drivers/tty/serial/clps711x.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  *  Driver for CLPS711x serial ports
  *
  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
  *
  *  Copyright 1999 ARM Limited
  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
  */

 #if defined(CONFIG_SERIAL_CLPS711X_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
 #define SUPPORT_SYSRQ
 #endif

 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/console.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/ioport.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>

 #include <linux/mfd/syscon.h>
 #include <linux/mfd/syscon/clps711x.h>

 #include "serial_mctrl_gpio.h"

 #define UART_CLPS711X_DEVNAME	"ttyCL"
 #define UART_CLPS711X_NR	2
 #define UART_CLPS711X_MAJOR	204
 #define UART_CLPS711X_MINOR	40

 #define UARTDR_OFFSET		(0x00)
 #define UBRLCR_OFFSET		(0x40)

 #define UARTDR_FRMERR		(1 << 8)
 #define UARTDR_PARERR		(1 << 9)
 #define UARTDR_OVERR		(1 << 10)

 #define UBRLCR_BAUD_MASK	((1 << 12) - 1)
 #define UBRLCR_BREAK		(1 << 12)
 #define UBRLCR_PRTEN		(1 << 13)
 #define UBRLCR_EVENPRT		(1 << 14)
 #define UBRLCR_XSTOP		(1 << 15)
 #define UBRLCR_FIFOEN		(1 << 16)
 #define UBRLCR_WRDLEN5		(0 << 17)
 #define UBRLCR_WRDLEN6		(1 << 17)
 #define UBRLCR_WRDLEN7		(2 << 17)
 #define UBRLCR_WRDLEN8		(3 << 17)
 #define UBRLCR_WRDLEN_MASK	(3 << 17)

 struct clps711x_port {
 	struct uart_port	port;
 	unsigned int		tx_enabled;
 	int			rx_irq;
 	struct regmap		*syscon;
 	struct mctrl_gpios	*gpios;
 };

 static struct uart_driver clps711x_uart = {
 	.owner		= THIS_MODULE,
 	.driver_name	= UART_CLPS711X_DEVNAME,
 	.dev_name	= UART_CLPS711X_DEVNAME,
 	.major		= UART_CLPS711X_MAJOR,
 	.minor		= UART_CLPS711X_MINOR,
 	.nr		= UART_CLPS711X_NR,
 };

 static void uart_clps711x_stop_tx(struct uart_port *port)
 {
 	struct clps711x_port *s = dev_get_drvdata(port->dev);

 	if (s->tx_enabled) {
 		disable_irq(port->irq);
 		s->tx_enabled = 0;
 	}
 }

 static void uart_clps711x_start_tx(struct uart_port *port)
 {
 	struct clps711x_port *s = dev_get_drvdata(port->dev);

 	if (!s->tx_enabled) {
 		s->tx_enabled = 1;
 		enable_irq(port->irq);
 	}
 }

 static irqreturn_t uart_clps711x_int_rx(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
 	struct clps711x_port *s = dev_get_drvdata(port->dev);
 	unsigned int status, flg;
 	u16 ch;

 	for (;;) {
 		u32 sysflg = 0;

 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 		if (sysflg & SYSFLG_URXFE)
 			break;

 		ch = readw(port->membase + UARTDR_OFFSET);
 		status = ch & (UARTDR_FRMERR | UARTDR_PARERR | UARTDR_OVERR);
 		ch &= 0xff;

 		port->icount.rx++;
 		flg = TTY_NORMAL;

 		if (unlikely(status)) {
 			if (status & UARTDR_PARERR)
 				port->icount.parity++;
 			else if (status & UARTDR_FRMERR)
 				port->icount.frame++;
 			else if (status & UARTDR_OVERR)
 				port->icount.overrun++;

 			status &= port->read_status_mask;

 			if (status & UARTDR_PARERR)
 				flg = TTY_PARITY;
 			else if (status & UARTDR_FRMERR)
 				flg = TTY_FRAME;
 			else if (status & UARTDR_OVERR)
 				flg = TTY_OVERRUN;
 		}

 		if (uart_handle_sysrq_char(port, ch))
 			continue;

 		if (status & port->ignore_status_mask)
 			continue;

 		uart_insert_char(port, status, UARTDR_OVERR, ch, flg);
 	}

 	tty_flip_buffer_push(&port->state->port);

 	return IRQ_HANDLED;
 }

 static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
 	struct clps711x_port *s = dev_get_drvdata(port->dev);
 	struct circ_buf *xmit = &port->state->xmit;

 	if (port->x_char) {
 		writew(port->x_char, port->membase + UARTDR_OFFSET);
 		port->icount.tx++;
 		port->x_char = 0;
 		return IRQ_HANDLED;
 	}

