[v3] serial: Add Milbeaut serial control

Message ID 1555555916-22251-1-git-send-email-sugaya.taichi@socionext.com
State Accepted
Commit ba44dc04300441b47618f9933bf36e75a280e5fe
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Series
  • [v3] serial: Add Milbeaut serial control
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Commit Message

Sugaya, Taichi April 18, 2019, 2:51 a.m.
Add Milbeaut serial control including earlycon and console.

Signed-off-by: Sugaya Taichi <sugaya.taichi@socionext.com>

---
Changes from v2:
 - Fix build warning.

Changes from v1:
 - Add "COMPILE_TEST" dependency for coverage test.

 drivers/tty/serial/Kconfig         |  26 ++
 drivers/tty/serial/Makefile        |   1 +
 drivers/tty/serial/milbeaut_usio.c | 621 +++++++++++++++++++++++++++++++++++++
 include/uapi/linux/serial_core.h   |   3 +
 4 files changed, 651 insertions(+)
 create mode 100644 drivers/tty/serial/milbeaut_usio.c

-- 
1.9.1

Comments

Greg Kroah-Hartman April 18, 2019, 5:17 a.m. | #1
On Thu, Apr 18, 2019 at 11:51:56AM +0900, Sugaya Taichi wrote:
> Add Milbeaut serial control including earlycon and console.

> 

> Signed-off-by: Sugaya Taichi <sugaya.taichi@socionext.com>

> ---

> Changes from v2:

>  - Fix build warning.


No, I only need an incremental patch fixing the one sparse warning
found, not a whole new patch as I have already merged your original
patch, right?

thanks,

greg k-h
Sugaya, Taichi April 18, 2019, 6:09 a.m. | #2
Hi,

On 2019/04/18 14:17, Greg Kroah-Hartman wrote:
> On Thu, Apr 18, 2019 at 11:51:56AM +0900, Sugaya Taichi wrote:

>> Add Milbeaut serial control including earlycon and console.

>>

>> Signed-off-by: Sugaya Taichi <sugaya.taichi@socionext.com>

>> ---

>> Changes from v2:

>>   - Fix build warning.

> 

> No, I only need an incremental patch fixing the one sparse warning

> found, not a whole new patch as I have already merged your original

> patch, right?

> 


Sorry for my misunderstanding.
I got it.

Thanks,
Sugaya Taichi


> thanks,

> 

> greg k-h

>
Alan Cox April 26, 2019, 6:15 p.m. | #3
O
> +static void mlb_usio_set_termios(struct uart_port *port,

> +			struct ktermios *termios, struct ktermios *old)

> +{

> +	unsigned int escr, smr = MLB_USIO_SMR_SOE;

> +	unsigned long flags, baud, quot;

> +

> +	switch (termios->c_cflag & CSIZE) {

> +	case CS5:

> +		escr = MLB_USIO_ESCR_L_5BIT;

> +		break;

> +	case CS6:

> +		escr = MLB_USIO_ESCR_L_6BIT;

> +		break;

> +	case CS7:

> +		escr = MLB_USIO_ESCR_L_7BIT;

> +		break;

> +	case CS8:

> +	default:

> +		escr = MLB_USIO_ESCR_L_8BIT;

> +		break;

> +	}

> +

> +	if (termios->c_cflag & CSTOPB)

> +		smr |= MLB_USIO_SMR_SBL;

> +

> +	if (termios->c_cflag & PARENB) {

> +		escr |= MLB_USIO_ESCR_PEN;

> +		if (termios->c_cflag & PARODD)

> +			escr |= MLB_USIO_ESCR_P;

> +	}


If you don't suport CMSPAR then clear that bit in termios as well

> +	/* Set hard flow control */

> +	if (of_property_read_bool(port->dev->of_node, "auto-flow-control") ||

> +			(termios->c_cflag & CRTSCTS))

> +		escr |= MLB_USIO_ESCR_FLWEN;


That's just broken. The termios bits are the definitive things for the
port, and in addition even if they are forced you need to correct the
termios data.

You might want to control flow control *at boot* with an OF property but
doing it post boot is just busted.

Alan

Patch

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 72966bc..d1971a8 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1582,6 +1582,32 @@  config SERIAL_RDA_CONSOLE
 	  Say 'Y' here if you wish to use the RDA8810PL UART as the system
 	  console. Only earlycon is implemented currently.
 
