGHS, 0x3);
-
-		/* Set to highest baudrate supported */
-		if (baud >= 1152000)
-			baud = 921600;
 		quot = DIV_ROUND_UP(port->uartclk, 256 * baud);
 	}
 

drivers/tty/serial/8250/8250_of.c

···
 	switch (port_type) {
 	case PORT_8250 ... PORT_MAX_8250:
 	{
+		u32 tx_threshold;
 		struct uart_8250_port port8250;
 		memset(&port8250, 0, sizeof(port8250));
 		port8250.port = port;
 
 		if (port.fifosize)
 			port8250.capabilities = UART_CAP_FIFO;
+
+		/* Check for TX FIFO threshold & set tx_loadsz */
+		if ((of_property_read_u32(ofdev->dev.of_node, "tx-threshold",
+					  &tx_threshold) == 0) &&
+		    (tx_threshold < port.fifosize))
+			port8250.tx_loadsz = port.fifosize - tx_threshold;
 
 		if (of_property_read_bool(ofdev->dev.of_node,
 					  "auto-flow-control"))

drivers/tty/serial/8250/8250_pci.c

···
 #include <linux/serial_core.h>
 #include <linux/8250_pci.h>
 #include <linux/bitops.h>
-#include <linux/rational.h>
 
 #include <asm/byteorder.h>
 #include <asm/io.h>
-
-#include <linux/dmaengine.h>
-#include <linux/platform_data/dma-dw.h>
 
 #include "8250.h"
 
···
 	return ret;
 }
 
-#define PCI_DEVICE_ID_INTEL_BYT_UART1	0x0f0a
-#define PCI_DEVICE_ID_INTEL_BYT_UART2	0x0f0c
-
-#define PCI_DEVICE_ID_INTEL_BSW_UART1	0x228a
-#define PCI_DEVICE_ID_INTEL_BSW_UART2	0x228c
-
-#define PCI_DEVICE_ID_INTEL_BDW_UART1	0x9ce3
-#define PCI_DEVICE_ID_INTEL_BDW_UART2	0x9ce4
-
-#define BYT_PRV_CLK			0x800
-#define BYT_PRV_CLK_EN			(1 << 0)
-#define BYT_PRV_CLK_M_VAL_SHIFT		1
-#define BYT_PRV_CLK_N_VAL_SHIFT		16
-#define BYT_PRV_CLK_UPDATE		(1 << 31)
-
-#define BYT_TX_OVF_INT			0x820
-#define BYT_TX_OVF_INT_MASK		(1 << 1)
-
-static void
-byt_set_termios(struct uart_port *p, struct ktermios *termios,
-		struct ktermios *old)
-{
-	unsigned int baud = tty_termios_baud_rate(termios);
-	unsigned long fref = 100000000, fuart = baud * 16;
-	unsigned long w = BIT(15) - 1;
-	unsigned long m, n;
-	u32 reg;
-
-	/* Gracefully handle the B0 case: fall back to B9600 */
-	fuart = fuart ? fuart : 9600 * 16;
-
-	/* Get Fuart closer to Fref */
-	fuart *= rounddown_pow_of_two(fref / fuart);
-
-	/*
-	 * For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M the
-	 * dividers must be adjusted.
-	 *
-	 * uartclk = (m / n) * 100 MHz, where m <= n
-	 */
-	rational_best_approximation(fuart, fref, w, w, &m, &n);
-	p->uartclk = fuart;
-
-	/* Reset the clock */
-	reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT);
-	writel(reg, p->membase + BYT_PRV_CLK);
-	reg |= BYT_PRV_CLK_EN | BYT_PRV_CLK_UPDATE;
-	writel(reg, p->membase + BYT_PRV_CLK);
-
-	p->status &= ~UPSTAT_AUTOCTS;
-	if (termios->c_cflag & CRTSCTS)
-		p->status |= UPSTAT_AUTOCTS;
-
-	serial8250_do_set_termios(p, termios, old);
-}
-
-static bool byt_dma_filter(struct dma_chan *chan, void *param)
-{
-	struct dw_dma_slave *dws = param;
-
-	if (dws->dma_dev != chan->device->dev)
-		return false;
-
-	chan->private = dws;
-	return true;
-}
-
-static unsigned int
-byt_get_mctrl(struct uart_port *port)
-{
-	unsigned int ret = serial8250_do_get_mctrl(port);
-
-	/* Force DCD and DSR signals to permanently be reported as active. */
-	ret |= TIOCM_CAR | TIOCM_DSR;
-
-	return ret;
-}
-
-static int
-byt_serial_setup(struct serial_private *priv,
-		 const struct pciserial_board *board,
-		 struct uart_8250_port *port, int idx)
-{
-	struct pci_dev *pdev = priv->dev;
-	struct device *dev = port->port.dev;
-	struct uart_8250_dma *dma;
-	struct dw_dma_slave *tx_param, *rx_param;
-	struct pci_dev *dma_dev;
-	int ret;
-
-	dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);
-	if (!dma)
-		return -ENOMEM;
-
-	tx_param = devm_kzalloc(dev, sizeof(*tx_param), GFP_KERNEL);
-	if (!tx_param)
-		return -ENOMEM;
-
-	rx_param = devm_kzalloc(dev, sizeof(*rx_param), GFP_KERNEL);
-	if (!rx_param)
-		return -ENOMEM;
-
-	switch (pdev->device) {
-	case PCI_DEVICE_ID_INTEL_BYT_UART1:
-	case PCI_DEVICE_ID_INTEL_BSW_UART1:
-	case PCI_DEVICE_ID_INTEL_BDW_UART1:
-		rx_param->src_id = 3;
-		tx_param->dst_id = 2;
-		break;
-	case PCI_DEVICE_ID_INTEL_BYT_UART2:
-	case PCI_DEVICE_ID_INTEL_BSW_UART2:
-	case PCI_DEVICE_ID_INTEL_BDW_UART2:
-		rx_param->src_id = 5;
-		tx_param->dst_id = 4;
-		break;
-	default:
-		return -EINVAL;
-	}
-
-	rx_param->m_master = 0;
-	rx_param->p_master = 1;
-
-	dma->rxconf.src_maxburst = 16;
-
-	tx_param->m_master = 0;
-	tx_param->p_master = 1;
-
-	dma->txconf.dst_maxburst = 16;
-
-	dma_dev = pci_get_slot(pdev->bus, PCI_DEVFN(PCI_SLOT(pdev->devfn), 0));
-	rx_param->dma_dev = &dma_dev->dev;
-	tx_param->dma_dev = &dma_dev->dev;
-
-	dma->fn = byt_dma_filter;
-	dma->rx_param = rx_param;
-	dma->tx_param = tx_param;
-
-	ret = pci_default_setup(priv, board, port, idx);
-	port->port.iotype = UPIO_MEM;
-	port->port.type = PORT_16550A;
-	port->port.flags = (port->port.flags | UPF_FIXED_PORT | UPF_FIXED_TYPE);
-	port->port.set_termios = byt_set_termios;
-	port->port.get_mctrl = byt_get_mctrl;
-	port->port.fifosize = 64;
-	port->tx_loadsz = 64;
-	port->dma = dma;
-	port->capabilities = UART_CAP_FIFO | UART_CAP_AFE;
-
-	/* Disable Tx counter interrupts */
-	writel(BYT_TX_OVF_INT_MASK, port->port.membase + BYT_TX_OVF_INT);
-
-	return ret;
-}
-
 static int
 pci_omegapci_setup(struct serial_private *priv,
 		      const struct pciserial_board *board,
···
 #define PCI_DEVICE_ID_EXAR_XR17V4358	0x4358
 #define PCI_DEVICE_ID_EXAR_XR17V8358	0x8358
 
+#define UART_EXAR_MPIOINT_7_0	0x8f	/* MPIOINT[7:0] */
+#define UART_EXAR_MPIOLVL_7_0	0x90	/* MPIOLVL[7:0] */
+#define UART_EXAR_MPIO3T_7_0	0x91	/* MPIO3T[7:0] */
+#define UART_EXAR_MPIOINV_7_0	0x92	/* MPIOINV[7:0] */
+#define UART_EXAR_MPIOSEL_7_0	0x93	/* MPIOSEL[7:0] */
+#define UART_EXAR_MPIOOD_7_0	0x94	/* MPIOOD[7:0] */
+#define UART_EXAR_MPIOINT_15_8	0x95	/* MPIOINT[15:8] */
+#define UART_EXAR_MPIOLVL_15_8	0x96	/* MPIOLVL[15:8] */
+#define UART_EXAR_MPIO3T_15_8	0x97	/* MPIO3T[15:8] */
+#define UART_EXAR_MPIOINV_15_8	0x98	/* MPIOINV[15:8] */
+#define UART_EXAR_MPIOSEL_15_8	0x99	/* MPIOSEL[15:8] */
+#define UART_EXAR_MPIOOD_15_8	0x9a	/* MPIOOD[15:8] */
+
 static int
 pci_xr17c154_setup(struct serial_private *priv,
 		  const struct pciserial_board *board,
···
 	 * Setup Multipurpose Input/Output pins.
 	 */
 	if (idx == 0) {
-		writeb(0x00, p + 0x8f); /*MPIOINT[7:0]*/
-		writeb(0x00, p + 0x90); /*MPIOLVL[7:0]*/
-		writeb(0x00, p + 0x91); /*MPIO3T[7:0]*/
-		writeb(0x00, p + 0x92); /*MPIOINV[7:0]*/
-		writeb(0x00, p + 0x93); /*MPIOSEL[7:0]*/
-		writeb(0x00, p + 0x94); /*MPIOOD[7:0]*/
-		writeb(0x00, p + 0x95); /*MPIOINT[15:8]*/
-		writeb(0x00, p + 0x96); /*MPIOLVL[15:8]*/
-		writeb(0x00, p + 0x97); /*MPIO3T[15:8]*/
-		writeb(0x00, p + 0x98); /*MPIOINV[15:8]*/
-		writeb(0x00, p + 0x99); /*MPIOSEL[15:8]*/
-		writeb(0x00, p + 0x9a); /*MPIOOD[15:8]*/
+		writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);
+		writeb(0x00, p + UART_EXAR_MPIO3T_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOINV_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOSEL_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOOD_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOINT_15_8);
+		writeb(0x00, p + UART_EXAR_MPIOLVL_15_8);
+		writeb(0x00, p + UART_EXAR_MPIO3T_15_8);
+		writeb(0x00, p + UART_EXAR_MPIOINV_15_8);
+		writeb(0x00, p + UART_EXAR_MPIOSEL_15_8);
+		writeb(0x00, p + UART_EXAR_MPIOOD_15_8);
 	}
 	writeb(0x00, p + UART_EXAR_8XMODE);
 	writeb(UART_FCTR_EXAR_TRGD, p + UART_EXAR_FCTR);
···
 		switch (priv->dev->device) {
 		case PCI_DEVICE_ID_COMMTECH_4222PCI335:
 		case PCI_DEVICE_ID_COMMTECH_4224PCI335:
-			writeb(0x78, p + 0x90); /* MPIOLVL[7:0] */
-			writeb(0x00, p + 0x92); /* MPIOINV[7:0] */
-			writeb(0x00, p + 0x93); /* MPIOSEL[7:0] */
+			writeb(0x78, p + UART_EXAR_MPIOLVL_7_0);
+			writeb(0x00, p + UART_EXAR_MPIOINV_7_0);
+			writeb(0x00, p + UART_EXAR_MPIOSEL_7_0);
 			break;
 		case PCI_DEVICE_ID_COMMTECH_2324PCI335:
 		case PCI_DEVICE_ID_COMMTECH_2328PCI335:
-			writeb(0x00, p + 0x90); /* MPIOLVL[7:0] */
-			writeb(0xc0, p + 0x92); /* MPIOINV[7:0] */
-			writeb(0xc0, p + 0x93); /* MPIOSEL[7:0] */
+			writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);
+			writeb(0xc0, p + UART_EXAR_MPIOINV_7_0);
+			writeb(0xc0, p + UART_EXAR_MPIOSEL_7_0);
 			break;
 		}
-		writeb(0x00, p + 0x8f); /* MPIOINT[7:0] */
-		writeb(0x00, p + 0x91); /* MPIO3T[7:0] */
-		writeb(0x00, p + 0x94); /* MPIOOD[7:0] */
+		writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
+		writeb(0x00, p + UART_EXAR_MPIO3T_7_0);
+		writeb(0x00, p + UART_EXAR_MPIOOD_7_0);
 	}
 	writeb(0x00, p + UART_EXAR_8XMODE);
 	writeb(UART_FCTR_EXAR_TRGD, p + UART_EXAR_FCTR);
···
 #define PCI_DEVICE_ID_COMMTECH_4222PCIE	0x0022
 #define PCI_DEVICE_ID_BROADCOM_TRUMANAGE 0x160a
 #define PCI_DEVICE_ID_AMCC_ADDIDATA_APCI7800 0x818e
-#define PCI_DEVICE_ID_INTEL_QRK_UART	0x0936
 
 #define PCI_VENDOR_ID_SUNIX		0x1fd4
 #define PCI_DEVICE_ID_SUNIX_1999	0x1999
···
 		.subvendor	= PCI_ANY_ID,
 		.subdevice	= PCI_ANY_ID,
 		.setup		= kt_serial_setup,
-	},
-	{
-		.vendor		= PCI_VENDOR_ID_INTEL,
-		.device		= PCI_DEVICE_ID_INTEL_BYT_UART1,
-		.subvendor	= PCI_ANY_ID,
-		.subdevice	= PCI_ANY_ID,
-		.setup		= byt_serial_setup,
-	},
-	{
-		.vendor		= PCI_VENDOR_ID_INTEL,
-		.device		= PCI_DEVICE_ID_INTEL_BYT_UART2,
-		.subvendor	= PCI_ANY_ID,
-		.subdevice	= PCI_ANY_ID,
-		.setup		= byt_serial_setup,
-	},
-	{
-		.vendor		= PCI_VENDOR_ID_INTEL,
-		.device		= PCI_DEVICE_ID_INTEL_BSW_UART1,
-		.subvendor	= PCI_ANY_ID,
-		.subdevice	= PCI_ANY_ID,
-		.setup		= byt_serial_setup,
-	},
-	{
-		.vendor		= PCI_VENDOR_ID_INTEL,
-		.device		= PCI_DEVICE_ID_INTEL_BSW_UART2,
-		.subvendor	= PCI_ANY_ID,
-		.subdevice	= PCI_ANY_ID,
-		.setup		= byt_serial_setup,
-	},
-	{
-		.vendor		= PCI_VENDOR_ID_INTEL,
-		.device		= PCI_DEVICE_ID_INTEL_BDW_UART1,
-		.subvendor	= PCI_ANY_ID,
-		.subdevice	= PCI_ANY_ID,
-		.setup		= byt_serial_setup,
-	},
-	{
-		.vendor		= PCI_VENDOR_ID_INTEL,
-		.device		= PCI_DEVICE_ID_INTEL_BDW_UART2,
-		.subvendor	= PCI_ANY_ID,
-		.subdevice	= PCI_ANY_ID,
-		.setup		= byt_serial_setup,
 	},
 	/*
 	 * ITE
···
 	pbn_ADDIDATA_PCIe_4_3906250,
 	pbn_ADDIDATA_PCIe_8_3906250,
 	pbn_ce4100_1_115200,
-	pbn_byt,
-	pbn_qrk,
 	pbn_omegapci,
 	pbn_NETMOS9900_2s_115200,
 	pbn_brcm_trumanage,
···
 		.base_baud	= 921600,
 		.reg_shift      = 2,
 	},
-	[pbn_byt] = {
-		.flags		= FL_BASE0,
-		.num_ports	= 1,
-		.base_baud	= 2764800,
-		.reg_shift      = 2,
-	},
-	[pbn_qrk] = {
-		.flags		= FL_BASE0,
-		.num_ports	= 1,
-		.base_baud	= 2764800,
-		.reg_shift	= 2,
-	},
 	[pbn_omegapci] = {
 		.flags		= FL_BASE0,
 		.num_ports	= 8,
···
 	{ PCI_VDEVICE(INTEL, 0x081d), },
 	{ PCI_VDEVICE(INTEL, 0x1191), },
 	{ PCI_VDEVICE(INTEL, 0x19d8), },
+
+	/* Intel platforms with DesignWare UART */
+	{ PCI_VDEVICE(INTEL, 0x0936), },
+	{ PCI_VDEVICE(INTEL, 0x0f0a), },
+	{ PCI_VDEVICE(INTEL, 0x0f0c), },
+	{ PCI_VDEVICE(INTEL, 0x228a), },
+	{ PCI_VDEVICE(INTEL, 0x228c), },
+	{ PCI_VDEVICE(INTEL, 0x9ce3), },
+	{ PCI_VDEVICE(INTEL, 0x9ce4), },
 };
 
 /*
···
 	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_CE4100_UART,
 		PCI_ANY_ID,  PCI_ANY_ID, 0, 0,
 		pbn_ce4100_1_115200 },
-	/* Intel BayTrail */
-	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BYT_UART1,
-		PCI_ANY_ID,  PCI_ANY_ID,
-		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
-		pbn_byt },
-	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BYT_UART2,
-		PCI_ANY_ID,  PCI_ANY_ID,
-		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
-		pbn_byt },
-	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BSW_UART1,
-		PCI_ANY_ID,  PCI_ANY_ID,
-		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
-		pbn_byt },
-	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BSW_UART2,
-		PCI_ANY_ID,  PCI_ANY_ID,
-		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
-		pbn_byt },
 
-	/* Intel Broadwell */
-	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BDW_UART1,
-		PCI_ANY_ID,  PCI_ANY_ID,
-		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
-		pbn_byt },
-	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BDW_UART2,
-		PCI_ANY_ID,  PCI_ANY_ID,
-		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
-		pbn_byt },
-
-	/*
-	 * Intel Quark x1000
-	 */
-	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_QRK_UART,
-		PCI_ANY_ID, PCI_ANY_ID, 0, 0,
-		pbn_qrk },
 	/*
 	 * Cronyx Omega PCI
 	 */

drivers/tty/serial/8250/8250_port.c

···
 		.fifo_size	= 16,
 		.tx_loadsz	= 16,
 		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_00,
-		.flags		= UART_CAP_FIFO | UART_CAP_AFE,
+		.flags		= UART_CAP_FIFO /* | UART_CAP_AFE */,
 	},
 	[PORT_U6_16550A] = {
 		.name		= "U6_16550A",
···
  */
 int serial8250_em485_init(struct uart_8250_port *p)
 {
-	if (p->em485 != NULL)
+	if (p->em485)
 		return 0;
 
 	p->em485 = kmalloc(sizeof(struct uart_8250_em485), GFP_ATOMIC);
-	if (p->em485 == NULL)
+	if (!p->em485)
 		return -ENOMEM;
 
 	setup_timer(&p->em485->stop_tx_timer,
···
  */
 void serial8250_em485_destroy(struct uart_8250_port *p)
 {
-	if (p->em485 == NULL)
+	if (!p->em485)
 		return;
 
 	del_timer(&p->em485->start_tx_timer);
···
 
 static void __do_stop_tx_rs485(struct uart_8250_port *p)
 {
-	if (!p->em485)
-		return;
-
 	serial8250_em485_rts_after_send(p);
+
 	/*
 	 * Empty the RX FIFO, we are not interested in anything
 	 * received during the half-duplex transmission.
···
 	if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
 		serial8250_clear_fifos(p);
 
-		serial8250_rpm_get(p);
-
 		p->ier |= UART_IER_RLSI | UART_IER_RDI;
 		serial_port_out(&p->port, UART_IER, p->ier);
-
-		serial8250_rpm_put(p);
 	}
 }
 
···
 	struct uart_8250_em485 *em485 = p->em485;
 	unsigned long flags;
 
+	serial8250_rpm_get(p);
 	spin_lock_irqsave(&p->port.lock, flags);
 	if (em485 &&
 	    em485->active_timer == &em485->stop_tx_timer) {
···
 		em485->active_timer = NULL;
 	}
 	spin_unlock_irqrestore(&p->port.lock, flags);
+	serial8250_rpm_put(p);
 }
 
 static void __stop_tx_rs485(struct uart_8250_port *p)
 {
 	struct uart_8250_em485 *em485 = p->em485;
-
-	if (!em485)
-		return;
 
 	/*
 	 * __do_stop_tx_rs485 is going to set RTS according to config
···
 		unsigned char lsr = serial_in(p, UART_LSR);
 		/*
 		 * To provide required timeing and allow FIFO transfer,
-		 * __stop_tx_rs485 must be called only when both FIFO and
+		 * __stop_tx_rs485() must be called only when both FIFO and
 		 * shift register are empty. It is for device driver to enable
 		 * interrupt on TEMT.
 		 */
···
 
 		del_timer(&em485->start_tx_timer);
 		em485->active_timer = NULL;
+
+		__stop_tx_rs485(p);
 	}
 	__do_stop_tx(p);
-	__stop_tx_rs485(p);
 }
 
 static void serial8250_stop_tx(struct uart_port *port)
···
 	return ret;
 }
 
+/*
+ * Newer 16550 compatible parts such as the SC16C650 & Altera 16550 Soft IP
+ * have a programmable TX threshold that triggers the THRE interrupt in
+ * the IIR register. In this case, the THRE interrupt indicates the FIFO
+ * has space available. Load it up with tx_loadsz bytes.
+ */
+static int serial8250_tx_threshold_handle_irq(struct uart_port *port)
+{
+	unsigned long flags;
+	unsigned int iir = serial_port_in(port, UART_IIR);
+
+	/* TX Threshold IRQ triggered so load up FIFO */
+	if ((iir & UART_IIR_ID) == UART_IIR_THRI) {
+		struct uart_8250_port *up = up_to_u8250p(port);
+
+		spin_lock_irqsave(&port->lock, flags);
+		serial8250_tx_chars(up);
+		spin_unlock_irqrestore(&port->lock, flags);
+	}
+
+	iir = serial_port_in(port, UART_IIR);
+	return serial8250_handle_irq(port, iir);
+}
+
 static unsigned int serial8250_tx_empty(struct uart_port *port)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
···
 		if (--tmout == 0)
 			break;
 		udelay(1);
+		touch_nmi_watchdog();
 	}
 
