drivers/tty/serial/digicolor-usart.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  *  Driver for Conexant Digicolor serial ports (USART)
  *
  * Author: Baruch Siach <baruch@tkos.co.il>
  *
  * Copyright (C) 2014 Paradox Innovation Ltd.
  */

 #include <linux/module.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/of.h>
 #include <linux/platform_device.h>
 #include <linux/workqueue.h>

 #define UA_ENABLE			0x00
 #define UA_ENABLE_ENABLE		BIT(0)

 #define UA_CONTROL			0x01
 #define UA_CONTROL_RX_ENABLE		BIT(0)
 #define UA_CONTROL_TX_ENABLE		BIT(1)
 #define UA_CONTROL_SOFT_RESET		BIT(2)

 #define UA_STATUS			0x02
 #define UA_STATUS_PARITY_ERR		BIT(0)
 #define UA_STATUS_FRAME_ERR		BIT(1)
 #define UA_STATUS_OVERRUN_ERR		BIT(2)
 #define UA_STATUS_TX_READY		BIT(6)

 #define UA_CONFIG			0x03
 #define UA_CONFIG_CHAR_LEN		BIT(0)
 #define UA_CONFIG_STOP_BITS		BIT(1)
 #define UA_CONFIG_PARITY		BIT(2)
 #define UA_CONFIG_ODD_PARITY		BIT(4)

 #define UA_EMI_REC			0x04

 #define UA_HBAUD_LO			0x08
 #define UA_HBAUD_HI			0x09

 #define UA_STATUS_FIFO			0x0a
 #define UA_STATUS_FIFO_RX_EMPTY		BIT(2)
 #define UA_STATUS_FIFO_RX_INT_ALMOST	BIT(3)
 #define UA_STATUS_FIFO_TX_FULL		BIT(4)
 #define UA_STATUS_FIFO_TX_INT_ALMOST	BIT(7)

 #define UA_CONFIG_FIFO			0x0b
 #define UA_CONFIG_FIFO_RX_THRESH	7
 #define UA_CONFIG_FIFO_RX_FIFO_MODE	BIT(3)
 #define UA_CONFIG_FIFO_TX_FIFO_MODE	BIT(7)

 #define UA_INTFLAG_CLEAR		0x1c
 #define UA_INTFLAG_SET			0x1d
 #define UA_INT_ENABLE			0x1e
 #define UA_INT_STATUS			0x1f

 #define UA_INT_TX			BIT(0)
 #define UA_INT_RX			BIT(1)

 #define DIGICOLOR_USART_NR		3

 /*
  * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
  * only produced when the FIFO is filled more than a certain configurable
  * threshold. Unfortunately, there is no way to set this threshold below half
  * FIFO. This means that we must periodically poll the FIFO status register to
  * see whether there are waiting Rx bytes.
  */

 struct digicolor_port {
 	struct uart_port port;
 	struct delayed_work rx_poll_work;
 };

 static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];

 static bool digicolor_uart_tx_full(struct uart_port *port)
 {
 	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
 		  UA_STATUS_FIFO_TX_FULL);
 }

 static bool digicolor_uart_rx_empty(struct uart_port *port)
 {
 	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
 		  UA_STATUS_FIFO_RX_EMPTY);
 }

 static void digicolor_uart_stop_tx(struct uart_port *port)
 {
 	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

 	int_enable &= ~UA_INT_TX;
 	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 }

 static void digicolor_uart_start_tx(struct uart_port *port)
 {
 	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

 	int_enable |= UA_INT_TX;
 	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 }

 static void digicolor_uart_stop_rx(struct uart_port *port)
 {
 	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

 	int_enable &= ~UA_INT_RX;
 	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 }

 static void digicolor_rx_poll(struct work_struct *work)
 {
 	struct digicolor_port *dp =
 		container_of(to_delayed_work(work),
 			     struct digicolor_port, rx_poll_work);

 	if (!digicolor_uart_rx_empty(&dp->port))
 		/* force RX interrupt */
 		writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);

 	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
 }

 static void digicolor_uart_rx(struct uart_port *port)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&port->lock, flags);

 	while (1) {
 		u8 status, ch;
 		unsigned int ch_flag;

 		if (digicolor_uart_rx_empty(port))
 			break;

 		ch = readb_relaxed(port->membase + UA_EMI_REC);
 		status = readb_relaxed(port->membase + UA_STATUS);

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

 		if (status) {
 			if (status & UA_STATUS_PARITY_ERR)
 				port->icount.parity++;
 			else if (status & UA_STATUS_FRAME_ERR)
 				port->icount.frame++;
 			else if (status & UA_STATUS_OVERRUN_ERR)
 				port->icount.overrun++;

 			status &= port->read_status_mask;

 			if (status & UA_STATUS_PARITY_ERR)
 				ch_flag = TTY_PARITY;
 			else if (status & UA_STATUS_FRAME_ERR)
 				ch_flag = TTY_FRAME;
 			else if (status & UA_STATUS_OVERRUN_ERR)
 				ch_flag = TTY_OVERRUN;
 		}

 		if (status & port->ignore_status_mask)
 			continue;

 		uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
 				 ch_flag);
 	}

 	spin_unlock_irqrestore(&port->lock, flags);

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

 static void digicolor_uart_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
 	unsigned long flags;

 	if (digicolor_uart_tx_full(port))
 		return;

 	spin_lock_irqsave(&port->lock, flags);

 	if (port->x_char) {
 		writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
 		port->icount.tx++;
 		port->x_char = 0;
 		goto out;
 	}

 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 		digicolor_uart_stop_tx(port);
 		goto out;
 	}

 	while (!uart_circ_empty(xmit)) {
 		writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;

 		if (digicolor_uart_tx_full(port))
 			break;
 	}

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

 out:
 	spin_unlock_irqrestore(&port->lock, flags);
 }

 static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
 	u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);

 	writeb_relaxed(UA_INT_RX | UA_INT_TX,
 		       port->membase + UA_INTFLAG_CLEAR);

 	if (int_status & UA_INT_RX)
 		digicolor_uart_rx(port);
 	if (int_status & UA_INT_TX)
 		digicolor_uart_tx(port);

 	return IRQ_HANDLED;
 }

 static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
 {
 	u8 status = readb_relaxed(port->membase + UA_STATUS);

 	return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
 }

 static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
 {
 	return TIOCM_CTS;
 }

 static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 }

 static void digicolor_uart_break_ctl(struct uart_port *port, int state)
 {
 }

 static int digicolor_uart_startup(struct uart_port *port)
 {
 	struct digicolor_port *dp =
 		container_of(port, struct digicolor_port, port);

 	writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
 	writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
 	writeb_relaxed(0, port->membase + UA_CONTROL);

 	writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
 		       | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
 		       port->membase + UA_CONFIG_FIFO);
 	writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
 		       port->membase + UA_STATUS_FIFO);
 	writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
 		       port->membase + UA_CONTROL);
 	writeb_relaxed(UA_INT_TX | UA_INT_RX,
 		       port->membase + UA_INT_ENABLE);

 	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));

 	return 0;
 }

 static void digicolor_uart_shutdown(struct uart_port *port)
 {
 	struct digicolor_port *dp =
 		container_of(port, struct digicolor_port, port);

 	writeb_relaxed(0, port->membase + UA_ENABLE);
 	cancel_delayed_work_sync(&dp->rx_poll_work);
 }

 static void digicolor_uart_set_termios(struct uart_port *port,
 				       struct ktermios *termios,
 				       struct ktermios *old)
 {
 	unsigned int baud, divisor;
 	u8 config = 0;
 	unsigned long flags;

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

 	/* Limit baud rates so that we don't need the fractional divider */
 	baud = uart_get_baud_rate(port, termios, old,
 				  port->uartclk / (0x10000*16),
 				  port->uartclk / 256);
 	divisor = uart_get_divisor(port, baud) - 1;

 	switch (termios->c_cflag & CSIZE) {
 	case CS7:
 		break;
 	case CS8:
 	default:
 		config |= UA_CONFIG_CHAR_LEN;
 		break;
 	}

 	if (termios->c_cflag & CSTOPB)
 		config |= UA_CONFIG_STOP_BITS;

 	if (termios->c_cflag & PARENB) {
 		config |= UA_CONFIG_PARITY;
 		if (termios->c_cflag & PARODD)
 			config |= UA_CONFIG_ODD_PARITY;
 	}

 	/* Set read status mask */
 	port->read_status_mask = UA_STATUS_OVERRUN_ERR;
 	if (termios->c_iflag & INPCK)
 		port->read_status_mask |= UA_STATUS_PARITY_ERR
 			| UA_STATUS_FRAME_ERR;

 	/* Set status ignore mask */
 	port->ignore_status_mask = 0;
 	if (!(termios->c_cflag & CREAD))
 		port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
 			| UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;

 	spin_lock_irqsave(&port->lock, flags);

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

 	writeb_relaxed(config, port->membase + UA_CONFIG);
 	writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
 	writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);

 	spin_unlock_irqrestore(&port->lock, flags);
 }

 static const char *digicolor_uart_type(struct uart_port *port)
 {
 	return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
 }

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

 static void digicolor_uart_release_port(struct uart_port *port)
 {
 }

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

 static const struct uart_ops digicolor_uart_ops = {
 	.tx_empty	= digicolor_uart_tx_empty,
 	.set_mctrl	= digicolor_uart_set_mctrl,
 	.get_mctrl	= digicolor_uart_get_mctrl,
 	.stop_tx	= digicolor_uart_stop_tx,
 	.start_tx	= digicolor_uart_start_tx,
 	.stop_rx	= digicolor_uart_stop_rx,
 	.break_ctl	= digicolor_uart_break_ctl,
 	.startup	= digicolor_uart_startup,
 	.shutdown	= digicolor_uart_shutdown,
 	.set_termios	= digicolor_uart_set_termios,
 	.type		= digicolor_uart_type,
 	.config_port	= digicolor_uart_config_port,
 	.release_port	= digicolor_uart_release_port,
 	.request_port	= digicolor_uart_request_port,
 };

 static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
 {
 	while (digicolor_uart_tx_full(port))
 		cpu_relax();

 	writeb_relaxed(ch, port->membase + UA_EMI_REC);
 }

 static void digicolor_uart_console_write(struct console *co, const char *c,
 					 unsigned n)
 {
 	struct uart_port *port = digicolor_ports[co->index];
 	u8 status;
 	unsigned long flags;
 	int locked = 1;

 	if (oops_in_progress)
 		locked = spin_trylock_irqsave(&port->lock, flags);
 	else
 		spin_lock_irqsave(&port->lock, flags);

 	uart_console_write(port, c, n, digicolor_uart_console_putchar);

 	if (locked)
 		spin_unlock_irqrestore(&port->lock, flags);

 	/* Wait for transmitter to become empty */
 	do {
 		status = readb_relaxed(port->membase + UA_STATUS);
 	} while ((status & UA_STATUS_TX_READY) == 0);
 }

 static int digicolor_uart_console_setup(struct console *co, char *options)
 {
 	int baud = 115200, bits = 8, parity = 'n', flow = 'n';
 	struct uart_port *port;

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

 	port = digicolor_ports[co->index];
 	if (!port)
 		return -ENODEV;

 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);

 	return uart_set_options(port, co, baud, parity, bits, flow);
 }

 static struct console digicolor_console = {
 	.name	= "ttyS",
 	.device	= uart_console_device,
 	.write	= digicolor_uart_console_write,
 	.setup	= digicolor_uart_console_setup,
 	.flags	= CON_PRINTBUFFER,
 	.index	= -1,
 };

 static struct uart_driver digicolor_uart = {
 	.driver_name	= "digicolor-usart",
 	.dev_name	= "ttyS",
 	.nr		= DIGICOLOR_USART_NR,
 };

 static int digicolor_uart_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	int irq, ret, index;
 	struct digicolor_port *dp;
 	struct resource *res;
 	struct clk *uart_clk;

 	if (!np) {
 		dev_err(&pdev->dev, "Missing device tree node\n");
 		return -ENXIO;
 	}

 	index = of_alias_get_id(np, "serial");
 	if (index < 0 || index >= DIGICOLOR_USART_NR)
 		return -EINVAL;

 	dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
 	if (!dp)
 		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);
 	dp->port.mapbase = res->start;
 	dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(dp->port.membase))
 		return PTR_ERR(dp->port.membase);