+config SERIAL_MILBEAUT_USIO
+	tristate "Milbeaut USIO/UART serial port support"
+	depends on ARCH_MILBEAUT || (COMPILE_TEST && OF)
+	default ARCH_MILBEAUT
+	select SERIAL_CORE
+	help
+	  This selects the USIO/UART IP found in Socionext Milbeaut SoCs.
+
+config SERIAL_MILBEAUT_USIO_PORTS
+	int "Maximum number of CSIO/UART ports (1-8)"
+	range 1 8
+	depends on SERIAL_MILBEAUT_USIO
+	default "4"
+
+config SERIAL_MILBEAUT_USIO_CONSOLE
+	bool "Support for console on MILBEAUT USIO/UART serial port"
+	depends on SERIAL_MILBEAUT_USIO=y
+	default y
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	help
+	  Say 'Y' here if you wish to use a USIO/UART of Socionext Milbeaut
+	  SoCs as the system console (the system console is the device which
+	  receives all kernel messages and warnings and which allows logins in
+	  single user mode).
+
 endmenu
 
 config SERIAL_MCTRL_GPIO
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 40b702a..43ca2d0 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -92,6 +92,7 @@  obj-$(CONFIG_SERIAL_PIC32)	+= pic32_uart.o
 obj-$(CONFIG_SERIAL_MPS2_UART)	+= mps2-uart.o
 obj-$(CONFIG_SERIAL_OWL)	+= owl-uart.o
 obj-$(CONFIG_SERIAL_RDA)	+= rda-uart.o
+obj-$(CONFIG_SERIAL_MILBEAUT_USIO) += milbeaut_usio.o
 