 	/* Wait up to 1s for flow control if necessary */
···
 		serial_port_out(port, UART_TRG, UART_TRG_96);
 
 		serial_port_out(port, UART_LCR, 0);
+	}
+
+	/*
+	 * For the Altera 16550 variants, set TX threshold trigger level.
+	 */
+	if (((port->type == PORT_ALTR_16550_F32) ||
+	     (port->type == PORT_ALTR_16550_F64) ||
+	     (port->type == PORT_ALTR_16550_F128)) && (port->fifosize > 1)) {
+		/* Bounds checking of TX threshold (valid 0 to fifosize-2) */
+		if ((up->tx_loadsz < 2) || (up->tx_loadsz > port->fifosize)) {
+			pr_err("ttyS%d TX FIFO Threshold errors, skipping\n",
+			       serial_index(port));
+		} else {
+			serial_port_out(port, UART_ALTR_AFR,
+					UART_ALTR_EN_TXFIFO_LW);
+			serial_port_out(port, UART_ALTR_TX_LOW,
+					port->fifosize - up->tx_loadsz);
+			port->handle_irq = serial8250_tx_threshold_handle_irq;
+		}
 	}
 
 	if (port->irq) {
···
 					     struct ktermios *termios,
 					     struct ktermios *old)
 {
-	unsigned int tolerance = port->uartclk / 100;
-
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 * Allow 1% tolerance at the upper limit so uart clks marginally
···
 	 */
 	return uart_get_baud_rate(port, termios, old,
 				  port->uartclk / 16 / 0xffff,
-				  (port->uartclk + tolerance) / 16);
+				  port->uartclk);
 }
 
 void
···
 	/*
 	 * MCR-based auto flow control.  When AFE is enabled, RTS will be
 	 * deasserted when the receive FIFO contains more characters than
-	 * the trigger, or the MCR RTS bit is cleared.  In the case where
-	 * the remote UART is not using CTS auto flow control, we must
-	 * have sufficient FIFO entries for the latency of the remote
-	 * UART to respond.  IOW, at least 32 bytes of FIFO.
+	 * the trigger, or the MCR RTS bit is cleared.
 	 */
-	if (up->capabilities & UART_CAP_AFE && port->fifosize >= 32) {
+	if (up->capabilities & UART_CAP_AFE) {
 		up->mcr &= ~UART_MCR_AFE;
 		if (termios->c_cflag & CRTSCTS)
 			up->mcr |= UART_MCR_AFE;

drivers/tty/serial/8250/Kconfig

···
 	tristate "8250/16550 PCI device support" if EXPERT
 	depends on SERIAL_8250 && PCI
 	default SERIAL_8250
-	select RATIONAL
 	help
 	  This builds standard PCI serial support. You may be able to
 	  disable this feature if you only need legacy serial support.
···
 	help
 	  If you have a system using an Ingenic SoC and wish to make use of
 	  its UARTs, say Y to this option. If unsure, say N.
+
+config SERIAL_8250_LPSS
+	tristate "Support for serial ports on Intel LPSS platforms" if EXPERT
+	default SERIAL_8250
+	depends on SERIAL_8250 && PCI
+	depends on X86 || COMPILE_TEST
+	select DW_DMAC_CORE if SERIAL_8250_DMA
+	select DW_DMAC_PCI if (SERIAL_8250_DMA && X86_INTEL_LPSS)
+	select RATIONAL
+	help
+	  Selecting this option will enable handling of the extra features
+	  present on the UART found on various Intel platforms such as:
+	    - Intel Baytrail SoC
+	    - Intel Braswell SoC
+	    - Intel Quark X1000 SoC
 
 config SERIAL_8250_MID
 	tristate "Support for serial ports on Intel MID platforms" if EXPERT

drivers/tty/serial/8250/Makefile

···
 obj-$(CONFIG_SERIAL_8250_MT6577)	+= 8250_mtk.o
 obj-$(CONFIG_SERIAL_8250_UNIPHIER)	+= 8250_uniphier.o
 obj-$(CONFIG_SERIAL_8250_INGENIC)	+= 8250_ingenic.o
+obj-$(CONFIG_SERIAL_8250_LPSS)		+= 8250_lpss.o
 obj-$(CONFIG_SERIAL_8250_MID)		+= 8250_mid.o
 obj-$(CONFIG_SERIAL_8250_MOXA)		+= 8250_moxa.o
 obj-$(CONFIG_SERIAL_OF_PLATFORM)	+= 8250_of.o

drivers/tty/serial/altera_jtaguart.c

···
 /*
  *	Define the basic serial functions we support.
  */
-static struct uart_ops altera_jtaguart_ops = {
+static const struct uart_ops altera_jtaguart_ops = {
 	.tx_empty	= altera_jtaguart_tx_empty,
 	.get_mctrl	= altera_jtaguart_get_mctrl,
 	.set_mctrl	= altera_jtaguart_set_mctrl,

drivers/tty/serial/altera_uart.c

···
 /*
  *	Define the basic serial functions we support.
  */
-static struct uart_ops altera_uart_ops = {
+static const struct uart_ops altera_uart_ops = {
 	.tx_empty	= altera_uart_tx_empty,
 	.get_mctrl	= altera_uart_get_mctrl,
 	.set_mctrl	= altera_uart_set_mctrl,

drivers/tty/serial/amba-pl011.c

···
 struct vendor_data {
 	const u16		*reg_offset;
 	unsigned int		ifls;
+	unsigned int		fr_busy;
+	unsigned int		fr_dsr;
+	unsigned int		fr_cts;
+	unsigned int		fr_ri;
 	bool			access_32b;
 	bool			oversampling;
 	bool			dma_threshold;
···
 static struct vendor_data vendor_arm = {
 	.reg_offset		= pl011_std_offsets,
 	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.oversampling		= false,
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
···
 
 static struct vendor_data vendor_sbsa = {
 	.reg_offset		= pl011_std_offsets,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.access_32b		= true,
 	.oversampling		= false,
 	.dma_threshold		= false,
···
 static struct vendor_data vendor_st = {
 	.reg_offset		= pl011_st_offsets,
 	.ifls			= UART011_IFLS_RX_HALF|UART011_IFLS_TX_HALF,
+	.fr_busy		= UART01x_FR_BUSY,
+	.fr_dsr			= UART01x_FR_DSR,
+	.fr_cts			= UART01x_FR_CTS,
+	.fr_ri			= UART011_FR_RI,
 	.oversampling		= true,
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
···
 	[REG_DMACR] = ZX_UART011_DMACR,
 };
 
-static struct vendor_data vendor_zte __maybe_unused = {
+static unsigned int get_fifosize_zte(struct amba_device *dev)
+{
+	return 16;
+}
+
+static struct vendor_data vendor_zte = {
 	.reg_offset		= pl011_zte_offsets,
 	.access_32b		= true,
 	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
-	.get_fifosize		= get_fifosize_arm,
+	.fr_busy		= ZX_UART01x_FR_BUSY,
+	.fr_dsr			= ZX_UART01x_FR_DSR,
+	.fr_cts			= ZX_UART01x_FR_CTS,
+	.fr_ri			= ZX_UART011_FR_RI,
+	.get_fifosize		= get_fifosize_zte,
 };
 
 /* Deals with DMA transactions */
···
 		return;
 
 	/* Disable RX and TX DMA */
-	while (pl011_read(uap, REG_FR) & UART01x_FR_BUSY)
+	while (pl011_read(uap, REG_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 
 	spin_lock_irq(&uap->port.lock);
···
 	if (delta & UART01x_FR_DCD)
 		uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);
 
-	if (delta & UART01x_FR_DSR)
+	if (delta & uap->vendor->fr_dsr)
 		uap->port.icount.dsr++;
 
-	if (delta & UART01x_FR_CTS)
-		uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);
+	if (delta & uap->vendor->fr_cts)
+		uart_handle_cts_change(&uap->port,
+				       status & uap->vendor->fr_cts);
 
 	wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
 }
···
 	struct uart_amba_port *uap =
 	    container_of(port, struct uart_amba_port, port);
 	unsigned int status = pl011_read(uap, REG_FR);
-	return status & (UART01x_FR_BUSY|UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT;
+	return status & (uap->vendor->fr_busy | UART01x_FR_TXFF) ?
+							0 : TIOCSER_TEMT;
 }
 
 static unsigned int pl011_get_mctrl(struct uart_port *port)
···
 		result |= tiocmbit
 
 	TIOCMBIT(UART01x_FR_DCD, TIOCM_CAR);
-	TIOCMBIT(UART01x_FR_DSR, TIOCM_DSR);
-	TIOCMBIT(UART01x_FR_CTS, TIOCM_CTS);
-	TIOCMBIT(UART011_FR_RI, TIOCM_RNG);
+	TIOCMBIT(uap->vendor->fr_dsr, TIOCM_DSR);
+	TIOCMBIT(uap->vendor->fr_cts, TIOCM_CTS);
+	TIOCMBIT(uap->vendor->fr_ri, TIOCM_RNG);
 #undef TIOCMBIT
 	return result;
 }
···
 	 *	Finally, wait for transmitter to become empty
 	 *	and restore the TCR
 	 */
-	while (pl011_read(uap, REG_FR) & UART01x_FR_BUSY)
+	while (pl011_read(uap, REG_FR) & uap->vendor->fr_busy)
 		cpu_relax();
 	if (!uap->vendor->always_enabled)
 		pl011_write(old_cr, uap, REG_CR);
···
 
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0) {
-		dev_err(&pdev->dev, "cannot obtain irq\n");
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "cannot obtain irq\n");
 		return ret;
 	}
 	uap->port.irq	= ret;
···
 		.id	= 0x00380802,
 		.mask	= 0x00ffffff,
 		.data	= &vendor_st,
+	},
+	{
+		.id	= AMBA_LINUX_ID(0x00, 0x1, 0xffe),
+		.mask	= 0x00ffffff,
+		.data	= &vendor_zte,
 	},
 	{ 0, 0 },
 };

drivers/tty/serial/arc_uart.c

···
 }
 #endif
 
-static struct uart_ops arc_serial_pops = {
+static const struct uart_ops arc_serial_pops = {
 	.tx_empty	= arc_serial_tx_empty,
 	.set_mctrl	= arc_serial_set_mctrl,
 	.get_mctrl	= arc_serial_get_mctrl,

drivers/tty/serial/atmel_serial.c

···
 	u32			rts_low;
 	bool			ms_irq_enabled;
 	u32			rtor;	/* address of receiver timeout register if it exists */
+	bool			has_frac_baudrate;
 	bool			has_hw_timer;
 	struct timer_list	uart_timer;
 
···
 
 	if (np) {
 		/* DMA/PDC usage specification */
-		if (of_get_property(np, "atmel,use-dma-rx", NULL)) {
-			if (of_get_property(np, "dmas", NULL)) {
+		if (of_property_read_bool(np, "atmel,use-dma-rx")) {
+			if (of_property_read_bool(np, "dmas")) {
 				atmel_port->use_dma_rx  = true;
 				atmel_port->use_pdc_rx  = false;
 			} else {
···
 			atmel_port->use_pdc_rx  = false;
 		}
 
-		if (of_get_property(np, "atmel,use-dma-tx", NULL)) {
-			if (of_get_property(np, "dmas", NULL)) {
+		if (of_property_read_bool(np, "atmel,use-dma-tx")) {
+			if (of_property_read_bool(np, "dmas")) {
 				atmel_port->use_dma_tx  = true;
 				atmel_port->use_pdc_tx  = false;
 			} else {
···
 	dbgu_uart = 0x44424755;	/* DBGU */
 	new_uart = 0x55415254;	/* UART */
 
+	/*
+	 * Only USART devices from at91sam9260 SOC implement fractional
+	 * baudrate.
+	 */
+	atmel_port->has_frac_baudrate = false;
 	atmel_port->has_hw_timer = false;
 
 	if (name == new_uart) {
···
 		atmel_port->rtor = ATMEL_UA_RTOR;
 	} else if (name == usart) {
 		dev_dbg(port->dev, "Usart\n");
+		atmel_port->has_frac_baudrate = true;
 		atmel_port->has_hw_timer = true;
 		atmel_port->rtor = ATMEL_US_RTOR;
 	} else if (name == dbgu_uart) {
···
 		case 0x302:
 		case 0x10213:
 			dev_dbg(port->dev, "This version is usart\n");
+			atmel_port->has_frac_baudrate = true;
 			atmel_port->has_hw_timer = true;
 			atmel_port->rtor = ATMEL_US_RTOR;
 			break;
···
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
+	/* Disable modem control lines interrupts */
+	atmel_disable_ms(port);
+
 	/* Disable interrupts at device level */
 	atmel_uart_writel(port, ATMEL_US_IDR, -1);
 
···
 	 */
 	free_irq(port->irq, port);
 
-	atmel_port->ms_irq_enabled = false;
-
 	atmel_flush_buffer(port);
 }
 
···
 static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 			      struct ktermios *old)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned long flags;
-	unsigned int old_mode, mode, imr, quot, baud;
+	unsigned int old_mode, mode, imr, quot, baud, div, cd, fp = 0;
 
 	/* save the current mode register */
 	mode = old_mode = atmel_uart_readl(port, ATMEL_US_MR);
···
 		  ATMEL_US_PAR | ATMEL_US_USMODE);
 
 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
-	quot = uart_get_divisor(port, baud);
-
-	if (quot > 65535) {	/* BRGR is 16-bit, so switch to slower clock */
-		quot /= 8;
-		mode |= ATMEL_US_USCLKS_MCK_DIV8;
-	}
 
 	/* byte size */
 	switch (termios->c_cflag & CSIZE) {
···
 		atmel_uart_writel(port, ATMEL_US_CR, rts_state);
 	}
 
-	/* set the baud rate */
+	/*
+	 * Set the baud rate:
+	 * Fractional baudrate allows to setup output frequency more
+	 * accurately. This feature is enabled only when using normal mode.
+	 * baudrate = selected clock / (8 * (2 - OVER) * (CD + FP / 8))
+	 * Currently, OVER is always set to 0 so we get
+	 * baudrate = selected clock / (16 * (CD + FP / 8))
+	 * then
+	 * 8 CD + FP = selected clock / (2 * baudrate)
+	 */
+	if (atmel_port->has_frac_baudrate &&
+	    (mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_NORMAL) {
+		div = DIV_ROUND_CLOSEST(port->uartclk, baud * 2);
+		cd = div >> 3;
+		fp = div & ATMEL_US_FP_MASK;
+	} else {
+		cd = uart_get_divisor(port, baud);
+	}
+
+	if (cd > 65535) {	/* BRGR is 16-bit, so switch to slower clock */
+		cd /= 8;
+		mode |= ATMEL_US_USCLKS_MCK_DIV8;
+	}
+	quot = cd | fp << ATMEL_US_FP_OFFSET;
+
 	atmel_uart_writel(port, ATMEL_US_BRGR, quot);
 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
 	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);
···
 }
 #endif
 
-static struct uart_ops atmel_pops = {
+static const struct uart_ops atmel_pops = {
 	.tx_empty	= atmel_tx_empty,
 	.set_mctrl	= atmel_set_mctrl,
 	.get_mctrl	= atmel_get_mctrl,

drivers/tty/serial/bcm63xx_uart.c

···
 }
 
 /* serial core callbacks */
-static struct uart_ops bcm_uart_ops = {
+static const struct uart_ops bcm_uart_ops = {
 	.tx_empty	= bcm_uart_tx_empty,
 	.get_mctrl	= bcm_uart_get_mctrl,
 	.set_mctrl	= bcm_uart_set_mctrl,

drivers/tty/serial/earlycon-arm-semihost.c

···
 	uart_console_write(&dev->port, s, n, smh_putc);
 }
 
-int __init early_smh_setup(struct earlycon_device *device, const char *opt)
+static int
+__init early_smh_setup(struct earlycon_device *device, const char *opt)
 {
 	device->con->write = smh_write;
 	return 0;

drivers/tty/serial/earlycon.c

···
 #include <linux/sizes.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
+#include <linux/acpi.h>
 
 #ifdef CONFIG_FIX_EARLYCON_MEM
 #include <asm/fixmap.h>
···
 	.con = &early_con,
 };
 
-static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
+static void __iomem * __init earlycon_map(resource_size_t paddr, size_t size)
 {
 	void __iomem *base;
 #ifdef CONFIG_FIX_EARLYCON_MEM
···
 	base = ioremap(paddr, size);
 #endif
 	if (!base)
-		pr_err("%s: Couldn't map 0x%llx\n", __func__,
-		       (unsigned long long)paddr);
+		pr_err("%s: Couldn't map %pa\n", __func__, &paddr);
 
 	return base;
 }
···
 {
 	struct uart_port *port = &device->port;
 	int length;
-	unsigned long addr;
+	resource_size_t addr;
 
 	if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
 		return -EINVAL;
···
 	return -ENOENT;
 }
 
+/*
+ * When CONFIG_ACPI_SPCR_TABLE is defined, "earlycon" without parameters in
+ * command line does not start DT earlycon immediately, instead it defers
+ * starting it until DT/ACPI decision is made.  At that time if ACPI is enabled
+ * call parse_spcr(), else call early_init_dt_scan_chosen_stdout()
+ */
+bool earlycon_init_is_deferred __initdata;
+
 /* early_param wrapper for setup_earlycon() */
 static int __init param_setup_earlycon(char *buf)
 {
···
 	 * Just 'earlycon' is a valid param for devicetree earlycons;
 	 * don't generate a warning from parse_early_params() in that case
 	 */
-	if (!buf || !buf[0])
-		return 0;
+	if (!buf || !buf[0]) {
+		if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
+			earlycon_init_is_deferred = true;
+			return 0;
+		} else {
+			return early_init_dt_scan_chosen_stdout();
+		}
+	}
 
 	err = setup_earlycon(buf);
 	if (err == -ENOENT || err == -EALREADY)

drivers/tty/serial/fsl_lpuart.c

···
 #define UARTWATER_TXWATER_OFF	0
 #define UARTWATER_RXWATER_OFF	16
 
-#define FSL_UART_RX_DMA_BUFFER_SIZE	64
+/* Rx DMA timeout in ms, which is used to calculate Rx ring buffer size */
+#define DMA_RX_TIMEOUT		(10)
 
 #define DRIVER_NAME	"fsl-lpuart"
 #define DEV_NAME	"ttyLP"
···
 	struct dma_chan		*dma_rx_chan;
 	struct dma_async_tx_descriptor  *dma_tx_desc;
 	struct dma_async_tx_descriptor  *dma_rx_desc;
-	dma_addr_t		dma_tx_buf_bus;
-	dma_addr_t		dma_rx_buf_bus;
 	dma_cookie_t		dma_tx_cookie;
 	dma_cookie_t		dma_rx_cookie;
-	unsigned char		*dma_tx_buf_virt;
-	unsigned char		*dma_rx_buf_virt;
 	unsigned int		dma_tx_bytes;
 	unsigned int		dma_rx_bytes;
-	int			dma_tx_in_progress;
-	int			dma_rx_in_progress;
+	bool			dma_tx_in_progress;
 	unsigned int		dma_rx_timeout;
 	struct timer_list	lpuart_timer;
+	struct scatterlist	rx_sgl, tx_sgl[2];
+	struct circ_buf		rx_ring;
+	int			rx_dma_rng_buf_len;
+	unsigned int		dma_tx_nents;
+	wait_queue_head_t	dma_wait;
 };
 
 static const struct of_device_id lpuart_dt_ids[] = {
···
 
 /* Forward declare this for the dma callbacks*/
 static void lpuart_dma_tx_complete(void *arg);
-static void lpuart_dma_rx_complete(void *arg);
 
 static u32 lpuart32_read(void __iomem *addr)
 {
···
 	lpuart32_write(temp & ~UARTCTRL_RE, port->membase + UARTCTRL);
 }
 
-static void lpuart_copy_rx_to_tty(struct lpuart_port *sport,
-		struct tty_port *tty, int count)
+static void lpuart_dma_tx(struct lpuart_port *sport)
 {
-	int copied;
+	struct circ_buf *xmit = &sport->port.state->xmit;
+	struct scatterlist *sgl = sport->tx_sgl;
+	struct device *dev = sport->port.dev;
+	int ret;
 
-	sport->port.icount.rx += count;
+	if (sport->dma_tx_in_progress)
+		return;
 
-	if (!tty) {
-		dev_err(sport->port.dev, "No tty port\n");
+	sport->dma_tx_bytes = uart_circ_chars_pending(xmit);
+
+	if (xmit->tail < xmit->head) {
+		sport->dma_tx_nents = 1;
+		sg_init_one(sgl, xmit->buf + xmit->tail, sport->dma_tx_bytes);
+	} else {
+		sport->dma_tx_nents = 2;
+		sg_init_table(sgl, 2);
+		sg_set_buf(sgl, xmit->buf + xmit->tail,
+				UART_XMIT_SIZE - xmit->tail);
+		sg_set_buf(sgl + 1, xmit->buf, xmit->head);
+	}
+
+	ret = dma_map_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+	if (!ret) {
+		dev_err(dev, "DMA mapping error for TX.\n");
 		return;
 	}
 
-	dma_sync_single_for_cpu(sport->port.dev, sport->dma_rx_buf_bus,
-			FSL_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
-	copied = tty_insert_flip_string(tty,
-			((unsigned char *)(sport->dma_rx_buf_virt)), count);
-
-	if (copied != count) {
-		WARN_ON(1);
-		dev_err(sport->port.dev, "RxData copy to tty layer failed\n");
-	}
-
-	dma_sync_single_for_device(sport->port.dev, sport->dma_rx_buf_bus,
-			FSL_UART_RX_DMA_BUFFER_SIZE, DMA_TO_DEVICE);
-}
-
-static void lpuart_pio_tx(struct lpuart_port *sport)
-{
-	struct circ_buf *xmit = &sport->port.state->xmit;
-	unsigned long flags;
-
-	spin_lock_irqsave(&sport->port.lock, flags);
-
-	while (!uart_circ_empty(xmit) &&
-		readb(sport->port.membase + UARTTCFIFO) < sport->txfifo_size) {
-		writeb(xmit->buf[xmit->tail], sport->port.membase + UARTDR);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		sport->port.icount.tx++;
-	}
-
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&sport->port);
-
-	if (uart_circ_empty(xmit))
-		writeb(readb(sport->port.membase + UARTCR5) | UARTCR5_TDMAS,
-			sport->port.membase + UARTCR5);
-
-	spin_unlock_irqrestore(&sport->port.lock, flags);
-}
-
-static int lpuart_dma_tx(struct lpuart_port *sport, unsigned long count)
-{
-	struct circ_buf *xmit = &sport->port.state->xmit;
-	dma_addr_t tx_bus_addr;
-
-	dma_sync_single_for_device(sport->port.dev, sport->dma_tx_buf_bus,
-				UART_XMIT_SIZE, DMA_TO_DEVICE);
-	sport->dma_tx_bytes = count & ~(sport->txfifo_size - 1);
-	tx_bus_addr = sport->dma_tx_buf_bus + xmit->tail;
-	sport->dma_tx_desc = dmaengine_prep_slave_single(sport->dma_tx_chan,
-					tx_bus_addr, sport->dma_tx_bytes,
+	sport->dma_tx_desc = dmaengine_prep_slave_sg(sport->dma_tx_chan, sgl,
+					sport->dma_tx_nents,
 					DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT);
-
 	if (!sport->dma_tx_desc) {
-		dev_err(sport->port.dev, "Not able to get desc for tx\n");
-		return -EIO;
+		dma_unmap_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+		dev_err(dev, "Cannot prepare TX slave DMA!\n");
+		return;
 	}
 
 	sport->dma_tx_desc->callback = lpuart_dma_tx_complete;
 	sport->dma_tx_desc->callback_param = sport;
-	sport->dma_tx_in_progress = 1;
+	sport->dma_tx_in_progress = true;
 	sport->dma_tx_cookie = dmaengine_submit(sport->dma_tx_desc);
 	dma_async_issue_pending(sport->dma_tx_chan);
 
