drivers/tty/serial/ar933x_uart.c - kernel/msm-4.19 - Gitiles

 /*
  *  Atheros AR933X SoC built-in UART driver
  *
  *  Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
  *
  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
  *
  *  This program is free software; you can redistribute it and/or modify it
  *  under the terms of the GNU General Public License version 2 as published
  *  by the Free Software Foundation.
  */

 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/console.h>
 #include <linux/sysrq.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/clk.h>

 #include <asm/div64.h>

 #include <asm/mach-ath79/ar933x_uart.h>

 #define DRIVER_NAME "ar933x-uart"

 #define AR933X_UART_MAX_SCALE	0xff
 #define AR933X_UART_MAX_STEP	0xffff

 #define AR933X_UART_MIN_BAUD	300
 #define AR933X_UART_MAX_BAUD	3000000

 #define AR933X_DUMMY_STATUS_RD	0x01

 static struct uart_driver ar933x_uart_driver;

 struct ar933x_uart_port {
 	struct uart_port	port;
 	unsigned int		ier;	/* shadow Interrupt Enable Register */
 	unsigned int		min_baud;
 	unsigned int		max_baud;
 	struct clk		*clk;
 };

 static inline bool ar933x_uart_console_enabled(void)
 {
 	return IS_ENABLED(CONFIG_SERIAL_AR933X_CONSOLE);
 }

 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
 					    int offset)
 {
 	return readl(up->port.membase + offset);
 }

 static inline void ar933x_uart_write(struct ar933x_uart_port *up,
 				     int offset, unsigned int value)
 {
 	writel(value, up->port.membase + offset);
 }

 static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
 				  unsigned int offset,
 				  unsigned int mask,
 				  unsigned int val)
 {
 	unsigned int t;

 	t = ar933x_uart_read(up, offset);
 	t &= ~mask;
 	t |= val;
 	ar933x_uart_write(up, offset, t);
 }

 static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
 				       unsigned int offset,
 				       unsigned int val)
 {
 	ar933x_uart_rmw(up, offset, 0, val);
 }

 static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
 					 unsigned int offset,
 					 unsigned int val)
 {
 	ar933x_uart_rmw(up, offset, val, 0);
 }

 static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
 {
 	up->ier |= AR933X_UART_INT_TX_EMPTY;
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
 }

 static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
 {
 	up->ier &= ~AR933X_UART_INT_TX_EMPTY;
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
 }

 static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
 {
 	unsigned int rdata;

 	rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
 	rdata |= AR933X_UART_DATA_TX_CSR;
 	ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
 }

 static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);
 	unsigned long flags;
 	unsigned int rdata;

 	spin_lock_irqsave(&up->port.lock, flags);
 	rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
 	spin_unlock_irqrestore(&up->port.lock, flags);

 	return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
 }

 static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
 {
 	return TIOCM_CAR;
 }

 static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 }

 static void ar933x_uart_start_tx(struct uart_port *port)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);

 	ar933x_uart_start_tx_interrupt(up);
 }

 static void ar933x_uart_stop_tx(struct uart_port *port)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);

 	ar933x_uart_stop_tx_interrupt(up);
 }

 static void ar933x_uart_stop_rx(struct uart_port *port)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);

 	up->ier &= ~AR933X_UART_INT_RX_VALID;
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
 }

 static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);
 	unsigned long flags;

 	spin_lock_irqsave(&up->port.lock, flags);
 	if (break_state == -1)
 		ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
 				    AR933X_UART_CS_TX_BREAK);
 	else
 		ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
 				      AR933X_UART_CS_TX_BREAK);
 	spin_unlock_irqrestore(&up->port.lock, flags);
 }

 /*
  * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
  */
 static unsigned long ar933x_uart_get_baud(unsigned int clk,
 					  unsigned int scale,
 					  unsigned int step)
 {
 	u64 t;
 	u32 div;

 	div = (2 << 16) * (scale + 1);
 	t = clk;
 	t *= step;
 	t += (div / 2);
 	do_div(t, div);

 	return t;
 }

 static void ar933x_uart_get_scale_step(unsigned int clk,
 				       unsigned int baud,
 				       unsigned int *scale,
 				       unsigned int *step)
 {
 	unsigned int tscale;
 	long min_diff;

 	*scale = 0;
 	*step = 0;

 	min_diff = baud;
 	for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
 		u64 tstep;
 		int diff;

 		tstep = baud * (tscale + 1);
 		tstep *= (2 << 16);
 		do_div(tstep, clk);

 		if (tstep > AR933X_UART_MAX_STEP)
 			break;

 		diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
 		if (diff < min_diff) {
 			min_diff = diff;
 			*scale = tscale;
 			*step = tstep;
 		}
 	}
 }

 static void ar933x_uart_set_termios(struct uart_port *port,
 				    struct ktermios *new,
 				    struct ktermios *old)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);
 	unsigned int cs;
 	unsigned long flags;
 	unsigned int baud, scale, step;

 	/* Only CS8 is supported */
 	new->c_cflag &= ~CSIZE;
 	new->c_cflag |= CS8;

 	/* Only one stop bit is supported */
 	new->c_cflag &= ~CSTOPB;

 	cs = 0;
 	if (new->c_cflag & PARENB) {
 		if (!(new->c_cflag & PARODD))
 			cs |= AR933X_UART_CS_PARITY_EVEN;
 		else
 			cs |= AR933X_UART_CS_PARITY_ODD;
 	} else {
 		cs |= AR933X_UART_CS_PARITY_NONE;
 	}

 	/* Mark/space parity is not supported */
 	new->c_cflag &= ~CMSPAR;

 	baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
 	ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);

 	/*
 	 * Ok, we're now changing the port state. Do it with
 	 * interrupts disabled.
 	 */
 	spin_lock_irqsave(&up->port.lock, flags);

 	/* disable the UART */
 	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
 		      AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);

 	/* Update the per-port timeout. */
 	uart_update_timeout(port, new->c_cflag, baud);

 	up->port.ignore_status_mask = 0;

 	/* ignore all characters if CREAD is not set */
 	if ((new->c_cflag & CREAD) == 0)
 		up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;

 	ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
 			  scale << AR933X_UART_CLOCK_SCALE_S | step);

 	/* setup configuration register */
 	ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);

 	/* enable host interrupt */
 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
 			    AR933X_UART_CS_HOST_INT_EN);

 	/* reenable the UART */
 	ar933x_uart_rmw(up, AR933X_UART_CS_REG,
 			AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
 			AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);

 	spin_unlock_irqrestore(&up->port.lock, flags);

 	if (tty_termios_baud_rate(new))
 		tty_termios_encode_baud_rate(new, baud, baud);
 }

 static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
 {
 	struct tty_port *port = &up->port.state->port;
 	int max_count = 256;

 	do {
 		unsigned int rdata;
 		unsigned char ch;

 		rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
 		if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
 			break;

 		/* remove the character from the FIFO */
 		ar933x_uart_write(up, AR933X_UART_DATA_REG,
 				  AR933X_UART_DATA_RX_CSR);

 		up->port.icount.rx++;
 		ch = rdata & AR933X_UART_DATA_TX_RX_MASK;

 		if (uart_handle_sysrq_char(&up->port, ch))
 			continue;

 		if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
 			tty_insert_flip_char(port, ch, TTY_NORMAL);
 	} while (max_count-- > 0);

 	spin_unlock(&up->port.lock);
 	tty_flip_buffer_push(port);
 	spin_lock(&up->port.lock);
 }

 static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
 {
 	struct circ_buf *xmit = &up->port.state->xmit;
 	int count;

 	if (uart_tx_stopped(&up->port))
 		return;

 	count = up->port.fifosize;
 	do {
 		unsigned int rdata;

 		rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
 		if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
 			break;

 		if (up->port.x_char) {
 			ar933x_uart_putc(up, up->port.x_char);
 			up->port.icount.tx++;
 			up->port.x_char = 0;
 			continue;
 		}

 		if (uart_circ_empty(xmit))
 			break;

 		ar933x_uart_putc(up, xmit->buf[xmit->tail]);

 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		up->port.icount.tx++;
 	} while (--count > 0);

 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);

 	if (!uart_circ_empty(xmit))
 		ar933x_uart_start_tx_interrupt(up);
 }

 static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
 {
 	struct ar933x_uart_port *up = dev_id;
 	unsigned int status;

 	status = ar933x_uart_read(up, AR933X_UART_CS_REG);
 	if ((status & AR933X_UART_CS_HOST_INT) == 0)
 		return IRQ_NONE;

 	spin_lock(&up->port.lock);

 	status = ar933x_uart_read(up, AR933X_UART_INT_REG);
 	status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);

 	if (status & AR933X_UART_INT_RX_VALID) {
 		ar933x_uart_write(up, AR933X_UART_INT_REG,
 				  AR933X_UART_INT_RX_VALID);
 		ar933x_uart_rx_chars(up);
 	}

 	if (status & AR933X_UART_INT_TX_EMPTY) {
 		ar933x_uart_write(up, AR933X_UART_INT_REG,
 				  AR933X_UART_INT_TX_EMPTY);
 		ar933x_uart_stop_tx_interrupt(up);
 		ar933x_uart_tx_chars(up);
 	}

 	spin_unlock(&up->port.lock);

 	return IRQ_HANDLED;
 }

 static int ar933x_uart_startup(struct uart_port *port)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);
 	unsigned long flags;
 	int ret;

 	ret = request_irq(up->port.irq, ar933x_uart_interrupt,
 			  up->port.irqflags, dev_name(up->port.dev), up);
 	if (ret)
 		return ret;

 	spin_lock_irqsave(&up->port.lock, flags);

 	/* Enable HOST interrupts */
 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
 			    AR933X_UART_CS_HOST_INT_EN);

 	/* Enable RX interrupts */
 	up->ier = AR933X_UART_INT_RX_VALID;
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);

 	spin_unlock_irqrestore(&up->port.lock, flags);

 	return 0;
 }

 static void ar933x_uart_shutdown(struct uart_port *port)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);

 	/* Disable all interrupts */
 	up->ier = 0;
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);

 	/* Disable break condition */
 	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
 			      AR933X_UART_CS_TX_BREAK);

 	free_irq(up->port.irq, up);
 }

 static const char *ar933x_uart_type(struct uart_port *port)
 {
 	return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
 }

 static void ar933x_uart_release_port(struct uart_port *port)
 {
 	/* Nothing to release ... */
 }

 static int ar933x_uart_request_port(struct uart_port *port)
 {
 	/* UARTs always present */
 	return 0;
 }

 static void ar933x_uart_config_port(struct uart_port *port, int flags)
 {
 	if (flags & UART_CONFIG_TYPE)
 		port->type = PORT_AR933X;
 }

 static int ar933x_uart_verify_port(struct uart_port *port,
 				   struct serial_struct *ser)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);

 	if (ser->type != PORT_UNKNOWN &&
 	    ser->type != PORT_AR933X)
 		return -EINVAL;

 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
 		return -EINVAL;

 	if (ser->baud_base < up->min_baud ||
 	    ser->baud_base > up->max_baud)
 		return -EINVAL;

 	return 0;
 }

 static struct uart_ops ar933x_uart_ops = {
 	.tx_empty	= ar933x_uart_tx_empty,
 	.set_mctrl	= ar933x_uart_set_mctrl,
 	.get_mctrl	= ar933x_uart_get_mctrl,
 	.stop_tx	= ar933x_uart_stop_tx,
 	.start_tx	= ar933x_uart_start_tx,
 	.stop_rx	= ar933x_uart_stop_rx,
 	.break_ctl	= ar933x_uart_break_ctl,
 	.startup	= ar933x_uart_startup,
 	.shutdown	= ar933x_uart_shutdown,
 	.set_termios	= ar933x_uart_set_termios,
 	.type		= ar933x_uart_type,
 	.release_port	= ar933x_uart_release_port,
 	.request_port	= ar933x_uart_request_port,
 	.config_port	= ar933x_uart_config_port,
 	.verify_port	= ar933x_uart_verify_port,
 };

 static struct ar933x_uart_port *
 ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];

 static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
 {
 	unsigned int status;
 	unsigned int timeout = 60000;

 	/* Wait up to 60ms for the character(s) to be sent. */
 	do {
 		status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
 		if (--timeout == 0)
 			break;
 		udelay(1);
 	} while ((status & AR933X_UART_DATA_TX_CSR) == 0);
 }

 static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);

 	ar933x_uart_wait_xmitr(up);
 	ar933x_uart_putc(up, ch);
 }

 static void ar933x_uart_console_write(struct console *co, const char *s,
 				      unsigned int count)
 {
 	struct ar933x_uart_port *up = ar933x_console_ports[co->index];
 	unsigned long flags;
 	unsigned int int_en;
 	int locked = 1;

 	local_irq_save(flags);

 	if (up->port.sysrq)
 		locked = 0;
 	else if (oops_in_progress)
 		locked = spin_trylock(&up->port.lock);
 	else
 		spin_lock(&up->port.lock);

 	/*
 	 * First save the IER then disable the interrupts
 	 */
 	int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);

 	uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);

 	/*
 	 * Finally, wait for transmitter to become empty
 	 * and restore the IER
 	 */
 	ar933x_uart_wait_xmitr(up);
 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);

 	ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);

 	if (locked)
 		spin_unlock(&up->port.lock);

 	local_irq_restore(flags);
 }

 static int ar933x_uart_console_setup(struct console *co, char *options)
 {
 	struct ar933x_uart_port *up;
 	int baud = 115200;
 	int bits = 8;
 	int parity = 'n';
 	int flow = 'n';

 	if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
 		return -EINVAL;

 	up = ar933x_console_ports[co->index];
 	if (!up)
 		return -ENODEV;

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

 	return uart_set_options(&up->port, co, baud, parity, bits, flow);
 }

 static struct console ar933x_uart_console = {
 	.name		= "ttyATH",
 	.write		= ar933x_uart_console_write,
 	.device		= uart_console_device,
 	.setup		= ar933x_uart_console_setup,
 	.flags		= CON_PRINTBUFFER,
 	.index		= -1,
 	.data		= &ar933x_uart_driver,
 };

 static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
 {
 	if (!ar933x_uart_console_enabled())
 		return;

 	ar933x_console_ports[up->port.line] = up;
 }

 static struct uart_driver ar933x_uart_driver = {
 	.owner		= THIS_MODULE,
 	.driver_name	= DRIVER_NAME,
 	.dev_name	= "ttyATH",
 	.nr		= CONFIG_SERIAL_AR933X_NR_UARTS,
 	.cons		= NULL, /* filled in runtime */
 };

 static int ar933x_uart_probe(struct platform_device *pdev)
 {
 	struct ar933x_uart_port *up;
 	struct uart_port *port;
 	struct resource *mem_res;
 	struct resource *irq_res;
 	struct device_node *np;
 	unsigned int baud;
 	int id;
 	int ret;

 	np = pdev->dev.of_node;
 	if (IS_ENABLED(CONFIG_OF) && np) {
 		id = of_alias_get_id(np, "serial");
 		if (id < 0) {
 			dev_err(&pdev->dev, "unable to get alias id, err=%d\n",
 				id);
 			return id;
 		}
 	} else {
 		id = pdev->id;
 		if (id == -1)
 			id = 0;
 	}

 	if (id >= CONFIG_SERIAL_AR933X_NR_UARTS)
 		return -EINVAL;

 	irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 	if (!irq_res) {
 		dev_err(&pdev->dev, "no IRQ resource\n");
 		return -EINVAL;
 	}

 	up = devm_kzalloc(&pdev->dev, sizeof(struct ar933x_uart_port),
 			  GFP_KERNEL);
 	if (!up)
 		return -ENOMEM;

 	up->clk = devm_clk_get(&pdev->dev, "uart");
 	if (IS_ERR(up->clk)) {
 		dev_err(&pdev->dev, "unable to get UART clock\n");
 		return PTR_ERR(up->clk);
 	}

 	port = &up->port;

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

 	ret = clk_prepare_enable(up->clk);
 	if (ret)
 		return ret;

 	port->uartclk = clk_get_rate(up->clk);
 	if (!port->uartclk) {
 		ret = -EINVAL;
 		goto err_disable_clk;
 	}

 	port->mapbase = mem_res->start;
 	port->line = id;
 	port->irq = irq_res->start;
 	port->dev = &pdev->dev;
 	port->type = PORT_AR933X;
 	port->iotype = UPIO_MEM32;

 	port->regshift = 2;
 	port->fifosize = AR933X_UART_FIFO_SIZE;
 	port->ops = &ar933x_uart_ops;

 	baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
 	up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);

 	baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
 	up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);

 	ar933x_uart_add_console_port(up);

 	ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
 	if (ret)
 		goto err_disable_clk;

 	platform_set_drvdata(pdev, up);
 	return 0;

 err_disable_clk:
 	clk_disable_unprepare(up->clk);
 	return ret;
 }

 static int ar933x_uart_remove(struct platform_device *pdev)
 {
 	struct ar933x_uart_port *up;

 	up = platform_get_drvdata(pdev);

 	if (up) {
 		uart_remove_one_port(&ar933x_uart_driver, &up->port);
 		clk_disable_unprepare(up->clk);
 	}

 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id ar933x_uart_of_ids[] = {
 	{ .compatible = "qca,ar9330-uart" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids);
 #endif

 static struct platform_driver ar933x_uart_platform_driver = {
 	.probe		= ar933x_uart_probe,
 	.remove		= ar933x_uart_remove,
 	.driver		= {
 		.name		= DRIVER_NAME,
 		.of_match_table = of_match_ptr(ar933x_uart_of_ids),
 	},
 };

 static int __init ar933x_uart_init(void)
 {
 	int ret;

 	if (ar933x_uart_console_enabled())
 		ar933x_uart_driver.cons = &ar933x_uart_console;

 	ret = uart_register_driver(&ar933x_uart_driver);
 	if (ret)
 		goto err_out;

 	ret = platform_driver_register(&ar933x_uart_platform_driver);
 	if (ret)
 		goto err_unregister_uart_driver;

 	return 0;

 err_unregister_uart_driver:
 	uart_unregister_driver(&ar933x_uart_driver);
 err_out:
 	return ret;
 }

 static void __exit ar933x_uart_exit(void)
 {
 	platform_driver_unregister(&ar933x_uart_platform_driver);
 	uart_unregister_driver(&ar933x_uart_driver);
 }

 module_init(ar933x_uart_init);
 module_exit(ar933x_uart_exit);

 MODULE_DESCRIPTION("Atheros AR933X UART driver");
 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:" DRIVER_NAME);
	/*
	* Atheros AR933X SoC built-in UART driver
	*
	* Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
	*
	* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 as published
	* by the Free Software Foundation.
	*/

	#include <linux/module.h>
	#include <linux/ioport.h>
	#include <linux/init.h>
	#include <linux/console.h>
	#include <linux/sysrq.h>
	#include <linux/delay.h>
	#include <linux/platform_device.h>
	#include <linux/of.h>
	#include <linux/of_platform.h>
	#include <linux/tty.h>
	#include <linux/tty_flip.h>
	#include <linux/serial_core.h>
	#include <linux/serial.h>
	#include <linux/slab.h>
	#include <linux/io.h>
	#include <linux/irq.h>
	#include <linux/clk.h>

	#include <asm/div64.h>

	#include <asm/mach-ath79/ar933x_uart.h>

	#define DRIVER_NAME "ar933x-uart"

	#define AR933X_UART_MAX_SCALE 0xff
	#define AR933X_UART_MAX_STEP 0xffff

	#define AR933X_UART_MIN_BAUD 300
	#define AR933X_UART_MAX_BAUD 3000000

	#define AR933X_DUMMY_STATUS_RD 0x01

	static struct uart_driver ar933x_uart_driver;

	struct ar933x_uart_port {
	struct uart_port port;
	unsigned int ier; /* shadow Interrupt Enable Register */
	unsigned int min_baud;
	unsigned int max_baud;
	struct clk *clk;
	};

	static inline bool ar933x_uart_console_enabled(void)
	{
	return IS_ENABLED(CONFIG_SERIAL_AR933X_CONSOLE);
	}

	static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
	int offset)
	{
	return readl(up->port.membase + offset);
	}

	static inline void ar933x_uart_write(struct ar933x_uart_port *up,
	int offset, unsigned int value)
	{
	writel(value, up->port.membase + offset);
	}

	static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
	unsigned int offset,
	unsigned int mask,
	unsigned int val)
	{
	unsigned int t;

	t = ar933x_uart_read(up, offset);
	t &= ~mask;
	t \|= val;
	ar933x_uart_write(up, offset, t);
	}

	static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
	unsigned int offset,
	unsigned int val)
	{
	ar933x_uart_rmw(up, offset, 0, val);
	}

	static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
	unsigned int offset,
	unsigned int val)
	{
	ar933x_uart_rmw(up, offset, val, 0);
	}

	static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
	{
	up->ier \|= AR933X_UART_INT_TX_EMPTY;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
	}

	static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
	{
	up->ier &= ~AR933X_UART_INT_TX_EMPTY;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
	}

	static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
	{
	unsigned int rdata;

	rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
	rdata \|= AR933X_UART_DATA_TX_CSR;
	ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
	}

	static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);
	unsigned long flags;
	unsigned int rdata;

	spin_lock_irqsave(&up->port.lock, flags);
	rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
	spin_unlock_irqrestore(&up->port.lock, flags);

	return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
	}

	static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
	{
	return TIOCM_CAR;
	}

	static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
	{
	}

	static void ar933x_uart_start_tx(struct uart_port *port)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);

	ar933x_uart_start_tx_interrupt(up);
	}

	static void ar933x_uart_stop_tx(struct uart_port *port)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);

	ar933x_uart_stop_tx_interrupt(up);
	}

	static void ar933x_uart_stop_rx(struct uart_port *port)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);

	up->ier &= ~AR933X_UART_INT_RX_VALID;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
	}

	static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);
	unsigned long flags;

	spin_lock_irqsave(&up->port.lock, flags);
	if (break_state == -1)
	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
	AR933X_UART_CS_TX_BREAK);
	else
	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
	AR933X_UART_CS_TX_BREAK);
	spin_unlock_irqrestore(&up->port.lock, flags);
	}

	/*
	* baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
	*/
	static unsigned long ar933x_uart_get_baud(unsigned int clk,
	unsigned int scale,
	unsigned int step)
	{
	u64 t;
	u32 div;

	div = (2 << 16) * (scale + 1);
	t = clk;
	t *= step;
	t += (div / 2);
	do_div(t, div);

	return t;
	}

	static void ar933x_uart_get_scale_step(unsigned int clk,
	unsigned int baud,
	unsigned int *scale,
	unsigned int *step)
	{
	unsigned int tscale;
	long min_diff;

	*scale = 0;
	*step = 0;

	min_diff = baud;
	for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
	u64 tstep;
	int diff;

	tstep = baud * (tscale + 1);
	tstep *= (2 << 16);
	do_div(tstep, clk);

	if (tstep > AR933X_UART_MAX_STEP)
	break;

	diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
	if (diff < min_diff) {
	min_diff = diff;
	*scale = tscale;
	*step = tstep;
	}
	}
	}

	static void ar933x_uart_set_termios(struct uart_port *port,
	struct ktermios *new,
	struct ktermios *old)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);
	unsigned int cs;
	unsigned long flags;
	unsigned int baud, scale, step;

	/* Only CS8 is supported */
	new->c_cflag &= ~CSIZE;
	new->c_cflag \|= CS8;

	/* Only one stop bit is supported */
	new->c_cflag &= ~CSTOPB;

	cs = 0;
	if (new->c_cflag & PARENB) {
	if (!(new->c_cflag & PARODD))
	cs \|= AR933X_UART_CS_PARITY_EVEN;
	else
	cs \|= AR933X_UART_CS_PARITY_ODD;
	} else {
	cs \|= AR933X_UART_CS_PARITY_NONE;
	}

	/* Mark/space parity is not supported */
	new->c_cflag &= ~CMSPAR;

	baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
	ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);

	/*
	* Ok, we're now changing the port state. Do it with
	* interrupts disabled.
	*/
	spin_lock_irqsave(&up->port.lock, flags);

	/* disable the UART */
	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
	AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);

	/* Update the per-port timeout. */
	uart_update_timeout(port, new->c_cflag, baud);

	up->port.ignore_status_mask = 0;

	/* ignore all characters if CREAD is not set */
	if ((new->c_cflag & CREAD) == 0)
	up->port.ignore_status_mask \|= AR933X_DUMMY_STATUS_RD;

	ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
	scale << AR933X_UART_CLOCK_SCALE_S \| step);

	/* setup configuration register */
	ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);

	/* enable host interrupt */
	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
	AR933X_UART_CS_HOST_INT_EN);

	/* reenable the UART */
	ar933x_uart_rmw(up, AR933X_UART_CS_REG,
	AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
	AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);

	spin_unlock_irqrestore(&up->port.lock, flags);

	if (tty_termios_baud_rate(new))
	tty_termios_encode_baud_rate(new, baud, baud);
	}

	static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
	{
	struct tty_port *port = &up->port.state->port;
	int max_count = 256;

	do {
	unsigned int rdata;
	unsigned char ch;

	rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
	if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
	break;

	/* remove the character from the FIFO */
	ar933x_uart_write(up, AR933X_UART_DATA_REG,
	AR933X_UART_DATA_RX_CSR);

	up->port.icount.rx++;
	ch = rdata & AR933X_UART_DATA_TX_RX_MASK;

	if (uart_handle_sysrq_char(&up->port, ch))
	continue;

	if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
	tty_insert_flip_char(port, ch, TTY_NORMAL);
	} while (max_count-- > 0);

	spin_unlock(&up->port.lock);
	tty_flip_buffer_push(port);
	spin_lock(&up->port.lock);
	}

	static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
	{
	struct circ_buf *xmit = &up->port.state->xmit;
	int count;

	if (uart_tx_stopped(&up->port))
	return;

	count = up->port.fifosize;
	do {
	unsigned int rdata;

	rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
	if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
	break;

	if (up->port.x_char) {
	ar933x_uart_putc(up, up->port.x_char);
	up->port.icount.tx++;
	up->port.x_char = 0;
	continue;
	}

	if (uart_circ_empty(xmit))
	break;

	ar933x_uart_putc(up, xmit->buf[xmit->tail]);

	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
	up->port.icount.tx++;
	} while (--count > 0);

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
	uart_write_wakeup(&up->port);

	if (!uart_circ_empty(xmit))
	ar933x_uart_start_tx_interrupt(up);
	}

	static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
	{
	struct ar933x_uart_port *up = dev_id;
	unsigned int status;

	status = ar933x_uart_read(up, AR933X_UART_CS_REG);
	if ((status & AR933X_UART_CS_HOST_INT) == 0)
	return IRQ_NONE;

	spin_lock(&up->port.lock);

	status = ar933x_uart_read(up, AR933X_UART_INT_REG);
	status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);

	if (status & AR933X_UART_INT_RX_VALID) {
	ar933x_uart_write(up, AR933X_UART_INT_REG,
	AR933X_UART_INT_RX_VALID);
	ar933x_uart_rx_chars(up);
	}

	if (status & AR933X_UART_INT_TX_EMPTY) {
	ar933x_uart_write(up, AR933X_UART_INT_REG,
	AR933X_UART_INT_TX_EMPTY);
	ar933x_uart_stop_tx_interrupt(up);
	ar933x_uart_tx_chars(up);
	}

	spin_unlock(&up->port.lock);

	return IRQ_HANDLED;
	}

	static int ar933x_uart_startup(struct uart_port *port)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);
	unsigned long flags;
	int ret;

	ret = request_irq(up->port.irq, ar933x_uart_interrupt,
	up->port.irqflags, dev_name(up->port.dev), up);
	if (ret)
	return ret;

	spin_lock_irqsave(&up->port.lock, flags);

	/* Enable HOST interrupts */
	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
	AR933X_UART_CS_HOST_INT_EN);

	/* Enable RX interrupts */
	up->ier = AR933X_UART_INT_RX_VALID;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);

	spin_unlock_irqrestore(&up->port.lock, flags);

	return 0;
	}

	static void ar933x_uart_shutdown(struct uart_port *port)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);

	/* Disable all interrupts */
	up->ier = 0;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);

	/* Disable break condition */
	ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
	AR933X_UART_CS_TX_BREAK);

	free_irq(up->port.irq, up);
	}

	static const char ar933x_uart_type(struct uart_port port)
	{
	return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
	}

	static void ar933x_uart_release_port(struct uart_port *port)
	{
	/* Nothing to release ... */
	}

	static int ar933x_uart_request_port(struct uart_port *port)
	{
	/* UARTs always present */
	return 0;
	}

	static void ar933x_uart_config_port(struct uart_port *port, int flags)
	{
	if (flags & UART_CONFIG_TYPE)
	port->type = PORT_AR933X;
	}

	static int ar933x_uart_verify_port(struct uart_port *port,
	struct serial_struct *ser)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);

	if (ser->type != PORT_UNKNOWN &&
	ser->type != PORT_AR933X)
	return -EINVAL;

	if (ser->irq < 0 \|\| ser->irq >= NR_IRQS)
	return -EINVAL;

	if (ser->baud_base < up->min_baud \|\|
	ser->baud_base > up->max_baud)
	return -EINVAL;

	return 0;
	}

	static struct uart_ops ar933x_uart_ops = {
	.tx_empty = ar933x_uart_tx_empty,
	.set_mctrl = ar933x_uart_set_mctrl,
	.get_mctrl = ar933x_uart_get_mctrl,
	.stop_tx = ar933x_uart_stop_tx,
	.start_tx = ar933x_uart_start_tx,
	.stop_rx = ar933x_uart_stop_rx,
	.break_ctl = ar933x_uart_break_ctl,
	.startup = ar933x_uart_startup,
	.shutdown = ar933x_uart_shutdown,
	.set_termios = ar933x_uart_set_termios,
	.type = ar933x_uart_type,
	.release_port = ar933x_uart_release_port,
	.request_port = ar933x_uart_request_port,
	.config_port = ar933x_uart_config_port,
	.verify_port = ar933x_uart_verify_port,
	};

	static struct ar933x_uart_port *
	ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];

	static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
	{
	unsigned int status;
	unsigned int timeout = 60000;

	/* Wait up to 60ms for the character(s) to be sent. */
	do {
	status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
	if (--timeout == 0)
	break;
	udelay(1);
	} while ((status & AR933X_UART_DATA_TX_CSR) == 0);
	}

	static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
	{
	struct ar933x_uart_port *up =
	container_of(port, struct ar933x_uart_port, port);

	ar933x_uart_wait_xmitr(up);
	ar933x_uart_putc(up, ch);
	}

	static void ar933x_uart_console_write(struct console co, const char s,
	unsigned int count)
	{
	struct ar933x_uart_port *up = ar933x_console_ports[co->index];
	unsigned long flags;
	unsigned int int_en;
	int locked = 1;

	local_irq_save(flags);

	if (up->port.sysrq)
	locked = 0;
	else if (oops_in_progress)
	locked = spin_trylock(&up->port.lock);
	else
	spin_lock(&up->port.lock);

	/*
	* First save the IER then disable the interrupts
	*/
	int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);

	uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);

	/*
	* Finally, wait for transmitter to become empty
	* and restore the IER
	*/
	ar933x_uart_wait_xmitr(up);
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);

	ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);

	if (locked)
	spin_unlock(&up->port.lock);

	local_irq_restore(flags);
	}

	static int ar933x_uart_console_setup(struct console co, char options)
	{
	struct ar933x_uart_port *up;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if (co->index < 0 \|\| co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
	return -EINVAL;

	up = ar933x_console_ports[co->index];
	if (!up)
	return -ENODEV;

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

	return uart_set_options(&up->port, co, baud, parity, bits, flow);
	}

	static struct console ar933x_uart_console = {
	.name = "ttyATH",
	.write = ar933x_uart_console_write,
	.device = uart_console_device,
	.setup = ar933x_uart_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	.data = &ar933x_uart_driver,
	};

	static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
	{
	if (!ar933x_uart_console_enabled())
	return;

	ar933x_console_ports[up->port.line] = up;
	}

	static struct uart_driver ar933x_uart_driver = {
	.owner = THIS_MODULE,
	.driver_name = DRIVER_NAME,
	.dev_name = "ttyATH",
	.nr = CONFIG_SERIAL_AR933X_NR_UARTS,
	.cons = NULL, /* filled in runtime */
	};

	static int ar933x_uart_probe(struct platform_device *pdev)
	{
	struct ar933x_uart_port *up;
	struct uart_port *port;
	struct resource *mem_res;
	struct resource *irq_res;
	struct device_node *np;
	unsigned int baud;
	int id;
	int ret;

	np = pdev->dev.of_node;
	if (IS_ENABLED(CONFIG_OF) && np) {
	id = of_alias_get_id(np, "serial");
	if (id < 0) {
	dev_err(&pdev->dev, "unable to get alias id, err=%d\n",
	id);
	return id;
	}
	} else {
	id = pdev->id;
	if (id == -1)
	id = 0;
	}

	if (id >= CONFIG_SERIAL_AR933X_NR_UARTS)
	return -EINVAL;

	irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (!irq_res) {
	dev_err(&pdev->dev, "no IRQ resource\n");
	return -EINVAL;
	}

	up = devm_kzalloc(&pdev->dev, sizeof(struct ar933x_uart_port),
	GFP_KERNEL);
	if (!up)
	return -ENOMEM;

	up->clk = devm_clk_get(&pdev->dev, "uart");
	if (IS_ERR(up->clk)) {
	dev_err(&pdev->dev, "unable to get UART clock\n");
	return PTR_ERR(up->clk);
	}

	port = &up->port;

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

	ret = clk_prepare_enable(up->clk);
	if (ret)
	return ret;

	port->uartclk = clk_get_rate(up->clk);
	if (!port->uartclk) {
	ret = -EINVAL;
	goto err_disable_clk;
	}

	port->mapbase = mem_res->start;
	port->line = id;
	port->irq = irq_res->start;
	port->dev = &pdev->dev;
	port->type = PORT_AR933X;
	port->iotype = UPIO_MEM32;

	port->regshift = 2;
	port->fifosize = AR933X_UART_FIFO_SIZE;
	port->ops = &ar933x_uart_ops;

	baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
	up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);

	baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
	up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);

	ar933x_uart_add_console_port(up);

	ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
	if (ret)
	goto err_disable_clk;

	platform_set_drvdata(pdev, up);
	return 0;

	err_disable_clk:
	clk_disable_unprepare(up->clk);
	return ret;
	}

	static int ar933x_uart_remove(struct platform_device *pdev)
	{
	struct ar933x_uart_port *up;

	up = platform_get_drvdata(pdev);

	if (up) {
	uart_remove_one_port(&ar933x_uart_driver, &up->port);
	clk_disable_unprepare(up->clk);
	}

	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id ar933x_uart_of_ids[] = {
	{ .compatible = "qca,ar9330-uart" },
	{},
	};
	MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids);
	#endif

	static struct platform_driver ar933x_uart_platform_driver = {
	.probe = ar933x_uart_probe,
	.remove = ar933x_uart_remove,
	.driver = {
	.name = DRIVER_NAME,
	.of_match_table = of_match_ptr(ar933x_uart_of_ids),
	},
	};

	static int __init ar933x_uart_init(void)
	{
	int ret;

	if (ar933x_uart_console_enabled())
	ar933x_uart_driver.cons = &ar933x_uart_console;

	ret = uart_register_driver(&ar933x_uart_driver);
	if (ret)
	goto err_out;

	ret = platform_driver_register(&ar933x_uart_platform_driver);
	if (ret)
	goto err_unregister_uart_driver;

	return 0;

	err_unregister_uart_driver:
	uart_unregister_driver(&ar933x_uart_driver);
	err_out:
	return ret;
	}

	static void __exit ar933x_uart_exit(void)
	{
	platform_driver_unregister(&ar933x_uart_platform_driver);
	uart_unregister_driver(&ar933x_uart_driver);
	}

	module_init(ar933x_uart_init);
	module_exit(ar933x_uart_exit);

	MODULE_DESCRIPTION("Atheros AR933X UART driver");
	MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:" DRIVER_NAME);