 # GPIOLIB helpers for modem control lines
 obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c
new file mode 100644
index 0000000..4a10604
--- /dev/null
+++ b/drivers/tty/serial/milbeaut_usio.c
@@ -0,0 +1,621 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Socionext Inc.
+ */
+
+#if defined(CONFIG_SERIAL_MILBEAUT_USIO_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#define USIO_NAME		"mlb-usio-uart"
+#define USIO_UART_DEV_NAME	"ttyUSI"
+
+static struct uart_port mlb_usio_ports[CONFIG_SERIAL_MILBEAUT_USIO_PORTS];
+
+#define RX	0
+#define TX	1
+static int mlb_usio_irq[CONFIG_SERIAL_MILBEAUT_USIO_PORTS][2];
+
+#define MLB_USIO_REG_SMR		0
+#define MLB_USIO_REG_SCR		1
+#define MLB_USIO_REG_ESCR		2
+#define MLB_USIO_REG_SSR		3
+#define MLB_USIO_REG_DR			4
+#define MLB_USIO_REG_BGR		6
+#define MLB_USIO_REG_FCR		12
+#define MLB_USIO_REG_FBYTE		14
+
+#define MLB_USIO_SMR_SOE		BIT(0)
+#define MLB_USIO_SMR_SBL		BIT(3)
+#define MLB_USIO_SCR_TXE		BIT(0)
+#define MLB_USIO_SCR_RXE		BIT(1)
+#define MLB_USIO_SCR_TBIE		BIT(2)
+#define MLB_USIO_SCR_TIE		BIT(3)
+#define MLB_USIO_SCR_RIE		BIT(4)
+#define MLB_USIO_SCR_UPCL		BIT(7)
+#define MLB_USIO_ESCR_L_8BIT		0
+#define MLB_USIO_ESCR_L_5BIT		1
+#define MLB_USIO_ESCR_L_6BIT		2
+#define MLB_USIO_ESCR_L_7BIT		3
+#define MLB_USIO_ESCR_P			BIT(3)
+#define MLB_USIO_ESCR_PEN		BIT(4)
+#define MLB_USIO_ESCR_FLWEN		BIT(7)
+#define MLB_USIO_SSR_TBI		BIT(0)
+#define MLB_USIO_SSR_TDRE		BIT(1)
+#define MLB_USIO_SSR_RDRF		BIT(2)
+#define MLB_USIO_SSR_ORE		BIT(3)
+#define MLB_USIO_SSR_FRE		BIT(4)
+#define MLB_USIO_SSR_PE			BIT(5)
+#define MLB_USIO_SSR_REC		BIT(7)
+#define MLB_USIO_SSR_BRK		BIT(8)
+#define MLB_USIO_FCR_FE1		BIT(0)
+#define MLB_USIO_FCR_FE2		BIT(1)
+#define MLB_USIO_FCR_FCL1		BIT(2)
+#define MLB_USIO_FCR_FCL2		BIT(3)
+#define MLB_USIO_FCR_FSET		BIT(4)
+#define MLB_USIO_FCR_FTIE		BIT(9)
+#define MLB_USIO_FCR_FDRQ		BIT(10)
+#define MLB_USIO_FCR_FRIIE		BIT(11)
+
+static void mlb_usio_stop_tx(struct uart_port *port)
+{
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FTIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) & ~MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_tx_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	int count;
+
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FTIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) &
+	       ~(MLB_USIO_SCR_TIE | MLB_USIO_SCR_TBIE),
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (port->x_char) {
+		writew(port->x_char, port->membase + MLB_USIO_REG_DR);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		mlb_usio_stop_tx(port);
+		return;
+	}
+
+	count = port->fifosize -
+		(readw(port->membase + MLB_USIO_REG_FBYTE) & 0xff);
+
+	do {
+		writew(xmit->buf[xmit->tail], port->membase + MLB_USIO_REG_DR);
+
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+
+	} while (--count > 0);
+
+	writew(readw(port->membase + MLB_USIO_REG_FCR) & ~MLB_USIO_FCR_FDRQ,
+	       port->membase + MLB_USIO_REG_FCR);
+
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) | MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit))
+		mlb_usio_stop_tx(port);
+}
+
+static void mlb_usio_start_tx(struct uart_port *port)
+{
+	u16 fcr = readw(port->membase + MLB_USIO_REG_FCR);
+
+	writew(fcr | MLB_USIO_FCR_FTIE, port->membase + MLB_USIO_REG_FCR);
+	if (!(fcr & MLB_USIO_FCR_FDRQ))
+		return;
+
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) | MLB_USIO_SCR_TBIE,
+	       port->membase + MLB_USIO_REG_SCR);
+
+	if (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI)
+		mlb_usio_tx_chars(port);
+}
+
+static void mlb_usio_stop_rx(struct uart_port *port)
+{
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) & ~MLB_USIO_SCR_RIE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_enable_ms(struct uart_port *port)
+{
+	writeb(readb(port->membase + MLB_USIO_REG_SCR) |
+	       MLB_USIO_SCR_RIE | MLB_USIO_SCR_RXE,
+	       port->membase + MLB_USIO_REG_SCR);
+}
+
+static void mlb_usio_rx_chars(struct uart_port *port)
+{
+	struct tty_port *ttyport = &port->state->port;
+	unsigned long flag = 0;
+	char ch = 0;