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

 	dp->port.iotype = UPIO_MEM;
 	dp->port.uartclk = clk_get_rate(uart_clk);
 	dp->port.fifosize = 16;
 	dp->port.dev = &pdev->dev;
 	dp->port.ops = &digicolor_uart_ops;
 	dp->port.line = index;
 	dp->port.type = PORT_DIGICOLOR;
 	spin_lock_init(&dp->port.lock);

 	digicolor_ports[index] = &dp->port;
 	platform_set_drvdata(pdev, &dp->port);

 	INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);

 	ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
 			       dev_name(&pdev->dev), &dp->port);
 	if (ret)
 		return ret;

 	return uart_add_one_port(&digicolor_uart, &dp->port);
 }

 static int digicolor_uart_remove(struct platform_device *pdev)
 {
 	struct uart_port *port = platform_get_drvdata(pdev);

 	uart_remove_one_port(&digicolor_uart, port);

 	return 0;
 }

 static const struct of_device_id digicolor_uart_dt_ids[] = {
 	{ .compatible = "cnxt,cx92755-usart", },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);

 static struct platform_driver digicolor_uart_platform = {
 	.driver = {
 		.name		= "digicolor-usart",
 		.of_match_table	= of_match_ptr(digicolor_uart_dt_ids),
 	},
 	.probe	= digicolor_uart_probe,
 	.remove	= digicolor_uart_remove,
 };

 static int __init digicolor_uart_init(void)
 {
 	int ret;

 	if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
 		digicolor_uart.cons = &digicolor_console;
 		digicolor_console.data = &digicolor_uart;
 	}

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

 	ret = platform_driver_register(&digicolor_uart_platform);
 	if (ret)
 		uart_unregister_driver(&digicolor_uart);

 	return ret;
 }
 module_init(digicolor_uart_init);

 static void __exit digicolor_uart_exit(void)
 {
 	platform_driver_unregister(&digicolor_uart_platform);
 	uart_unregister_driver(&digicolor_uart);
 }
 module_exit(digicolor_uart_exit);

 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Driver for Conexant Digicolor serial ports (USART)
	*
	* Author: Baruch Siach <baruch@tkos.co.il>
	*
	* Copyright (C) 2014 Paradox Innovation Ltd.
	*/

	#include <linux/module.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/of.h>
	#include <linux/platform_device.h>
	#include <linux/workqueue.h>

	#define UA_ENABLE 0x00
	#define UA_ENABLE_ENABLE BIT(0)

	#define UA_CONTROL 0x01
	#define UA_CONTROL_RX_ENABLE BIT(0)
	#define UA_CONTROL_TX_ENABLE BIT(1)
	#define UA_CONTROL_SOFT_RESET BIT(2)

	#define UA_STATUS 0x02
	#define UA_STATUS_PARITY_ERR BIT(0)
	#define UA_STATUS_FRAME_ERR BIT(1)
	#define UA_STATUS_OVERRUN_ERR BIT(2)
	#define UA_STATUS_TX_READY BIT(6)

	#define UA_CONFIG 0x03
	#define UA_CONFIG_CHAR_LEN BIT(0)
	#define UA_CONFIG_STOP_BITS BIT(1)
	#define UA_CONFIG_PARITY BIT(2)
	#define UA_CONFIG_ODD_PARITY BIT(4)

	#define UA_EMI_REC 0x04

	#define UA_HBAUD_LO 0x08
	#define UA_HBAUD_HI 0x09

	#define UA_STATUS_FIFO 0x0a
	#define UA_STATUS_FIFO_RX_EMPTY BIT(2)
	#define UA_STATUS_FIFO_RX_INT_ALMOST BIT(3)
	#define UA_STATUS_FIFO_TX_FULL BIT(4)
	#define UA_STATUS_FIFO_TX_INT_ALMOST BIT(7)

	#define UA_CONFIG_FIFO 0x0b
	#define UA_CONFIG_FIFO_RX_THRESH 7
	#define UA_CONFIG_FIFO_RX_FIFO_MODE BIT(3)
	#define UA_CONFIG_FIFO_TX_FIFO_MODE BIT(7)

	#define UA_INTFLAG_CLEAR 0x1c
	#define UA_INTFLAG_SET 0x1d
	#define UA_INT_ENABLE 0x1e
	#define UA_INT_STATUS 0x1f

	#define UA_INT_TX BIT(0)
	#define UA_INT_RX BIT(1)

	#define DIGICOLOR_USART_NR 3

	/*
	* We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
	* only produced when the FIFO is filled more than a certain configurable
	* threshold. Unfortunately, there is no way to set this threshold below half
	* FIFO. This means that we must periodically poll the FIFO status register to
	* see whether there are waiting Rx bytes.
	*/

	struct digicolor_port {
	struct uart_port port;
	struct delayed_work rx_poll_work;
	};

	static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];

	static bool digicolor_uart_tx_full(struct uart_port *port)
	{
	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
	UA_STATUS_FIFO_TX_FULL);
	}

	static bool digicolor_uart_rx_empty(struct uart_port *port)
	{
	return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
	UA_STATUS_FIFO_RX_EMPTY);
	}

	static void digicolor_uart_stop_tx(struct uart_port *port)
	{
	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

	int_enable &= ~UA_INT_TX;
	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
	}

	static void digicolor_uart_start_tx(struct uart_port *port)
	{
	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

	int_enable \|= UA_INT_TX;
	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
	}

	static void digicolor_uart_stop_rx(struct uart_port *port)
	{
	u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);

	int_enable &= ~UA_INT_RX;
	writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
	}

	static void digicolor_rx_poll(struct work_struct *work)
	{
	struct digicolor_port *dp =
	container_of(to_delayed_work(work),
	struct digicolor_port, rx_poll_work);

	if (!digicolor_uart_rx_empty(&dp->port))
	/* force RX interrupt */
	writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);

	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
	}

	static void digicolor_uart_rx(struct uart_port *port)
	{
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);

	while (1) {
	u8 status, ch;
	unsigned int ch_flag;

	if (digicolor_uart_rx_empty(port))
	break;

	ch = readb_relaxed(port->membase + UA_EMI_REC);
	status = readb_relaxed(port->membase + UA_STATUS);

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

	if (status) {
	if (status & UA_STATUS_PARITY_ERR)
	port->icount.parity++;
	else if (status & UA_STATUS_FRAME_ERR)
	port->icount.frame++;
	else if (status & UA_STATUS_OVERRUN_ERR)
	port->icount.overrun++;

	status &= port->read_status_mask;

	if (status & UA_STATUS_PARITY_ERR)
	ch_flag = TTY_PARITY;
	else if (status & UA_STATUS_FRAME_ERR)
	ch_flag = TTY_FRAME;
	else if (status & UA_STATUS_OVERRUN_ERR)
	ch_flag = TTY_OVERRUN;
	}

	if (status & port->ignore_status_mask)
	continue;

	uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
	ch_flag);
	}

	spin_unlock_irqrestore(&port->lock, flags);

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

	static void digicolor_uart_tx(struct uart_port *port)
	{
	struct circ_buf *xmit = &port->state->xmit;
	unsigned long flags;

	if (digicolor_uart_tx_full(port))
	return;

	spin_lock_irqsave(&port->lock, flags);

	if (port->x_char) {
	writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
	port->icount.tx++;
	port->x_char = 0;
	goto out;
	}

	if (uart_circ_empty(xmit) \|\| uart_tx_stopped(port)) {
	digicolor_uart_stop_tx(port);
	goto out;
	}

	while (!uart_circ_empty(xmit)) {
	writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
	port->icount.tx++;

	if (digicolor_uart_tx_full(port))
	break;
	}

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

	out:
	spin_unlock_irqrestore(&port->lock, flags);
	}

	static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
	{
	struct uart_port *port = dev_id;
	u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);

	writeb_relaxed(UA_INT_RX \| UA_INT_TX,
	port->membase + UA_INTFLAG_CLEAR);

	if (int_status & UA_INT_RX)
	digicolor_uart_rx(port);
	if (int_status & UA_INT_TX)
	digicolor_uart_tx(port);

	return IRQ_HANDLED;
	}

	static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
	{
	u8 status = readb_relaxed(port->membase + UA_STATUS);

	return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
	}

	static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
	{
	return TIOCM_CTS;
	}

	static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
	{
	}

	static void digicolor_uart_break_ctl(struct uart_port *port, int state)
	{
	}

	static int digicolor_uart_startup(struct uart_port *port)
	{
	struct digicolor_port *dp =
	container_of(port, struct digicolor_port, port);

	writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
	writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
	writeb_relaxed(0, port->membase + UA_CONTROL);

	writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
	\| UA_CONFIG_FIFO_TX_FIFO_MODE \| UA_CONFIG_FIFO_RX_THRESH,
	port->membase + UA_CONFIG_FIFO);
	writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
	port->membase + UA_STATUS_FIFO);
	writeb_relaxed(UA_CONTROL_RX_ENABLE \| UA_CONTROL_TX_ENABLE,
	port->membase + UA_CONTROL);
	writeb_relaxed(UA_INT_TX \| UA_INT_RX,
	port->membase + UA_INT_ENABLE);

	schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));

	return 0;
	}

	static void digicolor_uart_shutdown(struct uart_port *port)
	{
	struct digicolor_port *dp =
	container_of(port, struct digicolor_port, port);

	writeb_relaxed(0, port->membase + UA_ENABLE);
	cancel_delayed_work_sync(&dp->rx_poll_work);
	}

	static void digicolor_uart_set_termios(struct uart_port *port,
	struct ktermios *termios,
	struct ktermios *old)
	{
	unsigned int baud, divisor;
	u8 config = 0;
	unsigned long flags;

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

	/* Limit baud rates so that we don't need the fractional divider */
	baud = uart_get_baud_rate(port, termios, old,
	port->uartclk / (0x10000*16),
	port->uartclk / 256);
	divisor = uart_get_divisor(port, baud) - 1;

	switch (termios->c_cflag & CSIZE) {
	case CS7:
	break;
	case CS8:
	default:
	config \|= UA_CONFIG_CHAR_LEN;
	break;
	}

	if (termios->c_cflag & CSTOPB)
	config \|= UA_CONFIG_STOP_BITS;

	if (termios->c_cflag & PARENB) {
	config \|= UA_CONFIG_PARITY;
	if (termios->c_cflag & PARODD)
	config \|= UA_CONFIG_ODD_PARITY;
	}

	/* Set read status mask */
	port->read_status_mask = UA_STATUS_OVERRUN_ERR;
	if (termios->c_iflag & INPCK)
	port->read_status_mask \|= UA_STATUS_PARITY_ERR
	\| UA_STATUS_FRAME_ERR;

	/* Set status ignore mask */
	port->ignore_status_mask = 0;
	if (!(termios->c_cflag & CREAD))
	port->ignore_status_mask \|= UA_STATUS_OVERRUN_ERR
	\| UA_STATUS_PARITY_ERR \| UA_STATUS_FRAME_ERR;

	spin_lock_irqsave(&port->lock, flags);

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

	writeb_relaxed(config, port->membase + UA_CONFIG);
	writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
	writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);

	spin_unlock_irqrestore(&port->lock, flags);
	}

	static const char digicolor_uart_type(struct uart_port port)
	{
	return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
	}

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

	static void digicolor_uart_release_port(struct uart_port *port)
	{
	}

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

	static const struct uart_ops digicolor_uart_ops = {
	.tx_empty = digicolor_uart_tx_empty,
	.set_mctrl = digicolor_uart_set_mctrl,
	.get_mctrl = digicolor_uart_get_mctrl,
	.stop_tx = digicolor_uart_stop_tx,
	.start_tx = digicolor_uart_start_tx,
	.stop_rx = digicolor_uart_stop_rx,
	.break_ctl = digicolor_uart_break_ctl,
	.startup = digicolor_uart_startup,
	.shutdown = digicolor_uart_shutdown,
	.set_termios = digicolor_uart_set_termios,
	.type = digicolor_uart_type,
	.config_port = digicolor_uart_config_port,
	.release_port = digicolor_uart_release_port,
	.request_port = digicolor_uart_request_port,
	};

	static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
	{
	while (digicolor_uart_tx_full(port))
	cpu_relax();

	writeb_relaxed(ch, port->membase + UA_EMI_REC);
	}

	static void digicolor_uart_console_write(struct console co, const char c,
	unsigned n)
	{
	struct uart_port *port = digicolor_ports[co->index];
	u8 status;
	unsigned long flags;
	int locked = 1;

	if (oops_in_progress)
	locked = spin_trylock_irqsave(&port->lock, flags);
	else
	spin_lock_irqsave(&port->lock, flags);

	uart_console_write(port, c, n, digicolor_uart_console_putchar);

	if (locked)
	spin_unlock_irqrestore(&port->lock, flags);

	/* Wait for transmitter to become empty */
	do {
	status = readb_relaxed(port->membase + UA_STATUS);
	} while ((status & UA_STATUS_TX_READY) == 0);
	}

	static int digicolor_uart_console_setup(struct console co, char options)
	{
	int baud = 115200, bits = 8, parity = 'n', flow = 'n';
	struct uart_port *port;

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

	port = digicolor_ports[co->index];
	if (!port)
	return -ENODEV;

	if (options)
	uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(port, co, baud, parity, bits, flow);
	}

	static struct console digicolor_console = {
	.name = "ttyS",
	.device = uart_console_device,
	.write = digicolor_uart_console_write,
	.setup = digicolor_uart_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	};

	static struct uart_driver digicolor_uart = {
	.driver_name = "digicolor-usart",
	.dev_name = "ttyS",
	.nr = DIGICOLOR_USART_NR,
	};

	static int digicolor_uart_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	int irq, ret, index;
	struct digicolor_port *dp;
	struct resource *res;
	struct clk *uart_clk;

	if (!np) {
	dev_err(&pdev->dev, "Missing device tree node\n");
	return -ENXIO;
	}

	index = of_alias_get_id(np, "serial");
	if (index < 0 \|\| index >= DIGICOLOR_USART_NR)
	return -EINVAL;

	dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
	if (!dp)
	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);
	dp->port.mapbase = res->start;
	dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(dp->port.membase))
	return PTR_ERR(dp->port.membase);

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

	dp->port.iotype = UPIO_MEM;
	dp->port.uartclk = clk_get_rate(uart_clk);
	dp->port.fifosize = 16;
	dp->port.dev = &pdev->dev;
	dp->port.ops = &digicolor_uart_ops;
	dp->port.line = index;
	dp->port.type = PORT_DIGICOLOR;
	spin_lock_init(&dp->port.lock);

	digicolor_ports[index] = &dp->port;
	platform_set_drvdata(pdev, &dp->port);

	INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);

	ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
	dev_name(&pdev->dev), &dp->port);
	if (ret)
	return ret;

	return uart_add_one_port(&digicolor_uart, &dp->port);
	}

	static int digicolor_uart_remove(struct platform_device *pdev)
	{
	struct uart_port *port = platform_get_drvdata(pdev);

	uart_remove_one_port(&digicolor_uart, port);

	return 0;
	}

	static const struct of_device_id digicolor_uart_dt_ids[] = {
	{ .compatible = "cnxt,cx92755-usart", },
	{ }
	};
	MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);

	static struct platform_driver digicolor_uart_platform = {
	.driver = {
	.name = "digicolor-usart",
	.of_match_table = of_match_ptr(digicolor_uart_dt_ids),
	},
	.probe = digicolor_uart_probe,
	.remove = digicolor_uart_remove,
	};

	static int __init digicolor_uart_init(void)
	{
	int ret;

	if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
	digicolor_uart.cons = &digicolor_console;
	digicolor_console.data = &digicolor_uart;
	}

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

	ret = platform_driver_register(&digicolor_uart_platform);
	if (ret)
	uart_unregister_driver(&digicolor_uart);

	return ret;
	}
	module_init(digicolor_uart_init);

	static void __exit digicolor_uart_exit(void)
	{
	platform_driver_unregister(&digicolor_uart_platform);
	uart_unregister_driver(&digicolor_uart);
	}
	module_exit(digicolor_uart_exit);

	MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
	MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
	MODULE_LICENSE("GPL");