serial: sc16is7xx

The SC16IS7xx is a slave I2C-bus/SPI interface to a single-channel
high performance UART. The SC16IS7xx's internal register set is
backward-compatible with the widely used and widely popular 16C450.

The SC16IS7xx also provides additional advanced features such as
auto hardware and software flow control, automatic RS-485 support, and
software reset.

Signed-off-by: Jon Ringle <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/Kconfig

···
 	help
 	  Support for console on SCCNXP serial ports.
 
+config SERIAL_SC16IS7XX
+	tristate "SC16IS7xx serial support"
+	select SERIAL_CORE
+	select REGMAP_I2C if I2C
+	help
+	  This selects support for SC16IS7xx serial ports.
+	  Supported ICs are SC16IS740, SC16IS741, SC16IS750, SC16IS752,
+	  SC16IS760 and SC16IS762.
+
 config SERIAL_BFIN_SPORT
 	tristate "Blackfin SPORT emulate UART"
 	depends on BLACKFIN

drivers/tty/serial/Makefile

···
 obj-$(CONFIG_SERIAL_SB1250_DUART) += sb1250-duart.o
 obj-$(CONFIG_ETRAX_SERIAL) += crisv10.o
 obj-$(CONFIG_SERIAL_SCCNXP) += sccnxp.o
+obj-$(CONFIG_SERIAL_SC16IS7XX) += sc16is7xx.o
 obj-$(CONFIG_SERIAL_JSM) += jsm/
 obj-$(CONFIG_SERIAL_TXX9) += serial_txx9.o
 obj-$(CONFIG_SERIAL_VR41XX) += vr41xx_siu.o

drivers/tty/serial/sc16is7xx.c

···
+/*
+ * SC16IS7xx tty serial driver - Copyright (C) 2014 GridPoint
+ * Author: Jon Ringle <[e-mail]>
+ *
+ *  Based on max310x.c, by Alexander Shiyan <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#define SC16IS7XX_NAME			"sc16is7xx"
+
+/* SC16IS7XX register definitions */
+#define SC16IS7XX_RHR_REG		(0x00) /* RX FIFO */
+#define SC16IS7XX_THR_REG		(0x00) /* TX FIFO */
+#define SC16IS7XX_IER_REG		(0x01) /* Interrupt enable */
+#define SC16IS7XX_IIR_REG		(0x02) /* Interrupt Identification */
+#define SC16IS7XX_FCR_REG		(0x02) /* FIFO control */
+#define SC16IS7XX_LCR_REG		(0x03) /* Line Control */
+#define SC16IS7XX_MCR_REG		(0x04) /* Modem Control */
+#define SC16IS7XX_LSR_REG		(0x05) /* Line Status */
+#define SC16IS7XX_MSR_REG		(0x06) /* Modem Status */
+#define SC16IS7XX_SPR_REG		(0x07) /* Scratch Pad */
+#define SC16IS7XX_TXLVL_REG		(0x08) /* TX FIFO level */
+#define SC16IS7XX_RXLVL_REG		(0x09) /* RX FIFO level */
+#define SC16IS7XX_IODIR_REG		(0x0a) /* I/O Direction
+						* - only on 75x/76x
+						*/
+#define SC16IS7XX_IOSTATE_REG		(0x0b) /* I/O State
+						* - only on 75x/76x
+						*/
+#define SC16IS7XX_IOINTENA_REG		(0x0c) /* I/O Interrupt Enable
+						* - only on 75x/76x
+						*/
+#define SC16IS7XX_IOCONTROL_REG		(0x0e) /* I/O Control
+						* - only on 75x/76x
+						*/
+#define SC16IS7XX_EFCR_REG		(0x0f) /* Extra Features Control */
+
+/* TCR/TLR Register set: Only if ((MCR[2] == 1) && (EFR[4] == 1)) */
+#define SC16IS7XX_TCR_REG		(0x06) /* Transmit control */
+#define SC16IS7XX_TLR_REG		(0x07) /* Trigger level */
+
+/* Special Register set: Only if ((LCR[7] == 1) && (LCR != 0xBF)) */
+#define SC16IS7XX_DLL_REG		(0x00) /* Divisor Latch Low */
+#define SC16IS7XX_DLH_REG		(0x01) /* Divisor Latch High */
+
+/* Enhanced Register set: Only if (LCR == 0xBF) */
+#define SC16IS7XX_EFR_REG		(0x02) /* Enhanced Features */
+#define SC16IS7XX_XON1_REG		(0x04) /* Xon1 word */
+#define SC16IS7XX_XON2_REG		(0x05) /* Xon2 word */
+#define SC16IS7XX_XOFF1_REG		(0x06) /* Xoff1 word */
+#define SC16IS7XX_XOFF2_REG		(0x07) /* Xoff2 word */
+
+/* IER register bits */
+#define SC16IS7XX_IER_RDI_BIT		(1 << 0) /* Enable RX data interrupt */
+#define SC16IS7XX_IER_THRI_BIT		(1 << 1) /* Enable TX holding register
+						  * interrupt */
+#define SC16IS7XX_IER_RLSI_BIT		(1 << 2) /* Enable RX line status
+						  * interrupt */
+#define SC16IS7XX_IER_MSI_BIT		(1 << 3) /* Enable Modem status
+						  * interrupt */
+
+/* IER register bits - write only if (EFR[4] == 1) */
+#define SC16IS7XX_IER_SLEEP_BIT		(1 << 4) /* Enable Sleep mode */
+#define SC16IS7XX_IER_XOFFI_BIT		(1 << 5) /* Enable Xoff interrupt */
+#define SC16IS7XX_IER_RTSI_BIT		(1 << 6) /* Enable nRTS interrupt */
+#define SC16IS7XX_IER_CTSI_BIT		(1 << 7) /* Enable nCTS interrupt */
+
+/* FCR register bits */
+#define SC16IS7XX_FCR_FIFO_BIT		(1 << 0) /* Enable FIFO */
+#define SC16IS7XX_FCR_RXRESET_BIT	(1 << 1) /* Reset RX FIFO */
+#define SC16IS7XX_FCR_TXRESET_BIT	(1 << 2) /* Reset TX FIFO */
+#define SC16IS7XX_FCR_RXLVLL_BIT	(1 << 6) /* RX Trigger level LSB */
+#define SC16IS7XX_FCR_RXLVLH_BIT	(1 << 7) /* RX Trigger level MSB */
+
+/* FCR register bits - write only if (EFR[4] == 1) */
+#define SC16IS7XX_FCR_TXLVLL_BIT	(1 << 4) /* TX Trigger level LSB */
+#define SC16IS7XX_FCR_TXLVLH_BIT	(1 << 5) /* TX Trigger level MSB */
+
+/* IIR register bits */
+#define SC16IS7XX_IIR_NO_INT_BIT	(1 << 0) /* No interrupts pending */