+	u8 status;
+	int max_count = 2;
+
+	while (max_count--) {
+		status = readb(port->membase + MLB_USIO_REG_SSR);
+
+		if (!(status & MLB_USIO_SSR_RDRF))
+			break;
+
+		if (!(status & (MLB_USIO_SSR_ORE | MLB_USIO_SSR_FRE |
+				MLB_USIO_SSR_PE))) {
+			ch = readw(port->membase + MLB_USIO_REG_DR);
+			flag = TTY_NORMAL;
+			port->icount.rx++;
+			if (uart_handle_sysrq_char(port, ch))
+				continue;
+			uart_insert_char(port, status, MLB_USIO_SSR_ORE,
+					 ch, flag);
+			continue;
+		}
+		if (status & MLB_USIO_SSR_PE)
+			port->icount.parity++;
+		if (status & MLB_USIO_SSR_ORE)
+			port->icount.overrun++;
+		status &= port->read_status_mask;
+		if (status & MLB_USIO_SSR_BRK) {
+			flag = TTY_BREAK;
+			ch = 0;
+		} else
+			if (status & MLB_USIO_SSR_PE) {
+				flag = TTY_PARITY;
+				ch = 0;
+			} else
+				if (status & MLB_USIO_SSR_FRE) {
+					flag = TTY_FRAME;
+					ch = 0;
+				}
+		if (flag)
+			uart_insert_char(port, status, MLB_USIO_SSR_ORE,
+					 ch, flag);
+
+		writeb(readb(port->membase + MLB_USIO_REG_SSR) |
+				MLB_USIO_SSR_REC,
+				port->membase + MLB_USIO_REG_SSR);
+
+		max_count = readw(port->membase + MLB_USIO_REG_FBYTE) >> 8;
+		writew(readw(port->membase + MLB_USIO_REG_FCR) |
+		       MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+		port->membase + MLB_USIO_REG_FCR);
+	}
+
+	tty_flip_buffer_push(ttyport);
+}
+
+static irqreturn_t mlb_usio_rx_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+
+	spin_lock(&port->lock);
+	mlb_usio_rx_chars(port);
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t mlb_usio_tx_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+
+	spin_lock(&port->lock);
+	if (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI)
+		mlb_usio_tx_chars(port);
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int mlb_usio_tx_empty(struct uart_port *port)
+{
+	return (readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TBI) ?
+		TIOCSER_TEMT : 0;
+}
+
+static void mlb_usio_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static unsigned int mlb_usio_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+
+}
+
+static void mlb_usio_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+static int mlb_usio_startup(struct uart_port *port)
+{
+	const char *portname = to_platform_device(port->dev)->name;
+	unsigned long flags;
+	int ret, index = port->line;
+	unsigned char  escr;
+
+	ret = request_irq(mlb_usio_irq[index][RX], mlb_usio_rx_irq,
+				0, portname, port);
+	if (ret)
+		return ret;
+	ret = request_irq(mlb_usio_irq[index][TX], mlb_usio_tx_irq,
+				0, portname, port);
+	if (ret) {
+		free_irq(mlb_usio_irq[index][RX], port);
+		return ret;
+	}
+
+	escr = readb(port->membase + MLB_USIO_REG_ESCR);
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control"))
+		escr |= MLB_USIO_ESCR_FLWEN;
+	spin_lock_irqsave(&port->lock, flags);
+	writeb(0, port->membase + MLB_USIO_REG_SCR);
+	writeb(escr, port->membase + MLB_USIO_REG_ESCR);
+	writeb(MLB_USIO_SCR_UPCL, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SSR_REC, port->membase + MLB_USIO_REG_SSR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FCL1 | MLB_USIO_FCR_FCL2,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FE1 | MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(0, port->membase + MLB_USIO_REG_FBYTE);
+	writew(BIT(12), port->membase + MLB_USIO_REG_FBYTE);
+
+	writeb(MLB_USIO_SCR_TXE  | MLB_USIO_SCR_RIE | MLB_USIO_SCR_TBIE |
+	       MLB_USIO_SCR_RXE, port->membase + MLB_USIO_REG_SCR);
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return 0;
+}
+
+static void mlb_usio_shutdown(struct uart_port *port)
+{
+	int index = port->line;
+
+	free_irq(mlb_usio_irq[index][RX], port);
+	free_irq(mlb_usio_irq[index][TX], port);
+}
+
+static void mlb_usio_set_termios(struct uart_port *port,
+			struct ktermios *termios, struct ktermios *old)
+{
+	unsigned int escr, smr = MLB_USIO_SMR_SOE;
+	unsigned long flags, baud, quot;
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		escr = MLB_USIO_ESCR_L_5BIT;
+		break;
+	case CS6:
+		escr = MLB_USIO_ESCR_L_6BIT;
+		break;
+	case CS7:
+		escr = MLB_USIO_ESCR_L_7BIT;
+		break;
+	case CS8:
+	default:
+		escr = MLB_USIO_ESCR_L_8BIT;
+		break;
+	}
+
+	if (termios->c_cflag & CSTOPB)
+		smr |= MLB_USIO_SMR_SBL;
+
+	if (termios->c_cflag & PARENB) {
+		escr |= MLB_USIO_ESCR_PEN;
+		if (termios->c_cflag & PARODD)
+			escr |= MLB_USIO_ESCR_P;
+	}
+	/* Set hard flow control */
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control") ||
+			(termios->c_cflag & CRTSCTS))
+		escr |= MLB_USIO_ESCR_FLWEN;
+
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk);
+	if (baud > 1)
+		quot = port->uartclk / baud - 1;
+	else
+		quot = 0;
+
+	spin_lock_irqsave(&port->lock, flags);
+	uart_update_timeout(port, termios->c_cflag, baud);
+	port->read_status_mask = MLB_USIO_SSR_ORE | MLB_USIO_SSR_RDRF |
+				 MLB_USIO_SSR_TDRE;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= MLB_USIO_SSR_FRE | MLB_USIO_SSR_PE;
+
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask |= MLB_USIO_SSR_FRE | MLB_USIO_SSR_PE;
+	if ((termios->c_iflag & IGNBRK) && (termios->c_iflag & IGNPAR))
+		port->ignore_status_mask |= MLB_USIO_SSR_ORE;
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= MLB_USIO_SSR_RDRF;
+
+	writeb(0, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SCR_UPCL, port->membase + MLB_USIO_REG_SCR);
+	writeb(MLB_USIO_SSR_REC, port->membase + MLB_USIO_REG_SSR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writeb(smr, port->membase + MLB_USIO_REG_SMR);
+	writeb(escr, port->membase + MLB_USIO_REG_ESCR);
+	writew(quot, port->membase + MLB_USIO_REG_BGR);
+	writew(0, port->membase + MLB_USIO_REG_FCR);
+	writew(MLB_USIO_FCR_FCL1 | MLB_USIO_FCR_FCL2 | MLB_USIO_FCR_FE1 |
+	       MLB_USIO_FCR_FE2 | MLB_USIO_FCR_FRIIE,
+	       port->membase + MLB_USIO_REG_FCR);
+	writew(0, port->membase + MLB_USIO_REG_FBYTE);
+	writew(BIT(12), port->membase + MLB_USIO_REG_FBYTE);
+	writeb(MLB_USIO_SCR_RIE | MLB_USIO_SCR_RXE | MLB_USIO_SCR_TBIE |
+	       MLB_USIO_SCR_TXE, port->membase + MLB_USIO_REG_SCR);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *mlb_usio_type(struct uart_port *port)
+{
+	return ((port->type == PORT_MLB_USIO) ? USIO_NAME : NULL);
+}
+
+static void mlb_usio_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_MLB_USIO;
+}
+
+static const struct uart_ops mlb_usio_ops = {
+	.tx_empty	= mlb_usio_tx_empty,
+	.set_mctrl	= mlb_usio_set_mctrl,
+	.get_mctrl	= mlb_usio_get_mctrl,
+	.stop_tx	= mlb_usio_stop_tx,
+	.start_tx	= mlb_usio_start_tx,
+	.stop_rx	= mlb_usio_stop_rx,
+	.enable_ms	= mlb_usio_enable_ms,
+	.break_ctl	= mlb_usio_break_ctl,
+	.startup	= mlb_usio_startup,
+	.shutdown	= mlb_usio_shutdown,
+	.set_termios	= mlb_usio_set_termios,
+	.type		= mlb_usio_type,
+	.config_port	= mlb_usio_config_port,
+};
+
+#ifdef CONFIG_SERIAL_MILBEAUT_USIO_CONSOLE
+
+static void mlb_usio_console_putchar(struct uart_port *port, int c)
+{
+	while (!(readb(port->membase + MLB_USIO_REG_SSR) & MLB_USIO_SSR_TDRE))
+		cpu_relax();
+
+	writew(c, port->membase + MLB_USIO_REG_DR);
+}
+
+static void mlb_usio_console_write(struct console *co, const char *s,
+			       unsigned int count)
+{
+	struct uart_port *port = &mlb_usio_ports[co->index];
+
+	uart_console_write(port, s, count, mlb_usio_console_putchar);
+}
+
+static int __init mlb_usio_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port;
+	int baud = 115200;
+	int parity = 'n';
+	int flow = 'n';
+	int bits = 8;
+
+	if (co->index >= CONFIG_SERIAL_MILBEAUT_USIO_PORTS)
+		return -ENODEV;
+
+	port = &mlb_usio_ports[co->index];
+	if (!port->membase)
+		return -ENODEV;
+
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	if (of_property_read_bool(port->dev->of_node, "auto-flow-control"))
+		flow = 'r';
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+
+static struct uart_driver mlb_usio_uart_driver;
+static struct console mlb_usio_console = {
+	.name   = USIO_UART_DEV_NAME,
+	.write  = mlb_usio_console_write,
+	.device = uart_console_device,
+	.setup  = mlb_usio_console_setup,
+	.flags  = CON_PRINTBUFFER,
+	.index  = -1,
+	.data   = &mlb_usio_uart_driver,
+};
+
+static int __init mlb_usio_console_init(void)
+{