 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 		if (s->tx_enabled) {
 			disable_irq_nosync(port->irq);
 			s->tx_enabled = 0;
 		}
 		return IRQ_HANDLED;
 	}

 	while (!uart_circ_empty(xmit)) {
 		u32 sysflg = 0;

 		writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;

 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 		if (sysflg & SYSFLG_UTXFF)
 			break;
 	}

 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);

 	return IRQ_HANDLED;
 }

 static unsigned int uart_clps711x_tx_empty(struct uart_port *port)
 {
 	struct clps711x_port *s = dev_get_drvdata(port->dev);
 	u32 sysflg = 0;

 	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);

 	return (sysflg & SYSFLG_UBUSY) ? 0 : TIOCSER_TEMT;
 }

 static unsigned int uart_clps711x_get_mctrl(struct uart_port *port)
 {
 	unsigned int result = TIOCM_DSR | TIOCM_CTS | TIOCM_CAR;
 	struct clps711x_port *s = dev_get_drvdata(port->dev);

 	return mctrl_gpio_get(s->gpios, &result);
 }

 static void uart_clps711x_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	struct clps711x_port *s = dev_get_drvdata(port->dev);

 	mctrl_gpio_set(s->gpios, mctrl);
 }

 static void uart_clps711x_break_ctl(struct uart_port *port, int break_state)
 {
 	unsigned int ubrlcr;

 	ubrlcr = readl(port->membase + UBRLCR_OFFSET);
 	if (break_state)
 		ubrlcr |= UBRLCR_BREAK;
 	else
 		ubrlcr &= ~UBRLCR_BREAK;
 	writel(ubrlcr, port->membase + UBRLCR_OFFSET);
 }

 static void uart_clps711x_set_ldisc(struct uart_port *port,
 				    struct ktermios *termios)
 {
 	if (!port->line) {
 		struct clps711x_port *s = dev_get_drvdata(port->dev);

 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON1_SIREN,
 				   (termios->c_line == N_IRDA) ? SYSCON1_SIREN : 0);
 	}
 }

 static int uart_clps711x_startup(struct uart_port *port)
 {
 	struct clps711x_port *s = dev_get_drvdata(port->dev);

 	/* Disable break */
 	writel(readl(port->membase + UBRLCR_OFFSET) & ~UBRLCR_BREAK,
 	       port->membase + UBRLCR_OFFSET);

 	/* Enable the port */
 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
 				  SYSCON_UARTEN, SYSCON_UARTEN);
 }

 static void uart_clps711x_shutdown(struct uart_port *port)
 {
 	struct clps711x_port *s = dev_get_drvdata(port->dev);

 	/* Disable the port */
 	regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
 }

 static void uart_clps711x_set_termios(struct uart_port *port,
 				      struct ktermios *termios,
 				      struct ktermios *old)
 {
 	u32 ubrlcr;
 	unsigned int baud, quot;

 	/* Mask termios capabilities we don't support */
 	termios->c_cflag &= ~CMSPAR;
 	termios->c_iflag &= ~(BRKINT | IGNBRK);

 	/* Ask the core to calculate the divisor for us */
 	baud = uart_get_baud_rate(port, termios, old, port->uartclk / 4096,
 						      port->uartclk / 16);
 	quot = uart_get_divisor(port, baud);

 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
 		ubrlcr = UBRLCR_WRDLEN5;
 		break;
 	case CS6:
 		ubrlcr = UBRLCR_WRDLEN6;
 		break;
 	case CS7:
 		ubrlcr = UBRLCR_WRDLEN7;
 		break;
 	case CS8:
 	default:
 		ubrlcr = UBRLCR_WRDLEN8;
 		break;
 	}

 	if (termios->c_cflag & CSTOPB)
 		ubrlcr |= UBRLCR_XSTOP;

 	if (termios->c_cflag & PARENB) {
 		ubrlcr |= UBRLCR_PRTEN;
 		if (!(termios->c_cflag & PARODD))
 			ubrlcr |= UBRLCR_EVENPRT;
 	}

 	/* Enable FIFO */
 	ubrlcr |= UBRLCR_FIFOEN;

 	/* Set read status mask */
 	port->read_status_mask = UARTDR_OVERR;
 	if (termios->c_iflag & INPCK)
 		port->read_status_mask |= UARTDR_PARERR | UARTDR_FRMERR;

 	/* Set status ignore mask */
 	port->ignore_status_mask = 0;
 	if (!(termios->c_cflag & CREAD))
 		port->ignore_status_mask |= UARTDR_OVERR | UARTDR_PARERR |
 					    UARTDR_FRMERR;

 	uart_update_timeout(port, termios->c_cflag, baud);

 	writel(ubrlcr | (quot - 1), port->membase + UBRLCR_OFFSET);
 }

 static const char *uart_clps711x_type(struct uart_port *port)
 {
 	return (port->type == PORT_CLPS711X) ? "CLPS711X" : NULL;
 }

 static void uart_clps711x_config_port(struct uart_port *port, int flags)
 {
 	if (flags & UART_CONFIG_TYPE)
 		port->type = PORT_CLPS711X;
 }

 static void uart_clps711x_nop_void(struct uart_port *port)
 {
 }

 static int uart_clps711x_nop_int(struct uart_port *port)
 {
 	return 0;
 }

 static const struct uart_ops uart_clps711x_ops = {
 	.tx_empty	= uart_clps711x_tx_empty,
 	.set_mctrl	= uart_clps711x_set_mctrl,
 	.get_mctrl	= uart_clps711x_get_mctrl,
 	.stop_tx	= uart_clps711x_stop_tx,
 	.start_tx	= uart_clps711x_start_tx,
 	.stop_rx	= uart_clps711x_nop_void,
 	.break_ctl	= uart_clps711x_break_ctl,
 	.set_ldisc	= uart_clps711x_set_ldisc,
 	.startup	= uart_clps711x_startup,
 	.shutdown	= uart_clps711x_shutdown,
 	.set_termios	= uart_clps711x_set_termios,
 	.type		= uart_clps711x_type,
 	.config_port	= uart_clps711x_config_port,
 	.release_port	= uart_clps711x_nop_void,
 	.request_port	= uart_clps711x_nop_int,
 };

 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
 static void uart_clps711x_console_putchar(struct uart_port *port, int ch)
 {
 	struct clps711x_port *s = dev_get_drvdata(port->dev);
 	u32 sysflg = 0;

 	/* Wait for FIFO is not full */
 	do {
 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 	} while (sysflg & SYSFLG_UTXFF);

 	writew(ch, port->membase + UARTDR_OFFSET);
 }

 static void uart_clps711x_console_write(struct console *co, const char *c,
 					unsigned n)
 {
 	struct uart_port *port = clps711x_uart.state[co->index].uart_port;
 	struct clps711x_port *s = dev_get_drvdata(port->dev);
 	u32 sysflg = 0;

 	uart_console_write(port, c, n, uart_clps711x_console_putchar);

 	/* Wait for transmitter to become empty */
 	do {
 		regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
 	} while (sysflg & SYSFLG_UBUSY);
 }

 static int uart_clps711x_console_setup(struct console *co, char *options)
 {
 	int baud = 38400, bits = 8, parity = 'n', flow = 'n';
 	int ret, index = co->index;
 	struct clps711x_port *s;
 	struct uart_port *port;
 	unsigned int quot;
 	u32 ubrlcr;

 	if (index < 0 || index >= UART_CLPS711X_NR)
 		return -EINVAL;

 	port = clps711x_uart.state[index].uart_port;
 	if (!port)
 		return -ENODEV;

 	s = dev_get_drvdata(port->dev);

 	if (!options) {
 		u32 syscon = 0;

 		regmap_read(s->syscon, SYSCON_OFFSET, &syscon);
 		if (syscon & SYSCON_UARTEN) {
 			ubrlcr = readl(port->membase + UBRLCR_OFFSET);

 			if (ubrlcr & UBRLCR_PRTEN) {
 				if (ubrlcr & UBRLCR_EVENPRT)
 					parity = 'e';
 				else
 					parity = 'o';
 			}

 			if ((ubrlcr & UBRLCR_WRDLEN_MASK) == UBRLCR_WRDLEN7)
 				bits = 7;

 			quot = ubrlcr & UBRLCR_BAUD_MASK;
 			baud = port->uartclk / (16 * (quot + 1));
 		}
 	} else
 		uart_parse_options(options, &baud, &parity, &bits, &flow);

 	ret = uart_set_options(port, co, baud, parity, bits, flow);
 	if (ret)
 		return ret;

 	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
 				  SYSCON_UARTEN, SYSCON_UARTEN);
 }

 static struct console clps711x_console = {
 	.name	= UART_CLPS711X_DEVNAME,
 	.device	= uart_console_device,
 	.write	= uart_clps711x_console_write,
 	.setup	= uart_clps711x_console_setup,
 	.flags	= CON_PRINTBUFFER,
 	.index	= -1,
 };
 #endif

 static int uart_clps711x_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct clps711x_port *s;
 	struct resource *res;
 	struct clk *uart_clk;
 	int irq, ret;

 	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
 	if (!s)
 		return -ENOMEM;

 	uart_clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(uart_clk))
 		return PTR_ERR(uart_clk);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	s->port.membase = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(s->port.membase))
 		return PTR_ERR(s->port.membase);

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
 		return irq;
 	s->port.irq = irq;

 	s->rx_irq = platform_get_irq(pdev, 1);
 	if (s->rx_irq < 0)
 		return s->rx_irq;

 	s->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
 	if (IS_ERR(s->syscon))
 		return PTR_ERR(s->syscon);

 	s->port.line		= of_alias_get_id(np, "serial");
 	s->port.dev		= &pdev->dev;
 	s->port.iotype		= UPIO_MEM32;
 	s->port.mapbase		= res->start;
 	s->port.type		= PORT_CLPS711X;
 	s->port.fifosize	= 16;
 	s->port.flags		= UPF_SKIP_TEST | UPF_FIXED_TYPE;
 	s->port.uartclk		= clk_get_rate(uart_clk);
 	s->port.ops		= &uart_clps711x_ops;

 	platform_set_drvdata(pdev, s);

 	s->gpios = mctrl_gpio_init_noauto(&pdev->dev, 0);
 	if (IS_ERR(s->gpios))
 	    return PTR_ERR(s->gpios);

 	ret = uart_add_one_port(&clps711x_uart, &s->port);
 	if (ret)
 		return ret;

 	/* Disable port */
 	if (!uart_console(&s->port))
 		regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);

 	s->tx_enabled = 1;

 	ret = devm_request_irq(&pdev->dev, s->port.irq, uart_clps711x_int_tx, 0,
 			       dev_name(&pdev->dev), &s->port);
 	if (ret) {
 		uart_remove_one_port(&clps711x_uart, &s->port);
 		return ret;
 	}

 	ret = devm_request_irq(&pdev->dev, s->rx_irq, uart_clps711x_int_rx, 0,
 			       dev_name(&pdev->dev), &s->port);
 	if (ret)
 		uart_remove_one_port(&clps711x_uart, &s->port);

 	return ret;
 }

 static int uart_clps711x_remove(struct platform_device *pdev)
 {
 	struct clps711x_port *s = platform_get_drvdata(pdev);

 	return uart_remove_one_port(&clps711x_uart, &s->port);
 }

 static const struct of_device_id __maybe_unused clps711x_uart_dt_ids[] = {
 	{ .compatible = "cirrus,ep7209-uart", },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, clps711x_uart_dt_ids);

 static struct platform_driver clps711x_uart_platform = {
 	.driver = {
 		.name		= "clps711x-uart",
 		.of_match_table	= of_match_ptr(clps711x_uart_dt_ids),
 	},
 	.probe	= uart_clps711x_probe,
 	.remove	= uart_clps711x_remove,
 };

 static int __init uart_clps711x_init(void)
 {
 	int ret;

 #ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
 	clps711x_uart.cons = &clps711x_console;
 	clps711x_console.data = &clps711x_uart;
 #endif

 	ret = uart_register_driver(&clps711x_uart);
 	if (ret)
 		return ret;

 	return platform_driver_register(&clps711x_uart_platform);
 }
 module_init(uart_clps711x_init);

 static void __exit uart_clps711x_exit(void)
 {
 	platform_driver_unregister(&clps711x_uart_platform);
 	uart_unregister_driver(&clps711x_uart);
 }
 module_exit(uart_clps711x_exit);

 MODULE_AUTHOR("Deep Blue Solutions Ltd");
 MODULE_DESCRIPTION("CLPS711X serial driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Driver for CLPS711x serial ports
	*
	* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
	*
	* Copyright 1999 ARM Limited
	* Copyright (C) 2000 Deep Blue Solutions Ltd.
	*/

	#if defined(CONFIG_SERIAL_CLPS711X_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
	#define SUPPORT_SYSRQ
	#endif

	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/console.h>
	#include <linux/serial_core.h>
	#include <linux/serial.h>
	#include <linux/clk.h>
	#include <linux/io.h>
	#include <linux/tty.h>
	#include <linux/tty_flip.h>
	#include <linux/ioport.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>

	#include <linux/mfd/syscon.h>
	#include <linux/mfd/syscon/clps711x.h>

	#include "serial_mctrl_gpio.h"

	#define UART_CLPS711X_DEVNAME "ttyCL"
	#define UART_CLPS711X_NR 2
	#define UART_CLPS711X_MAJOR 204
	#define UART_CLPS711X_MINOR 40

	#define UARTDR_OFFSET (0x00)
	#define UBRLCR_OFFSET (0x40)

	#define UARTDR_FRMERR (1 << 8)
	#define UARTDR_PARERR (1 << 9)
	#define UARTDR_OVERR (1 << 10)

	#define UBRLCR_BAUD_MASK ((1 << 12) - 1)
	#define UBRLCR_BREAK (1 << 12)
	#define UBRLCR_PRTEN (1 << 13)
	#define UBRLCR_EVENPRT (1 << 14)
	#define UBRLCR_XSTOP (1 << 15)
	#define UBRLCR_FIFOEN (1 << 16)
	#define UBRLCR_WRDLEN5 (0 << 17)
	#define UBRLCR_WRDLEN6 (1 << 17)
	#define UBRLCR_WRDLEN7 (2 << 17)
	#define UBRLCR_WRDLEN8 (3 << 17)
	#define UBRLCR_WRDLEN_MASK (3 << 17)

	struct clps711x_port {
	struct uart_port port;
	unsigned int tx_enabled;
	int rx_irq;
	struct regmap *syscon;
	struct mctrl_gpios *gpios;
	};

	static struct uart_driver clps711x_uart = {
	.owner = THIS_MODULE,
	.driver_name = UART_CLPS711X_DEVNAME,
	.dev_name = UART_CLPS711X_DEVNAME,
	.major = UART_CLPS711X_MAJOR,
	.minor = UART_CLPS711X_MINOR,
	.nr = UART_CLPS711X_NR,
	};

	static void uart_clps711x_stop_tx(struct uart_port *port)
	{
	struct clps711x_port *s = dev_get_drvdata(port->dev);

	if (s->tx_enabled) {
	disable_irq(port->irq);
	s->tx_enabled = 0;
	}
	}

	static void uart_clps711x_start_tx(struct uart_port *port)
	{
	struct clps711x_port *s = dev_get_drvdata(port->dev);

	if (!s->tx_enabled) {
	s->tx_enabled = 1;
	enable_irq(port->irq);
	}
	}

	static irqreturn_t uart_clps711x_int_rx(int irq, void *dev_id)
	{
	struct uart_port *port = dev_id;
	struct clps711x_port *s = dev_get_drvdata(port->dev);
	unsigned int status, flg;
	u16 ch;

	for (;;) {
	u32 sysflg = 0;

	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
	if (sysflg & SYSFLG_URXFE)
	break;

	ch = readw(port->membase + UARTDR_OFFSET);
	status = ch & (UARTDR_FRMERR \| UARTDR_PARERR \| UARTDR_OVERR);
	ch &= 0xff;

	port->icount.rx++;
	flg = TTY_NORMAL;

	if (unlikely(status)) {
	if (status & UARTDR_PARERR)
	port->icount.parity++;
	else if (status & UARTDR_FRMERR)
	port->icount.frame++;
	else if (status & UARTDR_OVERR)
	port->icount.overrun++;

	status &= port->read_status_mask;

	if (status & UARTDR_PARERR)
	flg = TTY_PARITY;
	else if (status & UARTDR_FRMERR)
	flg = TTY_FRAME;
	else if (status & UARTDR_OVERR)
	flg = TTY_OVERRUN;
	}

	if (uart_handle_sysrq_char(port, ch))
	continue;

	if (status & port->ignore_status_mask)
	continue;

	uart_insert_char(port, status, UARTDR_OVERR, ch, flg);
	}

	tty_flip_buffer_push(&port->state->port);

	return IRQ_HANDLED;
	}

	static irqreturn_t uart_clps711x_int_tx(int irq, void *dev_id)
	{
	struct uart_port *port = dev_id;
	struct clps711x_port *s = dev_get_drvdata(port->dev);
	struct circ_buf *xmit = &port->state->xmit;

	if (port->x_char) {
	writew(port->x_char, port->membase + UARTDR_OFFSET);
	port->icount.tx++;
	port->x_char = 0;
	return IRQ_HANDLED;
	}

	if (uart_circ_empty(xmit) \|\| uart_tx_stopped(port)) {
	if (s->tx_enabled) {
	disable_irq_nosync(port->irq);
	s->tx_enabled = 0;
	}
	return IRQ_HANDLED;
	}

	while (!uart_circ_empty(xmit)) {
	u32 sysflg = 0;

	writew(xmit->buf[xmit->tail], port->membase + UARTDR_OFFSET);
	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
	port->icount.tx++;

	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
	if (sysflg & SYSFLG_UTXFF)
	break;
	}

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
	uart_write_wakeup(port);

	return IRQ_HANDLED;
	}

	static unsigned int uart_clps711x_tx_empty(struct uart_port *port)
	{
	struct clps711x_port *s = dev_get_drvdata(port->dev);
	u32 sysflg = 0;

	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);

	return (sysflg & SYSFLG_UBUSY) ? 0 : TIOCSER_TEMT;
	}

	static unsigned int uart_clps711x_get_mctrl(struct uart_port *port)
	{
	unsigned int result = TIOCM_DSR \| TIOCM_CTS \| TIOCM_CAR;
	struct clps711x_port *s = dev_get_drvdata(port->dev);

	return mctrl_gpio_get(s->gpios, &result);
	}

	static void uart_clps711x_set_mctrl(struct uart_port *port, unsigned int mctrl)
	{
	struct clps711x_port *s = dev_get_drvdata(port->dev);

	mctrl_gpio_set(s->gpios, mctrl);
	}

	static void uart_clps711x_break_ctl(struct uart_port *port, int break_state)
	{
	unsigned int ubrlcr;

	ubrlcr = readl(port->membase + UBRLCR_OFFSET);
	if (break_state)
	ubrlcr \|= UBRLCR_BREAK;
	else
	ubrlcr &= ~UBRLCR_BREAK;
	writel(ubrlcr, port->membase + UBRLCR_OFFSET);
	}

	static void uart_clps711x_set_ldisc(struct uart_port *port,
	struct ktermios *termios)
	{
	if (!port->line) {
	struct clps711x_port *s = dev_get_drvdata(port->dev);

	regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON1_SIREN,
	(termios->c_line == N_IRDA) ? SYSCON1_SIREN : 0);
	}
	}

	static int uart_clps711x_startup(struct uart_port *port)
	{
	struct clps711x_port *s = dev_get_drvdata(port->dev);

	/* Disable break */
	writel(readl(port->membase + UBRLCR_OFFSET) & ~UBRLCR_BREAK,
	port->membase + UBRLCR_OFFSET);

	/* Enable the port */
	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
	SYSCON_UARTEN, SYSCON_UARTEN);
	}

	static void uart_clps711x_shutdown(struct uart_port *port)
	{
	struct clps711x_port *s = dev_get_drvdata(port->dev);

	/* Disable the port */
	regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);
	}

	static void uart_clps711x_set_termios(struct uart_port *port,
	struct ktermios *termios,
	struct ktermios *old)
	{
	u32 ubrlcr;
	unsigned int baud, quot;

	/* Mask termios capabilities we don't support */
	termios->c_cflag &= ~CMSPAR;
	termios->c_iflag &= ~(BRKINT \| IGNBRK);

	/* Ask the core to calculate the divisor for us */
	baud = uart_get_baud_rate(port, termios, old, port->uartclk / 4096,
	port->uartclk / 16);
	quot = uart_get_divisor(port, baud);

	switch (termios->c_cflag & CSIZE) {
	case CS5:
	ubrlcr = UBRLCR_WRDLEN5;
	break;
	case CS6:
	ubrlcr = UBRLCR_WRDLEN6;
	break;
	case CS7:
	ubrlcr = UBRLCR_WRDLEN7;
	break;
	case CS8:
	default:
	ubrlcr = UBRLCR_WRDLEN8;
	break;
	}

	if (termios->c_cflag & CSTOPB)
	ubrlcr \|= UBRLCR_XSTOP;

	if (termios->c_cflag & PARENB) {
	ubrlcr \|= UBRLCR_PRTEN;
	if (!(termios->c_cflag & PARODD))
	ubrlcr \|= UBRLCR_EVENPRT;
	}

