Subject: [PATCH v4 04/10] serial: mps2-uart: add MPS2 UART driver

From: [email-masked] (Peter Hurley)
Date: Tue, 23 Feb 2016 07:28:23 -0800

Hi Vladimir,

On 02/23/2016 06:34 AM, Vladimir Murzin wrote:
> This driver adds support to the UART controller found on ARM MPS2
> platform.

Comments below.

> Signed-off-by: Vladimir Murzin <[email-masked]>
> ---
>  drivers/tty/serial/Kconfig       |   12 +
>  drivers/tty/serial/Makefile      |    1 +
>  drivers/tty/serial/mps2-uart.c   |  586 ++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/serial_core.h |    3 +
>  4 files changed, 602 insertions(+)
>  create mode 100644 drivers/tty/serial/mps2-uart.c
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 39721ec..3a248be 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -1450,6 +1450,18 @@ config SERIAL_EFM32_UART
>  	  This driver support the USART and UART ports on
>  	  Energy Micro's efm32 SoCs.
>  
> +config SERIAL_MPS2_UART_CONSOLE
> +	bool "MPS2 UART console support"
> +	depends on SERIAL_MPS2_UART
> +	select SERIAL_CORE_CONSOLE
> +
> +config SERIAL_MPS2_UART
> +	bool "MPS2 UART port"
> +	depends on ARM || COMPILE_TEST
> +	select SERIAL_CORE
> +	help
> +	  This driver support the UART ports on ARM MPS2.
> +
>  config SERIAL_EFM32_UART_CONSOLE
>  	bool "EFM32 UART/USART console support"
>  	depends on SERIAL_EFM32_UART=y
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index b391c9b..1062503 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -91,6 +91,7 @@ obj-$(CONFIG_SERIAL_CONEXANT_DIGICOLOR)	+= digicolor-usart.o
>  obj-$(CONFIG_SERIAL_MEN_Z135)	+= men_z135_uart.o
>  obj-$(CONFIG_SERIAL_SPRD) += sprd_serial.o
>  obj-$(CONFIG_SERIAL_STM32)	+= stm32-usart.o
> +obj-$(CONFIG_SERIAL_MPS2_UART)	+= mps2-uart.o
>  
>  # GPIOLIB helpers for modem control lines
>  obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
> diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
> new file mode 100644
> index 0000000..5a4e167
> --- /dev/null
> +++ b/drivers/tty/serial/mps2-uart.c
> @@ -0,0 +1,586 @@
> +/*
> + * Copyright (C) 2015 ARM Limited
> + *
> + * Author: Vladimir Murzin <[email-masked]>
> + *
> + * 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.
> + *
> + * TODO: support for SysRq
> + */
> +
> +#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
> +
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/console.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/serial_core.h>
> +#include <linux/tty_flip.h>
> +#include <linux/types.h>
> +
> +#define SERIAL_NAME	"ttyMPS"
> +#define DRIVER_NAME	"mps2-uart"
> +#define MAKE_NAME(x)	(DRIVER_NAME # x)
> +
> +#define UARTn_DATA				0x00
> +
> +#define UARTn_STATE				0x04
> +#define UARTn_STATE_TX_FULL			BIT(0)
> +#define UARTn_STATE_RX_FULL			BIT(1)
> +#define UARTn_STATE_TX_OVERRUN			BIT(2)
> +#define UARTn_STATE_RX_OVERRUN			BIT(3)
> +
> +#define UARTn_CTRL				0x08
> +#define UARTn_CTRL_TX_ENABLE			BIT(0)
> +#define UARTn_CTRL_RX_ENABLE			BIT(1)
> +#define UARTn_CTRL_TX_INT_ENABLE		BIT(2)
> +#define UARTn_CTRL_RX_INT_ENABLE		BIT(3)
> +#define UARTn_CTRL_TX_OVERRUN_INT_ENABLE	BIT(4)
> +#define UARTn_CTRL_RX_OVERRUN_INT_ENABLE	BIT(5)
> +
> +#define UARTn_INT				0x0c
> +#define UARTn_INT_TX				BIT(0)
> +#define UARTn_INT_RX				BIT(1)
> +#define UARTn_INT_TX_OVERRUN			BIT(2)
> +#define UARTn_INT_RX_OVERRUN			BIT(3)
> +
> +#define UARTn_BAUDDIV				0x10
> +#define UARTn_BAUDDIV_MASK			GENMASK(20, 0)
> +
> +/*
> + * Helpers to make typical enable/disable operations more readable.
> + */
> +#define UARTn_CTRL_TX_GRP 			(UARTn_CTRL_TX_ENABLE		 |\
> +						 UARTn_CTRL_TX_INT_ENABLE	 |\
> +						 UARTn_CTRL_TX_OVERRUN_INT_ENABLE)
> +
> +#define UARTn_CTRL_RX_GRP 			(UARTn_CTRL_RX_ENABLE		 |\
> +						 UARTn_CTRL_RX_INT_ENABLE	 |\
> +						 UARTn_CTRL_RX_OVERRUN_INT_ENABLE)
> +
> +#define MPS2_MAX_PORTS				3
> +
> +struct mps2_uart_port {
> +	struct uart_port port;
> +	struct clk *clk;
> +	unsigned int tx_irq;
> +	unsigned int rx_irq;
> +};
> +
> +static inline struct mps2_uart_port *to_mps2_port(struct uart_port *port)
> +{
> +	return container_of(port, struct mps2_uart_port, port);
> +}
> +
> +static void mps2_uart_write8(struct uart_port *port, u8 val, unsigned off)
> +{
> +	struct mps2_uart_port *mps_port = to_mps2_port(port);
> +
> +	writeb(val, mps_port->port.membase + off);
> +}
> +
> +static u8 mps2_uart_read8(struct uart_port *port, unsigned off)
> +{
> +	struct mps2_uart_port *mps_port = to_mps2_port(port);
> +
> +	return readb(mps_port->port.membase + off);
> +}
> +
> +static void mps2_uart_write32(struct uart_port *port, u32 val, unsigned off)
> +{
> +	struct mps2_uart_port *mps_port = to_mps2_port(port);
> +
> +	writel_relaxed(val, mps_port->port.membase + off);
> +}
> +
> +static unsigned int mps2_uart_tx_empty(struct uart_port *port)
> +{
> +	u8 status = mps2_uart_read8(port, UARTn_STATE);
> +
> +	return (status & UARTn_STATE_TX_FULL) ? 0 : TIOCSER_TEMT;
> +}
> +
> +static void mps2_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
> +{
> +}
> +
> +static unsigned int mps2_uart_get_mctrl(struct uart_port *port)
> +{
> +	return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;
> +}
> +
> +static void mps2_uart_stop_tx(struct uart_port *port)
> +{
> +	u8 control = mps2_uart_read8(port, UARTn_CTRL);
> +
> +	control &= ~UARTn_CTRL_TX_GRP;
> +
> +	mps2_uart_write8(port, control, UARTn_CTRL);
> +}
> +
> +static void mps2_uart_tx_chars(struct uart_port *port)
> +{
> +	struct circ_buf *xmit = &port->state->xmit;
> +
> +	while (!(mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)) {
> +		if (port->x_char) {
> +			mps2_uart_write8(port, port->x_char, UARTn_DATA);
> +			port->x_char = 0;
> +			port->icount.tx++;
> +			continue;
> +		}
> +
> +		if (uart_circ_empty(xmit) || uart_tx_stopped(port))
> +			break;
> +
> +		mps2_uart_write8(port, xmit->buf[xmit->tail], UARTn_DATA);
> +		xmit->tail = (xmit->tail + 1) % UART_XMIT_SIZE;
> +		port->icount.tx++;
> +	}
> +
> +	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> +		uart_write_wakeup(port);
> +
> +	if (uart_circ_empty(xmit))
> +		mps2_uart_stop_tx(port);
> +}
> +
> +static void mps2_uart_start_tx(struct uart_port *port)
> +{

Your start_tx() method should just enable tx interrupt (if not already
enabled), and not actually perform the transfer synchronously.

> +	u8 control = mps2_uart_read8(port, UARTn_CTRL);
> +
> +	control |= UARTn_CTRL_TX_GRP;
> +
> +	mps2_uart_write8(port, control, UARTn_CTRL);
> +	mps2_uart_tx_chars(port);
> +}
> +
> +static void mps2_uart_stop_rx(struct uart_port *port)
> +{
> +	u8 control = mps2_uart_read8(port, UARTn_CTRL);
> +
> +	control &= ~UARTn_CTRL_RX_GRP;
> +
> +	mps2_uart_write8(port, control, UARTn_CTRL);
> +}
> +
> +static void mps2_uart_break_ctl(struct uart_port *port, int ctl)
> +{
> +}
> +
> +static void mps2_uart_rx_chars(struct uart_port *port)
> +{
> +	struct tty_port *tport = &port->state->port;
> +
> +	while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_RX_FULL) {
> +		u8 rxdata = mps2_uart_read8(port, UARTn_DATA);
> +
> +		port->icount.rx++;
> +		tty_insert_flip_char(&port->state->port, rxdata, TTY_NORMAL);
> +	}
> +
> +	spin_unlock(&port->lock);
> +	tty_flip_buffer_push(tport);
> +	spin_lock(&port->lock);

Not necessary to drop the port lock across push.

> +}
> +
> +static irqreturn_t mps2_uart_rxirq(int irq, void *data)
> +{
> +
> +	struct uart_port *port = data;
> +	u8 irqflag = mps2_uart_read8(port, UARTn_INT);
> +
> +	if (unlikely(!(irqflag & UARTn_INT_RX)))
> +		return IRQ_NONE;
> +
> +	spin_lock(&port->lock);
> +
> +	mps2_uart_write8(port, UARTn_INT_RX, UARTn_INT);
> +	mps2_uart_rx_chars(port);
> +
> +	spin_unlock(&port->lock);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t mps2_uart_txirq(int irq, void *data)
> +{
> +	struct uart_port *port = data;
> +	u8 irqflag = mps2_uart_read8(port, UARTn_INT);
> +
> +	if (unlikely(!(irqflag & UARTn_INT_TX)))
> +		return IRQ_NONE;
> +
> +	mps2_uart_write8(port, UARTn_INT_TX, UARTn_INT);
> +	mps2_uart_tx_chars(port);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t mps2_uart_oerrirq(int irq, void *data)
> +{
> +	irqreturn_t handled = IRQ_NONE;
> +	struct uart_port *port = data;
> +	u8 irqflag = mps2_uart_read8(port, UARTn_INT);
> +
> +	spin_lock(&port->lock);
> +
> +	if (irqflag & UARTn_INT_RX_OVERRUN) {
> +		struct tty_port *tport = &port->state->port;
> +
> +		mps2_uart_write8(port, UARTn_INT_RX_OVERRUN, UARTn_INT);
> +		tty_insert_flip_char(tport, 0, TTY_OVERRUN);
> +		port->icount.overrun++;
> +		handled = IRQ_HANDLED;
> +	}
> +
> +	/*
> +	 * It's never been seen in practice and it never *should* happen since
> +	 * we check if there is enough room in TX buffer before sending data.
> +	 * So we keep this check in case something suspicious has happened.
> +	 */
> +	if (irqflag & UARTn_INT_TX_OVERRUN) {
> +		mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);
> +		handled = IRQ_HANDLED;
> +	}
> +
> +	spin_unlock(&port->lock);

No buffer push for the overrun char?

> +
> +	return handled;
> +}
> +
> +static int mps2_uart_startup(struct uart_port *port)
> +{
> +	struct mps2_uart_port *mps_port = to_mps2_port(port);
> +	u8 control = mps2_uart_read8(port, UARTn_CTRL);
> +	int ret;
> +
> +	control &= ~(UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP);
> +
> +	mps2_uart_write8(port, control, UARTn_CTRL);
> +
> +	ret = request_irq(mps_port->rx_irq, mps2_uart_rxirq, 0,
> +			  MAKE_NAME(-rx), mps_port);
> +	if (ret) {
> +		dev_err(port->dev, "failed to register rxirq (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0,
> +			  MAKE_NAME(-tx), mps_port);
> +	if (ret) {
> +		dev_err(port->dev, "failed to register txirq (%d)\n", ret);
> +		goto err_free_rxirq;
> +	}
> +
> +	ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED,
> +			  MAKE_NAME(-overrun), mps_port);
> +
> +	if (ret) {
> +		dev_err(port->dev, "failed to register oerrirq (%d)\n", ret);
> +		goto err_free_txirq;
> +	}
> +
> +	control |= UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP;
> +
> +	mps2_uart_write8(port, control, UARTn_CTRL);
> +
> +	return 0;
> +
> +err_free_txirq:
> +	free_irq(mps_port->tx_irq, mps_port);
> +err_free_rxirq:
> +	free_irq(mps_port->rx_irq, mps_port);
> +
> +	return ret;
> +}
> +
> +static void mps2_uart_shutdown(struct uart_port *port)
> +{
> +	struct mps2_uart_port *mps_port = to_mps2_port(port);
> +	u8 control = mps2_uart_read8(port, UARTn_CTRL);
> +
> +	control &= ~(UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP);
> +
> +	mps2_uart_write8(port, control, UARTn_CTRL);
> +
> +	free_irq(mps_port->rx_irq, mps_port);
> +	free_irq(mps_port->tx_irq, mps_port);
> +	free_irq(port->irq, mps_port);
> +}
> +
> +static void mps2_uart_set_termios(struct uart_port *port,
> +	struct ktermios *termios, struct ktermios *old)
> +{
> +	unsigned long flags;
> +	unsigned int baud, bauddiv;
> +
> +	termios->c_cflag &= ~(CRTSCTS | CMSPAR);
> +	termios->c_cflag &= ~CSIZE;
> +	termios->c_cflag |= CS8;
> +	termios->c_cflag &= ~PARENB;
> +	termios->c_cflag &= ~CSTOPB;
> +
> +	baud = uart_get_baud_rate(port, termios, old,
> +			DIV_ROUND_CLOSEST(port->uartclk, UARTn_BAUDDIV_MASK),
> +			DIV_ROUND_CLOSEST(port->uartclk, 16));
> +
> +	bauddiv = DIV_ROUND_CLOSEST(port->uartclk, baud);
> +
> +	spin_lock_irqsave(&port->lock, flags);
> +
> +	uart_update_timeout(port, termios->c_cflag, baud);
> +	mps2_uart_write32(port, bauddiv, UARTn_BAUDDIV);

termios structure itself is already protected from concurrent access
by the tty core so the port lock should only be used for
driver structures and the actual hardware i/o.

IOW, the lock can be dropped before encoding new line rate, like so:

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

> +	if (tty_termios_baud_rate(termios))
> +		tty_termios_encode_baud_rate(termios, baud, baud);
> +}

> +
> +static const char *mps2_uart_type(struct uart_port *port)
> +{
> +	return (port->type == PORT_MPS2UART) ? DRIVER_NAME : NULL;
> +}
> +
> +static void mps2_uart_release_port(struct uart_port *port)
> +{
> +}
> +
> +static int mps2_uart_request_port(struct uart_port *port)
> +{
> +	return 0;
> +}
> +
> +static void mps2_uart_config_port(struct uart_port *port, int type)
> +{
> +	if (type & UART_CONFIG_TYPE && !mps2_uart_request_port(port))
> +		port->type = PORT_MPS2UART;
> +}
> +
> +static int mps2_uart_verify_port(struct uart_port *port, struct serial_struct *serinfo)
> +{
> +	return -EINVAL;
> +}
> +
> +static const struct uart_ops mps2_uart_pops = {
> +	.tx_empty = mps2_uart_tx_empty,
> +	.set_mctrl = mps2_uart_set_mctrl,
> +	.get_mctrl = mps2_uart_get_mctrl,
> +	.stop_tx = mps2_uart_stop_tx,
> +	.start_tx = mps2_uart_start_tx,
> +	.stop_rx = mps2_uart_stop_rx,
> +	.break_ctl = mps2_uart_break_ctl,
> +	.startup = mps2_uart_startup,
> +	.shutdown = mps2_uart_shutdown,
> +	.set_termios = mps2_uart_set_termios,
> +	.type = mps2_uart_type,
> +	.release_port = mps2_uart_release_port,
> +	.request_port = mps2_uart_request_port,
> +	.config_port = mps2_uart_config_port,
> +	.verify_port = mps2_uart_verify_port,
> +};
> +
> +static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
> +
> +#ifdef CONFIG_SERIAL_MPS2_UART_CONSOLE
> +static void mps2_uart_console_putchar(struct uart_port *port, int ch)
> +{
> +	while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)
> +		cpu_relax();
> +
> +	mps2_uart_write8(port, ch, UARTn_DATA);
> +}
> +
> +static void mps2_uart_console_write(struct console *co, const char *s, unsigned int cnt)
> +{
> +	struct uart_port *port = &mps2_uart_ports[co->index].port;
> +
> +	uart_console_write(port, s, cnt, mps2_uart_console_putchar);
> +}
> +
> +static int mps2_uart_console_setup(struct console *co, char *options)
> +{
> +	struct mps2_uart_port *mps_port;
> +	int baud = 9600;
> +	int bits = 8;
> +	int parity = 'n';
> +	int flow = 'n';
> +
> +	if (co->index < 0 || co->index >= MPS2_MAX_PORTS)
> +		return -ENODEV;
> +
> +	mps_port = &mps2_uart_ports[co->index];
> +
> +	if (options)
> +		uart_parse_options(options, &baud, &parity, &bits, &flow);
> +
> +	return uart_set_options(&mps_port->port, co, baud, parity, bits, flow);
> +}
> +
> +static struct uart_driver mps2_uart_driver;
> +
> +static struct console mps2_uart_console = {
> +	.name = SERIAL_NAME,
> +	.device = uart_console_device,
> +	.write = mps2_uart_console_write,
> +	.setup = mps2_uart_console_setup,
> +	.flags = CON_PRINTBUFFER,
> +	.index = -1,
> +	.data = &mps2_uart_driver,
> +};
> +
> +#define MPS2_SERIAL_CONSOLE (&mps2_uart_console)
> +
> +#else
> +#define MPS2_SERIAL_CONSOLE NULL
> +#endif
> +
> +static struct uart_driver mps2_uart_driver = {
> +	.driver_name = DRIVER_NAME,
> +	.dev_name = SERIAL_NAME,
> +	.nr = MPS2_MAX_PORTS,
> +	.cons = MPS2_SERIAL_CONSOLE,
> +};
> +
> +static struct mps2_uart_port *mps2_of_get_port(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	int id;
> +
> +	if (!np)
> +		return NULL;
> +
> +	id = of_alias_get_id(np, "serial");
> +	if (id < 0)
> +		id = 0;
> +
> +	if (WARN_ON(id >= MPS2_MAX_PORTS))
> +		return NULL;
> +
> +	mps2_uart_ports[id].port.line = id;
> +	return &mps2_uart_ports[id];
> +}
> +
> +static int mps2_init_port(struct mps2_uart_port *mps_port,
> +			struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	int ret;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	mps_port->port.membase = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(mps_port->port.membase))
> +		return PTR_ERR(mps_port->port.membase);
> +
> +	mps_port->port.mapbase = res->start;
> +	mps_port->port.mapsize = resource_size(res);
> +
> +	mps_port->rx_irq = platform_get_irq(pdev, 0);
> +	mps_port->tx_irq = platform_get_irq(pdev, 1);
> +	mps_port->port.irq = platform_get_irq(pdev, 2);
> +
> +	mps_port->port.iotype = UPIO_MEM;
> +	mps_port->port.flags = UPF_BOOT_AUTOCONF;
> +	mps_port->port.fifosize = 1;
> +	mps_port->port.ops = &mps2_uart_pops;
> +	mps_port->port.dev = &pdev->dev;
> +
> +	mps_port->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(mps_port->clk))
> +		return PTR_ERR(mps_port->clk);
> +
> +	ret = clk_prepare_enable(mps_port->clk);
> +	if (ret)
> +		return ret;
> +
> +	mps_port->port.uartclk = clk_get_rate(mps_port->clk);
> +
> +	clk_disable_unprepare(mps_port->clk);
> +
> +	return ret;
> +}
> +
> +static int mps2_serial_probe(struct platform_device *pdev)
> +{
> +	struct mps2_uart_port *mps_port;
> +	int ret;
> +
> +	mps_port = mps2_of_get_port(pdev);
> +	if (!mps_port)
> +		return -ENODEV;
> +
> +	ret = mps2_init_port(mps_port, pdev);
> +	if (ret)
> +		return ret;
> +
> +	ret = uart_add_one_port(&mps2_uart_driver, &mps_port->port);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, mps_port);
> +
> +	return 0;
> +}
> +
> +static int mps2_serial_remove(struct platform_device *pdev)
> +{
> +	struct mps2_uart_port *mps_port = platform_get_drvdata(pdev);
> +
> +	uart_remove_one_port(&mps2_uart_driver, &mps_port->port);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id mps2_match[] = {
> +	{ .compatible = "arm,mps2-uart", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, mps2_match);
> +#endif
> +
> +static struct platform_driver mps2_serial_driver = {
> +	.probe = mps2_serial_probe,
> +	.remove = mps2_serial_remove,
> +
> +	.driver = {
> +		.name = DRIVER_NAME,
> +		.of_match_table = of_match_ptr(mps2_match),
> +	},
> +};
> +
> +static int __init mps2_uart_init(void)
> +{
> +	int ret;
> +
> +	ret = uart_register_driver(&mps2_uart_driver);
> +	if (ret)
> +		return ret;
> +
> +	ret = platform_driver_register(&mps2_serial_driver);
> +	if (ret)
> +		uart_unregister_driver(&mps2_uart_driver);
> +
> +	return ret;
> +}
> +module_init(mps2_uart_init);
> +
> +static void __exit mps2_uart_exit(void)
> +{
> +	platform_driver_unregister(&mps2_serial_driver);
> +	uart_unregister_driver(&mps2_uart_driver);
> +}
> +module_exit(mps2_uart_exit);
> +
> +MODULE_AUTHOR("Vladimir Murzin <[email-masked]>");
> +MODULE_DESCRIPTION("MPS2 UART driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:" DRIVER_NAME);
> diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
> index 3e5d757..1fa57bb 100644
> --- a/include/uapi/linux/serial_core.h
> +++ b/include/uapi/linux/serial_core.h
> @@ -261,4 +261,7 @@
>  /* STM32 USART */
>  #define PORT_STM32	113
>  
> +/* MPS2 UART */
> +#define PORT_MPS2UART	114
> +
>  #endif /* _UAPILINUX_SERIAL_CORE_H */
>