+#define SC16IS7XX_IIR_ID_MASK		0x3e     /* Mask for the interrupt ID */
+#define SC16IS7XX_IIR_THRI_SRC		0x02     /* TX holding register empty */
+#define SC16IS7XX_IIR_RDI_SRC		0x04     /* RX data interrupt */
+#define SC16IS7XX_IIR_RLSE_SRC		0x06     /* RX line status error */
+#define SC16IS7XX_IIR_RTOI_SRC		0x0c     /* RX time-out interrupt */
+#define SC16IS7XX_IIR_MSI_SRC		0x00     /* Modem status interrupt
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_IIR_INPIN_SRC		0x30     /* Input pin change of state
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_IIR_XOFFI_SRC		0x10     /* Received Xoff */
+#define SC16IS7XX_IIR_CTSRTS_SRC	0x20     /* nCTS,nRTS change of state
+						  * from active (LOW)
+						  * to inactive (HIGH)
+						  */
+/* LCR register bits */
+#define SC16IS7XX_LCR_LENGTH0_BIT	(1 << 0) /* Word length bit 0 */
+#define SC16IS7XX_LCR_LENGTH1_BIT	(1 << 1) /* Word length bit 1
+						  *
+						  * Word length bits table:
+						  * 00 -> 5 bit words
+						  * 01 -> 6 bit words
+						  * 10 -> 7 bit words
+						  * 11 -> 8 bit words
+						  */
+#define SC16IS7XX_LCR_STOPLEN_BIT	(1 << 2) /* STOP length bit
+						  *
+						  * STOP length bit table:
+						  * 0 -> 1 stop bit
+						  * 1 -> 1-1.5 stop bits if
+						  *      word length is 5,
+						  *      2 stop bits otherwise
+						  */
+#define SC16IS7XX_LCR_PARITY_BIT	(1 << 3) /* Parity bit enable */
+#define SC16IS7XX_LCR_EVENPARITY_BIT	(1 << 4) /* Even parity bit enable */
+#define SC16IS7XX_LCR_FORCEPARITY_BIT	(1 << 5) /* 9-bit multidrop parity */
+#define SC16IS7XX_LCR_TXBREAK_BIT	(1 << 6) /* TX break enable */
+#define SC16IS7XX_LCR_DLAB_BIT		(1 << 7) /* Divisor Latch enable */
+#define SC16IS7XX_LCR_WORD_LEN_5	(0x00)
+#define SC16IS7XX_LCR_WORD_LEN_6	(0x01)
+#define SC16IS7XX_LCR_WORD_LEN_7	(0x02)
+#define SC16IS7XX_LCR_WORD_LEN_8	(0x03)
+#define SC16IS7XX_LCR_CONF_MODE_A	SC16IS7XX_LCR_DLAB_BIT /* Special
+								* reg set */
+#define SC16IS7XX_LCR_CONF_MODE_B	0xBF                   /* Enhanced
+								* reg set */
+
+/* MCR register bits */
+#define SC16IS7XX_MCR_DTR_BIT		(1 << 0) /* DTR complement
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_MCR_RTS_BIT		(1 << 1) /* RTS complement */
+#define SC16IS7XX_MCR_TCRTLR_BIT	(1 << 2) /* TCR/TLR register enable */
+#define SC16IS7XX_MCR_LOOP_BIT		(1 << 4) /* Enable loopback test mode */
+#define SC16IS7XX_MCR_XONANY_BIT	(1 << 5) /* Enable Xon Any
+						  * - write enabled
+						  * if (EFR[4] == 1)
+						  */
+#define SC16IS7XX_MCR_IRDA_BIT		(1 << 6) /* Enable IrDA mode
+						  * - write enabled
+						  * if (EFR[4] == 1)
+						  */
+#define SC16IS7XX_MCR_CLKSEL_BIT	(1 << 7) /* Divide clock by 4
+						  * - write enabled
+						  * if (EFR[4] == 1)
+						  */
+
+/* LSR register bits */
+#define SC16IS7XX_LSR_DR_BIT		(1 << 0) /* Receiver data ready */
+#define SC16IS7XX_LSR_OE_BIT		(1 << 1) /* Overrun Error */
+#define SC16IS7XX_LSR_PE_BIT		(1 << 2) /* Parity Error */
+#define SC16IS7XX_LSR_FE_BIT		(1 << 3) /* Frame Error */
+#define SC16IS7XX_LSR_BI_BIT		(1 << 4) /* Break Interrupt */
+#define SC16IS7XX_LSR_BRK_ERROR_MASK	0x1E     /* BI, FE, PE, OE bits */
+#define SC16IS7XX_LSR_THRE_BIT		(1 << 5) /* TX holding register empty */
+#define SC16IS7XX_LSR_TEMT_BIT		(1 << 6) /* Transmitter empty */
+#define SC16IS7XX_LSR_FIFOE_BIT		(1 << 7) /* Fifo Error */
+
+/* MSR register bits */
+#define SC16IS7XX_MSR_DCTS_BIT		(1 << 0) /* Delta CTS Clear To Send */
+#define SC16IS7XX_MSR_DDSR_BIT		(1 << 1) /* Delta DSR Data Set Ready
+						  * or (IO4)
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_MSR_DRI_BIT		(1 << 2) /* Delta RI Ring Indicator
+						  * or (IO7)
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_MSR_DCD_BIT		(1 << 3) /* Delta CD Carrier Detect
+						  * or (IO6)
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_MSR_CTS_BIT		(1 << 0) /* CTS */
+#define SC16IS7XX_MSR_DSR_BIT		(1 << 1) /* DSR (IO4)
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_MSR_RI_BIT		(1 << 2) /* RI (IO7)
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_MSR_CD_BIT		(1 << 3) /* CD (IO6)
+						  * - only on 75x/76x
+						  */
+#define SC16IS7XX_MSR_DELTA_MASK	0x0F     /* Any of the delta bits! */
+
+/*
+ * TCR register bits
+ * TCR trigger levels are available from 0 to 60 characters with a granularity
+ * of four.
+ * The programmer must program the TCR such that TCR[3:0] > TCR[7:4]. There is
+ * no built-in hardware check to make sure this condition is met. Also, the TCR
+ * must be programmed with this condition before auto RTS or software flow
+ * control is enabled to avoid spurious operation of the device.