-	return 0;
-}
-
-static void lpuart_prepare_tx(struct lpuart_port *sport)
-{
-	struct circ_buf *xmit = &sport->port.state->xmit;
-	unsigned long count =  CIRC_CNT_TO_END(xmit->head,
-					xmit->tail, UART_XMIT_SIZE);
-
-	if (!count)
-		return;
-
-	if (count < sport->txfifo_size)
-		writeb(readb(sport->port.membase + UARTCR5) & ~UARTCR5_TDMAS,
-				sport->port.membase + UARTCR5);
-	else {
-		writeb(readb(sport->port.membase + UARTCR5) | UARTCR5_TDMAS,
-				sport->port.membase + UARTCR5);
-		lpuart_dma_tx(sport, count);
-	}
 }
 
 static void lpuart_dma_tx_complete(void *arg)
 {
 	struct lpuart_port *sport = arg;
+	struct scatterlist *sgl = &sport->tx_sgl[0];
 	struct circ_buf *xmit = &sport->port.state->xmit;
 	unsigned long flags;
 
-	async_tx_ack(sport->dma_tx_desc);
-
 	spin_lock_irqsave(&sport->port.lock, flags);
 
+	dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
+
 	xmit->tail = (xmit->tail + sport->dma_tx_bytes) & (UART_XMIT_SIZE - 1);
-	sport->dma_tx_in_progress = 0;
+
+	sport->port.icount.tx += sport->dma_tx_bytes;
+	sport->dma_tx_in_progress = false;
+	spin_unlock_irqrestore(&sport->port.lock, flags);
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(&sport->port);
 
-	lpuart_prepare_tx(sport);
+	if (waitqueue_active(&sport->dma_wait)) {
+		wake_up(&sport->dma_wait);
+		return;
+	}
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	if (!uart_circ_empty(xmit) && !uart_tx_stopped(&sport->port))
+		lpuart_dma_tx(sport);
 
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
-static int lpuart_dma_rx(struct lpuart_port *sport)
+static int lpuart_dma_tx_request(struct uart_port *port)
 {
-	dma_sync_single_for_device(sport->port.dev, sport->dma_rx_buf_bus,
-			FSL_UART_RX_DMA_BUFFER_SIZE, DMA_TO_DEVICE);
-	sport->dma_rx_desc = dmaengine_prep_slave_single(sport->dma_rx_chan,
-			sport->dma_rx_buf_bus, FSL_UART_RX_DMA_BUFFER_SIZE,
-			DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
+	struct lpuart_port *sport = container_of(port,
+					struct lpuart_port, port);
+	struct dma_slave_config dma_tx_sconfig = {};
+	int ret;
 
-	if (!sport->dma_rx_desc) {
-		dev_err(sport->port.dev, "Not able to get desc for rx\n");
-		return -EIO;
+	dma_tx_sconfig.dst_addr = sport->port.mapbase + UARTDR;
+	dma_tx_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma_tx_sconfig.dst_maxburst = 1;
+	dma_tx_sconfig.direction = DMA_MEM_TO_DEV;
+	ret = dmaengine_slave_config(sport->dma_tx_chan, &dma_tx_sconfig);
+
+	if (ret) {
+		dev_err(sport->port.dev,
+				"DMA slave config failed, err = %d\n", ret);
+		return ret;
 	}
-
-	sport->dma_rx_desc->callback = lpuart_dma_rx_complete;
-	sport->dma_rx_desc->callback_param = sport;
-	sport->dma_rx_in_progress = 1;
-	sport->dma_rx_cookie = dmaengine_submit(sport->dma_rx_desc);
-	dma_async_issue_pending(sport->dma_rx_chan);
 
 	return 0;
 }
···
 static void lpuart_flush_buffer(struct uart_port *port)
 {
 	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
+
 	if (sport->lpuart_dma_tx_use) {
+		if (sport->dma_tx_in_progress) {
+			dma_unmap_sg(sport->port.dev, &sport->tx_sgl[0],
+				sport->dma_tx_nents, DMA_TO_DEVICE);
+			sport->dma_tx_in_progress = false;
+		}
 		dmaengine_terminate_all(sport->dma_tx_chan);
-		sport->dma_tx_in_progress = 0;
 	}
-}
-
-static void lpuart_dma_rx_complete(void *arg)
-{
-	struct lpuart_port *sport = arg;
-	struct tty_port *port = &sport->port.state->port;
-	unsigned long flags;
-
-	async_tx_ack(sport->dma_rx_desc);
-	mod_timer(&sport->lpuart_timer, jiffies + sport->dma_rx_timeout);
-
-	spin_lock_irqsave(&sport->port.lock, flags);
-
-	sport->dma_rx_in_progress = 0;
-	lpuart_copy_rx_to_tty(sport, port, FSL_UART_RX_DMA_BUFFER_SIZE);
-	tty_flip_buffer_push(port);
-	lpuart_dma_rx(sport);
-
-	spin_unlock_irqrestore(&sport->port.lock, flags);
-}
-
-static void lpuart_timer_func(unsigned long data)
-{
-	struct lpuart_port *sport = (struct lpuart_port *)data;
-	struct tty_port *port = &sport->port.state->port;
-	struct dma_tx_state state;
-	unsigned long flags;
-	unsigned char temp;
-	int count;
-
-	del_timer(&sport->lpuart_timer);
-	dmaengine_pause(sport->dma_rx_chan);
-	dmaengine_tx_status(sport->dma_rx_chan, sport->dma_rx_cookie, &state);
-	dmaengine_terminate_all(sport->dma_rx_chan);
-	count = FSL_UART_RX_DMA_BUFFER_SIZE - state.residue;
-	async_tx_ack(sport->dma_rx_desc);
-
-	spin_lock_irqsave(&sport->port.lock, flags);
-
-	sport->dma_rx_in_progress = 0;
-	lpuart_copy_rx_to_tty(sport, port, count);
-	tty_flip_buffer_push(port);
-	temp = readb(sport->port.membase + UARTCR5);
-	writeb(temp & ~UARTCR5_RDMAS, sport->port.membase + UARTCR5);
-
-	spin_unlock_irqrestore(&sport->port.lock, flags);
-}
-
-static inline void lpuart_prepare_rx(struct lpuart_port *sport)
-{
-	unsigned long flags;
-	unsigned char temp;
-
-	spin_lock_irqsave(&sport->port.lock, flags);
-
-	sport->lpuart_timer.expires = jiffies + sport->dma_rx_timeout;
-	add_timer(&sport->lpuart_timer);
-
-	lpuart_dma_rx(sport);
-	temp = readb(sport->port.membase + UARTCR5);
-	writeb(temp | UARTCR5_RDMAS, sport->port.membase + UARTCR5);
-
-	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 static inline void lpuart_transmit_buffer(struct lpuart_port *sport)
···
 	writeb(temp | UARTCR2_TIE, port->membase + UARTCR2);
 
 	if (sport->lpuart_dma_tx_use) {
-		if (!uart_circ_empty(xmit) && !sport->dma_tx_in_progress)
-			lpuart_prepare_tx(sport);
+		if (!uart_circ_empty(xmit) && !uart_tx_stopped(port))
+			lpuart_dma_tx(sport);
 	} else {
 		if (readb(port->membase + UARTSR1) & UARTSR1_TDRE)
 			lpuart_transmit_buffer(sport);
···
 
 	if (lpuart32_read(port->membase + UARTSTAT) & UARTSTAT_TDRE)
 		lpuart32_transmit_buffer(sport);
+}
+
+/* return TIOCSER_TEMT when transmitter is not busy */
+static unsigned int lpuart_tx_empty(struct uart_port *port)
+{
+	struct lpuart_port *sport = container_of(port,
+			struct lpuart_port, port);
+	unsigned char sr1 = readb(port->membase + UARTSR1);
+	unsigned char sfifo = readb(port->membase + UARTSFIFO);
+
+	if (sport->dma_tx_in_progress)
+		return 0;
+
+	if (sr1 & UARTSR1_TC && sfifo & UARTSFIFO_TXEMPT)
+		return TIOCSER_TEMT;
+
+	return 0;
+}
+
+static unsigned int lpuart32_tx_empty(struct uart_port *port)
+{
+	return (lpuart32_read(port->membase + UARTSTAT) & UARTSTAT_TC) ?
+		TIOCSER_TEMT : 0;
 }
 
 static irqreturn_t lpuart_txint(int irq, void *dev_id)
···
 static irqreturn_t lpuart_int(int irq, void *dev_id)
 {
 	struct lpuart_port *sport = dev_id;
-	unsigned char sts, crdma;
+	unsigned char sts;
 
 	sts = readb(sport->port.membase + UARTSR1);
-	crdma = readb(sport->port.membase + UARTCR5);
 
-	if (sts & UARTSR1_RDRF && !(crdma & UARTCR5_RDMAS)) {
-		if (sport->lpuart_dma_rx_use)
-			lpuart_prepare_rx(sport);
-		else
-			lpuart_rxint(irq, dev_id);
-	}
-	if (sts & UARTSR1_TDRE && !(crdma & UARTCR5_TDMAS)) {
-		if (sport->lpuart_dma_tx_use)
-			lpuart_pio_tx(sport);
-		else
-			lpuart_txint(irq, dev_id);
-	}
+	if (sts & UARTSR1_RDRF)
+		lpuart_rxint(irq, dev_id);
+
+	if (sts & UARTSR1_TDRE)
+		lpuart_txint(irq, dev_id);
 
 	return IRQ_HANDLED;
 }
···
 	return IRQ_HANDLED;
 }
 
-/* return TIOCSER_TEMT when transmitter is not busy */
-static unsigned int lpuart_tx_empty(struct uart_port *port)
+static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 {
-	return (readb(port->membase + UARTSR1) & UARTSR1_TC) ?
-		TIOCSER_TEMT : 0;
+	struct tty_port *port = &sport->port.state->port;
+	struct dma_tx_state state;
+	enum dma_status dmastat;
+	struct circ_buf *ring = &sport->rx_ring;
+	unsigned long flags;
+	int count = 0;
+	unsigned char sr;
+
+	sr = readb(sport->port.membase + UARTSR1);
+
+	if (sr & (UARTSR1_PE | UARTSR1_FE)) {
+		/* Read DR to clear the error flags */
+		readb(sport->port.membase + UARTDR);
+
+		if (sr & UARTSR1_PE)
+		    sport->port.icount.parity++;
+		else if (sr & UARTSR1_FE)
+		    sport->port.icount.frame++;
+	}
+
+	async_tx_ack(sport->dma_rx_desc);
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	dmastat = dmaengine_tx_status(sport->dma_rx_chan,
+				sport->dma_rx_cookie,
+				&state);
+
+	if (dmastat == DMA_ERROR) {
+		dev_err(sport->port.dev, "Rx DMA transfer failed!\n");
+		spin_unlock_irqrestore(&sport->port.lock, flags);
+		return;
+	}
+
+	/* CPU claims ownership of RX DMA buffer */
+	dma_sync_sg_for_cpu(sport->port.dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
+
+	/*
+	 * ring->head points to the end of data already written by the DMA.
+	 * ring->tail points to the beginning of data to be read by the
+	 * framework.
+	 * The current transfer size should not be larger than the dma buffer
+	 * length.
+	 */
+	ring->head = sport->rx_sgl.length - state.residue;
+	BUG_ON(ring->head > sport->rx_sgl.length);
+	/*
+	 * At this point ring->head may point to the first byte right after the
+	 * last byte of the dma buffer:
+	 * 0 <= ring->head <= sport->rx_sgl.length
+	 *
+	 * However ring->tail must always points inside the dma buffer:
+	 * 0 <= ring->tail <= sport->rx_sgl.length - 1
+	 *
+	 * Since we use a ring buffer, we have to handle the case
+	 * where head is lower than tail. In such a case, we first read from
+	 * tail to the end of the buffer then reset tail.
+	 */
+	if (ring->head < ring->tail) {
+		count = sport->rx_sgl.length - ring->tail;
+
+		tty_insert_flip_string(port, ring->buf + ring->tail, count);
+		ring->tail = 0;
+		sport->port.icount.rx += count;
+	}
+
+	/* Finally we read data from tail to head */
+	if (ring->tail < ring->head) {
+		count = ring->head - ring->tail;
+		tty_insert_flip_string(port, ring->buf + ring->tail, count);
+		/* Wrap ring->head if needed */
+		if (ring->head >= sport->rx_sgl.length)
+			ring->head = 0;
+		ring->tail = ring->head;
+		sport->port.icount.rx += count;
+	}
+
+	dma_sync_sg_for_device(sport->port.dev, &sport->rx_sgl, 1,
+			       DMA_FROM_DEVICE);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	tty_flip_buffer_push(port);
+	mod_timer(&sport->lpuart_timer, jiffies + sport->dma_rx_timeout);
 }
 
-static unsigned int lpuart32_tx_empty(struct uart_port *port)
+static void lpuart_dma_rx_complete(void *arg)
 {
-	return (lpuart32_read(port->membase + UARTSTAT) & UARTSTAT_TC) ?
-		TIOCSER_TEMT : 0;
+	struct lpuart_port *sport = arg;
+
+	lpuart_copy_rx_to_tty(sport);
+}
+
+static void lpuart_timer_func(unsigned long data)
+{
+	struct lpuart_port *sport = (struct lpuart_port *)data;
+
+	lpuart_copy_rx_to_tty(sport);
+}
+
+static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
+{
+	struct dma_slave_config dma_rx_sconfig = {};
+	struct circ_buf *ring = &sport->rx_ring;
+	int ret, nent;
+	int bits, baud;
+	struct tty_struct *tty = tty_port_tty_get(&sport->port.state->port);
+	struct ktermios *termios = &tty->termios;
+
+	baud = tty_get_baud_rate(tty);
+
+	bits = (termios->c_cflag & CSIZE) == CS7 ? 9 : 10;
+	if (termios->c_cflag & PARENB)
+		bits++;
+
+	/*
+	 * Calculate length of one DMA buffer size to keep latency below
+	 * 10ms at any baud rate.
+	 */
+	sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud /  bits / 1000) * 2;
+	sport->rx_dma_rng_buf_len = (1 << (fls(sport->rx_dma_rng_buf_len) - 1));
+	if (sport->rx_dma_rng_buf_len < 16)
+		sport->rx_dma_rng_buf_len = 16;
+
+	ring->buf = kmalloc(sport->rx_dma_rng_buf_len, GFP_ATOMIC);
+	if (!ring->buf) {
+		dev_err(sport->port.dev, "Ring buf alloc failed\n");
+		return -ENOMEM;
+	}
+
+	sg_init_one(&sport->rx_sgl, ring->buf, sport->rx_dma_rng_buf_len);
+	sg_set_buf(&sport->rx_sgl, ring->buf, sport->rx_dma_rng_buf_len);
+	nent = dma_map_sg(sport->port.dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
+
+	if (!nent) {
+		dev_err(sport->port.dev, "DMA Rx mapping error\n");
+		return -EINVAL;
+	}
+
+	dma_rx_sconfig.src_addr = sport->port.mapbase + UARTDR;
+	dma_rx_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma_rx_sconfig.src_maxburst = 1;
+	dma_rx_sconfig.direction = DMA_DEV_TO_MEM;
+	ret = dmaengine_slave_config(sport->dma_rx_chan, &dma_rx_sconfig);
+
+	if (ret < 0) {
+		dev_err(sport->port.dev,
+				"DMA Rx slave config failed, err = %d\n", ret);
+		return ret;
+	}
+
+	sport->dma_rx_desc = dmaengine_prep_dma_cyclic(sport->dma_rx_chan,
+				 sg_dma_address(&sport->rx_sgl),
+				 sport->rx_sgl.length,
+				 sport->rx_sgl.length / 2,
+				 DMA_DEV_TO_MEM,
+				 DMA_PREP_INTERRUPT);
+	if (!sport->dma_rx_desc) {
+		dev_err(sport->port.dev, "Cannot prepare cyclic DMA\n");
+		return -EFAULT;
+	}
+
+	sport->dma_rx_desc->callback = lpuart_dma_rx_complete;
+	sport->dma_rx_desc->callback_param = sport;
+	sport->dma_rx_cookie = dmaengine_submit(sport->dma_rx_desc);
+	dma_async_issue_pending(sport->dma_rx_chan);
+
+	writeb(readb(sport->port.membase + UARTCR5) | UARTCR5_RDMAS,
+				sport->port.membase + UARTCR5);
+
+	return 0;
+}
+
+static void lpuart_dma_rx_free(struct uart_port *port)
+{
+	struct lpuart_port *sport = container_of(port,
+					struct lpuart_port, port);
+
+	if (sport->dma_rx_chan)
+		dmaengine_terminate_all(sport->dma_rx_chan);
+
+	dma_unmap_sg(sport->port.dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
+	kfree(sport->rx_ring.buf);
+	sport->rx_ring.tail = 0;
+	sport->rx_ring.head = 0;
+	sport->dma_rx_desc = NULL;
+	sport->dma_rx_cookie = -EINVAL;
+}
+
+static int lpuart_config_rs485(struct uart_port *port,
+			struct serial_rs485 *rs485)
+{
+	struct lpuart_port *sport = container_of(port,
+			struct lpuart_port, port);
+
+	u8 modem = readb(sport->port.membase + UARTMODEM) &
+		~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
+	writeb(modem, sport->port.membase + UARTMODEM);
+
+	if (rs485->flags & SER_RS485_ENABLED) {
+		/* Enable auto RS-485 RTS mode */
+		modem |= UARTMODEM_TXRTSE;
+
+		/*
+		 * RTS needs to be logic HIGH either during transer _or_ after
+		 * transfer, other variants are not supported by the hardware.
+		 */
+
+		if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
+				SER_RS485_RTS_AFTER_SEND)))
+			rs485->flags |= SER_RS485_RTS_ON_SEND;
+
+		if (rs485->flags & SER_RS485_RTS_ON_SEND &&
+				rs485->flags & SER_RS485_RTS_AFTER_SEND)
+			rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
+
+		/*
+		 * The hardware defaults to RTS logic HIGH while transfer.
+		 * Switch polarity in case RTS shall be logic HIGH
+		 * after transfer.
+		 * Note: UART is assumed to be active high.
+		 */
+		if (rs485->flags & SER_RS485_RTS_ON_SEND)
+			modem &= ~UARTMODEM_TXRTSPOL;
+		else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
+			modem |= UARTMODEM_TXRTSPOL;
+	}
+
+	/* Store the new configuration */
+	sport->port.rs485 = *rs485;
+
+	writeb(modem, sport->port.membase + UARTMODEM);
+	return 0;
 }
 
 static unsigned int lpuart_get_mctrl(struct uart_port *port)
···
 static void lpuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	unsigned char temp;
+	struct lpuart_port *sport = container_of(port,
+				struct lpuart_port, port);
 
-	temp = readb(port->membase + UARTMODEM) &
+	/* Make sure RXRTSE bit is not set when RS485 is enabled */
+	if (!(sport->port.rs485.flags & SER_RS485_ENABLED)) {
+		temp = readb(sport->port.membase + UARTMODEM) &
 			~(UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
 
-	if (mctrl & TIOCM_RTS)
-		temp |= UARTMODEM_RXRTSE;
+		if (mctrl & TIOCM_RTS)
+			temp |= UARTMODEM_RXRTSE;
 
-	if (mctrl & TIOCM_CTS)
-		temp |= UARTMODEM_TXCTSE;
+		if (mctrl & TIOCM_CTS)
+			temp |= UARTMODEM_TXCTSE;
 
-	writeb(temp, port->membase + UARTMODEM);
+		writeb(temp, port->membase + UARTMODEM);
+	}
 }
 
 static void lpuart32_set_mctrl(struct uart_port *port, unsigned int mctrl)
···
 	writeb(val | UARTPFIFO_TXFE | UARTPFIFO_RXFE,
 			sport->port.membase + UARTPFIFO);
 
-	/* explicitly clear RDRF */
-	readb(sport->port.membase + UARTSR1);
-
 	/* flush Tx and Rx FIFO */
 	writeb(UARTCFIFO_TXFLUSH | UARTCFIFO_RXFLUSH,
 			sport->port.membase + UARTCFIFO);
+
+	/* explicitly clear RDRF */
+	if (readb(sport->port.membase + UARTSR1) & UARTSR1_RDRF) {
+		readb(sport->port.membase + UARTDR);
+		writeb(UARTSFIFO_RXUF, sport->port.membase + UARTSFIFO);
+	}
 
 	writeb(0, sport->port.membase + UARTTWFIFO);
 	writeb(1, sport->port.membase + UARTRWFIFO);
···
 	lpuart32_write(ctrl_saved, sport->port.membase + UARTCTRL);
 }
 
-static int lpuart_dma_tx_request(struct uart_port *port)
+static void rx_dma_timer_init(struct lpuart_port *sport)
 {
-	struct lpuart_port *sport = container_of(port,
-					struct lpuart_port, port);
-	struct dma_slave_config dma_tx_sconfig;
-	dma_addr_t dma_bus;
-	unsigned char *dma_buf;
-	int ret;
-
-	dma_bus = dma_map_single(sport->dma_tx_chan->device->dev,
-				sport->port.state->xmit.buf,
-				UART_XMIT_SIZE, DMA_TO_DEVICE);
-
-	if (dma_mapping_error(sport->dma_tx_chan->device->dev, dma_bus)) {
-		dev_err(sport->port.dev, "dma_map_single tx failed\n");
-		return -ENOMEM;
-	}
-
-	dma_buf = sport->port.state->xmit.buf;
-	dma_tx_sconfig.dst_addr = sport->port.mapbase + UARTDR;
-	dma_tx_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
-	dma_tx_sconfig.dst_maxburst = sport->txfifo_size;
-	dma_tx_sconfig.direction = DMA_MEM_TO_DEV;
-	ret = dmaengine_slave_config(sport->dma_tx_chan, &dma_tx_sconfig);
-
-	if (ret < 0) {
-		dev_err(sport->port.dev,
-				"Dma slave config failed, err = %d\n", ret);
-		return ret;
-	}
-
-	sport->dma_tx_buf_virt = dma_buf;
-	sport->dma_tx_buf_bus = dma_bus;
-	sport->dma_tx_in_progress = 0;
-
-	return 0;
-}
-
-static int lpuart_dma_rx_request(struct uart_port *port)
-{
-	struct lpuart_port *sport = container_of(port,
-					struct lpuart_port, port);
-	struct dma_slave_config dma_rx_sconfig;
-	dma_addr_t dma_bus;
-	unsigned char *dma_buf;
-	int ret;
-
-	dma_buf = devm_kzalloc(sport->port.dev,
-				FSL_UART_RX_DMA_BUFFER_SIZE, GFP_KERNEL);
-
-	if (!dma_buf) {
-		dev_err(sport->port.dev, "Dma rx alloc failed\n");
-		return -ENOMEM;
-	}
-
-	dma_bus = dma_map_single(sport->dma_rx_chan->device->dev, dma_buf,
-				FSL_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
-
-	if (dma_mapping_error(sport->dma_rx_chan->device->dev, dma_bus)) {
-		dev_err(sport->port.dev, "dma_map_single rx failed\n");
-		return -ENOMEM;
-	}
-
-	dma_rx_sconfig.src_addr = sport->port.mapbase + UARTDR;
-	dma_rx_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
-	dma_rx_sconfig.src_maxburst = 1;
-	dma_rx_sconfig.direction = DMA_DEV_TO_MEM;
-	ret = dmaengine_slave_config(sport->dma_rx_chan, &dma_rx_sconfig);
-
-	if (ret < 0) {
-		dev_err(sport->port.dev,
-				"Dma slave config failed, err = %d\n", ret);
-		return ret;
-	}
-
-	sport->dma_rx_buf_virt = dma_buf;
-	sport->dma_rx_buf_bus = dma_bus;
-	sport->dma_rx_in_progress = 0;
-
-	return 0;
-}
-
-static void lpuart_dma_tx_free(struct uart_port *port)
-{
-	struct lpuart_port *sport = container_of(port,
-					struct lpuart_port, port);
-
-	dma_unmap_single(sport->port.dev, sport->dma_tx_buf_bus,
-			UART_XMIT_SIZE, DMA_TO_DEVICE);
-
-	sport->dma_tx_buf_bus = 0;
-	sport->dma_tx_buf_virt = NULL;
-}
-
-static void lpuart_dma_rx_free(struct uart_port *port)
-{
-	struct lpuart_port *sport = container_of(port,
-					struct lpuart_port, port);
-
-	dma_unmap_single(sport->port.dev, sport->dma_rx_buf_bus,
-			FSL_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
-
-	sport->dma_rx_buf_bus = 0;
-	sport->dma_rx_buf_virt = NULL;
+		setup_timer(&sport->lpuart_timer, lpuart_timer_func,
+				(unsigned long)sport);
+		sport->lpuart_timer.expires = jiffies + sport->dma_rx_timeout;
+		add_timer(&sport->lpuart_timer);
 }
 
 static int lpuart_startup(struct uart_port *port)
···
 	sport->rxfifo_size = 0x1 << (((temp >> UARTPFIFO_RXSIZE_OFF) &
 		UARTPFIFO_FIFOSIZE_MASK) + 1);
 
-	if (sport->dma_rx_chan && !lpuart_dma_rx_request(port)) {
-		sport->lpuart_dma_rx_use = true;
-		setup_timer(&sport->lpuart_timer, lpuart_timer_func,
-			    (unsigned long)sport);
-	} else
-		sport->lpuart_dma_rx_use = false;
-
-
-	if (sport->dma_tx_chan && !lpuart_dma_tx_request(port)) {
-		sport->lpuart_dma_tx_use = true;
-		temp = readb(port->membase + UARTCR5);
-		temp &= ~UARTCR5_RDMAS;
-		writeb(temp | UARTCR5_TDMAS, port->membase + UARTCR5);
-	} else
-		sport->lpuart_dma_tx_use = false;
-
 	ret = devm_request_irq(port->dev, port->irq, lpuart_int, 0,
 				DRIVER_NAME, sport);
 	if (ret)
···
 	temp |= (UARTCR2_RIE | UARTCR2_TIE | UARTCR2_RE | UARTCR2_TE);
 	writeb(temp, sport->port.membase + UARTCR2);
 
+	if (sport->dma_rx_chan && !lpuart_start_rx_dma(sport)) {
+		/* set Rx DMA timeout */
+		sport->dma_rx_timeout = msecs_to_jiffies(DMA_RX_TIMEOUT);
+		if (!sport->dma_rx_timeout)
+		     sport->dma_rx_timeout = 1;
+
+		sport->lpuart_dma_rx_use = true;
+		rx_dma_timer_init(sport);
+	} else {
+		sport->lpuart_dma_rx_use = false;
+	}
+
+	if (sport->dma_tx_chan && !lpuart_dma_tx_request(port)) {
+		init_waitqueue_head(&sport->dma_wait);
+		sport->lpuart_dma_tx_use = true;
+		temp = readb(port->membase + UARTCR5);
+		writeb(temp | UARTCR5_TDMAS, port->membase + UARTCR5);
+	} else {
+		sport->lpuart_dma_tx_use = false;
+	}
+
 	spin_unlock_irqrestore(&sport->port.lock, flags);
+
 	return 0;
 }
 
···
 	devm_free_irq(port->dev, port->irq, sport);
 
 	if (sport->lpuart_dma_rx_use) {
-		lpuart_dma_rx_free(&sport->port);
 		del_timer_sync(&sport->lpuart_timer);
+		lpuart_dma_rx_free(&sport->port);
 	}
 
-	if (sport->lpuart_dma_tx_use)
-		lpuart_dma_tx_free(&sport->port);
+	if (sport->lpuart_dma_tx_use) {
+		if (wait_event_interruptible(sport->dma_wait,
+			!sport->dma_tx_in_progress) != false) {
+			sport->dma_tx_in_progress = false;
+			dmaengine_terminate_all(sport->dma_tx_chan);
+		}
+
+		lpuart_stop_tx(port);
+	}
 }
 
 static void lpuart32_shutdown(struct uart_port *port)
···
 {
 	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
 	unsigned long flags;
-	unsigned char cr1, old_cr1, old_cr2, cr4, bdh, modem;
+	unsigned char cr1, old_cr1, old_cr2, cr3, cr4, bdh, modem;
 	unsigned int  baud;
 	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
 	unsigned int sbr, brfa;
 
 	cr1 = old_cr1 = readb(sport->port.membase + UARTCR1);
 	old_cr2 = readb(sport->port.membase + UARTCR2);
+	cr3 = readb(sport->port.membase + UARTCR3);
 	cr4 = readb(sport->port.membase + UARTCR4);
 	bdh = readb(sport->port.membase + UARTBDH);
 	modem = readb(sport->port.membase + UARTMODEM);
···
 		cr1 |= UARTCR1_M;
 	}
 
+	/*
+	 * When auto RS-485 RTS mode is enabled,
+	 * hardware flow control need to be disabled.
+	 */
+	if (sport->port.rs485.flags & SER_RS485_ENABLED)
+		termios->c_cflag &= ~CRTSCTS;
+
 	if (termios->c_cflag & CRTSCTS) {
 		modem |= (UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
 	} else {
···
 	if ((termios->c_cflag & PARENB)) {
 		if (termios->c_cflag & CMSPAR) {
 			cr1 &= ~UARTCR1_PE;
-			cr1 |= UARTCR1_M;
+			if (termios->c_cflag & PARODD)
+				cr3 |= UARTCR3_T8;
+			else
+				cr3 &= ~UARTCR3_T8;
 		} else {
 			cr1 |= UARTCR1_PE;
 			if ((termios->c_cflag & CSIZE) == CS8)
···
 	/* update the per-port timeout */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	if (sport->lpuart_dma_rx_use) {
-		/* Calculate delay for 1.5 DMA buffers */
-		sport->dma_rx_timeout = (sport->port.timeout - HZ / 50) *
-					FSL_UART_RX_DMA_BUFFER_SIZE * 3 /
-					sport->rxfifo_size / 2;
-		dev_dbg(port->dev, "DMA Rx t-out %ums, tty t-out %u jiffies\n",
-			sport->dma_rx_timeout * 1000 / HZ, sport->port.timeout);
-		if (sport->dma_rx_timeout < msecs_to_jiffies(20))
-			sport->dma_rx_timeout = msecs_to_jiffies(20);
-	}
-
 	/* wait transmit engin complete */
 	while (!(readb(sport->port.membase + UARTSR1) & UARTSR1_TC))
 		barrier();
···
 	writeb(cr4 | brfa, sport->port.membase + UARTCR4);
 	writeb(bdh, sport->port.membase + UARTBDH);
 	writeb(sbr & 0xFF, sport->port.membase + UARTBDL);
+	writeb(cr3, sport->port.membase + UARTCR3);
 	writeb(cr1, sport->port.membase + UARTCR1);
 	writeb(modem, sport->port.membase + UARTMODEM);
 
 	/* restore control register */
 	writeb(old_cr2, sport->port.membase + UARTCR2);
+
+	/*
+	 * If new baud rate is set, we will also need to update the Ring buffer
+	 * length according to the selected baud rate and restart Rx DMA path.
+	 */
+	if (old) {
+		if (sport->lpuart_dma_rx_use) {
+			del_timer_sync(&sport->lpuart_timer);
+			lpuart_dma_rx_free(&sport->port);
+		}
+
+		if (sport->dma_rx_chan && !lpuart_start_rx_dma(sport)) {
+			sport->lpuart_dma_rx_use = true;
+			rx_dma_timer_init(sport);
+		} else {
+			sport->lpuart_dma_rx_use = false;
+		}
+	}
 
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
···
 	return ret;
 }
 
-static struct uart_ops lpuart_pops = {
+static const struct uart_ops lpuart_pops = {
 	.tx_empty	= lpuart_tx_empty,
 	.set_mctrl	= lpuart_set_mctrl,
 	.get_mctrl	= lpuart_get_mctrl,
···
 	.flush_buffer	= lpuart_flush_buffer,
 };
 
-static struct uart_ops lpuart32_pops = {
+static const struct uart_ops lpuart32_pops = {
 	.tx_empty	= lpuart32_tx_empty,
 	.set_mctrl	= lpuart32_set_mctrl,
 	.get_mctrl	= lpuart32_get_mctrl,
···
 		sport->port.ops = &lpuart_pops;
 	sport->port.flags = UPF_BOOT_AUTOCONF;
 
+	sport->port.rs485_config = lpuart_config_rs485;
+
 	sport->clk = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(sport->clk)) {
 		ret = PTR_ERR(sport->clk);
···
 	if (!sport->dma_rx_chan)
 		dev_info(sport->port.dev, "DMA rx channel request failed, "
 				"operating without rx DMA\n");
+
+	if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time")) {
+		sport->port.rs485.flags |= SER_RS485_ENABLED;
+		sport->port.rs485.flags |= SER_RS485_RTS_ON_SEND;
+		writeb(UARTMODEM_TXRTSE, sport->port.membase + UARTMODEM);
+	}
 
 	return 0;
 }
···
 
 	uart_suspend_port(&lpuart_reg, &sport->port);
 
+	if (sport->lpuart_dma_rx_use) {
+		/*
+		 * EDMA driver during suspend will forcefully release any
+		 * non-idle DMA channels. If port wakeup is enabled or if port
+		 * is console port or 'no_console_suspend' is set the Rx DMA
+		 * cannot resume as as expected, hence gracefully release the
+		 * Rx DMA path before suspend and start Rx DMA path on resume.
+		 */
+		if (sport->port.irq_wake) {
+			del_timer_sync(&sport->lpuart_timer);
+			lpuart_dma_rx_free(&sport->port);
+		}
+
+		/* Disable Rx DMA to use UART port as wakeup source */
+		writeb(readb(sport->port.membase + UARTCR5) & ~UARTCR5_RDMAS,
+					sport->port.membase + UARTCR5);
+	}
+
+	if (sport->lpuart_dma_tx_use) {
+		sport->dma_tx_in_progress = false;
+		dmaengine_terminate_all(sport->dma_tx_chan);
+	}
+
+	if (sport->port.suspended && !sport->port.irq_wake)
+		clk_disable_unprepare(sport->clk);
+
 	return 0;
 }
 
···
 {
 	struct lpuart_port *sport = dev_get_drvdata(dev);
 	unsigned long temp;
+
+	if (sport->port.suspended && !sport->port.irq_wake)
+		clk_prepare_enable(sport->clk);
 
 	if (sport->lpuart32) {
 		lpuart32_setup_watermark(sport);
···
 		temp = readb(sport->port.membase + UARTCR2);
 		temp |= (UARTCR2_RIE | UARTCR2_TIE | UARTCR2_RE | UARTCR2_TE);
 		writeb(temp, sport->port.membase + UARTCR2);
+	}
+
+	if (sport->lpuart_dma_rx_use) {
+		if (sport->port.irq_wake) {
+			if (!lpuart_start_rx_dma(sport)) {
+				sport->lpuart_dma_rx_use = true;
+				rx_dma_timer_init(sport);
+			} else {
+				sport->lpuart_dma_rx_use = false;
+			}
+		}
+	}
+
+	if (sport->dma_tx_chan && !lpuart_dma_tx_request(&sport->port)) {
+			init_waitqueue_head(&sport->dma_wait);
+			sport->lpuart_dma_tx_use = true;
+			writeb(readb(sport->port.membase + UARTCR5) |
+				UARTCR5_TDMAS, sport->port.membase + UARTCR5);
+	} else {
+		sport->lpuart_dma_tx_use = false;
 	}
 
 	uart_resume_port(&lpuart_reg, &sport->port);

drivers/tty/serial/imx.c

···
 enum imx_uart_type {
 	IMX1_UART,
 	IMX21_UART,
+	IMX53_UART,
 	IMX6Q_UART,
 };
 
···
 	struct dma_chan		*dma_chan_rx, *dma_chan_tx;
 	struct scatterlist	rx_sgl, tx_sgl[2];
 	void			*rx_buf;
+	struct circ_buf		rx_ring;
+	unsigned int		rx_periods;
+	dma_cookie_t		rx_cookie;
 	unsigned int		tx_bytes;
 	unsigned int		dma_tx_nents;
 	wait_queue_head_t	dma_wait;
···
 		.uts_reg = IMX21_UTS,
 		.devtype = IMX21_UART,
 	},
+	[IMX53_UART] = {
+		.uts_reg = IMX21_UTS,
+		.devtype = IMX53_UART,
+	},
 	[IMX6Q_UART] = {
 		.uts_reg = IMX21_UTS,
 		.devtype = IMX6Q_UART,
···
 		.name = "imx21-uart",
 		.driver_data = (kernel_ulong_t) &imx_uart_devdata[IMX21_UART],
 	}, {
+		.name = "imx53-uart",
+		.driver_data = (kernel_ulong_t) &imx_uart_devdata[IMX53_UART],
+	}, {
 		.name = "imx6q-uart",
 		.driver_data = (kernel_ulong_t) &imx_uart_devdata[IMX6Q_UART],
 	}, {
···
 
 static const struct of_device_id imx_uart_dt_ids[] = {
 	{ .compatible = "fsl,imx6q-uart", .data = &imx_uart_devdata[IMX6Q_UART], },
+	{ .compatible = "fsl,imx53-uart", .data = &imx_uart_devdata[IMX53_UART], },
 	{ .compatible = "fsl,imx1-uart", .data = &imx_uart_devdata[IMX1_UART], },
 	{ .compatible = "fsl,imx21-uart", .data = &imx_uart_devdata[IMX21_UART], },
 	{ /* sentinel */ }
···
 static inline int is_imx21_uart(struct imx_port *sport)
 {
 	return sport->devdata->devtype == IMX21_UART;
+}
+
+static inline int is_imx53_uart(struct imx_port *sport)
+{
+	return sport->devdata->devtype == IMX53_UART;
 }
 
 static inline int is_imx6q_uart(struct imx_port *sport)
···
 	return IRQ_HANDLED;
 }
 
+static void clear_rx_errors(struct imx_port *sport);
 static int start_rx_dma(struct imx_port *sport);
 /*
  * If the RXFIFO is filled with some data, and then we
···
 		temp &= ~(UCR2_ATEN);
 		writel(temp, sport->port.membase + UCR2);
 
+		/* disable the rx errors interrupts */
+		temp = readl(sport->port.membase + UCR4);
+		temp &= ~UCR4_OREN;
+		writel(temp, sport->port.membase + UCR4);
+
 		/* tell the DMA to receive the data. */
 		start_rx_dma(sport);
 	}
···
 {
 	unsigned int tmp = TIOCM_DSR;
 	unsigned usr1 = readl(sport->port.membase + USR1);
+	unsigned usr2 = readl(sport->port.membase + USR2);
 
 	if (usr1 & USR1_RTSS)
 		tmp |= TIOCM_CTS;
 
 	/* in DCE mode DCDIN is always 0 */
-	if (!(usr1 & USR2_DCDIN))
+	if (!(usr2 & USR2_DCDIN))
 		tmp |= TIOCM_CAR;
 
 	if (sport->dte_mode)
···
 }
 
 #define RX_BUF_SIZE	(PAGE_SIZE)
-static void imx_rx_dma_done(struct imx_port *sport)
-{
-	unsigned long temp;
-	unsigned long flags;
-
-	spin_lock_irqsave(&sport->port.lock, flags);
-
-	/* re-enable interrupts to get notified when new symbols are incoming */
-	temp = readl(sport->port.membase + UCR1);
-	temp |= UCR1_RRDYEN;
-	writel(temp, sport->port.membase + UCR1);
-
-	temp = readl(sport->port.membase + UCR2);
-	temp |= UCR2_ATEN;
-	writel(temp, sport->port.membase + UCR2);
-
-	sport->dma_is_rxing = 0;
-
-	/* Is the shutdown waiting for us? */
-	if (waitqueue_active(&sport->dma_wait))
-		wake_up(&sport->dma_wait);
-
-	spin_unlock_irqrestore(&sport->port.lock, flags);
-}
 
 /*
  * There are two kinds of RX DMA interrupts(such as in the MX6Q):
···
 	struct scatterlist *sgl = &sport->rx_sgl;
 	struct tty_port *port = &sport->port.state->port;
 	struct dma_tx_state state;
+	struct circ_buf *rx_ring = &sport->rx_ring;
 	enum dma_status status;
-	unsigned int count;
-
-	/* unmap it first */
-	dma_unmap_sg(sport->port.dev, sgl, 1, DMA_FROM_DEVICE);
+	unsigned int w_bytes = 0;
+	unsigned int r_bytes;
+	unsigned int bd_size;
 
 	status = dmaengine_tx_status(chan, (dma_cookie_t)0, &state);
-	count = RX_BUF_SIZE - state.residue;
 
-	dev_dbg(sport->port.dev, "We get %d bytes.\n", count);
-
-	if (count) {
-		if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) {
-			int bytes = tty_insert_flip_string(port, sport->rx_buf,
-					count);
-
-			if (bytes != count)
-				sport->port.icount.buf_overrun++;
-		}
-		tty_flip_buffer_push(port);
-		sport->port.icount.rx += count;
+	if (status == DMA_ERROR) {
+		dev_err(sport->port.dev, "DMA transaction error.\n");
+		clear_rx_errors(sport);
+		return;
 	}
 
-	/*
-	 * Restart RX DMA directly if more data is available in order to skip
-	 * the roundtrip through the IRQ handler. If there is some data already
-	 * in the FIFO, DMA needs to be restarted soon anyways.
-	 *
-	 * Otherwise stop the DMA and reactivate FIFO IRQs to restart DMA once
-	 * data starts to arrive again.
-	 */
-	if (readl(sport->port.membase + USR2) & USR2_RDR)
-		start_rx_dma(sport);
-	else
-		imx_rx_dma_done(sport);
+	if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) {
+
+		/*
+		 * The state-residue variable represents the empty space
+		 * relative to the entire buffer. Taking this in consideration
+		 * the head is always calculated base on the buffer total
+		 * length - DMA transaction residue. The UART script from the
+		 * SDMA firmware will jump to the next buffer descriptor,
+		 * once a DMA transaction if finalized (IMX53 RM - A.4.1.2.4).
+		 * Taking this in consideration the tail is always at the
+		 * beginning of the buffer descriptor that contains the head.
+		 */
+
+		/* Calculate the head */
+		rx_ring->head = sg_dma_len(sgl) - state.residue;
+
+		/* Calculate the tail. */
+		bd_size = sg_dma_len(sgl) / sport->rx_periods;
+		rx_ring->tail = ((rx_ring->head-1) / bd_size) * bd_size;
+
+		if (rx_ring->head <= sg_dma_len(sgl) &&
+		    rx_ring->head > rx_ring->tail) {
+
+			/* Move data from tail to head */
+			r_bytes = rx_ring->head - rx_ring->tail;
+
+			/* CPU claims ownership of RX DMA buffer */
+			dma_sync_sg_for_cpu(sport->port.dev, sgl, 1,
+				DMA_FROM_DEVICE);
+
+			w_bytes = tty_insert_flip_string(port,
+				sport->rx_buf + rx_ring->tail, r_bytes);
+
+			/* UART retrieves ownership of RX DMA buffer */
+			dma_sync_sg_for_device(sport->port.dev, sgl, 1,
+				DMA_FROM_DEVICE);
+
+			if (w_bytes != r_bytes)
+				sport->port.icount.buf_overrun++;
+
+			sport->port.icount.rx += w_bytes;
+		} else	{
+			WARN_ON(rx_ring->head > sg_dma_len(sgl));
+			WARN_ON(rx_ring->head <= rx_ring->tail);
+		}
+	}
+
+	if (w_bytes) {
+		tty_flip_buffer_push(port);
+		dev_dbg(sport->port.dev, "We get %d bytes.\n", w_bytes);
+	}
 }
+
+/* RX DMA buffer periods */
+#define RX_DMA_PERIODS 4
 
 static int start_rx_dma(struct imx_port *sport)
 {
···
 	struct dma_async_tx_descriptor *desc;
 	int ret;
 
+	sport->rx_ring.head = 0;
+	sport->rx_ring.tail = 0;
+	sport->rx_periods = RX_DMA_PERIODS;
+
 	sg_init_one(sgl, sport->rx_buf, RX_BUF_SIZE);
 	ret = dma_map_sg(dev, sgl, 1, DMA_FROM_DEVICE);
 	if (ret == 0) {
 		dev_err(dev, "DMA mapping error for RX.\n");
 		return -EINVAL;
 	}
-	desc = dmaengine_prep_slave_sg(chan, sgl, 1, DMA_DEV_TO_MEM,
-					DMA_PREP_INTERRUPT);
+
+	desc = dmaengine_prep_dma_cyclic(chan, sg_dma_address(sgl),
+		sg_dma_len(sgl), sg_dma_len(sgl) / sport->rx_periods,
+		DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
+
 	if (!desc) {
 		dma_unmap_sg(dev, sgl, 1, DMA_FROM_DEVICE);
 		dev_err(dev, "We cannot prepare for the RX slave dma!\n");
···
 	desc->callback_param = sport;
 
 	dev_dbg(dev, "RX: prepare for the DMA.\n");
-	dmaengine_submit(desc);
+	sport->rx_cookie = dmaengine_submit(desc);
 	dma_async_issue_pending(chan);
 	return 0;
+}
+
+static void clear_rx_errors(struct imx_port *sport)
+{
+	unsigned int status_usr1, status_usr2;
+
+	status_usr1 = readl(sport->port.membase + USR1);
+	status_usr2 = readl(sport->port.membase + USR2);
+
+	if (status_usr2 & USR2_BRCD) {
+		sport->port.icount.brk++;
+		writel(USR2_BRCD, sport->port.membase + USR2);
+	} else if (status_usr1 & USR1_FRAMERR) {
+		sport->port.icount.frame++;
+		writel(USR1_FRAMERR, sport->port.membase + USR1);
+	} else if (status_usr1 & USR1_PARITYERR) {
+		sport->port.icount.parity++;
+		writel(USR1_PARITYERR, sport->port.membase + USR1);
+	}
+
+	if (status_usr2 & USR2_ORE) {
+		sport->port.icount.overrun++;
+		writel(USR2_ORE, sport->port.membase + USR2);
+	}
+
 }
 
 #define TXTL_DEFAULT 2 /* reset default */
···
 static void imx_uart_dma_exit(struct imx_port *sport)
 {
 	if (sport->dma_chan_rx) {
+		dmaengine_terminate_sync(sport->dma_chan_rx);
 		dma_release_channel(sport->dma_chan_rx);
 		sport->dma_chan_rx = NULL;
-
+		sport->rx_cookie = -EINVAL;
 		kfree(sport->rx_buf);
 		sport->rx_buf = NULL;
 	}
 
 	if (sport->dma_chan_tx) {
+		dmaengine_terminate_sync(sport->dma_chan_tx);
 		dma_release_channel(sport->dma_chan_tx);
 		sport->dma_chan_tx = NULL;
 	}
···
 		ret = -ENOMEM;
 		goto err;
 	}
+	sport->rx_ring.buf = sport->rx_buf;
 
 	/* Prepare for TX : */
 	sport->dma_chan_tx = dma_request_slave_channel(dev, "tx");
···
 	writel(temp & ~UCR4_DREN, sport->port.membase + UCR4);
 
 	/* Can we enable the DMA support? */
-	if (is_imx6q_uart(sport) && !uart_console(port) &&
-	    !sport->dma_is_inited)
+	if (!uart_console(port) && !sport->dma_is_inited)
 		imx_uart_dma_init(sport);
 
 	spin_lock_irqsave(&sport->port.lock, flags);
···
 	unsigned long flags;
 
 	if (sport->dma_is_enabled) {
-		int ret;
+		sport->dma_is_rxing = 0;
+		sport->dma_is_txing = 0;
+		dmaengine_terminate_sync(sport->dma_chan_tx);
+		dmaengine_terminate_sync(sport->dma_chan_rx);
 
-		/* We have to wait for the DMA to finish. */
-		ret = wait_event_interruptible(sport->dma_wait,
-			!sport->dma_is_rxing && !sport->dma_is_txing);
-		if (ret != 0) {
-			sport->dma_is_rxing = 0;
-			sport->dma_is_txing = 0;
-			dmaengine_terminate_all(sport->dma_chan_tx);
-			dmaengine_terminate_all(sport->dma_chan_rx);
-		}
 		spin_lock_irqsave(&sport->port.lock, flags);
 		imx_stop_tx(port);
 		imx_stop_rx(port);
···
 	return 0;
 }
 
-static struct uart_ops imx_pops = {
+static const struct uart_ops imx_pops = {
 	.tx_empty	= imx_tx_empty,
 	.set_mctrl	= imx_set_mctrl,
 	.get_mctrl	= imx_get_mctrl,
···
 
 	/* For register access, we only need to enable the ipg clock. */
 	ret = clk_prepare_enable(sport->clk_ipg);
-	if (ret)
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable per clk: %d\n", ret);
 		return ret;
+	}
 
 	/* Disable interrupts before requesting them */
 	reg = readl_relaxed(sport->port.membase + UCR1);
···
 	if (txirq > 0) {
 		ret = devm_request_irq(&pdev->dev, rxirq, imx_rxint, 0,
 				       dev_name(&pdev->dev), sport);
-		if (ret)
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request rx irq: %d\n",
+				ret);
 			return ret;
+		}
 
 		ret = devm_request_irq(&pdev->dev, txirq, imx_txint, 0,
 				       dev_name(&pdev->dev), sport);
-		if (ret)
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request tx irq: %d\n",
+				ret);
 			return ret;
+		}
 	} else {
 		ret = devm_request_irq(&pdev->dev, rxirq, imx_int, 0,
 				       dev_name(&pdev->dev), sport);
-		if (ret)
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request irq: %d\n", ret);
 			return ret;
+		}
 	}
 
 	imx_ports[sport->port.line] = sport;

drivers/tty/serial/jsm/jsm_tty.c

···
 	port->type = PORT_JSM;
 }
 
-static struct uart_ops jsm_ops = {
+static const struct uart_ops jsm_ops = {
 	.tx_empty	= jsm_tty_tx_empty,
 	.set_mctrl	= jsm_tty_set_mctrl,
 	.get_mctrl	= jsm_tty_get_mctrl,

drivers/tty/serial/max3100.c

···
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
 }
 
-static struct uart_ops max3100_ops = {
+static const struct uart_ops max3100_ops = {
 	.tx_empty	= max3100_tx_empty,
 	.set_mctrl	= max3100_set_mctrl,
 	.get_mctrl	= max3100_get_mctrl,

drivers/tty/serial/max310x.c

···
 		const struct spi_device_id *id_entry = spi_get_device_id(spi);
 
 		devtype = (struct max310x_devtype *)id_entry->driver_data;
-		flags = IRQF_TRIGGER_FALLING;
 	}
 
+	flags = IRQF_TRIGGER_FALLING;
 	regcfg.max_register = devtype->nr * 0x20 - 1;
 	regmap = devm_regmap_init_spi(spi, &regcfg);
 

drivers/tty/serial/men_z135_uart.c

···
 	return -EINVAL;
 }
 
-static struct uart_ops men_z135_ops = {
+static const struct uart_ops men_z135_ops = {
 	.tx_empty = men_z135_tx_empty,
 	.set_mctrl = men_z135_set_mctrl,
 	.get_mctrl = men_z135_get_mctrl,

drivers/tty/serial/mxs-auart.c

···
 		mxs_clr(AUART_LINECTRL_BRK, s, REG_LINECTRL);
 }
 
-static struct uart_ops mxs_auart_ops = {
+static const struct uart_ops mxs_auart_ops = {
 	.tx_empty       = mxs_auart_tx_empty,
 	.start_tx       = mxs_auart_start_tx,
 	.stop_tx	= mxs_auart_stop_tx,
···
 
 	if (!is_asm9260_auart(s)) {
 		s->clk = devm_clk_get(&pdev->dev, NULL);
-		if (IS_ERR(s->clk))
-			return PTR_ERR(s->clk);
-
-		return 0;
+		return PTR_ERR_OR_ZERO(s->clk);
 	}
 
 	s->clk = devm_clk_get(s->dev, "mod");
···
 	err = clk_set_rate(s->clk, clk_get_rate(s->clk_ahb));
 	if (err) {
 		dev_err(s->dev, "Failed to set rate!\n");
-		return err;
+		goto disable_clk_ahb;
 	}
 
 	err = clk_prepare_enable(s->clk);
 	if (err) {
 		dev_err(s->dev, "Failed to enable clk!\n");
-		return err;
+		goto disable_clk_ahb;
 	}
 
 	return 0;
+
+disable_clk_ahb:
+	clk_disable_unprepare(s->clk_ahb);
+	return err;
 }
 
 /*

drivers/tty/serial/pch_uart.c

···
 }
 #endif /* CONFIG_CONSOLE_POLL */
 
-static struct uart_ops pch_uart_ops = {
+static const struct uart_ops pch_uart_ops = {
 	.tx_empty = pch_uart_tx_empty,
 	.set_mctrl = pch_uart_set_mctrl,
 	.get_mctrl = pch_uart_get_mctrl,

drivers/tty/serial/samsung.c

···
 }
 
 
-#ifdef CONFIG_CPU_FREQ
+#ifdef CONFIG_ARM_S3C24XX_CPUFREQ
 
 static int s3c24xx_serial_cpufreq_transition(struct notifier_block *nb,
 					     unsigned long val, void *data)

drivers/tty/serial/samsung.h

···
 
 	struct s3c24xx_uart_dma		*dma;
 
-#ifdef CONFIG_CPU_FREQ
+#ifdef CONFIG_ARM_S3C24XX_CPUFREQ
 	struct notifier_block		freq_transition;
 #endif
 };

drivers/tty/serial/sc16is7xx.c

···
 	}
 #endif
 
+	/* reset device, purging any pending irq / data */
+	regmap_write(s->regmap, SC16IS7XX_IOCONTROL_REG << SC16IS7XX_REG_SHIFT,
+			SC16IS7XX_IOCONTROL_SRESET_BIT);
+
 	for (i = 0; i < devtype->nr_uart; ++i) {
 		s->p[i].line		= i;
 		/* Initialize port data */
···
 		init_kthread_work(&s->p[i].reg_work, sc16is7xx_reg_proc);
 		/* Register port */
 		uart_add_one_port(&sc16is7xx_uart, &s->p[i].port);
+
+		/* Enable EFR */
+		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_LCR_REG,
+				     SC16IS7XX_LCR_CONF_MODE_B);
+
+		regcache_cache_bypass(s->regmap, true);
+
+		/* Enable write access to enhanced features */
+		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_EFR_REG,
+				     SC16IS7XX_EFR_ENABLE_BIT);
+
+		regcache_cache_bypass(s->regmap, false);
+
+		/* Restore access to general registers */
+		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_LCR_REG, 0x00);
+
 		/* Go to suspend mode */
 		sc16is7xx_power(&s->p[i].port, 0);
 	}

drivers/tty/serial/serial_core.c

···
 	if (tty_port_initialized(port))
 		return 0;
 
-	/*
-	 * Set the TTY IO error marker - we will only clear this
-	 * once we have successfully opened the port.
-	 */
-	set_bit(TTY_IO_ERROR, &tty->flags);
-
 	retval = uart_port_startup(tty, state, init_hw);
-	if (!retval) {
-		tty_port_set_initialized(port, 1);
-		clear_bit(TTY_IO_ERROR, &tty->flags);
-	} else if (retval > 0)
-		retval = 0;
+	if (retval)
+		set_bit(TTY_IO_ERROR, &tty->flags);
 
 	return retval;
 }
···
 			}
 			uart_change_speed(tty, state, NULL);
 		}
-	} else
+	} else {
 		retval = uart_startup(tty, state, 1);
+		if (retval > 0)
+			retval = 0;
+	}
  exit:
 	return retval;
 }
···
 		uport->ops->config_port(uport, flags);
 
 		ret = uart_startup(tty, state, 1);
+		if (ret > 0)
+			ret = 0;
 	}
 out:
 	mutex_unlock(&port->mutex);
···
 {
 	struct uart_state *state = tty->driver_data;
 	struct tty_port *port;
-	struct uart_port *uport;
 
 	if (!state) {
 		struct uart_driver *drv = tty->driver->driver_state;
···
 	port = &state->port;
 	pr_debug("uart_close(%d) called\n", tty->index);
 
-	if (tty_port_close_start(port, tty, filp) == 0)
-		return;
+	tty_port_close(tty->port, tty, filp);
+}
 
-	mutex_lock(&port->mutex);
-	uport = uart_port_check(state);
+static void uart_tty_port_shutdown(struct tty_port *port)
+{
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport = uart_port_check(state);
 
 	/*
 	 * At this point, we stop accepting input.  To do this, we
 	 * disable the receive line status interrupts.
 	 */
-	if (tty_port_initialized(port) &&
-	    !WARN(!uport, "detached port still initialized!\n")) {
-		spin_lock_irq(&uport->lock);
-		uport->ops->stop_rx(uport);
-		spin_unlock_irq(&uport->lock);
-		/*
-		 * Before we drop DTR, make sure the UART transmitter
-		 * has completely drained; this is especially
-		 * important if there is a transmit FIFO!
-		 */
-		uart_wait_until_sent(tty, uport->timeout);
-	}
+	if (WARN(!uport, "detached port still initialized!\n"))
+		return;
 
-	uart_shutdown(tty, state);
-	tty_port_tty_set(port, NULL);
+	spin_lock_irq(&uport->lock);
+	uport->ops->stop_rx(uport);
+	spin_unlock_irq(&uport->lock);
 
-	spin_lock_irq(&port->lock);
-
-	if (port->blocked_open) {
-		spin_unlock_irq(&port->lock);
-		if (port->close_delay)
-			msleep_interruptible(jiffies_to_msecs(port->close_delay));
-		spin_lock_irq(&port->lock);
-	} else if (uport && !uart_console(uport)) {
-		spin_unlock_irq(&port->lock);
-		uart_change_pm(state, UART_PM_STATE_OFF);
-		spin_lock_irq(&port->lock);
-	}
-	spin_unlock_irq(&port->lock);
-	tty_port_set_active(port, 0);
+	uart_port_shutdown(port);
 
 	/*
-	 * Wake up anyone trying to open this port.
+	 * It's possible for shutdown to be called after suspend if we get
+	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
+	 * we don't try to resume a port that has been shutdown.
 	 */
-	wake_up_interruptible(&port->open_wait);
+	tty_port_set_suspended(port, 0);
 
-	mutex_unlock(&port->mutex);
+	uart_change_pm(state, UART_PM_STATE_OFF);
 
-	tty_ldisc_flush(tty);
-	tty->closing = 0;
 }
 
 static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
···
 	struct uart_driver *drv = tty->driver->driver_state;
 	int retval, line = tty->index;
 	struct uart_state *state = drv->state + line;
-	struct tty_port *port = &state->port;
-	struct uart_port *uport;
-
-	pr_debug("uart_open(%d) called\n", line);
-
-	spin_lock_irq(&port->lock);
-	++port->count;
-	spin_unlock_irq(&port->lock);
-
-	/*
-	 * We take the semaphore here to guarantee that we won't be re-entered
-	 * while allocating the state structure, or while we request any IRQs
-	 * that the driver may need.  This also has the nice side-effect that
-	 * it delays the action of uart_hangup, so we can guarantee that
-	 * state->port.tty will always contain something reasonable.
-	 */
-	if (mutex_lock_interruptible(&port->mutex)) {
-		retval = -ERESTARTSYS;
-		goto end;
-	}
-
-	uport = uart_port_check(state);
-	if (!uport || uport->flags & UPF_DEAD) {
-		retval = -ENXIO;
-		goto err_unlock;
-	}
 
 	tty->driver_data = state;
-	uport->state = state;
+
+	retval = tty_port_open(&state->port, tty, filp);
+	if (retval > 0)
+		retval = 0;
+
+	return retval;
+}
+
+static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
+{
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport;
+
+	uport = uart_port_check(state);
+	if (!uport || uport->flags & UPF_DEAD)
+		return -ENXIO;
+
 	port->low_latency = (uport->flags & UPF_LOW_LATENCY) ? 1 : 0;
-	tty_port_tty_set(port, tty);
 
 	/*
 	 * Start up the serial port.
 	 */
-	retval = uart_startup(tty, state, 0);
-
-	/*
-	 * If we succeeded, wait until the port is ready.
-	 */
-err_unlock:
-	mutex_unlock(&port->mutex);
-	if (retval == 0)
-		retval = tty_port_block_til_ready(port, tty, filp);
-end:
-	return retval;
+	return uart_startup(tty, state, 0);
 }
 
 static const char *uart_type(struct uart_port *port)
···
  *
  *	Returns 0 on success or -EINVAL on failure
  */
-int uart_parse_earlycon(char *p, unsigned char *iotype, unsigned long *addr,
+int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
 			char **options)
 {
 	if (strncmp(p, "mmio,", 5) == 0) {
···
 		return -EINVAL;
 	}
 
-	*addr = simple_strtoul(p, NULL, 0);
+	/*
+	 * Before you replace it with kstrtoull(), think about options separator
+	 * (',') it will not tolerate
+	 */
+	*addr = simple_strtoull(p, NULL, 0);
 	p = strchr(p, ',');
 	if (p)
 		p++;
···
 static const struct tty_port_operations uart_port_ops = {
 	.carrier_raised = uart_carrier_raised,
 	.dtr_rts	= uart_dtr_rts,
+	.activate	= uart_port_activate,
+	.shutdown	= uart_tty_port_shutdown,
 };
 
 /**
···
 	state->pm_state = UART_PM_STATE_UNDEFINED;
 	uport->cons = drv->cons;
 	uport->minor = drv->tty_driver->minor_start + uport->line;
+
+	port->console = uart_console(uport);
 
 	/*
 	 * If this port is a console, then the spinlock is already

drivers/tty/serial/sh-sci.c

···
 	return 0;
 }
 
-static struct uart_ops sci_uart_ops = {
+static const struct uart_ops sci_uart_ops = {
 	.tx_empty	= sci_tx_empty,
 	.set_mctrl	= sci_set_mctrl,
 	.get_mctrl	= sci_get_mctrl,

drivers/tty/serial/st-asc.c

···
 
 /*---------------------------------------------------------------------*/
 
-static struct uart_ops asc_uart_ops = {
+static const struct uart_ops asc_uart_ops = {
 	.tx_empty	= asc_tx_empty,
 	.set_mctrl	= asc_set_mctrl,
 	.get_mctrl	= asc_get_mctrl,

drivers/tty/serial/stm32-usart.c

···
 /*
  * Copyright (C) Maxime Coquelin 2015
- * Author:  Maxime Coquelin <[e-mail]>
+ * Authors:  Maxime Coquelin <[e-mail]>
+ *	     Gerald Baeza <[e-mail]>
  * License terms:  GNU General Public License (GPL), version 2
  *
  * Inspired by st-asc.c from STMicroelectronics (c)
···
 #define SUPPORT_SYSRQ
 #endif
 
-#include <linux/module.h>
-#include <linux/serial.h>
+#include <linux/clk.h>
 #include <linux/console.h>
-#include <linux/sysrq.h>
-#include <linux/platform_device.h>
-#include <linux/io.h>
-#include <linux/irq.h>
-#include <linux/tty.h>
-#include <linux/tty_flip.h>
 #include <linux/delay.h>
-#include <linux/spinlock.h>
-#include <linux/pm_runtime.h>
+#include <linux/dma-direction.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/irq.h>
+#include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/serial_core.h>
-#include <linux/clk.h>
+#include <linux/serial.h>
+#include <linux/spinlock.h>
+#include <linux/sysrq.h>
+#include <linux/tty_flip.h>
+#include <linux/tty.h>
 
-#define DRIVER_NAME "stm32-usart"
-
-/* Register offsets */
-#define USART_SR		0x00
-#define USART_DR		0x04
-#define USART_BRR		0x08
-#define USART_CR1		0x0c
-#define USART_CR2		0x10
-#define USART_CR3		0x14
-#define USART_GTPR		0x18
-
-/* USART_SR */
-#define USART_SR_PE		BIT(0)
-#define USART_SR_FE		BIT(1)
-#define USART_SR_NF		BIT(2)
-#define USART_SR_ORE		BIT(3)
-#define USART_SR_IDLE		BIT(4)
-#define USART_SR_RXNE		BIT(5)
-#define USART_SR_TC		BIT(6)
-#define USART_SR_TXE		BIT(7)
-#define USART_SR_LBD		BIT(8)
-#define USART_SR_CTS		BIT(9)
-#define USART_SR_ERR_MASK	(USART_SR_LBD | USART_SR_ORE | \
-				 USART_SR_FE | USART_SR_PE)
-/* Dummy bits */
-#define USART_SR_DUMMY_RX	BIT(16)
-
-/* USART_DR */
-#define USART_DR_MASK		GENMASK(8, 0)
-
-/* USART_BRR */
-#define USART_BRR_DIV_F_MASK	GENMASK(3, 0)
-#define USART_BRR_DIV_M_MASK	GENMASK(15, 4)
-#define USART_BRR_DIV_M_SHIFT	4
-
-/* USART_CR1 */
-#define USART_CR1_SBK		BIT(0)
-#define USART_CR1_RWU		BIT(1)
-#define USART_CR1_RE		BIT(2)
-#define USART_CR1_TE		BIT(3)
-#define USART_CR1_IDLEIE	BIT(4)
-#define USART_CR1_RXNEIE	BIT(5)
-#define USART_CR1_TCIE		BIT(6)
-#define USART_CR1_TXEIE		BIT(7)
-#define USART_CR1_PEIE		BIT(8)
-#define USART_CR1_PS		BIT(9)
-#define USART_CR1_PCE		BIT(10)
-#define USART_CR1_WAKE		BIT(11)
-#define USART_CR1_M		BIT(12)
-#define USART_CR1_UE		BIT(13)
-#define USART_CR1_OVER8		BIT(15)
-#define USART_CR1_IE_MASK	GENMASK(8, 4)
-
-/* USART_CR2 */
-#define USART_CR2_ADD_MASK	GENMASK(3, 0)
-#define USART_CR2_LBDL		BIT(5)
-#define USART_CR2_LBDIE		BIT(6)
-#define USART_CR2_LBCL		BIT(8)
-#define USART_CR2_CPHA		BIT(9)
-#define USART_CR2_CPOL		BIT(10)
-#define USART_CR2_CLKEN		BIT(11)
-#define USART_CR2_STOP_2B	BIT(13)
-#define USART_CR2_STOP_MASK	GENMASK(13, 12)
-#define USART_CR2_LINEN		BIT(14)
-
-/* USART_CR3 */
-#define USART_CR3_EIE		BIT(0)
-#define USART_CR3_IREN		BIT(1)
-#define USART_CR3_IRLP		BIT(2)
-#define USART_CR3_HDSEL		BIT(3)
-#define USART_CR3_NACK		BIT(4)
-#define USART_CR3_SCEN		BIT(5)
-#define USART_CR3_DMAR		BIT(6)
-#define USART_CR3_DMAT		BIT(7)
-#define USART_CR3_RTSE		BIT(8)
-#define USART_CR3_CTSE		BIT(9)
-#define USART_CR3_CTSIE		BIT(10)
-#define USART_CR3_ONEBIT	BIT(11)
-
-/* USART_GTPR */
-#define USART_GTPR_PSC_MASK	GENMASK(7, 0)
-#define USART_GTPR_GT_MASK	GENMASK(15, 8)
-
-#define DRIVER_NAME "stm32-usart"
-#define STM32_SERIAL_NAME "ttyS"
-#define STM32_MAX_PORTS 6
-
-struct stm32_port {
-	struct uart_port port;
-	struct clk *clk;
-	bool hw_flow_control;
-};
-
-static struct stm32_port stm32_ports[STM32_MAX_PORTS];
-static struct uart_driver stm32_usart_driver;
+#include "stm32-usart.h"
 
 static void stm32_stop_tx(struct uart_port *port);
+static void stm32_transmit_chars(struct uart_port *port);
 
 static inline struct stm32_port *to_stm32_port(struct uart_port *port)
 {
···
 	writel_relaxed(val, port->membase + reg);
 }
 
-static void stm32_receive_chars(struct uart_port *port)
+static int stm32_pending_rx(struct uart_port *port, u32 *sr, int *last_res,
+			    bool threaded)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	enum dma_status status;
+	struct dma_tx_state state;
+
+	*sr = readl_relaxed(port->membase + ofs->isr);
+
+	if (threaded && stm32_port->rx_ch) {
+		status = dmaengine_tx_status(stm32_port->rx_ch,
+					     stm32_port->rx_ch->cookie,
+					     &state);
+		if ((status == DMA_IN_PROGRESS) &&
+		    (*last_res != state.residue))
+			return 1;
+		else
+			return 0;
+	} else if (*sr & USART_SR_RXNE) {
+		return 1;
+	}
+	return 0;
+}
+
+static unsigned long
+stm32_get_char(struct uart_port *port, u32 *sr, int *last_res)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	unsigned long c;
+
+	if (stm32_port->rx_ch) {
+		c = stm32_port->rx_buf[RX_BUF_L - (*last_res)--];
+		if ((*last_res) == 0)
+			*last_res = RX_BUF_L;
+		return c;
+	} else {
+		return readl_relaxed(port->membase + ofs->rdr);
+	}
+}
+
+static void stm32_receive_chars(struct uart_port *port, bool threaded)
 {
 	struct tty_port *tport = &port->state->port;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	unsigned long c;
 	u32 sr;
 	char flag;
+	static int last_res = RX_BUF_L;
 
 	if (port->irq_wake)
 		pm_wakeup_event(tport->tty->dev, 0);
 
-	while ((sr = readl_relaxed(port->membase + USART_SR)) & USART_SR_RXNE) {
+	while (stm32_pending_rx(port, &sr, &last_res, threaded)) {
 		sr |= USART_SR_DUMMY_RX;
-		c = readl_relaxed(port->membase + USART_DR);
+		c = stm32_get_char(port, &sr, &last_res);
 		flag = TTY_NORMAL;
 		port->icount.rx++;
 
···
 				if (uart_handle_break(port))
 					continue;
 			} else if (sr & USART_SR_ORE) {
+				if (ofs->icr != UNDEF_REG)
+					writel_relaxed(USART_ICR_ORECF,
+						       port->membase +
+						       ofs->icr);
 				port->icount.overrun++;
 			} else if (sr & USART_SR_PE) {
 				port->icount.parity++;
···
 	spin_lock(&port->lock);
 }
 
+static void stm32_tx_dma_complete(void *arg)
+{
+	struct uart_port *port = arg;
+	struct stm32_port *stm32port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	unsigned int isr;
+	int ret;
+
+	ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
+						isr,
+						(isr & USART_SR_TC),
+						10, 100000);
+
+	if (ret)
+		dev_err(port->dev, "terminal count not set\n");
+
+	if (ofs->icr == UNDEF_REG)
+		stm32_clr_bits(port, ofs->isr, USART_SR_TC);
+	else
+		stm32_set_bits(port, ofs->icr, USART_CR_TC);
+
+	stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+	stm32port->tx_dma_busy = false;
+
+	/* Let's see if we have pending data to send */
+	stm32_transmit_chars(port);
+}
+
+static void stm32_transmit_chars_pio(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned int isr;
+	int ret;
+
+	if (stm32_port->tx_dma_busy) {
+		stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+		stm32_port->tx_dma_busy = false;
+	}
+
+	ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
+						isr,
+						(isr & USART_SR_TXE),
+						10, 100);
+
+	if (ret)
+		dev_err(port->dev, "tx empty not set\n");
+
+	stm32_set_bits(port, ofs->cr1, USART_CR1_TXEIE);
+
+	writel_relaxed(xmit->buf[xmit->tail], port->membase + ofs->tdr);
+	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+	port->icount.tx++;
+}
+
+static void stm32_transmit_chars_dma(struct uart_port *port)
+{
+	struct stm32_port *stm32port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	struct circ_buf *xmit = &port->state->xmit;
+	struct dma_async_tx_descriptor *desc = NULL;
+	dma_cookie_t cookie;
+	unsigned int count, i;
+
+	if (stm32port->tx_dma_busy)
+		return;
+
+	stm32port->tx_dma_busy = true;
+
+	count = uart_circ_chars_pending(xmit);
+
+	if (count > TX_BUF_L)
+		count = TX_BUF_L;
+
+	if (xmit->tail < xmit->head) {
+		memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], count);
+	} else {
+		size_t one = UART_XMIT_SIZE - xmit->tail;
+		size_t two;
+
+		if (one > count)
+			one = count;
+		two = count - one;
+
+		memcpy(&stm32port->tx_buf[0], &xmit->buf[xmit->tail], one);
+		if (two)
+			memcpy(&stm32port->tx_buf[one], &xmit->buf[0], two);
+	}
+
+	desc = dmaengine_prep_slave_single(stm32port->tx_ch,
+					   stm32port->tx_dma_buf,
+					   count,
+					   DMA_MEM_TO_DEV,
+					   DMA_PREP_INTERRUPT);
+
+	if (!desc) {
+		for (i = count; i > 0; i--)
+			stm32_transmit_chars_pio(port);
+		return;
+	}
+
+	desc->callback = stm32_tx_dma_complete;
+	desc->callback_param = port;
+
+	/* Push current DMA TX transaction in the pending queue */
+	cookie = dmaengine_submit(desc);
+
+	/* Issue pending DMA TX requests */
+	dma_async_issue_pending(stm32port->tx_ch);
+
+	stm32_clr_bits(port, ofs->isr, USART_SR_TC);
+	stm32_set_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+	port->icount.tx += count;
+}
+
 static void stm32_transmit_chars(struct uart_port *port)
 {
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	struct circ_buf *xmit = &port->state->xmit;
 
 	if (port->x_char) {
-		writel_relaxed(port->x_char, port->membase + USART_DR);
+		if (stm32_port->tx_dma_busy)
+			stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+		writel_relaxed(port->x_char, port->membase + ofs->tdr);
 		port->x_char = 0;
 		port->icount.tx++;
+		if (stm32_port->tx_dma_busy)
+			stm32_set_bits(port, ofs->cr3, USART_CR3_DMAT);
 		return;
 	}
 
···
 		return;
 	}
 
-	writel_relaxed(xmit->buf[xmit->tail], port->membase + USART_DR);
-	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-	port->icount.tx++;
+	if (stm32_port->tx_ch)
+		stm32_transmit_chars_dma(port);
+	else
+		stm32_transmit_chars_pio(port);
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
···
 static irqreturn_t stm32_interrupt(int irq, void *ptr)
 {
 	struct uart_port *port = ptr;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	u32 sr;
 
 	spin_lock(&port->lock);
 
-	sr = readl_relaxed(port->membase + USART_SR);
+	sr = readl_relaxed(port->membase + ofs->isr);
 
-	if (sr & USART_SR_RXNE)
-		stm32_receive_chars(port);
+	if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch))
+		stm32_receive_chars(port, false);
 
-	if (sr & USART_SR_TXE)
+	if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch))
 		stm32_transmit_chars(port);
+
+	spin_unlock(&port->lock);
+
+	if (stm32_port->rx_ch)
+		return IRQ_WAKE_THREAD;
+	else
+		return IRQ_HANDLED;
+}
+
+static irqreturn_t stm32_threaded_interrupt(int irq, void *ptr)
+{
+	struct uart_port *port = ptr;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+
+	spin_lock(&port->lock);
+
+	if (stm32_port->rx_ch)
+		stm32_receive_chars(port, true);
 
 	spin_unlock(&port->lock);
 
···
 
 static unsigned int stm32_tx_empty(struct uart_port *port)
 {
-	return readl_relaxed(port->membase + USART_SR) & USART_SR_TXE;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	return readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE;
 }
 
 static void stm32_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
 	if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
-		stm32_set_bits(port, USART_CR3, USART_CR3_RTSE);
+		stm32_set_bits(port, ofs->cr3, USART_CR3_RTSE);
 	else
-		stm32_clr_bits(port, USART_CR3, USART_CR3_RTSE);
+		stm32_clr_bits(port, ofs->cr3, USART_CR3_RTSE);
 }
 
 static unsigned int stm32_get_mctrl(struct uart_port *port)
···
 /* Transmit stop */
 static void stm32_stop_tx(struct uart_port *port)
 {
-	stm32_clr_bits(port, USART_CR1, USART_CR1_TXEIE);
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	stm32_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
 }
 
 /* There are probably characters waiting to be transmitted. */
···
 	if (uart_circ_empty(xmit))
 		return;
 
-	stm32_set_bits(port, USART_CR1, USART_CR1_TXEIE | USART_CR1_TE);
+	stm32_transmit_chars(port);
 }
 
 /* Throttle the remote when input buffer is about to overflow. */
 static void stm32_throttle(struct uart_port *port)
 {
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	unsigned long flags;
 
 	spin_lock_irqsave(&port->lock, flags);
-	stm32_clr_bits(port, USART_CR1, USART_CR1_RXNEIE);
+	stm32_clr_bits(port, ofs->cr1, USART_CR1_RXNEIE);
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 /* Unthrottle the remote, the input buffer can now accept data. */
 static void stm32_unthrottle(struct uart_port *port)
 {
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	unsigned long flags;
 
 	spin_lock_irqsave(&port->lock, flags);
-	stm32_set_bits(port, USART_CR1, USART_CR1_RXNEIE);
+	stm32_set_bits(port, ofs->cr1, USART_CR1_RXNEIE);
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 /* Receive stop */
 static void stm32_stop_rx(struct uart_port *port)
 {
-	stm32_clr_bits(port, USART_CR1, USART_CR1_RXNEIE);
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	stm32_clr_bits(port, ofs->cr1, USART_CR1_RXNEIE);
 }
 
 /* Handle breaks - ignored by us */
···
 
 static int stm32_startup(struct uart_port *port)
 {
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
 	const char *name = to_platform_device(port->dev)->name;
 	u32 val;
 	int ret;
 
-	ret = request_irq(port->irq, stm32_interrupt, 0, name, port);
+	ret = request_threaded_irq(port->irq, stm32_interrupt,
+				   stm32_threaded_interrupt,
+				   IRQF_NO_SUSPEND, name, port);
 	if (ret)
 		return ret;
 
 	val = USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE;
-	stm32_set_bits(port, USART_CR1, val);
+	stm32_set_bits(port, ofs->cr1, val);
 
 	return 0;
 }
 
 static void stm32_shutdown(struct uart_port *port)
 {
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	struct stm32_usart_config *cfg = &stm32_port->info->cfg;
 	u32 val;
 
 	val = USART_CR1_TXEIE | USART_CR1_RXNEIE | USART_CR1_TE | USART_CR1_RE;
-	stm32_set_bits(port, USART_CR1, val);
+	val |= BIT(cfg->uart_enable_bit);
+	stm32_clr_bits(port, ofs->cr1, val);
 
 	free_irq(port->irq, port);
 }
···
 			    struct ktermios *old)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	struct stm32_usart_config *cfg = &stm32_port->info->cfg;
 	unsigned int baud;
 	u32 usartdiv, mantissa, fraction, oversampling;
 	tcflag_t cflag = termios->c_cflag;
···
 	spin_lock_irqsave(&port->lock, flags);
 
 	/* Stop serial port and reset value */
-	writel_relaxed(0, port->membase + USART_CR1);
+	writel_relaxed(0, port->membase + ofs->cr1);
 
-	cr1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE | USART_CR1_RXNEIE;
+	cr1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_RXNEIE;
+	cr1 |= BIT(cfg->uart_enable_bit);
 	cr2 = 0;
 	cr3 = 0;
 
···
 
 	if (cflag & PARENB) {
 		cr1 |= USART_CR1_PCE;
-		if ((cflag & CSIZE) == CS8)
-			cr1 |= USART_CR1_M;
+		if ((cflag & CSIZE) == CS8) {
+			if (cfg->has_7bits_data)
+				cr1 |= USART_CR1_M0;
+			else
+				cr1 |= USART_CR1_M;
+		}
 	}
 
 	if (cflag & PARODD)
···
 	 */
 	if (usartdiv < 16) {
 		oversampling = 8;
-		stm32_set_bits(port, USART_CR1, USART_CR1_OVER8);
+		stm32_set_bits(port, ofs->cr1, USART_CR1_OVER8);
 	} else {
 		oversampling = 16;
-		stm32_clr_bits(port, USART_CR1, USART_CR1_OVER8);
+		stm32_clr_bits(port, ofs->cr1, USART_CR1_OVER8);
 	}
 
 	mantissa = (usartdiv / oversampling) << USART_BRR_DIV_M_SHIFT;
 	fraction = usartdiv % oversampling;
-	writel_relaxed(mantissa | fraction, port->membase + USART_BRR);
+	writel_relaxed(mantissa | fraction, port->membase + ofs->brr);
 
 	uart_update_timeout(port, cflag, baud);
 
···
 	if ((termios->c_cflag & CREAD) == 0)
 		port->ignore_status_mask |= USART_SR_DUMMY_RX;
 
-	writel_relaxed(cr3, port->membase + USART_CR3);
-	writel_relaxed(cr2, port->membase + USART_CR2);
-	writel_relaxed(cr1, port->membase + USART_CR1);
+	if (stm32_port->rx_ch)
+		cr3 |= USART_CR3_DMAR;
+
+	writel_relaxed(cr3, port->membase + ofs->cr3);
+	writel_relaxed(cr2, port->membase + ofs->cr2);
+	writel_relaxed(cr1, port->membase + ofs->cr1);
 
 	spin_unlock_irqrestore(&port->lock, flags);
 }
···
 {
 	struct stm32_port *stm32port = container_of(port,
 			struct stm32_port, port);
+	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	struct stm32_usart_config *cfg = &stm32port->info->cfg;
 	unsigned long flags = 0;
 
 	switch (state) {
···
 		break;
 	case UART_PM_STATE_OFF:
 		spin_lock_irqsave(&port->lock, flags);
-		stm32_clr_bits(port, USART_CR1, USART_CR1_UE);
+		stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
 		spin_unlock_irqrestore(&port->lock, flags);
 		clk_disable_unprepare(stm32port->clk);
 		break;
···
 	if (!stm32port->port.uartclk)
 		ret = -EINVAL;
 
-	clk_disable_unprepare(stm32port->clk);
-
 	return ret;
 }
 
···
 		return NULL;
 
 	stm32_ports[id].hw_flow_control = of_property_read_bool(np,
-							"auto-flow-control");
+							"st,hw-flow-ctrl");
 	stm32_ports[id].port.line = id;
 	return &stm32_ports[id];
 }
 
 #ifdef CONFIG_OF
 static const struct of_device_id stm32_match[] = {
-	{ .compatible = "st,stm32-usart", },
-	{ .compatible = "st,stm32-uart", },
+	{ .compatible = "st,stm32-usart", .data = &stm32f4_info},
+	{ .compatible = "st,stm32-uart", .data = &stm32f4_info},
+	{ .compatible = "st,stm32f7-usart", .data = &stm32f7_info},
+	{ .compatible = "st,stm32f7-uart", .data = &stm32f7_info},
 	{},
 };
 
 MODULE_DEVICE_TABLE(of, stm32_match);
 #endif
 
+static int stm32_of_dma_rx_probe(struct stm32_port *stm32port,
+				 struct platform_device *pdev)
+{
+	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	struct uart_port *port = &stm32port->port;
+	struct device *dev = &pdev->dev;
+	struct dma_slave_config config;
+	struct dma_async_tx_descriptor *desc = NULL;
+	dma_cookie_t cookie;
+	int ret;
+
+	/* Request DMA RX channel */
+	stm32port->rx_ch = dma_request_slave_channel(dev, "rx");
+	if (!stm32port->rx_ch) {
+		dev_info(dev, "rx dma alloc failed\n");
+		return -ENODEV;
+	}
+	stm32port->rx_buf = dma_alloc_coherent(&pdev->dev, RX_BUF_L,
+						 &stm32port->rx_dma_buf,
+						 GFP_KERNEL);
+	if (!stm32port->rx_buf) {
+		ret = -ENOMEM;
+		goto alloc_err;
+	}
+
+	/* Configure DMA channel */
+	memset(&config, 0, sizeof(config));
+	config.src_addr = port->mapbase + ofs->rdr;
+	config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+
+	ret = dmaengine_slave_config(stm32port->rx_ch, &config);
+	if (ret < 0) {
+		dev_err(dev, "rx dma channel config failed\n");
+		ret = -ENODEV;
+		goto config_err;
+	}
+
+	/* Prepare a DMA cyclic transaction */
+	desc = dmaengine_prep_dma_cyclic(stm32port->rx_ch,
+					 stm32port->rx_dma_buf,
+					 RX_BUF_L, RX_BUF_P, DMA_DEV_TO_MEM,
+					 DMA_PREP_INTERRUPT);
+	if (!desc) {
+		dev_err(dev, "rx dma prep cyclic failed\n");
+		ret = -ENODEV;
+		goto config_err;
+	}
+
+	/* No callback as dma buffer is drained on usart interrupt */
+	desc->callback = NULL;
+	desc->callback_param = NULL;
+
+	/* Push current DMA transaction in the pending queue */
+	cookie = dmaengine_submit(desc);
+
+	/* Issue pending DMA requests */
+	dma_async_issue_pending(stm32port->rx_ch);
+
+	return 0;
+
+config_err:
+	dma_free_coherent(&pdev->dev,
+			  RX_BUF_L, stm32port->rx_buf,
+			  stm32port->rx_dma_buf);
+
+alloc_err:
+	dma_release_channel(stm32port->rx_ch);
+	stm32port->rx_ch = NULL;
+
+	return ret;
+}
+
+static int stm32_of_dma_tx_probe(struct stm32_port *stm32port,
+				 struct platform_device *pdev)
+{
+	struct stm32_usart_offsets *ofs = &stm32port->info->ofs;
+	struct uart_port *port = &stm32port->port;
+	struct device *dev = &pdev->dev;
+	struct dma_slave_config config;
+	int ret;
+
+	stm32port->tx_dma_busy = false;
+
+	/* Request DMA TX channel */
+	stm32port->tx_ch = dma_request_slave_channel(dev, "tx");
+	if (!stm32port->tx_ch) {
+		dev_info(dev, "tx dma alloc failed\n");
+		return -ENODEV;
+	}
+	stm32port->tx_buf = dma_alloc_coherent(&pdev->dev, TX_BUF_L,
+						 &stm32port->tx_dma_buf,
+						 GFP_KERNEL);
+	if (!stm32port->tx_buf) {
+		ret = -ENOMEM;
+		goto alloc_err;
+	}
+
+	/* Configure DMA channel */
+	memset(&config, 0, sizeof(config));
+	config.dst_addr = port->mapbase + ofs->tdr;
+	config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+
+	ret = dmaengine_slave_config(stm32port->tx_ch, &config);
+	if (ret < 0) {
+		dev_err(dev, "tx dma channel config failed\n");
+		ret = -ENODEV;
+		goto config_err;
+	}
+
+	return 0;
+
+config_err:
+	dma_free_coherent(&pdev->dev,
+			  TX_BUF_L, stm32port->tx_buf,
+			  stm32port->tx_dma_buf);
+
+alloc_err:
+	dma_release_channel(stm32port->tx_ch);
+	stm32port->tx_ch = NULL;
+
+	return ret;
+}
+
 static int stm32_serial_probe(struct platform_device *pdev)
 {
-	int ret;
+	const struct of_device_id *match;
 	struct stm32_port *stm32port;
+	int ret;
 
 	stm32port = stm32_of_get_stm32_port(pdev);
 	if (!stm32port)
 		return -ENODEV;
+
+	match = of_match_device(stm32_match, &pdev->dev);
+	if (match && match->data)
+		stm32port->info = (struct stm32_usart_info *)match->data;
+	else
+		return -EINVAL;
 
 	ret = stm32_init_port(stm32port, pdev);
 	if (ret)
···
 	if (ret)
 		return ret;
 
+	ret = stm32_of_dma_rx_probe(stm32port, pdev);
+	if (ret)
+		dev_info(&pdev->dev, "interrupt mode used for rx (no dma)\n");
+
+	ret = stm32_of_dma_tx_probe(stm32port, pdev);
+	if (ret)
+		dev_info(&pdev->dev, "interrupt mode used for tx (no dma)\n");
+
 	platform_set_drvdata(pdev, &stm32port->port);
 
 	return 0;
···
 static int stm32_serial_remove(struct platform_device *pdev)
 {
 	struct uart_port *port = platform_get_drvdata(pdev);
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+
+	if (stm32_port->rx_ch)
+		dma_release_channel(stm32_port->rx_ch);
+
+	if (stm32_port->rx_dma_buf)
+		dma_free_coherent(&pdev->dev,
+				  RX_BUF_L, stm32_port->rx_buf,
+				  stm32_port->rx_dma_buf);
+
+	stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
+
+	if (stm32_port->tx_ch)
+		dma_release_channel(stm32_port->tx_ch);
+
+	if (stm32_port->tx_dma_buf)
+		dma_free_coherent(&pdev->dev,
+				  TX_BUF_L, stm32_port->tx_buf,
+				  stm32_port->tx_dma_buf);
+
+	clk_disable_unprepare(stm32_port->clk);
 
 	return uart_remove_one_port(&stm32_usart_driver, port);
 }
···
 #ifdef CONFIG_SERIAL_STM32_CONSOLE
 static void stm32_console_putchar(struct uart_port *port, int ch)
 {
-	while (!(readl_relaxed(port->membase + USART_SR) & USART_SR_TXE))
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+
+	while (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE))
 		cpu_relax();
 
-	writel_relaxed(ch, port->membase + USART_DR);
+	writel_relaxed(ch, port->membase + ofs->tdr);
 }
 
 static void stm32_console_write(struct console *co, const char *s, unsigned cnt)
 {
 	struct uart_port *port = &stm32_ports[co->index].port;
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+	struct stm32_usart_config *cfg = &stm32_port->info->cfg;
 	unsigned long flags;
 	u32 old_cr1, new_cr1;
 	int locked = 1;
···
 	else
 		spin_lock(&port->lock);
 
-	/* Save and disable interrupts */
-	old_cr1 = readl_relaxed(port->membase + USART_CR1);
+	/* Save and disable interrupts, enable the transmitter */
+	old_cr1 = readl_relaxed(port->membase + ofs->cr1);
 	new_cr1 = old_cr1 & ~USART_CR1_IE_MASK;
-	writel_relaxed(new_cr1, port->membase + USART_CR1);
+	new_cr1 |=  USART_CR1_TE | BIT(cfg->uart_enable_bit);
+	writel_relaxed(new_cr1, port->membase + ofs->cr1);
 
 	uart_console_write(port, s, cnt, stm32_console_putchar);
 
 	/* Restore interrupt state */
-	writel_relaxed(old_cr1, port->membase + USART_CR1);
+	writel_relaxed(old_cr1, port->membase + ofs->cr1);
 
 	if (locked)
 		spin_unlock(&port->lock);

drivers/tty/serial/stm32-usart.h

···
+/*
+ * Copyright (C) Maxime Coquelin 2015
+ * Authors:  Maxime Coquelin <[e-mail]>
+ *	     Gerald Baeza <[e-mail]>
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#define DRIVER_NAME "stm32-usart"
+
+struct stm32_usart_offsets {
+	u8 cr1;
+	u8 cr2;
+	u8 cr3;
+	u8 brr;
+	u8 gtpr;
+	u8 rtor;
+	u8 rqr;
+	u8 isr;
+	u8 icr;
+	u8 rdr;
+	u8 tdr;
+};
+
+struct stm32_usart_config {
+	u8 uart_enable_bit; /* USART_CR1_UE */
+	bool has_7bits_data;
+};
+
+struct stm32_usart_info {
+	struct stm32_usart_offsets ofs;
+	struct stm32_usart_config cfg;
+};
+
+#define UNDEF_REG ~0
+
+/* Register offsets */
+struct stm32_usart_info stm32f4_info = {
+	.ofs = {
+		.isr	= 0x00,
+		.rdr	= 0x04,
+		.tdr	= 0x04,
+		.brr	= 0x08,
+		.cr1	= 0x0c,
+		.cr2	= 0x10,
+		.cr3	= 0x14,
+		.gtpr	= 0x18,
+		.rtor	= UNDEF_REG,
+		.rqr	= UNDEF_REG,
+		.icr	= UNDEF_REG,
+	},
+	.cfg = {
+		.uart_enable_bit = 13,
+		.has_7bits_data = false,
+	}
+};
+
+struct stm32_usart_info stm32f7_info = {
+	.ofs = {
+		.cr1	= 0x00,
+		.cr2	= 0x04,
+		.cr3	= 0x08,
+		.brr	= 0x0c,
+		.gtpr	= 0x10,
+		.rtor	= 0x14,
+		.rqr	= 0x18,
+		.isr	= 0x1c,
+		.icr	= 0x20,
+		.rdr	= 0x24,
+		.tdr	= 0x28,
+	},
+	.cfg = {
+		.uart_enable_bit = 0,
+		.has_7bits_data = true,
+	}
+};
+
+/* USART_SR (F4) / USART_ISR (F7) */
+#define USART_SR_PE		BIT(0)
+#define USART_SR_FE		BIT(1)
+#define USART_SR_NF		BIT(2)
+#define USART_SR_ORE		BIT(3)
+#define USART_SR_IDLE		BIT(4)
+#define USART_SR_RXNE		BIT(5)
+#define USART_SR_TC		BIT(6)
+#define USART_SR_TXE		BIT(7)
+#define USART_SR_LBD		BIT(8)
+#define USART_SR_CTSIF		BIT(9)
+#define USART_SR_CTS		BIT(10)		/* F7 */
+#define USART_SR_RTOF		BIT(11)		/* F7 */
+#define USART_SR_EOBF		BIT(12)		/* F7 */
+#define USART_SR_ABRE		BIT(14)		/* F7 */
+#define USART_SR_ABRF		BIT(15)		/* F7 */
+#define USART_SR_BUSY		BIT(16)		/* F7 */
+#define USART_SR_CMF		BIT(17)		/* F7 */
+#define USART_SR_SBKF		BIT(18)		/* F7 */
+#define USART_SR_TEACK		BIT(21)		/* F7 */
+#define USART_SR_ERR_MASK	(USART_SR_LBD | USART_SR_ORE | \
+				 USART_SR_FE | USART_SR_PE)
+/* Dummy bits */
+#define USART_SR_DUMMY_RX	BIT(16)
+
+/* USART_ICR (F7) */
+#define USART_CR_TC		BIT(6)
+
+/* USART_DR */
+#define USART_DR_MASK		GENMASK(8, 0)
+
+/* USART_BRR */
+#define USART_BRR_DIV_F_MASK	GENMASK(3, 0)
+#define USART_BRR_DIV_M_MASK	GENMASK(15, 4)
+#define USART_BRR_DIV_M_SHIFT	4
+
+/* USART_CR1 */
+#define USART_CR1_SBK		BIT(0)
+#define USART_CR1_RWU		BIT(1)		/* F4 */
+#define USART_CR1_RE		BIT(2)
+#define USART_CR1_TE		BIT(3)
+#define USART_CR1_IDLEIE	BIT(4)
+#define USART_CR1_RXNEIE	BIT(5)
+#define USART_CR1_TCIE		BIT(6)
+#define USART_CR1_TXEIE		BIT(7)
+#define USART_CR1_PEIE		BIT(8)
+#define USART_CR1_PS		BIT(9)
+#define USART_CR1_PCE		BIT(10)
+#define USART_CR1_WAKE		BIT(11)
+#define USART_CR1_M		BIT(12)
+#define USART_CR1_M0		BIT(12)		/* F7 */
+#define USART_CR1_MME		BIT(13)		/* F7 */
+#define USART_CR1_CMIE		BIT(14)		/* F7 */
+#define USART_CR1_OVER8		BIT(15)
+#define USART_CR1_DEDT_MASK	GENMASK(20, 16)	/* F7 */
+#define USART_CR1_DEAT_MASK	GENMASK(25, 21)	/* F7 */
+#define USART_CR1_RTOIE		BIT(26)		/* F7 */
+#define USART_CR1_EOBIE		BIT(27)		/* F7 */
+#define USART_CR1_M1		BIT(28)		/* F7 */
+#define USART_CR1_IE_MASK	(GENMASK(8, 4) | BIT(14) | BIT(26) | BIT(27))
+
+/* USART_CR2 */
+#define USART_CR2_ADD_MASK	GENMASK(3, 0)	/* F4 */
+#define USART_CR2_ADDM7		BIT(4)		/* F7 */
+#define USART_CR2_LBDL		BIT(5)
+#define USART_CR2_LBDIE		BIT(6)
+#define USART_CR2_LBCL		BIT(8)
+#define USART_CR2_CPHA		BIT(9)
+#define USART_CR2_CPOL		BIT(10)
+#define USART_CR2_CLKEN		BIT(11)
+#define USART_CR2_STOP_2B	BIT(13)
+#define USART_CR2_STOP_MASK	GENMASK(13, 12)
+#define USART_CR2_LINEN		BIT(14)
+#define USART_CR2_SWAP		BIT(15)		/* F7 */
+#define USART_CR2_RXINV		BIT(16)		/* F7 */
+#define USART_CR2_TXINV		BIT(17)		/* F7 */
+#define USART_CR2_DATAINV	BIT(18)		/* F7 */
+#define USART_CR2_MSBFIRST	BIT(19)		/* F7 */
+#define USART_CR2_ABREN		BIT(20)		/* F7 */
+#define USART_CR2_ABRMOD_MASK	GENMASK(22, 21)	/* F7 */
+#define USART_CR2_RTOEN		BIT(23)		/* F7 */
+#define USART_CR2_ADD_F7_MASK	GENMASK(31, 24)	/* F7 */
+
+/* USART_CR3 */
+#define USART_CR3_EIE		BIT(0)
+#define USART_CR3_IREN		BIT(1)
+#define USART_CR3_IRLP		BIT(2)
+#define USART_CR3_HDSEL		BIT(3)
+#define USART_CR3_NACK		BIT(4)
+#define USART_CR3_SCEN		BIT(5)
+#define USART_CR3_DMAR		BIT(6)
+#define USART_CR3_DMAT		BIT(7)
+#define USART_CR3_RTSE		BIT(8)
+#define USART_CR3_CTSE		BIT(9)
+#define USART_CR3_CTSIE		BIT(10)
+#define USART_CR3_ONEBIT	BIT(11)
+#define USART_CR3_OVRDIS	BIT(12)		/* F7 */
+#define USART_CR3_DDRE		BIT(13)		/* F7 */
+#define USART_CR3_DEM		BIT(14)		/* F7 */
+#define USART_CR3_DEP		BIT(15)		/* F7 */
+#define USART_CR3_SCARCNT_MASK	GENMASK(19, 17)	/* F7 */
+
+/* USART_GTPR */
+#define USART_GTPR_PSC_MASK	GENMASK(7, 0)
+#define USART_GTPR_GT_MASK	GENMASK(15, 8)
+
+/* USART_RTOR */
+#define USART_RTOR_RTO_MASK	GENMASK(23, 0)	/* F7 */
+#define USART_RTOR_BLEN_MASK	GENMASK(31, 24)	/* F7 */
+
+/* USART_RQR */
+#define USART_RQR_ABRRQ		BIT(0)		/* F7 */
+#define USART_RQR_SBKRQ		BIT(1)		/* F7 */
+#define USART_RQR_MMRQ		BIT(2)		/* F7 */
+#define USART_RQR_RXFRQ		BIT(3)		/* F7 */
+#define USART_RQR_TXFRQ		BIT(4)		/* F7 */
+
+/* USART_ICR */
+#define USART_ICR_PECF		BIT(0)		/* F7 */
+#define USART_ICR_FFECF		BIT(1)		/* F7 */
+#define USART_ICR_NCF		BIT(2)		/* F7 */
+#define USART_ICR_ORECF		BIT(3)		/* F7 */
+#define USART_ICR_IDLECF	BIT(4)		/* F7 */
+#define USART_ICR_TCCF		BIT(6)		/* F7 */
+#define USART_ICR_LBDCF		BIT(8)		/* F7 */
+#define USART_ICR_CTSCF		BIT(9)		/* F7 */
+#define USART_ICR_RTOCF		BIT(11)		/* F7 */
+#define USART_ICR_EOBCF		BIT(12)		/* F7 */
+#define USART_ICR_CMCF		BIT(17)		/* F7 */
+
+#define STM32_SERIAL_NAME "ttyS"
+#define STM32_MAX_PORTS 6
+
+#define RX_BUF_L 200		 /* dma rx buffer length     */
+#define RX_BUF_P RX_BUF_L	 /* dma rx buffer period     */
+#define TX_BUF_L 200		 /* dma tx buffer length     */
+
+struct stm32_port {
+	struct uart_port port;
+	struct clk *clk;
+	struct stm32_usart_info *info;
+	struct dma_chan *rx_ch;  /* dma rx channel            */
+	dma_addr_t rx_dma_buf;   /* dma rx buffer bus address */
+	unsigned char *rx_buf;   /* dma rx buffer cpu address */
+	struct dma_chan *tx_ch;  /* dma tx channel            */
+	dma_addr_t tx_dma_buf;   /* dma tx buffer bus address */
+	unsigned char *tx_buf;   /* dma tx buffer cpu address */
+	bool tx_dma_busy;	 /* dma tx busy               */
+	bool hw_flow_control;
+};
+
+static struct stm32_port stm32_ports[STM32_MAX_PORTS];
+static struct uart_driver stm32_usart_driver;

drivers/tty/serial/timbuart.c

···
 	return -EINVAL;
 }
 
-static struct uart_ops timbuart_ops = {
+static const struct uart_ops timbuart_ops = {
 	.tx_empty = timbuart_tx_empty,
 	.set_mctrl = timbuart_set_mctrl,
 	.get_mctrl = timbuart_get_mctrl,

drivers/tty/serial/uartlite.c

···
 }
 #endif
 
-static struct uart_ops ulite_ops = {
+static const struct uart_ops ulite_ops = {
 	.tx_empty	= ulite_tx_empty,
 	.set_mctrl	= ulite_set_mctrl,
 	.get_mctrl	= ulite_get_mctrl,

drivers/tty/serial/vt8500_serial.c

···
  * have been allocated as we can't use pdev->id in
  * devicetree
  */
-static unsigned long vt8500_ports_in_use;
+static DECLARE_BITMAP(vt8500_ports_in_use, VT8500_MAX_PORTS);
 
 static inline void vt8500_write(struct uart_port *port, unsigned int val,
 			     unsigned int off)
···
 
 	if (port < 0) {
 		/* calculate the port id */
-		port = find_first_zero_bit(&vt8500_ports_in_use,
-					sizeof(vt8500_ports_in_use));
+		port = find_first_zero_bit(vt8500_ports_in_use,
+					   VT8500_MAX_PORTS);
 	}
 
 	if (port >= VT8500_MAX_PORTS)
 		return -ENODEV;
 
 	/* reserve the port id */
-	if (test_and_set_bit(port, &vt8500_ports_in_use)) {
+	if (test_and_set_bit(port, vt8500_ports_in_use)) {
 		/* port already in use - shouldn't really happen */
 		return -EBUSY;
 	}

drivers/tty/serial/xilinx_uartps.c

···
 #define CDNS_UART_IMR		0x10  /* Interrupt Mask */
 #define CDNS_UART_ISR		0x14  /* Interrupt Status */
 #define CDNS_UART_BAUDGEN	0x18  /* Baud Rate Generator */
-#define CDNS_UART_RXTOUT		0x1C  /* RX Timeout */
+#define CDNS_UART_RXTOUT	0x1C  /* RX Timeout */
 #define CDNS_UART_RXWM		0x20  /* RX FIFO Trigger Level */
 #define CDNS_UART_MODEMCR	0x24  /* Modem Control */
 #define CDNS_UART_MODEMSR	0x28  /* Modem Status */
···
 #define CDNS_UART_IRRX_PWIDTH	0x3C  /* IR Min Received Pulse Width */
 #define CDNS_UART_IRTX_PWIDTH	0x40  /* IR Transmitted pulse Width */
 #define CDNS_UART_TXWM		0x44  /* TX FIFO Trigger Level */
+#define CDNS_UART_RXBS		0x48  /* RX FIFO byte status register */
 
 /* Control Register Bit Definitions */
 #define CDNS_UART_CR_STOPBRK	0x00000100  /* Stop TX break */
···
 #define CDNS_UART_CR_TXRST	0x00000002  /* TX logic reset */
 #define CDNS_UART_CR_RXRST	0x00000001  /* RX logic reset */
 #define CDNS_UART_CR_RST_TO	0x00000040  /* Restart Timeout Counter */
+#define CDNS_UART_RXBS_PARITY    0x00000001 /* Parity error status */
+#define CDNS_UART_RXBS_FRAMING   0x00000002 /* Framing error status */
+#define CDNS_UART_RXBS_BRK       0x00000004 /* Overrun error status */
 
 /*
  * Mode Register:
···
 #define CDNS_UART_IXR_RXEMPTY	0x00000002 /* RX FIFO empty interrupt. */
 #define CDNS_UART_IXR_MASK	0x00001FFF /* Valid bit mask */
 
-#define CDNS_UART_RX_IRQS	(CDNS_UART_IXR_PARITY | CDNS_UART_IXR_FRAMING | \
-				 CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_RXTRIG | \
+	/*
+	 * Do not enable parity error interrupt for the following
+	 * reason: When parity error interrupt is enabled, each Rx
+	 * parity error always results in 2 events. The first one
+	 * being parity error interrupt and the second one with a
+	 * proper Rx interrupt with the incoming data.  Disabling
+	 * parity error interrupt ensures better handling of parity
+	 * error events. With this change, for a parity error case, we
+	 * get a Rx interrupt with parity error set in ISR register
+	 * and we still handle parity errors in the desired way.
+	 */
+
+#define CDNS_UART_RX_IRQS	(CDNS_UART_IXR_FRAMING | \
+				 CDNS_UART_IXR_OVERRUN | \
+				 CDNS_UART_IXR_RXTRIG |	 \
 				 CDNS_UART_IXR_TOUT)
 
 /* Goes in read_status_mask for break detection as the HW doesn't do it*/
-#define CDNS_UART_IXR_BRK	0x80000000
+#define CDNS_UART_IXR_BRK	0x00002000
 
+#define CDNS_UART_RXBS_SUPPORT BIT(1)
 /*
  * Modem Control register:
  * The read/write Modem Control register controls the interface with the modem
···
 	struct clk		*pclk;
 	unsigned int		baud;
 	struct notifier_block	clk_rate_change_nb;
+	u32			quirks;
+};
+struct cdns_platform_data {
+	u32 quirks;
 };
 #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \
 		clk_rate_change_nb);
 
-static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
+/**
+ * cdns_uart_handle_rx - Handle the received bytes along with Rx errors.
+ * @dev_id: Id of the UART port
+ * @isrstatus: The interrupt status register value as read
+ * Return: None
+ */
+static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus)
 {
-	/*
-	 * There is no hardware break detection, so we interpret framing
-	 * error with all-zeros data as a break sequence. Most of the time,
-	 * there's another non-zero byte at the end of the sequence.
-	 */
-	if (isrstatus & CDNS_UART_IXR_FRAMING) {
-		while (!(readl(port->membase + CDNS_UART_SR) &
-					CDNS_UART_SR_RXEMPTY)) {
-			if (!readl(port->membase + CDNS_UART_FIFO)) {
+	struct uart_port *port = (struct uart_port *)dev_id;
+	struct cdns_uart *cdns_uart = port->private_data;
+	unsigned int data;
+	unsigned int rxbs_status = 0;
+	unsigned int status_mask;
+	unsigned int framerrprocessed = 0;
+	char status = TTY_NORMAL;
+	bool is_rxbs_support;
+
+	is_rxbs_support = cdns_uart->quirks & CDNS_UART_RXBS_SUPPORT;
+
+	while ((readl(port->membase + CDNS_UART_SR) &
+		CDNS_UART_SR_RXEMPTY) != CDNS_UART_SR_RXEMPTY) {
+		if (is_rxbs_support)
+			rxbs_status = readl(port->membase + CDNS_UART_RXBS);
+		data = readl(port->membase + CDNS_UART_FIFO);
+		port->icount.rx++;
+		/*
+		 * There is no hardware break detection in Zynq, so we interpret
+		 * framing error with all-zeros data as a break sequence.
+		 * Most of the time, there's another non-zero byte at the
+		 * end of the sequence.
+		 */
+		if (!is_rxbs_support && (isrstatus & CDNS_UART_IXR_FRAMING)) {
+			if (!data) {
 				port->read_status_mask |= CDNS_UART_IXR_BRK;
-				isrstatus &= ~CDNS_UART_IXR_FRAMING;
+				framerrprocessed = 1;
+				continue;
 			}
 		}
-		writel(CDNS_UART_IXR_FRAMING, port->membase + CDNS_UART_ISR);
-	}
+		if (is_rxbs_support && (rxbs_status & CDNS_UART_RXBS_BRK)) {
+			port->icount.brk++;
+			status = TTY_BREAK;
+			if (uart_handle_break(port))
+				continue;
+		}
 
-	/* drop byte with parity error if IGNPAR specified */
-	if (isrstatus & port->ignore_status_mask & CDNS_UART_IXR_PARITY)
-		isrstatus &= ~(CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT);
+		isrstatus &= port->read_status_mask;
+		isrstatus &= ~port->ignore_status_mask;
+		status_mask = port->read_status_mask;
+		status_mask &= ~port->ignore_status_mask;
 
-	isrstatus &= port->read_status_mask;
-	isrstatus &= ~port->ignore_status_mask;
-
-	if (!(isrstatus & (CDNS_UART_IXR_TOUT | CDNS_UART_IXR_RXTRIG)))
-		return;
-
-	while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_RXEMPTY)) {
-		u32 data;
-		char status = TTY_NORMAL;
-
-		data = readl(port->membase + CDNS_UART_FIFO);
-
-		/* Non-NULL byte after BREAK is garbage (99%) */
-		if (data && (port->read_status_mask & CDNS_UART_IXR_BRK)) {
+		if (data &&
+		    (port->read_status_mask & CDNS_UART_IXR_BRK)) {
 			port->read_status_mask &= ~CDNS_UART_IXR_BRK;
 			port->icount.brk++;
 			if (uart_handle_break(port))
···
 		if (uart_handle_sysrq_char(port, data))
 			continue;
 
-		port->icount.rx++;
-
-		if (isrstatus & CDNS_UART_IXR_PARITY) {
-			port->icount.parity++;
-			status = TTY_PARITY;
-		} else if (isrstatus & CDNS_UART_IXR_FRAMING) {
-			port->icount.frame++;
-			status = TTY_FRAME;
-		} else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
-			port->icount.overrun++;
+		if (is_rxbs_support) {
+			if ((rxbs_status & CDNS_UART_RXBS_PARITY)
+			    && (status_mask & CDNS_UART_IXR_PARITY)) {
+				port->icount.parity++;
+				status = TTY_PARITY;
+			}
+			if ((rxbs_status & CDNS_UART_RXBS_FRAMING)
+			    && (status_mask & CDNS_UART_IXR_PARITY)) {
+				port->icount.frame++;
+				status = TTY_FRAME;
+			}
+		} else {
+			if (isrstatus & CDNS_UART_IXR_PARITY) {
+				port->icount.parity++;
+				status = TTY_PARITY;
+			}
+			if ((isrstatus & CDNS_UART_IXR_FRAMING) &&
+			    !framerrprocessed) {
+				port->icount.frame++;
+				status = TTY_FRAME;
+			}
 		}
-
-		uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
-				 data, status);
+		if (isrstatus & CDNS_UART_IXR_OVERRUN) {
+			port->icount.overrun++;
+			tty_insert_flip_char(&port->state->port, 0,
+					     TTY_OVERRUN);
+		}
+		tty_insert_flip_char(&port->state->port, data, status);
+		isrstatus = 0;
 	}
+	spin_unlock(&port->lock);
 	tty_flip_buffer_push(&port->state->port);
+	spin_lock(&port->lock);
 }
 
-static void cdns_uart_handle_tx(struct uart_port *port)
+/**
+ * cdns_uart_handle_tx - Handle the bytes to be Txed.
+ * @dev_id: Id of the UART port
+ * Return: None
+ */
+static void cdns_uart_handle_tx(void *dev_id)
 {
+	struct uart_port *port = (struct uart_port *)dev_id;
 	unsigned int numbytes;
 
 	if (uart_circ_empty(&port->state->xmit)) {
 		writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IDR);
-		return;
+	} else {
+		numbytes = port->fifosize;
+		while (numbytes && !uart_circ_empty(&port->state->xmit) &&
+		       !(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXFULL)) {
+			/*
+			 * Get the data from the UART circular buffer
+			 * and write it to the cdns_uart's TX_FIFO
+			 * register.
+			 */
+			writel(
+				port->state->xmit.buf[port->state->xmit.
+				tail], port->membase + CDNS_UART_FIFO);
+
+			port->icount.tx++;
+
+			/*
+			 * Adjust the tail of the UART buffer and wrap
+			 * the buffer if it reaches limit.
+			 */
+			port->state->xmit.tail =
+				(port->state->xmit.tail + 1) &
+					(UART_XMIT_SIZE - 1);
+
+			numbytes--;
+		}
+
+		if (uart_circ_chars_pending(
+				&port->state->xmit) < WAKEUP_CHARS)
+			uart_write_wakeup(port);
 	}
-
-	numbytes = port->fifosize;
-	while (numbytes && !uart_circ_empty(&port->state->xmit) &&
-	       !(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXFULL)) {
-		/*
-		 * Get the data from the UART circular buffer
-		 * and write it to the cdns_uart's TX_FIFO
-		 * register.
-		 */
-		writel(port->state->xmit.buf[port->state->xmit.tail],
-			port->membase + CDNS_UART_FIFO);
-		port->icount.tx++;
-
-		/*
-		 * Adjust the tail of the UART buffer and wrap
-		 * the buffer if it reaches limit.
-		 */
-		port->state->xmit.tail =
-			(port->state->xmit.tail + 1) & (UART_XMIT_SIZE - 1);
-
-		numbytes--;
-	}
-
-	if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
 }
 
 /**
···
 static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 {
 	struct uart_port *port = (struct uart_port *)dev_id;
-	unsigned long flags;
 	unsigned int isrstatus;
 
-	spin_lock_irqsave(&port->lock, flags);
+	spin_lock(&port->lock);
 
 	/* Read the interrupt status register to determine which
-	 * interrupt(s) is/are active.
+	 * interrupt(s) is/are active and clear them.
 	 */
 	isrstatus = readl(port->membase + CDNS_UART_ISR);
-
-	if (isrstatus & CDNS_UART_RX_IRQS)
-		cdns_uart_handle_rx(port, isrstatus);
-
-	if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY)
-		cdns_uart_handle_tx(port);
-
 	writel(isrstatus, port->membase + CDNS_UART_ISR);
 
-	/* be sure to release the lock and tty before leaving */
-	spin_unlock_irqrestore(&port->lock, flags);
+	if (isrstatus & CDNS_UART_IXR_TXEMPTY) {
+		cdns_uart_handle_tx(dev_id);
+		isrstatus &= ~CDNS_UART_IXR_TXEMPTY;
+	}
+	if (isrstatus & CDNS_UART_IXR_MASK)
+		cdns_uart_handle_rx(dev_id, isrstatus);
 
+	spin_unlock(&port->lock);
 	return IRQ_HANDLED;
 }
 
···
 	ctrl_reg |= CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST;
 	writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
+	while (readl(port->membase + CDNS_UART_CR) &
+		(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST))
+		cpu_relax();
+
 	/*
 	 * Clear the RX disable and TX disable bits and then set the TX enable
 	 * bit and RX enable bit to enable the transmitter and receiver.
···
  */
 static int cdns_uart_startup(struct uart_port *port)
 {
+	struct cdns_uart *cdns_uart = port->private_data;
+	bool is_brk_support;
 	int ret;
 	unsigned long flags;
 	unsigned int status = 0;
+
+	is_brk_support = cdns_uart->quirks & CDNS_UART_RXBS_SUPPORT;
 
 	spin_lock_irqsave(&port->lock, flags);
 
···
 	 */
 	writel(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST,
 			port->membase + CDNS_UART_CR);
+
+	while (readl(port->membase + CDNS_UART_CR) &
+		(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST))
+		cpu_relax();
 
 	/*
 	 * Clear the RX disable bit and then set the RX enable bit to enable
···
 	}
 
 	/* Set the Interrupt Registers with desired interrupts */
-	writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IER);
+	if (is_brk_support)
+		writel(CDNS_UART_RX_IRQS | CDNS_UART_IXR_BRK,
+					port->membase + CDNS_UART_IER);
+	else
+		writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IER);
 
 	return 0;
 }
···
 	}
 }
 
-static struct uart_ops cdns_uart_ops = {
+static const struct uart_ops cdns_uart_ops = {
 	.set_mctrl	= cdns_uart_set_mctrl,
 	.get_mctrl	= cdns_uart_get_mctrl,
 	.start_tx	= cdns_uart_start_tx,
···
 static int __init cdns_early_console_setup(struct earlycon_device *device,
 					   const char *opt)
 {
-	if (!device->port.membase)
+	struct uart_port *port = &device->port;
+
+	if (!port->membase)
 		return -ENODEV;
+
+	/* initialise control register */
+	writel(CDNS_UART_CR_TX_EN|CDNS_UART_CR_TXRST|CDNS_UART_CR_RXRST,
+	       port->membase + CDNS_UART_CR);
+
+	/* only set baud if specified on command line - otherwise
+	 * assume it has been initialized by a boot loader.
+	 */
+	if (device->baud) {
+		u32 cd = 0, bdiv = 0;
+		u32 mr;
+		int div8;
+
+		cdns_uart_calc_baud_divs(port->uartclk, device->baud,
+					 &bdiv, &cd, &div8);
+		mr = CDNS_UART_MR_PARITY_NONE;
+		if (div8)
+			mr |= CDNS_UART_MR_CLKSEL;
+
+		writel(mr,   port->membase + CDNS_UART_MR);
+		writel(cd,   port->membase + CDNS_UART_BAUDGEN);
+		writel(bdiv, port->membase + CDNS_UART_BAUDDIV);
+	}
 
 	device->con->write = cdns_early_write;
 
···
 static SIMPLE_DEV_PM_OPS(cdns_uart_dev_pm_ops, cdns_uart_suspend,
 		cdns_uart_resume);
 
+static const struct cdns_platform_data zynqmp_uart_def = {
+				.quirks = CDNS_UART_RXBS_SUPPORT, };
+
+/* Match table for of_platform binding */
+static const struct of_device_id cdns_uart_of_match[] = {
+	{ .compatible = "xlnx,xuartps", },
+	{ .compatible = "cdns,uart-r1p8", },
+	{ .compatible = "cdns,uart-r1p12", .data = &zynqmp_uart_def },
+	{}
+};
+MODULE_DEVICE_TABLE(of, cdns_uart_of_match);
+
 /**
  * cdns_uart_probe - Platform driver probe
  * @pdev: Pointer to the platform device structure
···
 	struct uart_port *port;
 	struct resource *res;
 	struct cdns_uart *cdns_uart_data;
+	const struct of_device_id *match;
 
 	cdns_uart_data = devm_kzalloc(&pdev->dev, sizeof(*cdns_uart_data),
 			GFP_KERNEL);
 	if (!cdns_uart_data)
 		return -ENOMEM;
+
+	match = of_match_node(cdns_uart_of_match, pdev->dev.of_node);
+	if (match && match->data) {
+		const struct cdns_platform_data *data = match->data;
+
+		cdns_uart_data->quirks = data->quirks;
+	}
 
 	cdns_uart_data->pclk = devm_clk_get(&pdev->dev, "pclk");
 	if (IS_ERR(cdns_uart_data->pclk)) {
···
 	clk_unprepare(cdns_uart_data->pclk);
 	return rc;
 }
-
-/* Match table for of_platform binding */
-static const struct of_device_id cdns_uart_of_match[] = {
-	{ .compatible = "xlnx,xuartps", },
-	{ .compatible = "cdns,uart-r1p8", },
-	{}
-};
-MODULE_DEVICE_TABLE(of, cdns_uart_of_match);
 
 static struct platform_driver cdns_uart_platform_driver = {
 	.probe   = cdns_uart_probe,

drivers/tty/vt/vt.c

···
 	if (i > vc->vc_npar)
 		return i;
 
-	if (vc->vc_par[i] == 5 && i < vc->vc_npar) {
-		/* 256 colours -- ubiquitous */
+	if (vc->vc_par[i] == 5 && i + 1 <= vc->vc_npar) {
+		/* 256 colours */
 		i++;
 		rgb_from_256(vc->vc_par[i], &c);
-	} else if (vc->vc_par[i] == 2 && i <= vc->vc_npar + 3) {
-		/* 24 bit -- extremely rare */
+	} else if (vc->vc_par[i] == 2 && i + 3 <= vc->vc_npar) {
+		/* 24 bit */
 		c.r = vc->vc_par[i + 1];
 		c.g = vc->vc_par[i + 2];
 		c.b = vc->vc_par[i + 3];
···
 				(vc->vc_color & 0x0f);
 			break;
 		default:
+			if (vc->vc_par[i] >= 90 && vc->vc_par[i] <= 107) {
+				if (vc->vc_par[i] < 100)
+					vc->vc_intensity = 2;
+				vc->vc_par[i] -= 60;
+			}
 			if (vc->vc_par[i] >= 30 && vc->vc_par[i] <= 37)
 				vc->vc_color = color_table[vc->vc_par[i] - 30]
 					| (vc->vc_color & 0xf0);

fs/devpts/inode.c

···
 	struct dentry *root = sb->s_root;
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 	struct pts_mount_opts *opts = &fsi->mount_opts;
-	kuid_t root_uid;
-	kgid_t root_gid;
-
-	root_uid = make_kuid(current_user_ns(), 0);
-	root_gid = make_kgid(current_user_ns(), 0);
-	if (!uid_valid(root_uid) || !gid_valid(root_gid))
-		return -EINVAL;
+	kuid_t ptmx_uid = current_fsuid();
+	kgid_t ptmx_gid = current_fsgid();
 
 	inode_lock(d_inode(root));
 
···
 
 	mode = S_IFCHR|opts->ptmxmode;
 	init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
-	inode->i_uid = root_uid;
-	inode->i_gid = root_gid;
+	inode->i_uid = ptmx_uid;
+	inode->i_gid = ptmx_gid;
 
 	d_add(dentry, inode);
 
···
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 	struct pts_mount_opts *opts = &fsi->mount_opts;
 
-	sync_filesystem(sb);
 	err = parse_mount_options(data, PARSE_REMOUNT, opts);
 
 	/*
···
 devpts_fill_super(struct super_block *s, void *data, int silent)
 {
 	struct inode *inode;
+	int error;
 
 	s->s_iflags &= ~SB_I_NODEV;
 	s->s_blocksize = 1024;
···
 	s->s_op = &devpts_sops;
 	s->s_time_gran = 1;
 
+	error = -ENOMEM;
 	s->s_fs_info = new_pts_fs_info(s);
 	if (!s->s_fs_info)
 		goto fail;
 
+	error = parse_mount_options(data, PARSE_MOUNT, &DEVPTS_SB(s)->mount_opts);
+	if (error)
+		goto fail;
+
+	error = -ENOMEM;
 	inode = new_inode(s);
 	if (!inode)
 		goto fail;
···
 	set_nlink(inode, 2);
 
 	s->s_root = d_make_root(inode);
-	if (s->s_root)
-		return 0;
+	if (!s->s_root) {
+		pr_err("get root dentry failed\n");
+		goto fail;
+	}
 
-	pr_err("get root dentry failed\n");
+	error = mknod_ptmx(s);
+	if (error)
+		goto fail_dput;
 
+	return 0;
+fail_dput:
+	dput(s->s_root);
+	s->s_root = NULL;
 fail:
-	return -ENOMEM;
+	return error;
 }
 
 /*
···
 static struct dentry *devpts_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
-	int error;
-	struct pts_mount_opts opts;
-	struct super_block *s;
-
-	error = parse_mount_options(data, PARSE_MOUNT, &opts);
-	if (error)
-		return ERR_PTR(error);
-
-	s = sget(fs_type, NULL, set_anon_super, flags, NULL);
-	if (IS_ERR(s))
-		return ERR_CAST(s);
-
-	if (!s->s_root) {
-		error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
-		if (error)
-			goto out_undo_sget;
-		s->s_flags |= MS_ACTIVE;
-	}
-
-	memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
-
-	error = mknod_ptmx(s);
-	if (error)
-		goto out_undo_sget;
-
-	return dget(s->s_root);
-
-out_undo_sget:
-	deactivate_locked_super(s);
-	return ERR_PTR(error);
+	return mount_nodev(fs_type, flags, data, devpts_fill_super);
 }
 
 static void devpts_kill_sb(struct super_block *sb)
 {
 	struct pts_fs_info *fsi = DEVPTS_SB(sb);
 
-	ida_destroy(&fsi->allocated_ptys);
+	if (fsi)
+		ida_destroy(&fsi->allocated_ptys);
 	kfree(fsi);
 	kill_litter_super(sb);
 }

include/linux/acpi.h

···
 static inline bool acpi_has_watchdog(void) { return false; }
 #endif
 
+#ifdef CONFIG_ACPI_SPCR_TABLE
+int parse_spcr(bool earlycon);
+#else
+static inline int parse_spcr(bool earlycon) { return 0; }
+#endif
+
 #endif	/*_LINUX_ACPI_H*/

include/linux/amba/bus.h

···
 	AMBA_VENDOR_ST = 0x80,
 	AMBA_VENDOR_QCOM = 0x51,
 	AMBA_VENDOR_LSI = 0xb6,
+	AMBA_VENDOR_LINUX = 0xfe,	/* This value is not official */
 };
+
+/* This is used to generate pseudo-ID for AMBA device */
+#define AMBA_LINUX_ID(conf, rev, part) \
+	(((conf) & 0xff) << 24 | ((rev) & 0xf) << 20 | \
+	AMBA_VENDOR_LINUX << 12 | ((part) & 0xfff))
 
 extern struct bus_type amba_bustype;
 

include/linux/amba/serial.h

···
 #define UART01x_FR_CTS 		0x001
 #define UART01x_FR_TMSK		(UART01x_FR_TXFF + UART01x_FR_BUSY)
 
+/*
+ * Some bits of Flag Register on ZTE device have different position from
+ * standard ones.
+ */
+#define ZX_UART01x_FR_BUSY	0x100
+#define ZX_UART01x_FR_DSR	0x008
+#define ZX_UART01x_FR_CTS	0x002
+#define ZX_UART011_FR_RI	0x001
+
 #define UART011_CR_CTSEN	0x8000	/* CTS hardware flow control */
 #define UART011_CR_RTSEN	0x4000	/* RTS hardware flow control */
 #define UART011_CR_OUT2		0x2000	/* OUT2 */

include/linux/atmel_serial.h

···
 
 #define ATMEL_US_BRGR		0x20	/* Baud Rate Generator Register */
 #define	ATMEL_US_CD		GENMASK(15, 0)	/* Clock Divider */
+#define ATMEL_US_FP_OFFSET	16	/* Fractional Part */
+#define ATMEL_US_FP_MASK	0x7
 
 #define ATMEL_US_RTOR		0x24	/* Receiver Time-out Register for USART */
 #define ATMEL_UA_RTOR		0x28	/* Receiver Time-out Register for UART */

include/linux/dma/dw.h

···
 };
 
 /* Export to the platform drivers */
+#if IS_ENABLED(CONFIG_DW_DMAC_CORE)
 int dw_dma_probe(struct dw_dma_chip *chip);
 int dw_dma_remove(struct dw_dma_chip *chip);
+#else
+static inline int dw_dma_probe(struct dw_dma_chip *chip) { return -ENODEV; }
+static inline int dw_dma_remove(struct dw_dma_chip *chip) { return 0; }
+#endif /* CONFIG_DW_DMAC_CORE */
 
 /* DMA API extensions */
 struct dw_desc;

include/linux/dma/hsu.h

···
 /* Export to the internal users */
 int hsu_dma_get_status(struct hsu_dma_chip *chip, unsigned short nr,
 		       u32 *status);
-irqreturn_t hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr,
-			   u32 status);
+int hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr, u32 status);
 
 /* Export to the platform drivers */
 int hsu_dma_probe(struct hsu_dma_chip *chip);
···
 {
 	return 0;
 }
-static inline irqreturn_t hsu_dma_do_irq(struct hsu_dma_chip *chip,
-					 unsigned short nr, u32 status)
+static inline int hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr,
+				 u32 status)
 {
-	return IRQ_NONE;
+	return 0;
 }
 static inline int hsu_dma_probe(struct hsu_dma_chip *chip) { return -ENODEV; }
 static inline int hsu_dma_remove(struct hsu_dma_chip *chip) { return 0; }

include/linux/of_fdt.h

···
 
 #include <linux/types.h>
 #include <linux/init.h>
+#include <linux/errno.h>
 
 /* Definitions used by the flattened device tree */
 #define OF_DT_HEADER		0xd00dfeed	/* marker */
···
 				     int depth, void *data);
 extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
 				     int depth, void *data);
+extern int early_init_dt_scan_chosen_stdout(void);
 extern void early_init_fdt_scan_reserved_mem(void);
 extern void early_init_fdt_reserve_self(void);
 extern void early_init_dt_add_memory_arch(u64 base, u64 size);
···
 extern u64 of_flat_dt_translate_address(unsigned long node);
 extern void of_fdt_limit_memory(int limit);
 #else /* CONFIG_OF_FLATTREE */
+static inline int early_init_dt_scan_chosen_stdout(void) { return -ENODEV; }
 static inline void early_init_fdt_scan_reserved_mem(void) {}
 static inline void early_init_fdt_reserve_self(void) {}
 static inline const char *of_flat_dt_get_machine_name(void) { return NULL; }

include/linux/platform_data/dma-dw.h

···
  * @dst_id:	dst request line
  * @m_master:	memory master for transfers on allocated channel
  * @p_master:	peripheral master for transfers on allocated channel
+ * @hs_polarity:set active low polarity of handshake interface
  */
 struct dw_dma_slave {
 	struct device		*dma_dev;
···
 	u8			dst_id;
 	u8			m_master;
 	u8			p_master;
+	bool			hs_polarity;
 };
 
 /**
···
  * @is_private: The device channels should be marked as private and not for
  *	by the general purpose DMA channel allocator.
  * @is_memcpy: The device channels do support memory-to-memory transfers.
+ * @is_nollp: The device channels does not support multi block transfers.
  * @chan_allocation_order: Allocate channels starting from 0 or 7
  * @chan_priority: Set channel priority increasing from 0 to 7 or 7 to 0.
  * @block_size: Maximum block size supported by the controller
···
 	unsigned int	nr_channels;
 	bool		is_private;
 	bool		is_memcpy;
+	bool		is_nollp;
 #define CHAN_ALLOCATION_ASCENDING	0	/* zero to seven */
 #define CHAN_ALLOCATION_DESCENDING	1	/* seven to zero */
 	unsigned char	chan_allocation_order;

include/linux/serial_core.h

···
 
 #define EARLYCON_DECLARE(_name, fn)	OF_EARLYCON_DECLARE(_name, "", fn)
 
-extern int setup_earlycon(char *buf);
 extern int of_setup_earlycon(const struct earlycon_id *match,
 			     unsigned long node,
 			     const char *options);
 
+#ifdef CONFIG_SERIAL_EARLYCON
+extern bool earlycon_init_is_deferred __initdata;
+int setup_earlycon(char *buf);
+#else
+static const bool earlycon_init_is_deferred;
+static inline int setup_earlycon(char *buf) { return 0; }
+#endif
+
 struct uart_port *uart_get_console(struct uart_port *ports, int nr,
 				   struct console *c);
-int uart_parse_earlycon(char *p, unsigned char *iotype, unsigned long *addr,
+int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
 			char **options);
 void uart_parse_options(char *options, int *baud, int *parity, int *bits,
 			int *flow);
···
 static inline int uart_tx_stopped(struct uart_port *port)
 {
 	struct tty_struct *tty = port->state->port.tty;
-	if (tty->stopped || port->hw_stopped)
+	if ((tty && tty->stopped) || port->hw_stopped)
 		return 1;
 	return 0;
 }

include/uapi/linux/serial_reg.h

···
 #define UART_EXAR_TXTRG		0x0a	/* Tx FIFO trigger level write-only */
 #define UART_EXAR_RXTRG		0x0b	/* Rx FIFO trigger level write-only */
 
+/*
+ * These are definitions for the Altera ALTR_16550_F32/F64/F128
+ * Normalized from 0x100 to 0x40 because of shift by 2 (32 bit regs).
+ */
+#define UART_ALTR_AFR		0x40	/* Additional Features Register */
+#define UART_ALTR_EN_TXFIFO_LW	0x01	/* Enable the TX FIFO Low Watermark */
+#define UART_ALTR_TX_LOW	0x41	/* Tx FIFO Low Watermark */
+
 #endif /* _LINUX_SERIAL_REG_H */