	/* Enable FIFO */
	ubrlcr \|= UBRLCR_FIFOEN;

	/* Set read status mask */
	port->read_status_mask = UARTDR_OVERR;
	if (termios->c_iflag & INPCK)
	port->read_status_mask \|= UARTDR_PARERR \| UARTDR_FRMERR;

	/* Set status ignore mask */
	port->ignore_status_mask = 0;
	if (!(termios->c_cflag & CREAD))
	port->ignore_status_mask \|= UARTDR_OVERR \| UARTDR_PARERR \|
	UARTDR_FRMERR;

	uart_update_timeout(port, termios->c_cflag, baud);

	writel(ubrlcr \| (quot - 1), port->membase + UBRLCR_OFFSET);
	}

	static const char uart_clps711x_type(struct uart_port port)
	{
	return (port->type == PORT_CLPS711X) ? "CLPS711X" : NULL;
	}

	static void uart_clps711x_config_port(struct uart_port *port, int flags)
	{
	if (flags & UART_CONFIG_TYPE)
	port->type = PORT_CLPS711X;
	}

	static void uart_clps711x_nop_void(struct uart_port *port)
	{
	}

	static int uart_clps711x_nop_int(struct uart_port *port)
	{
	return 0;
	}

	static const struct uart_ops uart_clps711x_ops = {
	.tx_empty = uart_clps711x_tx_empty,
	.set_mctrl = uart_clps711x_set_mctrl,
	.get_mctrl = uart_clps711x_get_mctrl,
	.stop_tx = uart_clps711x_stop_tx,
	.start_tx = uart_clps711x_start_tx,
	.stop_rx = uart_clps711x_nop_void,
	.break_ctl = uart_clps711x_break_ctl,
	.set_ldisc = uart_clps711x_set_ldisc,
	.startup = uart_clps711x_startup,
	.shutdown = uart_clps711x_shutdown,
	.set_termios = uart_clps711x_set_termios,
	.type = uart_clps711x_type,
	.config_port = uart_clps711x_config_port,
	.release_port = uart_clps711x_nop_void,
	.request_port = uart_clps711x_nop_int,
	};

	#ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
	static void uart_clps711x_console_putchar(struct uart_port *port, int ch)
	{
	struct clps711x_port *s = dev_get_drvdata(port->dev);
	u32 sysflg = 0;

	/* Wait for FIFO is not full */
	do {
	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
	} while (sysflg & SYSFLG_UTXFF);

	writew(ch, port->membase + UARTDR_OFFSET);
	}

	static void uart_clps711x_console_write(struct console co, const char c,
	unsigned n)
	{
	struct uart_port *port = clps711x_uart.state[co->index].uart_port;
	struct clps711x_port *s = dev_get_drvdata(port->dev);
	u32 sysflg = 0;

	uart_console_write(port, c, n, uart_clps711x_console_putchar);

	/* Wait for transmitter to become empty */
	do {
	regmap_read(s->syscon, SYSFLG_OFFSET, &sysflg);
	} while (sysflg & SYSFLG_UBUSY);
	}

	static int uart_clps711x_console_setup(struct console co, char options)
	{
	int baud = 38400, bits = 8, parity = 'n', flow = 'n';
	int ret, index = co->index;
	struct clps711x_port *s;
	struct uart_port *port;
	unsigned int quot;
	u32 ubrlcr;

	if (index < 0 \|\| index >= UART_CLPS711X_NR)
	return -EINVAL;

	port = clps711x_uart.state[index].uart_port;
	if (!port)
	return -ENODEV;

	s = dev_get_drvdata(port->dev);

	if (!options) {
	u32 syscon = 0;

	regmap_read(s->syscon, SYSCON_OFFSET, &syscon);
	if (syscon & SYSCON_UARTEN) {
	ubrlcr = readl(port->membase + UBRLCR_OFFSET);

	if (ubrlcr & UBRLCR_PRTEN) {
	if (ubrlcr & UBRLCR_EVENPRT)
	parity = 'e';
	else
	parity = 'o';
	}

	if ((ubrlcr & UBRLCR_WRDLEN_MASK) == UBRLCR_WRDLEN7)
	bits = 7;

	quot = ubrlcr & UBRLCR_BAUD_MASK;
	baud = port->uartclk / (16 * (quot + 1));
	}
	} else
	uart_parse_options(options, &baud, &parity, &bits, &flow);

	ret = uart_set_options(port, co, baud, parity, bits, flow);
	if (ret)
	return ret;

	return regmap_update_bits(s->syscon, SYSCON_OFFSET,
	SYSCON_UARTEN, SYSCON_UARTEN);
	}

	static struct console clps711x_console = {
	.name = UART_CLPS711X_DEVNAME,
	.device = uart_console_device,
	.write = uart_clps711x_console_write,
	.setup = uart_clps711x_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	};
	#endif

	static int uart_clps711x_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	struct clps711x_port *s;
	struct resource *res;
	struct clk *uart_clk;
	int irq, ret;

	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
	if (!s)
	return -ENOMEM;

	uart_clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(uart_clk))
	return PTR_ERR(uart_clk);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	s->port.membase = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(s->port.membase))
	return PTR_ERR(s->port.membase);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
	return irq;
	s->port.irq = irq;

	s->rx_irq = platform_get_irq(pdev, 1);
	if (s->rx_irq < 0)
	return s->rx_irq;

	s->syscon = syscon_regmap_lookup_by_phandle(np, "syscon");
	if (IS_ERR(s->syscon))
	return PTR_ERR(s->syscon);

	s->port.line = of_alias_get_id(np, "serial");
	s->port.dev = &pdev->dev;
	s->port.iotype = UPIO_MEM32;
	s->port.mapbase = res->start;
	s->port.type = PORT_CLPS711X;
	s->port.fifosize = 16;
	s->port.flags = UPF_SKIP_TEST \| UPF_FIXED_TYPE;
	s->port.uartclk = clk_get_rate(uart_clk);
	s->port.ops = &uart_clps711x_ops;

	platform_set_drvdata(pdev, s);

	s->gpios = mctrl_gpio_init_noauto(&pdev->dev, 0);
	if (IS_ERR(s->gpios))
	return PTR_ERR(s->gpios);

	ret = uart_add_one_port(&clps711x_uart, &s->port);
	if (ret)
	return ret;

	/* Disable port */
	if (!uart_console(&s->port))
	regmap_update_bits(s->syscon, SYSCON_OFFSET, SYSCON_UARTEN, 0);

	s->tx_enabled = 1;

	ret = devm_request_irq(&pdev->dev, s->port.irq, uart_clps711x_int_tx, 0,
	dev_name(&pdev->dev), &s->port);
	if (ret) {
	uart_remove_one_port(&clps711x_uart, &s->port);
	return ret;
	}

	ret = devm_request_irq(&pdev->dev, s->rx_irq, uart_clps711x_int_rx, 0,
	dev_name(&pdev->dev), &s->port);
	if (ret)
	uart_remove_one_port(&clps711x_uart, &s->port);

	return ret;
	}

	static int uart_clps711x_remove(struct platform_device *pdev)
	{
	struct clps711x_port *s = platform_get_drvdata(pdev);

	return uart_remove_one_port(&clps711x_uart, &s->port);
	}

	static const struct of_device_id __maybe_unused clps711x_uart_dt_ids[] = {
	{ .compatible = "cirrus,ep7209-uart", },
	{ }
	};
	MODULE_DEVICE_TABLE(of, clps711x_uart_dt_ids);

	static struct platform_driver clps711x_uart_platform = {
	.driver = {
	.name = "clps711x-uart",
	.of_match_table = of_match_ptr(clps711x_uart_dt_ids),
	},
	.probe = uart_clps711x_probe,
	.remove = uart_clps711x_remove,
	};

	static int __init uart_clps711x_init(void)
	{
	int ret;

	#ifdef CONFIG_SERIAL_CLPS711X_CONSOLE
	clps711x_uart.cons = &clps711x_console;
	clps711x_console.data = &clps711x_uart;
	#endif

	ret = uart_register_driver(&clps711x_uart);
	if (ret)
	return ret;

	return platform_driver_register(&clps711x_uart_platform);
	}
	module_init(uart_clps711x_init);

	static void __exit uart_clps711x_exit(void)
	{
	platform_driver_unregister(&clps711x_uart_platform);
	uart_unregister_driver(&clps711x_uart);
	}
	module_exit(uart_clps711x_exit);

	MODULE_AUTHOR("Deep Blue Solutions Ltd");
	MODULE_DESCRIPTION("CLPS711X serial driver");
	MODULE_LICENSE("GPL");