+ */
+#define SC16IS7XX_TCR_RX_HALT(words)	((((words) / 4) & 0x0f) << 0)
+#define SC16IS7XX_TCR_RX_RESUME(words)	((((words) / 4) & 0x0f) << 4)
+
+/*
+ * TLR register bits
+ * If TLR[3:0] or TLR[7:4] are logical 0, the selectable trigger levels via the
+ * FIFO Control Register (FCR) are used for the transmit and receive FIFO
+ * trigger levels. Trigger levels from 4 characters to 60 characters are
+ * available with a granularity of four.
+ *
+ * When the trigger level setting in TLR is zero, the SC16IS740/750/760 uses the
+ * trigger level setting defined in FCR. If TLR has non-zero trigger level value
+ * the trigger level defined in FCR is discarded. This applies to both transmit
+ * FIFO and receive FIFO trigger level setting.
+ *
+ * When TLR is used for RX trigger level control, FCR[7:6] should be left at the
+ * default state, that is, '00'.
+ */
+#define SC16IS7XX_TLR_TX_TRIGGER(words)	((((words) / 4) & 0x0f) << 0)
+#define SC16IS7XX_TLR_RX_TRIGGER(words)	((((words) / 4) & 0x0f) << 4)
+
+/* IOControl register bits (Only 750/760) */
+#define SC16IS7XX_IOCONTROL_LATCH_BIT	(1 << 0) /* Enable input latching */
+#define SC16IS7XX_IOCONTROL_GPIO_BIT	(1 << 1) /* Enable GPIO[7:4] */
+#define SC16IS7XX_IOCONTROL_SRESET_BIT	(1 << 3) /* Software Reset */
+
+/* EFCR register bits */
+#define SC16IS7XX_EFCR_9BIT_MODE_BIT	(1 << 0) /* Enable 9-bit or Multidrop
+						  * mode (RS485) */
+#define SC16IS7XX_EFCR_RXDISABLE_BIT	(1 << 1) /* Disable receiver */
+#define SC16IS7XX_EFCR_TXDISABLE_BIT	(1 << 2) /* Disable transmitter */
+#define SC16IS7XX_EFCR_AUTO_RS485_BIT	(1 << 4) /* Auto RS485 RTS direction */
+#define SC16IS7XX_EFCR_RTS_INVERT_BIT	(1 << 5) /* RTS output inversion */
+#define SC16IS7XX_EFCR_IRDA_MODE_BIT	(1 << 7) /* IrDA mode
+						  * 0 = rate upto 115.2 kbit/s
+						  *   - Only 750/760
+						  * 1 = rate upto 1.152 Mbit/s
+						  *   - Only 760
+						  */
+
+/* EFR register bits */
+#define SC16IS7XX_EFR_AUTORTS_BIT	(1 << 6) /* Auto RTS flow ctrl enable */
+#define SC16IS7XX_EFR_AUTOCTS_BIT	(1 << 7) /* Auto CTS flow ctrl enable */
+#define SC16IS7XX_EFR_XOFF2_DETECT_BIT	(1 << 5) /* Enable Xoff2 detection */
+#define SC16IS7XX_EFR_ENABLE_BIT	(1 << 4) /* Enable enhanced functions
+						  * and writing to IER[7:4],
+						  * FCR[5:4], MCR[7:5]
+						  */
+#define SC16IS7XX_EFR_SWFLOW3_BIT	(1 << 3) /* SWFLOW bit 3 */
+#define SC16IS7XX_EFR_SWFLOW2_BIT	(1 << 2) /* SWFLOW bit 2
+						  *
+						  * SWFLOW bits 3 & 2 table:
+						  * 00 -> no transmitter flow
+						  *       control
+						  * 01 -> transmitter generates
+						  *       XON2 and XOFF2
+						  * 10 -> transmitter generates
+						  *       XON1 and XOFF1
+						  * 11 -> transmitter generates
+						  *       XON1, XON2, XOFF1 and
+						  *       XOFF2
+						  */
+#define SC16IS7XX_EFR_SWFLOW1_BIT	(1 << 1) /* SWFLOW bit 2 */
+#define SC16IS7XX_EFR_SWFLOW0_BIT	(1 << 0) /* SWFLOW bit 3
+						  *
+						  * SWFLOW bits 3 & 2 table:
+						  * 00 -> no received flow
+						  *       control
+						  * 01 -> receiver compares
+						  *       XON2 and XOFF2
+						  * 10 -> receiver compares
+						  *       XON1 and XOFF1
+						  * 11 -> receiver compares
+						  *       XON1, XON2, XOFF1 and
+						  *       XOFF2
+						  */
+
+/* Misc definitions */
+#define SC16IS7XX_FIFO_SIZE		(64)
+#define SC16IS7XX_REG_SHIFT		2
+
+struct sc16is7xx_devtype {
+	char	name[10];
+	int	nr_gpio;
+	int	nr_uart;
+};
+
+struct sc16is7xx_one {
+	struct uart_port		port;
+	struct work_struct		tx_work;
+	struct work_struct		md_work;
+
+	struct serial_rs485		rs485;
+};
+
+struct sc16is7xx_port {
+	struct uart_driver		uart;
+	struct sc16is7xx_devtype	*devtype;
+	struct regmap			*regmap;
+	struct mutex			mutex;
+	struct clk			*clk;
+#ifdef CONFIG_GPIOLIB
+	struct gpio_chip		gpio;
+#endif
+	struct sc16is7xx_one		p[0];
+};
+
+#define to_sc16is7xx_one(p,e)	((container_of((p), struct sc16is7xx_one, e)))
+
+static u8 sc16is7xx_port_read(struct uart_port *port, u8 reg)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	unsigned int val = 0;
+
+	regmap_read(s->regmap,
+		    (reg << SC16IS7XX_REG_SHIFT) | port->line, &val);
+
+	return val;
+}
+
+static void sc16is7xx_port_write(struct uart_port *port, u8 reg, u8 val)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+
+	regmap_write(s->regmap,
+		     (reg << SC16IS7XX_REG_SHIFT) | port->line, val);
+}
+
+static void sc16is7xx_port_update(struct uart_port *port, u8 reg,
+				  u8 mask, u8 val)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+
+	regmap_update_bits(s->regmap,
+			   (reg << SC16IS7XX_REG_SHIFT) | port->line,
+			   mask, val);
+}
+
+
+static void sc16is7xx_power(struct uart_port *port, int on)
+{
+	sc16is7xx_port_update(port, SC16IS7XX_IER_REG,
+			      SC16IS7XX_IER_SLEEP_BIT,
+			      on ? 0 : SC16IS7XX_IER_SLEEP_BIT);
+}
+
+static const struct sc16is7xx_devtype sc16is74x_devtype = {
+	.name		= "SC16IS74X",
+	.nr_gpio	= 0,
+	.nr_uart	= 1,
+};
+
+static const struct sc16is7xx_devtype sc16is750_devtype = {
+	.name		= "SC16IS750",
+	.nr_gpio	= 8,
+	.nr_uart	= 1,
+};
+
+static const struct sc16is7xx_devtype sc16is752_devtype = {
+	.name		= "SC16IS752",
+	.nr_gpio	= 8,
+	.nr_uart	= 2,
+};
+
+static const struct sc16is7xx_devtype sc16is760_devtype = {
+	.name		= "SC16IS760",
+	.nr_gpio	= 8,
+	.nr_uart	= 1,
+};
+
+static const struct sc16is7xx_devtype sc16is762_devtype = {
+	.name		= "SC16IS762",
+	.nr_gpio	= 8,
+	.nr_uart	= 2,
+};
+
+static bool sc16is7xx_regmap_volatile(struct device *dev, unsigned int reg)
+{
+	switch (reg >> SC16IS7XX_REG_SHIFT) {
+	case SC16IS7XX_RHR_REG:
+	case SC16IS7XX_IIR_REG:
+	case SC16IS7XX_LSR_REG:
+	case SC16IS7XX_MSR_REG:
+	case SC16IS7XX_TXLVL_REG:
+	case SC16IS7XX_RXLVL_REG:
+	case SC16IS7XX_IOSTATE_REG:
+		return true;
+	default:
+		break;
+	}
+
+	return false;
+}
+
+static bool sc16is7xx_regmap_precious(struct device *dev, unsigned int reg)
+{
+	switch (reg >> SC16IS7XX_REG_SHIFT) {
+	case SC16IS7XX_RHR_REG:
+		return true;
+	default:
+		break;
+	}
+
+	return false;
+}
+
+static int sc16is7xx_set_baud(struct uart_port *port, int baud)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	u8 lcr;
+	u8 prescaler = 0;
+	unsigned long clk = port->uartclk, div = clk / 16 / baud;
+
+	if (div > 0xffff) {
+		prescaler = SC16IS7XX_MCR_CLKSEL_BIT;
+		div /= 4;
+	}
+
+	lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG);
+
+	/* Open the LCR divisors for configuration */
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
+			     SC16IS7XX_LCR_CONF_MODE_B);
+
+	/* Enable enhanced features */
+	regcache_cache_bypass(s->regmap, true);
+	sc16is7xx_port_write(port, SC16IS7XX_EFR_REG,
+			     SC16IS7XX_EFR_ENABLE_BIT);
+	regcache_cache_bypass(s->regmap, false);
+
+	/* Put LCR back to the normal mode */
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
+
+	sc16is7xx_port_update(port, SC16IS7XX_MCR_REG,
+			      SC16IS7XX_MCR_CLKSEL_BIT,
+			      prescaler);
+
+	/* Open the LCR divisors for configuration */
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
+			     SC16IS7XX_LCR_CONF_MODE_A);
+
+	/* Write the new divisor */
+	regcache_cache_bypass(s->regmap, true);
+	sc16is7xx_port_write(port, SC16IS7XX_DLH_REG, div / 256);
+	sc16is7xx_port_write(port, SC16IS7XX_DLL_REG, div % 256);
+	regcache_cache_bypass(s->regmap, false);
+
+	/* Put LCR back to the normal mode */
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
+
+	return DIV_ROUND_CLOSEST(clk / 16, div);
+}
+
+static void sc16is7xx_handle_rx(struct uart_port *port, unsigned int rxlen,
+				unsigned int iir)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	unsigned int lsr = 0, ch, flag, bytes_read, i;
+	u8 buf[port->fifosize];
+	bool read_lsr = (iir == SC16IS7XX_IIR_RLSE_SRC) ? true : false;
+
+	if (unlikely(rxlen >= port->fifosize)) {
+		dev_warn_ratelimited(port->dev,
+				     "Port %i: Possible RX FIFO overrun: %d\n",
+				     port->line, rxlen);
+		port->icount.buf_overrun++;
+		/* Ensure sanity of RX level */
+		rxlen = port->fifosize;
+	}
+
+	while (rxlen) {
+		/* Only read lsr if there are possible errors in FIFO */
+		if (read_lsr) {
+			lsr = sc16is7xx_port_read(port, SC16IS7XX_LSR_REG);
+			if (!(lsr & SC16IS7XX_LSR_FIFOE_BIT))
+				read_lsr = false; /* No errors left in FIFO */
+		} else
+			lsr = 0;
+
+		if (read_lsr) {
+			buf[0] = sc16is7xx_port_read(port, SC16IS7XX_RHR_REG);
+			bytes_read = 1;
+		} else {
+			regcache_cache_bypass(s->regmap, true);
+			regmap_raw_read(s->regmap, SC16IS7XX_RHR_REG,
+					buf, rxlen);
+			regcache_cache_bypass(s->regmap, false);
+			bytes_read = rxlen;
+		}
+
+		lsr &= SC16IS7XX_LSR_BRK_ERROR_MASK;
+
+		port->icount.rx++;
+		flag = TTY_NORMAL;
+
+		if (unlikely(lsr)) {
+			if (lsr & SC16IS7XX_LSR_BI_BIT) {
+				port->icount.brk++;
+				if (uart_handle_break(port))
+					continue;
+			} else if (lsr & SC16IS7XX_LSR_PE_BIT)
+				port->icount.parity++;
+			else if (lsr & SC16IS7XX_LSR_FE_BIT)
+				port->icount.frame++;
+			else if (lsr & SC16IS7XX_LSR_OE_BIT)
+				port->icount.overrun++;
+
+			lsr &= port->read_status_mask;
+			if (lsr & SC16IS7XX_LSR_BI_BIT)
+				flag = TTY_BREAK;
+			else if (lsr & SC16IS7XX_LSR_PE_BIT)
+				flag = TTY_PARITY;
+			else if (lsr & SC16IS7XX_LSR_FE_BIT)
+				flag = TTY_FRAME;
+			else if (lsr & SC16IS7XX_LSR_OE_BIT)
+				flag = TTY_OVERRUN;
+		}
+
+		for (i = 0; i < bytes_read; ++i) {
+			ch = buf[i];
+			if (uart_handle_sysrq_char(port, ch))
+				continue;
+
+			if (lsr & port->ignore_status_mask)
+				continue;
+