+	register_console(&mlb_usio_console);
+	return 0;
+}
+console_initcall(mlb_usio_console_init);
+
+
+static void mlb_usio_early_console_write(struct console *co, const char *s,
+					u_int count)
+{
+	struct earlycon_device *dev = co->data;
+
+	uart_console_write(&dev->port, s, count, mlb_usio_console_putchar);
+}
+
+static int __init mlb_usio_early_console_setup(struct earlycon_device *device,
+						const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+	device->con->write = mlb_usio_early_console_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(mlb_usio, "socionext,milbeaut-usio-uart",
+			mlb_usio_early_console_setup);
+
+#define USIO_CONSOLE	(&mlb_usio_console)
+#else
+#define USIO_CONSOLE	NULL
+#endif
+
+static struct  uart_driver mlb_usio_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= USIO_NAME,
+	.dev_name	= USIO_UART_DEV_NAME,
+	.cons           = USIO_CONSOLE,
+	.nr		= CONFIG_SERIAL_MILBEAUT_USIO_PORTS,
+};
+
+static int mlb_usio_probe(struct platform_device *pdev)
+{
+	struct clk *clk = devm_clk_get(&pdev->dev, NULL);
+	struct uart_port *port;
+	struct resource *res;
+	int index = 0;
+	int ret;
+
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "Missing clock\n");
+		return PTR_ERR(clk);
+	}
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Clock enable failed: %d\n", ret);
+		return ret;
+	}
+	of_property_read_u32(pdev->dev.of_node, "index", &index);
+	port = &mlb_usio_ports[index];
+
+	port->private_data = (void *)clk;
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(&pdev->dev, "Missing regs\n");
+		ret = -ENODEV;
+		goto failed;
+	}
+	port->mapbase = res->start;
+	port->membase = ioremap(res->start, (res->end - res->start + 1));
+	port->membase = devm_ioremap(&pdev->dev, res->start,
+				resource_size(res));
+
+	ret = platform_get_irq_byname(pdev, "rx");
+	mlb_usio_irq[index][RX] = ret;
+
+	ret = platform_get_irq_byname(pdev, "tx");
+	mlb_usio_irq[index][TX] = ret;
+
+	port->irq = mlb_usio_irq[index][RX];
+	port->uartclk = clk_get_rate(clk);
+	port->fifosize = 128;
+	port->iotype = UPIO_MEM32;
+	port->flags = UPF_BOOT_AUTOCONF | UPF_SPD_VHI;
+	port->line = index;
+	port->ops = &mlb_usio_ops;
+	port->dev = &pdev->dev;
+
+	ret = uart_add_one_port(&mlb_usio_uart_driver, port);
+	if (ret) {
+		dev_err(&pdev->dev, "Adding port failed: %d\n", ret);
+		goto failed1;
+	}
+	return 0;
+
+failed1:
+	iounmap(port->membase);
+
+failed:
+	clk_disable_unprepare(clk);
+	clk_put(clk);
+
+	return ret;
+}
+
+static int mlb_usio_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = &mlb_usio_ports[pdev->id];
+	struct clk *clk = port->private_data;
+
+	uart_remove_one_port(&mlb_usio_uart_driver, port);
+	clk_disable_unprepare(clk);
+	clk_put(clk);
+
+	return 0;
+}
+
+static const struct of_device_id mlb_usio_dt_ids[] = {
+	{ .compatible = "socionext,milbeaut-usio-uart" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mlb_usio_dt_ids);
+
+static struct platform_driver mlb_usio_driver = {
+	.probe          = mlb_usio_probe,
+	.remove         = mlb_usio_remove,
+	.driver         = {
+		.name   = USIO_NAME,
+		.of_match_table = mlb_usio_dt_ids,
+	},
+};
+
+static int __init mlb_usio_init(void)
+{
+	int ret = uart_register_driver(&mlb_usio_uart_driver);
+
+	if (ret) {
+		pr_err("%s: uart registration failed: %d\n", __func__, ret);
+		return ret;
+	}
+	ret = platform_driver_register(&mlb_usio_driver);
+	if (ret) {
+		uart_unregister_driver(&mlb_usio_uart_driver);
+		pr_err("%s: drv registration failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit mlb_usio_exit(void)
+{
+	platform_driver_unregister(&mlb_usio_driver);
+	uart_unregister_driver(&mlb_usio_uart_driver);
+}
+
+module_init(mlb_usio_init);
+module_exit(mlb_usio_exit);
+
+MODULE_AUTHOR("SOCIONEXT");
+MODULE_DESCRIPTION("MILBEAUT_USIO/UART Driver");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 6009ee2..a51c747 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -287,4 +287,7 @@ 
 /* RDA UART */
 #define PORT_RDA	118
 
+/* Socionext Milbeaut UART */
+#define PORT_MLB_USIO	119
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */