diff mbox

[v1,04/10] serial: mps2-uart: add MPS2 UART driver

Message ID 1449048790-25859-5-git-send-email-vladimir.murzin@arm.com
State New, archived
Headers show

Commit Message

Vladimir Murzin Dec. 2, 2015, 9:33 a.m. UTC
This driver adds support to the UART controller found on ARM MPS2
platform.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 drivers/tty/serial/Kconfig       |   12 +
 drivers/tty/serial/Makefile      |    1 +
 drivers/tty/serial/mps2-uart.c   |  596 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/serial_core.h |    3 +
 4 files changed, 612 insertions(+)
 create mode 100644 drivers/tty/serial/mps2-uart.c

Comments

Vladimir Murzin Dec. 7, 2015, 9:26 a.m. UTC | #1
Gentle ping...

On 02/12/15 09:33, Vladimir Murzin wrote:
> This driver adds support to the UART controller found on ARM MPS2
> platform.
> 
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
>  drivers/tty/serial/Kconfig       |   12 +
>  drivers/tty/serial/Makefile      |    1 +
>  drivers/tty/serial/mps2-uart.c   |  596 ++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/serial_core.h |    3 +
>  4 files changed, 612 insertions(+)
>  create mode 100644 drivers/tty/serial/mps2-uart.c
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index f38beb2..e98bfea 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -1473,6 +1473,18 @@ 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 5ab4111..7f589f5 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -93,6 +93,7 @@ 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..09bac16
> --- /dev/null
> +++ b/drivers/tty/serial/mps2-uart.c
> @@ -0,0 +1,596 @@
> +/*
> + * Copyright (C) 2015 ARM Limited
> + *
> + * Author: Vladimir Murzin <vladimir.murzin@arm.com>
> + *
> + * 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				0x0
> +
> +#define UARTn_STATE				0x4
> +#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				0x8
> +#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				0xc
> +#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)
> +
> +#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_ENABLE		|
> +		     UARTn_CTRL_TX_INT_ENABLE		|
> +		     UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
> +
> +	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 - 1);
> +		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)
> +{
> +	u8 control = mps2_uart_read8(port, UARTn_CTRL);
> +
> +	control |= (UARTn_CTRL_TX_ENABLE		|
> +		    UARTn_CTRL_TX_INT_ENABLE		|
> +		    UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
> +
> +	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_ENABLE		|
> +		     UARTn_CTRL_RX_INT_ENABLE		|
> +		     UARTn_CTRL_RX_OVERRUN_INT_ENABLE);
> +
> +	mps2_uart_write8(port, control, UARTn_CTRL);
> +}
> +
> +static void mps2_uart_enable_ms(struct uart_port *port)
> +{
> +}
> +
> +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);
> +}
> +
> +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;
> +	}
> +
> +	/* XXX: this shouldn't happen? */
> +	if (irqflag & UARTn_INT_TX_OVERRUN) {
> +		mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);
> +		handled = IRQ_HANDLED;
> +	}
> +
> +	spin_unlock(&port->lock);
> +
> +	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_ENABLE		|
> +		     UARTn_CTRL_TX_ENABLE		|
> +		     UARTn_CTRL_RX_INT_ENABLE		|
> +		     UARTn_CTRL_TX_INT_ENABLE		|
> +		     UARTn_CTRL_RX_OVERRUN_INT_ENABLE	|
> +		     UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
> +
> +	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) {
> +		pr_info("failed to register rxirq (%d)\n", ret);
> +		goto err_no_rxirq;
> +	}
> +
> +	ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0,
> +			  MAKE_NAME(-tx), mps_port);
> +	if (ret) {
> +		pr_info("failed to register txirq (%d)\n", ret);
> +		goto err_no_txirq;
> +	}
> +
> +	ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED,
> +			  MAKE_NAME(-overrun), mps_port);
> +
> +	if (ret)
> +		pr_info("failed to register oerrirq (%d)\n", ret);
> +	else {
> +		control |= UARTn_CTRL_RX_ENABLE			|
> +			   UARTn_CTRL_TX_ENABLE			|
> +			   UARTn_CTRL_RX_INT_ENABLE		|
> +			   UARTn_CTRL_TX_INT_ENABLE		|
> +			   UARTn_CTRL_RX_OVERRUN_INT_ENABLE	|
> +			   UARTn_CTRL_TX_OVERRUN_INT_ENABLE;
> +
> +		mps2_uart_write8(port, control, UARTn_CTRL);
> +
> +		return 0;
> +	}
> +
> +	free_irq(mps_port->tx_irq, mps_port);
> +err_no_txirq:
> +	free_irq(mps_port->rx_irq, mps_port);
> +err_no_rxirq:
> +	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_ENABLE		|
> +		     UARTn_CTRL_TX_ENABLE		|
> +		     UARTn_CTRL_RX_INT_ENABLE		|
> +		     UARTn_CTRL_TX_INT_ENABLE		|
> +		     UARTn_CTRL_RX_OVERRUN_INT_ENABLE	|
> +		     UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
> +
> +	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 *new, struct ktermios *old)
> +{
> +	unsigned long flags;
> +	unsigned int baud, bauddiv;
> +
> +	new->c_cflag &= ~(CRTSCTS | CMSPAR);
> +	new->c_cflag &= ~CSIZE;
> +	new->c_cflag |= CS8;
> +	new->c_cflag &= ~PARENB;
> +	new->c_cflag &= ~CSTOPB;
> +
> +	baud = uart_get_baud_rate(port, new, 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, new->c_cflag, baud);
> +	mps2_uart_write32(port, bauddiv, UARTn_BAUDDIV);
> +
> +	spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +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,
> +	.enable_ms = mps2_uart_enable_ms,
> +	.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)
> +{
> +	int ret = 0;
> +	struct resource *res;
> +
> +	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);
> +	if (!mps_port->port.uartclk)
> +		ret = -EINVAL;
> +
> +	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);
> +
> +	pr_info("MPS2 UART driver initialized\n");
> +
> +	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 <vladimir.murzin@arm.com>");
> +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 93ba148..f097fe9 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 */
>
Andy Shevchenko Dec. 12, 2015, 11:39 p.m. UTC | #2
On Wed, Dec 2, 2015 at 11:33 AM, Vladimir Murzin
<vladimir.murzin@arm.com> wrote:
> This driver adds support to the UART controller found on ARM MPS2
> platform.

Just few comments (have neither time not big desire to do full review).

>
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
>  drivers/tty/serial/Kconfig       |   12 +
>  drivers/tty/serial/Makefile      |    1 +
>  drivers/tty/serial/mps2-uart.c   |  596 ++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/serial_core.h |    3 +
>  4 files changed, 612 insertions(+)
>  create mode 100644 drivers/tty/serial/mps2-uart.c
>
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index f38beb2..e98bfea 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -1473,6 +1473,18 @@ 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 5ab4111..7f589f5 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -93,6 +93,7 @@ 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..09bac16
> --- /dev/null
> +++ b/drivers/tty/serial/mps2-uart.c
> @@ -0,0 +1,596 @@
> +/*
> + * Copyright (C) 2015 ARM Limited
> + *
> + * Author: Vladimir Murzin <vladimir.murzin@arm.com>
> + *
> + * 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"

Can it be ttyS?

> +#define DRIVER_NAME "mps2-uart"
> +#define MAKE_NAME(x) (DRIVER_NAME # x)
> +
> +#define UARTn_DATA                             0x0

I think it makes sense to have same width for all offsets, i.e. 0x00
here and so on below.

> +
> +#define UARTn_STATE                            0x4
> +#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                             0x8
> +#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                              0xc
> +#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)
> +
> +#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_ENABLE               |
> +                    UARTn_CTRL_TX_INT_ENABLE           |
> +                    UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
> +
> +       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 - 1);

More flexible here to use % UART_XMIT_SIZE. I believe compiler makes it optimal.

> +               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)
> +{
> +       u8 control = mps2_uart_read8(port, UARTn_CTRL);
> +
> +       control |= (UARTn_CTRL_TX_ENABLE                |
> +                   UARTn_CTRL_TX_INT_ENABLE            |
> +                   UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
> +
> +       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_ENABLE               |
> +                    UARTn_CTRL_RX_INT_ENABLE           |
> +                    UARTn_CTRL_RX_OVERRUN_INT_ENABLE);
> +
> +       mps2_uart_write8(port, control, UARTn_CTRL);
> +}
> +
> +static void mps2_uart_enable_ms(struct uart_port *port)
> +{
> +}
> +
> +static void mps2_uart_break_ctl(struct uart_port *port, int ctl)
> +{
> +}

Are those required to be present? If not, remove them until you have
alive code there.

> +
> +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);
> +}
> +
> +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;
> +       }
> +
> +       /* XXX: this shouldn't happen? */

If shouldn't why it's there? Otherwise better to explain which
conditions may lead to this.

> +       if (irqflag & UARTn_INT_TX_OVERRUN) {
> +               mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);
> +               handled = IRQ_HANDLED;
> +       }
> +
> +       spin_unlock(&port->lock);
> +
> +       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_ENABLE               |
> +                    UARTn_CTRL_TX_ENABLE               |
> +                    UARTn_CTRL_RX_INT_ENABLE           |
> +                    UARTn_CTRL_TX_INT_ENABLE           |
> +                    UARTn_CTRL_RX_OVERRUN_INT_ENABLE   |
> +                    UARTn_CTRL_TX_OVERRUN_INT_ENABLE);


If you unifyf both RX and TX groups you may use them here, and above.

control &= ~(UART…RX | UART…TX);

Above case just RX. Maybe something alike below.

> +
> +       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) {
> +               pr_info("failed to register rxirq (%d)\n", ret);

And why not _err() and even dev_err()? Same for stuff below.

> +               goto err_no_rxirq;
> +       }
> +
> +       ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0,
> +                         MAKE_NAME(-tx), mps_port);
> +       if (ret) {
> +               pr_info("failed to register txirq (%d)\n", ret);
> +               goto err_no_txirq;
> +       }
> +
> +       ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED,
> +                         MAKE_NAME(-overrun), mps_port);
> +
> +       if (ret)
> +               pr_info("failed to register oerrirq (%d)\n", ret);
> +       else {

Keep style according to requirement.
} else {

> +               control |= UARTn_CTRL_RX_ENABLE                 |
> +                          UARTn_CTRL_TX_ENABLE                 |
> +                          UARTn_CTRL_RX_INT_ENABLE             |
> +                          UARTn_CTRL_TX_INT_ENABLE             |
> +                          UARTn_CTRL_RX_OVERRUN_INT_ENABLE     |
> +                          UARTn_CTRL_TX_OVERRUN_INT_ENABLE;
> +
> +               mps2_uart_write8(port, control, UARTn_CTRL);
> +
> +               return 0;
> +       }
> +
> +       free_irq(mps_port->tx_irq, mps_port);
> +err_no_txirq:
> +       free_irq(mps_port->rx_irq, mps_port);
> +err_no_rxirq:
> +       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_ENABLE               |
> +                    UARTn_CTRL_TX_ENABLE               |
> +                    UARTn_CTRL_RX_INT_ENABLE           |
> +                    UARTn_CTRL_TX_INT_ENABLE           |
> +                    UARTn_CTRL_RX_OVERRUN_INT_ENABLE   |
> +                    UARTn_CTRL_TX_OVERRUN_INT_ENABLE);

TX group + RX group, see above.

> +
> +       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 *new, struct ktermios *old)
> +{
> +       unsigned long flags;
> +       unsigned int baud, bauddiv;
> +
> +       new->c_cflag &= ~(CRTSCTS | CMSPAR);
> +       new->c_cflag &= ~CSIZE;
> +       new->c_cflag |= CS8;
> +       new->c_cflag &= ~PARENB;
> +       new->c_cflag &= ~CSTOPB;
> +
> +       baud = uart_get_baud_rate(port, new, 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, new->c_cflag, baud);
> +       mps2_uart_write32(port, bauddiv, UARTn_BAUDDIV);
> +
> +       spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +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;
> +}
> +

Same question about empty stubs.

> +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,
> +       .enable_ms = mps2_uart_enable_ms,
> +       .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)
> +{
> +       int ret = 0;

Redundant assignment.

> +       struct resource *res;
> +
> +       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);
> +       if (!mps_port->port.uartclk)
> +               ret = -EINVAL;

So, 1 is OK, 0 is not. I think 1 is too low to be provided by hardware.

> +
> +       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);
> +
> +       pr_info("MPS2 UART driver initialized\n");
> +
> +       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_platform_driver();
And move uart_*register calls to probe/remove.

> +
> +MODULE_AUTHOR("Vladimir Murzin <vladimir.murzin@arm.com>");
> +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 93ba148..f097fe9 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 */
> --
> 1.7.9.5
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
Greg Kroah-Hartman Dec. 13, 2015, 7 a.m. UTC | #3
On Sun, Dec 13, 2015 at 01:39:26AM +0200, Andy Shevchenko wrote:
> On Wed, Dec 2, 2015 at 11:33 AM, Vladimir Murzin
> <vladimir.murzin@arm.com> wrote:
> > This driver adds support to the UART controller found on ARM MPS2
> > platform.
> 
> Just few comments (have neither time not big desire to do full review).
> 
> >
> > Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> > ---
> >  drivers/tty/serial/Kconfig       |   12 +
> >  drivers/tty/serial/Makefile      |    1 +
> >  drivers/tty/serial/mps2-uart.c   |  596 ++++++++++++++++++++++++++++++++++++++
> >  include/uapi/linux/serial_core.h |    3 +
> >  4 files changed, 612 insertions(+)
> >  create mode 100644 drivers/tty/serial/mps2-uart.c
> >
> > diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> > index f38beb2..e98bfea 100644
> > --- a/drivers/tty/serial/Kconfig
> > +++ b/drivers/tty/serial/Kconfig
> > @@ -1473,6 +1473,18 @@ 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 5ab4111..7f589f5 100644
> > --- a/drivers/tty/serial/Makefile
> > +++ b/drivers/tty/serial/Makefile
> > @@ -93,6 +93,7 @@ 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..09bac16
> > --- /dev/null
> > +++ b/drivers/tty/serial/mps2-uart.c
> > @@ -0,0 +1,596 @@
> > +/*
> > + * Copyright (C) 2015 ARM Limited
> > + *
> > + * Author: Vladimir Murzin <vladimir.murzin@arm.com>
> > + *
> > + * 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"
> 
> Can it be ttyS?

It must be ttyS, please fix this.  Don't go creating new tty device
names, it never will work out and will eventually come back to cause
problems if you do not.

thanks,

greg k-h
Vladimir Murzin Dec. 15, 2015, 12:40 p.m. UTC | #4
On 12/12/15 23:39, Andy Shevchenko wrote:
> On Wed, Dec 2, 2015 at 11:33 AM, Vladimir Murzin
> <vladimir.murzin@arm.com> wrote:
>> This driver adds support to the UART controller found on ARM MPS2
>> platform.
> 
> Just few comments (have neither time not big desire to do full review).
> 

Still better than nothing ;) I'm mostly agree on points you had, so I've
just left some I'm doubt about...

>> +
>> +static void mps2_uart_enable_ms(struct uart_port *port)
>> +{
>> +}
>> +
>> +static void mps2_uart_break_ctl(struct uart_port *port, int ctl)
>> +{
>> +}
> 
> Are those required to be present? If not, remove them until you have
> alive code there.

A quick grep shows that core calls mps2_uart_break_ctl()
unconditionally, but, yes, it checks for presence of
mps2_uart_enable_ms() before jumping there, so it is safe to remove latter.

>> +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;
>> +       }
>> +
>> +       /* XXX: this shouldn't happen? */
> 
> If shouldn't why it's there? Otherwise better to explain which
> conditions may lead to this.
> 

In practice I've never seen that happened and I think it never *should*
happen since we check if there is room in TX buffer. However, I could be
wrong here, so it is why that statement has question mark.

>> +       if (irqflag & UARTn_INT_TX_OVERRUN) {
>> +               mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);
>> +               handled = IRQ_HANDLED;
>> +       }
>> +
>> +       spin_unlock(&port->lock);
>> +
>> +       return handled;
>> +}
>> +
...
>> +static void mps2_uart_release_port(struct uart_port *port)
>> +{
>> +}
>> +
>> +static int mps2_uart_request_port(struct uart_port *port)
>> +{
>> +       return 0;
>> +}
>> +
> 
> Same question about empty stubs.

Looks like they called unconditionally by the core.

>> +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);
>> +
>> +       pr_info("MPS2 UART driver initialized\n");
>> +
>> +       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_platform_driver();
> And move uart_*register calls to probe/remove.
> 

With this move we'll get uart_*register for every device probed, no?

Thanks
Vladimir
Andy Shevchenko Dec. 17, 2015, 1:15 p.m. UTC | #5
On Tue, Dec 15, 2015 at 2:40 PM, Vladimir Murzin
<vladimir.murzin@arm.com> wrote:
> On 12/12/15 23:39, Andy Shevchenko wrote:
>> On Wed, Dec 2, 2015 at 11:33 AM, Vladimir Murzin
>> <vladimir.murzin@arm.com> wrote:
>>> This driver adds support to the UART controller found on ARM MPS2
>>> platform.
>>
>> Just few comments (have neither time not big desire to do full review).
>>
>
> Still better than nothing ;) I'm mostly agree on points you had, so I've
> just left some I'm doubt about...
>
>>> +
>>> +static void mps2_uart_enable_ms(struct uart_port *port)
>>> +{
>>> +}
>>> +
>>> +static void mps2_uart_break_ctl(struct uart_port *port, int ctl)
>>> +{
>>> +}
>>
>> Are those required to be present? If not, remove them until you have
>> alive code there.
>
> A quick grep shows that core calls mps2_uart_break_ctl()
> unconditionally, but, yes, it checks for presence of
> mps2_uart_enable_ms() before jumping there, so it is safe to remove latter.

OK.

>>> +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;
>>> +       }
>>> +
>>> +       /* XXX: this shouldn't happen? */
>>
>> If shouldn't why it's there? Otherwise better to explain which
>> conditions may lead to this.
>>
>
> In practice I've never seen that happened and I think it never *should*
> happen since we check if there is room in TX buffer. However, I could be
> wrong here, so it is why that statement has question mark.

So, worth to have a proper comment then.

>>> +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);
>>> +
>>> +       pr_info("MPS2 UART driver initialized\n");
>>> +
>>> +       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_platform_driver();
>> And move uart_*register calls to probe/remove.
>>
>
> With this move we'll get uart_*register for every device probed, no?

Don't see a problem, maybe someone else could share an authoritive opinion.
Some of the drivers do that, though most do in __init stage. So, see above.
diff mbox

Patch

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index f38beb2..e98bfea 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1473,6 +1473,18 @@  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 5ab4111..7f589f5 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -93,6 +93,7 @@  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..09bac16
--- /dev/null
+++ b/drivers/tty/serial/mps2-uart.c
@@ -0,0 +1,596 @@ 
+/*
+ * Copyright (C) 2015 ARM Limited
+ *
+ * Author: Vladimir Murzin <vladimir.murzin@arm.com>
+ *
+ * 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				0x0
+
+#define UARTn_STATE				0x4
+#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				0x8
+#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				0xc
+#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)
+
+#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_ENABLE		|
+		     UARTn_CTRL_TX_INT_ENABLE		|
+		     UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+	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 - 1);
+		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)
+{
+	u8 control = mps2_uart_read8(port, UARTn_CTRL);
+
+	control |= (UARTn_CTRL_TX_ENABLE		|
+		    UARTn_CTRL_TX_INT_ENABLE		|
+		    UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+	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_ENABLE		|
+		     UARTn_CTRL_RX_INT_ENABLE		|
+		     UARTn_CTRL_RX_OVERRUN_INT_ENABLE);
+
+	mps2_uart_write8(port, control, UARTn_CTRL);
+}
+
+static void mps2_uart_enable_ms(struct uart_port *port)
+{
+}
+
+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);
+}
+
+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;
+	}
+
+	/* XXX: this shouldn't happen? */
+	if (irqflag & UARTn_INT_TX_OVERRUN) {
+		mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);
+		handled = IRQ_HANDLED;
+	}
+
+	spin_unlock(&port->lock);
+
+	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_ENABLE		|
+		     UARTn_CTRL_TX_ENABLE		|
+		     UARTn_CTRL_RX_INT_ENABLE		|
+		     UARTn_CTRL_TX_INT_ENABLE		|
+		     UARTn_CTRL_RX_OVERRUN_INT_ENABLE	|
+		     UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+	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) {
+		pr_info("failed to register rxirq (%d)\n", ret);
+		goto err_no_rxirq;
+	}
+
+	ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0,
+			  MAKE_NAME(-tx), mps_port);
+	if (ret) {
+		pr_info("failed to register txirq (%d)\n", ret);
+		goto err_no_txirq;
+	}
+
+	ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED,
+			  MAKE_NAME(-overrun), mps_port);
+
+	if (ret)
+		pr_info("failed to register oerrirq (%d)\n", ret);
+	else {
+		control |= UARTn_CTRL_RX_ENABLE			|
+			   UARTn_CTRL_TX_ENABLE			|
+			   UARTn_CTRL_RX_INT_ENABLE		|
+			   UARTn_CTRL_TX_INT_ENABLE		|
+			   UARTn_CTRL_RX_OVERRUN_INT_ENABLE	|
+			   UARTn_CTRL_TX_OVERRUN_INT_ENABLE;
+
+		mps2_uart_write8(port, control, UARTn_CTRL);
+
+		return 0;
+	}
+
+	free_irq(mps_port->tx_irq, mps_port);
+err_no_txirq:
+	free_irq(mps_port->rx_irq, mps_port);
+err_no_rxirq:
+	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_ENABLE		|
+		     UARTn_CTRL_TX_ENABLE		|
+		     UARTn_CTRL_RX_INT_ENABLE		|
+		     UARTn_CTRL_TX_INT_ENABLE		|
+		     UARTn_CTRL_RX_OVERRUN_INT_ENABLE	|
+		     UARTn_CTRL_TX_OVERRUN_INT_ENABLE);
+
+	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 *new, struct ktermios *old)
+{
+	unsigned long flags;
+	unsigned int baud, bauddiv;
+
+	new->c_cflag &= ~(CRTSCTS | CMSPAR);
+	new->c_cflag &= ~CSIZE;
+	new->c_cflag |= CS8;
+	new->c_cflag &= ~PARENB;
+	new->c_cflag &= ~CSTOPB;
+
+	baud = uart_get_baud_rate(port, new, 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, new->c_cflag, baud);
+	mps2_uart_write32(port, bauddiv, UARTn_BAUDDIV);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+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,
+	.enable_ms = mps2_uart_enable_ms,
+	.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)
+{
+	int ret = 0;
+	struct resource *res;
+
+	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);
+	if (!mps_port->port.uartclk)
+		ret = -EINVAL;
+
+	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);
+
+	pr_info("MPS2 UART driver initialized\n");
+
+	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 <vladimir.murzin@arm.com>");
+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 93ba148..f097fe9 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 */