+			uart_insert_char(port, lsr, SC16IS7XX_LSR_OE_BIT, ch,
+					 flag);
+		}
+		rxlen -= bytes_read;
+	}
+
+	tty_flip_buffer_push(&port->state->port);
+}
+
+static void sc16is7xx_handle_tx(struct uart_port *port)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned int txlen, to_send, i;
+	u8 buf[port->fifosize];
+
+	if (unlikely(port->x_char)) {
+		sc16is7xx_port_write(port, SC16IS7XX_THR_REG, port->x_char);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+		return;
+
+	/* Get length of data pending in circular buffer */
+	to_send = uart_circ_chars_pending(xmit);
+	if (likely(to_send)) {
+		/* Limit to size of TX FIFO */
+		txlen = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG);
+		to_send = (to_send > txlen) ? txlen : to_send;
+
+		/* Add data to send */
+		port->icount.tx += to_send;
+
+		/* Convert to linear buffer */
+		for (i = 0; i < to_send; ++i) {
+			buf[i] = xmit->buf[xmit->tail];
+			xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		}
+		regcache_cache_bypass(s->regmap, true);
+		regmap_raw_write(s->regmap, SC16IS7XX_THR_REG, buf, to_send);
+		regcache_cache_bypass(s->regmap, false);
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
+static void sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
+{
+	struct uart_port *port = &s->p[portno].port;
+
+	do {
+		unsigned int iir, msr, rxlen;
+
+		iir = sc16is7xx_port_read(port, SC16IS7XX_IIR_REG);
+		if (iir & SC16IS7XX_IIR_NO_INT_BIT)
+			break;
+
+		iir &= SC16IS7XX_IIR_ID_MASK;
+
+		switch (iir) {
+		case SC16IS7XX_IIR_RDI_SRC:
+		case SC16IS7XX_IIR_RLSE_SRC:
+		case SC16IS7XX_IIR_RTOI_SRC:
+		case SC16IS7XX_IIR_XOFFI_SRC:
+			rxlen = sc16is7xx_port_read(port, SC16IS7XX_RXLVL_REG);
+			if (rxlen)
+				sc16is7xx_handle_rx(port, rxlen, iir);
+			break;
+
+		case SC16IS7XX_IIR_CTSRTS_SRC:
+			msr = sc16is7xx_port_read(port, SC16IS7XX_MSR_REG);
+			uart_handle_cts_change(port,
+					       !!(msr & SC16IS7XX_MSR_CTS_BIT));
+			break;
+		case SC16IS7XX_IIR_THRI_SRC:
+			mutex_lock(&s->mutex);
+			sc16is7xx_handle_tx(port);
+			mutex_unlock(&s->mutex);
+			break;
+		default:
+			dev_err_ratelimited(port->dev,
+					    "Port %i: Unexpected interrupt: %x",
+					    port->line, iir);
+			break;
+		}
+	} while (1);
+}
+
+static irqreturn_t sc16is7xx_ist(int irq, void *dev_id)
+{
+	struct sc16is7xx_port *s = (struct sc16is7xx_port *)dev_id;
+	int i;
+
+	for (i = 0; i < s->uart.nr; ++i)
+		sc16is7xx_port_irq(s, i);
+
+	return IRQ_HANDLED;
+}
+
+static void sc16is7xx_wq_proc(struct work_struct *ws)
+{
+	struct sc16is7xx_one *one = to_sc16is7xx_one(ws, tx_work);
+	struct sc16is7xx_port *s = dev_get_drvdata(one->port.dev);
+
+	mutex_lock(&s->mutex);
+	sc16is7xx_handle_tx(&one->port);
+	mutex_unlock(&s->mutex);
+}
+
+static void sc16is7xx_stop_tx(struct uart_port* port)
+{
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+	struct circ_buf *xmit = &one->port.state->xmit;
+
+	/* handle rs485 */
+	if (one->rs485.flags & SER_RS485_ENABLED) {
+		/* do nothing if current tx not yet completed */
+		int lsr = sc16is7xx_port_read(port, SC16IS7XX_LSR_REG);
+		if (!(lsr & SC16IS7XX_LSR_TEMT_BIT))
+			return;
+
+		if (uart_circ_empty(xmit) &&
+		    (one->rs485.delay_rts_after_send > 0))
+			mdelay(one->rs485.delay_rts_after_send);
+	}
+
+	sc16is7xx_port_update(port, SC16IS7XX_IER_REG,
+			      SC16IS7XX_IER_THRI_BIT,
+			      0);
+}
+
+static void sc16is7xx_stop_rx(struct uart_port* port)
+{
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+	one->port.read_status_mask &= ~SC16IS7XX_LSR_DR_BIT;
+	sc16is7xx_port_update(port, SC16IS7XX_IER_REG,
+			      SC16IS7XX_LSR_DR_BIT,
+			      0);
+}
+
+static void sc16is7xx_start_tx(struct uart_port *port)
+{
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+	/* handle rs485 */
+	if ((one->rs485.flags & SER_RS485_ENABLED) &&
+	    (one->rs485.delay_rts_before_send > 0)) {
+		mdelay(one->rs485.delay_rts_before_send);
+	}
+
+	if (!work_pending(&one->tx_work))
+		schedule_work(&one->tx_work);
+}
+
+static unsigned int sc16is7xx_tx_empty(struct uart_port *port)
+{
+	unsigned int lvl, lsr;
+
+	lvl = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG);
+	lsr = sc16is7xx_port_read(port, SC16IS7XX_LSR_REG);
+
+	return ((lsr & SC16IS7XX_LSR_THRE_BIT) && !lvl) ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int sc16is7xx_get_mctrl(struct uart_port *port)
+{
+	/* DCD and DSR are not wired and CTS/RTS is handled automatically
+	 * so just indicate DSR and CAR asserted
+	 */
+	return TIOCM_DSR | TIOCM_CAR;
+}
+
+static void sc16is7xx_md_proc(struct work_struct *ws)
+{
+	struct sc16is7xx_one *one = to_sc16is7xx_one(ws, md_work);
+
+	sc16is7xx_port_update(&one->port, SC16IS7XX_MCR_REG,
+			      SC16IS7XX_MCR_LOOP_BIT,
+			      (one->port.mctrl & TIOCM_LOOP) ?
+				      SC16IS7XX_MCR_LOOP_BIT : 0);
+}
+
+static void sc16is7xx_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+	schedule_work(&one->md_work);
+}
+
+static void sc16is7xx_break_ctl(struct uart_port *port, int break_state)
+{
+	sc16is7xx_port_update(port, SC16IS7XX_LCR_REG,
+			      SC16IS7XX_LCR_TXBREAK_BIT,
+			      break_state ? SC16IS7XX_LCR_TXBREAK_BIT : 0);
+}
+
+static void sc16is7xx_set_termios(struct uart_port *port,
+				  struct ktermios *termios,
+				  struct ktermios *old)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	unsigned int lcr, flow = 0;
+	int baud;
+
+	/* Mask termios capabilities we don't support */
+	termios->c_cflag &= ~CMSPAR;
+
+	/* Word size */
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		lcr = SC16IS7XX_LCR_WORD_LEN_5;
+		break;
+	case CS6:
+		lcr = SC16IS7XX_LCR_WORD_LEN_6;
+		break;
+	case CS7:
+		lcr = SC16IS7XX_LCR_WORD_LEN_7;
+		break;
+	case CS8:
+		lcr = SC16IS7XX_LCR_WORD_LEN_8;
+		break;
+	default:
+		lcr = SC16IS7XX_LCR_WORD_LEN_8;
+		termios->c_cflag &= ~CSIZE;
+		termios->c_cflag |= CS8;
+		break;
+	}
+
+	/* Parity */
+	if (termios->c_cflag & PARENB) {
+		lcr |= SC16IS7XX_LCR_PARITY_BIT;
+		if (!(termios->c_cflag & PARODD))
+			lcr |= SC16IS7XX_LCR_EVENPARITY_BIT;
+	}
+
+	/* Stop bits */
+	if (termios->c_cflag & CSTOPB)
+		lcr |= SC16IS7XX_LCR_STOPLEN_BIT; /* 2 stops */
+
+	/* Set read status mask */
+	port->read_status_mask = SC16IS7XX_LSR_OE_BIT;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= SC16IS7XX_LSR_PE_BIT |
+					  SC16IS7XX_LSR_FE_BIT;
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		port->read_status_mask |= SC16IS7XX_LSR_BI_BIT;
+
+	/* Set status ignore mask */
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNBRK)
+		port->ignore_status_mask |= SC16IS7XX_LSR_BI_BIT;
+	if (!(termios->c_cflag & CREAD))
+		port->ignore_status_mask |= SC16IS7XX_LSR_BRK_ERROR_MASK;
+
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
+			     SC16IS7XX_LCR_CONF_MODE_B);
+
+	/* Configure flow control */
+	regcache_cache_bypass(s->regmap, true);
+	sc16is7xx_port_write(port, SC16IS7XX_XON1_REG, termios->c_cc[VSTART]);
+	sc16is7xx_port_write(port, SC16IS7XX_XOFF1_REG, termios->c_cc[VSTOP]);
+	if (termios->c_cflag & CRTSCTS)
+		flow |= SC16IS7XX_EFR_AUTOCTS_BIT |
+			SC16IS7XX_EFR_AUTORTS_BIT;
+	if (termios->c_iflag & IXON)
+		flow |= SC16IS7XX_EFR_SWFLOW3_BIT;
+	if (termios->c_iflag & IXOFF)
+		flow |= SC16IS7XX_EFR_SWFLOW1_BIT;
+
+	sc16is7xx_port_write(port, SC16IS7XX_EFR_REG, flow);
+	regcache_cache_bypass(s->regmap, false);
+
+	/* Update LCR register */
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr);
+
+	/* Get baud rate generator configuration */
+	baud = uart_get_baud_rate(port, termios, old,
+				  port->uartclk / 16 / 4 / 0xffff,
+				  port->uartclk / 16);
+
+	/* Setup baudrate generator */
+	baud = sc16is7xx_set_baud(port, baud);
+
+	/* Update timeout according to new baud rate */
+	uart_update_timeout(port, termios->c_cflag, baud);
+}
+
+#if defined(TIOCSRS485) && defined(TIOCGRS485)
+static void sc16is7xx_config_rs485(struct uart_port *port,
+				   struct serial_rs485 *rs485)
+{
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
+
+	one->rs485 = *rs485;
+
+	if (one->rs485.flags & SER_RS485_ENABLED) {
+		sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
+				      SC16IS7XX_EFCR_AUTO_RS485_BIT,
+				      SC16IS7XX_EFCR_AUTO_RS485_BIT);
+	} else {
+		sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
+				      SC16IS7XX_EFCR_AUTO_RS485_BIT,
+				      0);
+	}
+}
+#endif
+
+static int sc16is7xx_ioctl(struct uart_port *port, unsigned int cmd,
+			   unsigned long arg)
+{
+#if defined(TIOCSRS485) && defined(TIOCGRS485)
+	struct serial_rs485 rs485;
+
+	switch (cmd) {
+	case TIOCSRS485:
+		if (copy_from_user(&rs485, (void __user *)arg, sizeof(rs485)))
+			return -EFAULT;
+
+		sc16is7xx_config_rs485(port, &rs485);
+		return 0;
+	case TIOCGRS485:
+		if (copy_to_user((void __user *)arg,
+				 &(to_sc16is7xx_one(port, port)->rs485),
+				 sizeof(rs485)))
+			return -EFAULT;
+		return 0;
+	default:
+		break;
+	}
+#endif
+
+	return -ENOIOCTLCMD;
+}
+
+static int sc16is7xx_startup(struct uart_port *port)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	unsigned int val;
+
+	sc16is7xx_power(port, 1);
+
+	/* Reset FIFOs*/
+	val = SC16IS7XX_FCR_RXRESET_BIT | SC16IS7XX_FCR_TXRESET_BIT;
+	sc16is7xx_port_write(port, SC16IS7XX_FCR_REG, val);
+	udelay(5);
+	sc16is7xx_port_write(port, SC16IS7XX_FCR_REG,
+			     SC16IS7XX_FCR_FIFO_BIT);
+
+	/* Enable EFR */
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG,
+			     SC16IS7XX_LCR_CONF_MODE_B);
+
+	regcache_cache_bypass(s->regmap, true);
+
+	/* Enable write access to enhanced features and internal clock div */
+	sc16is7xx_port_write(port, SC16IS7XX_EFR_REG,
+			     SC16IS7XX_EFR_ENABLE_BIT);
+
+	/* Enable TCR/TLR */
+	sc16is7xx_port_update(port, SC16IS7XX_MCR_REG,
+			      SC16IS7XX_MCR_TCRTLR_BIT,
+			      SC16IS7XX_MCR_TCRTLR_BIT);
+
+	/* Configure flow control levels */
+	/* Flow control halt level 48, resume level 24 */
+	sc16is7xx_port_write(port, SC16IS7XX_TCR_REG,
+			     SC16IS7XX_TCR_RX_RESUME(24) |
+			     SC16IS7XX_TCR_RX_HALT(48));
+
+	regcache_cache_bypass(s->regmap, false);
+
+	/* Now, initialize the UART */
+	sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, SC16IS7XX_LCR_WORD_LEN_8);
+
+	/* Enable the Rx and Tx FIFO */
+	sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
+			      SC16IS7XX_EFCR_RXDISABLE_BIT |
+			      SC16IS7XX_EFCR_TXDISABLE_BIT,
+			      0);
+
+	/* Enable RX, TX, CTS change interrupts */
+	val = SC16IS7XX_IER_RDI_BIT | SC16IS7XX_IER_THRI_BIT |
+	      SC16IS7XX_IER_CTSI_BIT;
+	sc16is7xx_port_write(port, SC16IS7XX_IER_REG, val);
+
+	return 0;
+}
+
+static void sc16is7xx_shutdown(struct uart_port *port)
+{
+	/* Disable all interrupts */
+	sc16is7xx_port_write(port, SC16IS7XX_IER_REG, 0);
+	/* Disable TX/RX */
+	sc16is7xx_port_write(port, SC16IS7XX_EFCR_REG,
+			     SC16IS7XX_EFCR_RXDISABLE_BIT |
+			     SC16IS7XX_EFCR_TXDISABLE_BIT);
+
+	sc16is7xx_power(port, 0);
+}
+
+static const char *sc16is7xx_type(struct uart_port *port)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+
+	return (port->type == PORT_SC16IS7XX) ? s->devtype->name : NULL;
+}
+
+static int sc16is7xx_request_port(struct uart_port *port)
+{
+	/* Do nothing */
+	return 0;
+}
+
+static void sc16is7xx_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_SC16IS7XX;
+}
+
+static int sc16is7xx_verify_port(struct uart_port *port,
+				 struct serial_struct *s)
+{
+	if ((s->type != PORT_UNKNOWN) && (s->type != PORT_SC16IS7XX))
+		return -EINVAL;
+	if (s->irq != port->irq)
+		return -EINVAL;
+
+	return 0;
+}
+
+static void sc16is7xx_pm(struct uart_port *port, unsigned int state,
+			 unsigned int oldstate)
+{
+	sc16is7xx_power(port, (state == UART_PM_STATE_ON) ? 1 : 0);
+}
+
+static void sc16is7xx_null_void(struct uart_port *port)
+{
+	/* Do nothing */
+}
+
+static const struct uart_ops sc16is7xx_ops = {
+	.tx_empty	= sc16is7xx_tx_empty,
+	.set_mctrl	= sc16is7xx_set_mctrl,
+	.get_mctrl	= sc16is7xx_get_mctrl,
+	.stop_tx	= sc16is7xx_stop_tx,
+	.start_tx	= sc16is7xx_start_tx,
+	.stop_rx	= sc16is7xx_stop_rx,
+	.enable_ms	= sc16is7xx_null_void,
+	.break_ctl	= sc16is7xx_break_ctl,
+	.startup	= sc16is7xx_startup,
+	.shutdown	= sc16is7xx_shutdown,
+	.set_termios	= sc16is7xx_set_termios,
+	.type		= sc16is7xx_type,
+	.request_port	= sc16is7xx_request_port,
+	.release_port	= sc16is7xx_null_void,
+	.config_port	= sc16is7xx_config_port,
+	.verify_port	= sc16is7xx_verify_port,
+	.ioctl		= sc16is7xx_ioctl,
+	.pm		= sc16is7xx_pm,
+};
+
+#ifdef CONFIG_GPIOLIB
+static int sc16is7xx_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	unsigned int val;
+	struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,
+						gpio);
+	struct uart_port *port = &s->p[0].port;
+
+	val = sc16is7xx_port_read(port, SC16IS7XX_IOSTATE_REG);
+
+	return !!(val & BIT(offset));
+}
+
+static void sc16is7xx_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
+{
+	struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,
+						gpio);
+	struct uart_port *port = &s->p[0].port;
+
+	sc16is7xx_port_update(port, SC16IS7XX_IOSTATE_REG, BIT(offset),
+			      val ? BIT(offset) : 0);
+}
+
+static int sc16is7xx_gpio_direction_input(struct gpio_chip *chip,
+					  unsigned offset)
+{
+	struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,
+						gpio);
+	struct uart_port *port = &s->p[0].port;
+
+	sc16is7xx_port_update(port, SC16IS7XX_IODIR_REG, BIT(offset), 0);
+
+	return 0;
+}
+
+static int sc16is7xx_gpio_direction_output(struct gpio_chip *chip,
+					   unsigned offset, int val)
+{
+	struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,
+						gpio);
+	struct uart_port *port = &s->p[0].port;
+
+	sc16is7xx_port_update(port, SC16IS7XX_IOSTATE_REG, BIT(offset),
+			      val ? BIT(offset) : 0);
+	sc16is7xx_port_update(port, SC16IS7XX_IODIR_REG, BIT(offset),
+			      BIT(offset));
+
+	return 0;
+}
+#endif
+
+static int sc16is7xx_probe(struct device *dev,
+			   struct sc16is7xx_devtype *devtype,
+			   struct regmap *regmap, int irq, unsigned long flags)
+{
+	unsigned long freq, *pfreq = dev_get_platdata(dev);
+	struct clk *clk;
+	int i, ret;
+	struct sc16is7xx_port *s;
+
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	/* Alloc port structure */
+	s = devm_kzalloc(dev, sizeof(*s) +
+			 sizeof(struct sc16is7xx_one) * devtype->nr_uart,
+			 GFP_KERNEL);
+	if (!s) {
+		dev_err(dev, "Error allocating port structure\n");
+		return -ENOMEM;
+	}
+
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		if (pfreq)
+			freq = *pfreq;
+		else
+			return PTR_ERR(clk);
+	} else {
+		freq = clk_get_rate(clk);
+	}
+
+	s->regmap = regmap;
+	s->devtype = devtype;
+	dev_set_drvdata(dev, s);
+
+	/* Register UART driver */
+	s->uart.owner		= THIS_MODULE;
+	s->uart.dev_name	= "ttySC";
+	s->uart.nr		= devtype->nr_uart;
+	ret = uart_register_driver(&s->uart);
+	if (ret) {
+		dev_err(dev, "Registering UART driver failed\n");
+		goto out_clk;
+	}
+
+#ifdef CONFIG_GPIOLIB
+	if (devtype->nr_gpio) {
+		/* Setup GPIO cotroller */
+		s->gpio.owner		 = THIS_MODULE;
+		s->gpio.dev		 = dev;
+		s->gpio.label		 = dev_name(dev);
+		s->gpio.direction_input	 = sc16is7xx_gpio_direction_input;
+		s->gpio.get		 = sc16is7xx_gpio_get;
+		s->gpio.direction_output = sc16is7xx_gpio_direction_output;
+		s->gpio.set		 = sc16is7xx_gpio_set;
+		s->gpio.base		 = -1;
+		s->gpio.ngpio		 = devtype->nr_gpio;
+		s->gpio.can_sleep	 = 1;
+		ret = gpiochip_add(&s->gpio);
+		if (ret)
+			goto out_uart;
+	}
+#endif
+
+	mutex_init(&s->mutex);
+
+	for (i = 0; i < devtype->nr_uart; ++i) {
+		/* Initialize port data */
+		s->p[i].port.line	= i;
+		s->p[i].port.dev	= dev;
+		s->p[i].port.irq	= irq;
+		s->p[i].port.type	= PORT_SC16IS7XX;
+		s->p[i].port.fifosize	= SC16IS7XX_FIFO_SIZE;
+		s->p[i].port.flags	= UPF_FIXED_TYPE | UPF_LOW_LATENCY;
+		s->p[i].port.iotype	= UPIO_PORT;
+		s->p[i].port.uartclk	= freq;
+		s->p[i].port.ops	= &sc16is7xx_ops;
+		/* Disable all interrupts */
+		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_IER_REG, 0);
+		/* Disable TX/RX */
+		sc16is7xx_port_write(&s->p[i].port, SC16IS7XX_EFCR_REG,
+				     SC16IS7XX_EFCR_RXDISABLE_BIT |
+				     SC16IS7XX_EFCR_TXDISABLE_BIT);
+		/* Initialize queue for start TX */
+		INIT_WORK(&s->p[i].tx_work, sc16is7xx_wq_proc);
+		/* Initialize queue for changing mode */
+		INIT_WORK(&s->p[i].md_work, sc16is7xx_md_proc);
+		/* Register port */
+		uart_add_one_port(&s->uart, &s->p[i].port);
+		/* Go to suspend mode */
+		sc16is7xx_power(&s->p[i].port, 0);
+	}
+
+	/* Setup interrupt */
+	ret = devm_request_threaded_irq(dev, irq, NULL, sc16is7xx_ist,
+					IRQF_ONESHOT | flags, dev_name(dev), s);
+	if (!ret)
+		return 0;
+
+	mutex_destroy(&s->mutex);
+
+#ifdef CONFIG_GPIOLIB
+	if (devtype->nr_gpio)
+		WARN_ON(gpiochip_remove(&s->gpio));
+
+out_uart:
+#endif
+	uart_unregister_driver(&s->uart);
+
+out_clk:
+	if (!IS_ERR(s->clk))
+		clk_disable_unprepare(s->clk);
+
+	return ret;
+}
+
+static int sc16is7xx_remove(struct device *dev)
+{
+	struct sc16is7xx_port *s = dev_get_drvdata(dev);
+	int i, ret = 0;
+
+#ifdef CONFIG_GPIOLIB
+	if (s->devtype->nr_gpio) {
+		ret = gpiochip_remove(&s->gpio);
+		if (ret)
+			return ret;
+	}
+#endif
+
+	for (i = 0; i < s->uart.nr; i++) {
+		cancel_work_sync(&s->p[i].tx_work);
+		cancel_work_sync(&s->p[i].md_work);
+		uart_remove_one_port(&s->uart, &s->p[i].port);
+		sc16is7xx_power(&s->p[i].port, 0);
+	}
+
+	mutex_destroy(&s->mutex);
+	uart_unregister_driver(&s->uart);
+	if (!IS_ERR(s->clk))
+		clk_disable_unprepare(s->clk);
+
+	return ret;
+}
+
+static const struct of_device_id __maybe_unused sc16is7xx_dt_ids[] = {
+	{ .compatible = "nxp,sc16is740",	.data = &sc16is74x_devtype, },
+	{ .compatible = "nxp,sc16is741",	.data = &sc16is74x_devtype, },
+	{ .compatible = "nxp,sc16is750",	.data = &sc16is750_devtype, },
+	{ .compatible = "nxp,sc16is752",	.data = &sc16is752_devtype, },
+	{ .compatible = "nxp,sc16is760",	.data = &sc16is760_devtype, },
+	{ .compatible = "nxp,sc16is762",	.data = &sc16is762_devtype, },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sc16is7xx_dt_ids);
+
+static struct regmap_config regcfg = {
+	.reg_bits = 7,
+	.pad_bits = 1,
+	.val_bits = 8,
+	.cache_type = REGCACHE_RBTREE,
+	.volatile_reg = sc16is7xx_regmap_volatile,
+	.precious_reg = sc16is7xx_regmap_precious,
+};
+
+#ifdef CONFIG_REGMAP_I2C
+static int sc16is7xx_i2c_probe(struct i2c_client *i2c,
+			       const struct i2c_device_id *id)
+{
+	struct sc16is7xx_devtype *devtype;
+	unsigned long flags = 0;
+	struct regmap *regmap;
+
+	if (i2c->dev.of_node) {
+		const struct of_device_id *of_id =
+				of_match_device(sc16is7xx_dt_ids, &i2c->dev);
+
+		devtype = (struct sc16is7xx_devtype *)of_id->data;
+	} else {
+		devtype = (struct sc16is7xx_devtype *)id->driver_data;
+		flags = IRQF_TRIGGER_FALLING;
+	}
+
+	regcfg.max_register = (0xf << SC16IS7XX_REG_SHIFT) |
+			      (devtype->nr_uart - 1);
+	regmap = devm_regmap_init_i2c(i2c, &regcfg);
+
+	return sc16is7xx_probe(&i2c->dev, devtype, regmap, i2c->irq, flags);
+}
+
+static int sc16is7xx_i2c_remove(struct i2c_client *client)
+{
+	return sc16is7xx_remove(&client->dev);
+}
+
+static const struct i2c_device_id sc16is7xx_i2c_id_table[] = {
+	{ "sc16is74x",	(kernel_ulong_t)&sc16is74x_devtype, },
+	{ "sc16is750",	(kernel_ulong_t)&sc16is750_devtype, },
+	{ "sc16is752",	(kernel_ulong_t)&sc16is752_devtype, },
+	{ "sc16is760",	(kernel_ulong_t)&sc16is760_devtype, },
+	{ "sc16is762",	(kernel_ulong_t)&sc16is762_devtype, },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sc16is7xx_i2c_id_table);
+
+static struct i2c_driver sc16is7xx_i2c_uart_driver = {
+	.driver = {
+		.name		= SC16IS7XX_NAME,
+		.owner		= THIS_MODULE,
+		.of_match_table	= of_match_ptr(sc16is7xx_dt_ids),
+	},
+	.probe		= sc16is7xx_i2c_probe,
+	.remove		= sc16is7xx_i2c_remove,
+	.id_table	= sc16is7xx_i2c_id_table,
+};
+module_i2c_driver(sc16is7xx_i2c_uart_driver);
+MODULE_ALIAS("i2c:sc16is7xx");
+#endif
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jon Ringle <[e-mail]>");
+MODULE_DESCRIPTION("SC16IS7XX serial driver");

include/uapi/linux/serial_core.h

···
 /* MEN 16z135 UART */
 #define PORT_MEN_Z135	107
 
+/* SC16IS74xx */
+#define PORT_SC16IS7XX   108
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */