serial:st-asc: Add ST ASC driver.

This patch adds support to ASC (asynchronous serial controller)
driver, which is basically a standard serial driver. This IP is common
across all the ST parts for settop box platforms.

ASC is embedded in ST COMMS IP block. It supports Rx & Tx functionality.
It support all industry standard baud rates.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
CC: Stephen Gallimore <stephen.gallimore@st.com>
CC: Stuart Menefy <stuart.menefy@st.com>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 937 insertions, 0 deletions

diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
new file mode 100644
index 000000000000..183879825695
--- /dev/null
+++ b/drivers/tty/serial/st-asc.c
@@ -0,0 +1,937 @@
+/*
+ * st-asc.c: ST Asynchronous serial controller (ASC) driver
+ *
+ * Copyright (C) 2003-2013 STMicroelectronics (R&D) Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#if defined(CONFIG_SERIAL_ST_ASC_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/module.h>
+#include <linux/serial.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/serial_core.h>
+#include <linux/clk.h>
+
+#define DRIVER_NAME "st-asc"
+#define ASC_SERIAL_NAME "ttyAS"
+#define ASC_FIFO_SIZE 16
+#define ASC_MAX_PORTS 8
+
+struct asc_port {
+	struct uart_port port;
+	struct clk *clk;
+	unsigned int hw_flow_control:1;
+	unsigned int force_m1:1;
+};
+
+static struct asc_port asc_ports[ASC_MAX_PORTS];
+static struct uart_driver asc_uart_driver;
+
+/*---- UART Register definitions ------------------------------*/
+
+/* Register offsets */
+
+#define ASC_BAUDRATE			0x00
+#define ASC_TXBUF			0x04
+#define ASC_RXBUF			0x08
+#define ASC_CTL				0x0C
+#define ASC_INTEN			0x10
+#define ASC_STA				0x14
+#define ASC_GUARDTIME			0x18
+#define ASC_TIMEOUT			0x1C
+#define ASC_TXRESET			0x20
+#define ASC_RXRESET			0x24
+#define ASC_RETRIES			0x28
+
+/* ASC_RXBUF */
+#define ASC_RXBUF_PE			0x100
+#define ASC_RXBUF_FE			0x200
+/**
+ * Some of status comes from higher bits of the character and some come from
+ * the status register. Combining both of them in to single status using dummy
+ * bits.
+ */
+#define ASC_RXBUF_DUMMY_RX		0x10000
+#define ASC_RXBUF_DUMMY_BE		0x20000
+#define ASC_RXBUF_DUMMY_OE		0x40000
+
+/* ASC_CTL */
+
+#define ASC_CTL_MODE_MSK		0x0007
+#define  ASC_CTL_MODE_8BIT		0x0001
+#define  ASC_CTL_MODE_7BIT_PAR		0x0003
+#define  ASC_CTL_MODE_9BIT		0x0004
+#define  ASC_CTL_MODE_8BIT_WKUP		0x0005
+#define  ASC_CTL_MODE_8BIT_PAR		0x0007
+#define ASC_CTL_STOP_MSK		0x0018
+#define  ASC_CTL_STOP_HALFBIT		0x0000
+#define  ASC_CTL_STOP_1BIT		0x0008
+#define  ASC_CTL_STOP_1_HALFBIT		0x0010
+#define  ASC_CTL_STOP_2BIT		0x0018
+#define ASC_CTL_PARITYODD		0x0020
+#define ASC_CTL_LOOPBACK		0x0040
+#define ASC_CTL_RUN			0x0080
+#define ASC_CTL_RXENABLE		0x0100
+#define ASC_CTL_SCENABLE		0x0200
+#define ASC_CTL_FIFOENABLE		0x0400
+#define ASC_CTL_CTSENABLE		0x0800
+#define ASC_CTL_BAUDMODE		0x1000
+
+/* ASC_GUARDTIME */
+
+#define ASC_GUARDTIME_MSK		0x00FF
+
+/* ASC_INTEN */
+
+#define ASC_INTEN_RBE			0x0001
+#define ASC_INTEN_TE			0x0002
+#define ASC_INTEN_THE			0x0004
+#define ASC_INTEN_PE			0x0008
+#define ASC_INTEN_FE			0x0010
+#define ASC_INTEN_OE			0x0020
+#define ASC_INTEN_TNE			0x0040
+#define ASC_INTEN_TOI			0x0080
+#define ASC_INTEN_RHF			0x0100
+
+/* ASC_RETRIES */
+
+#define ASC_RETRIES_MSK			0x00FF
+
+/* ASC_RXBUF */
+
+#define ASC_RXBUF_MSK			0x03FF
+
+/* ASC_STA */
+
+#define ASC_STA_RBF			0x0001
+#define ASC_STA_TE			0x0002
+#define ASC_STA_THE			0x0004
+#define ASC_STA_PE			0x0008
+#define ASC_STA_FE			0x0010
+#define ASC_STA_OE			0x0020
+#define ASC_STA_TNE			0x0040
+#define ASC_STA_TOI			0x0080
+#define ASC_STA_RHF			0x0100
+#define ASC_STA_TF			0x0200
+#define ASC_STA_NKD			0x0400
+
+/* ASC_TIMEOUT */
+
+#define ASC_TIMEOUT_MSK			0x00FF
+
+/* ASC_TXBUF */
+
+#define ASC_TXBUF_MSK			0x01FF
+
+/*---- Inline function definitions ---------------------------*/
+
+static inline struct asc_port *to_asc_port(struct uart_port *port)
+{
+	return container_of(port, struct asc_port, port);
+}
+
+static inline u32 asc_in(struct uart_port *port, u32 offset)
+{
+	return readl(port->membase + offset);
+}
+
+static inline void asc_out(struct uart_port *port, u32 offset, u32 value)
+{
+	writel(value, port->membase + offset);
+}
+
+/*
+ * Some simple utility functions to enable and disable interrupts.
+ * Note that these need to be called with interrupts disabled.
+ */
+static inline void asc_disable_tx_interrupts(struct uart_port *port)
+{
+	u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_THE;
+	asc_out(port, ASC_INTEN, intenable);
+	(void)asc_in(port, ASC_INTEN);	/* Defeat bus write posting */
+}
+
+static inline void asc_enable_tx_interrupts(struct uart_port *port)
+{
+	u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_THE;
+	asc_out(port, ASC_INTEN, intenable);
+}
+
+static inline void asc_disable_rx_interrupts(struct uart_port *port)
+{
+	u32 intenable = asc_in(port, ASC_INTEN) & ~ASC_INTEN_RBE;
+	asc_out(port, ASC_INTEN, intenable);
+	(void)asc_in(port, ASC_INTEN);	/* Defeat bus write posting */
+}
+
+static inline void asc_enable_rx_interrupts(struct uart_port *port)
+{
+	u32 intenable = asc_in(port, ASC_INTEN) | ASC_INTEN_RBE;
+	asc_out(port, ASC_INTEN, intenable);
+}
+
+static inline u32 asc_txfifo_is_empty(struct uart_port *port)
+{
+	return asc_in(port, ASC_STA) & ASC_STA_TE;
+}
+
+static inline int asc_txfifo_is_full(struct uart_port *port)
+{
+	return asc_in(port, ASC_STA) & ASC_STA_TF;
+}
+
+static inline const char *asc_port_name(struct uart_port *port)
+{
+	return to_platform_device(port->dev)->name;
+}
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * This section contains code to support the use of the ASC as a
+ * generic serial port.
+ */
+
+static inline unsigned asc_hw_txroom(struct uart_port *port)
+{
+	u32 status = asc_in(port, ASC_STA);
+
+	if (status & ASC_STA_THE)
+		return port->fifosize / 2;
+	else if (!(status & ASC_STA_TF))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Start transmitting chars.
+ * This is called from both interrupt and task level.
+ * Either way interrupts are disabled.
+ */
+static void asc_transmit_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	int txroom;
+	unsigned char c;
+
+	txroom = asc_hw_txroom(port);
+
+	if ((txroom != 0) && port->x_char) {
+		c = port->x_char;
+		port->x_char = 0;
+		asc_out(port, ASC_TXBUF, c);
+		port->icount.tx++;
+		txroom = asc_hw_txroom(port);
+	}
+
+	if (uart_tx_stopped(port)) {
+		/*
+		 * We should try and stop the hardware here, but I
+		 * don't think the ASC has any way to do that.
+		 */
+		asc_disable_tx_interrupts(port);
+		return;
+	}
+
+	if (uart_circ_empty(xmit)) {
+		asc_disable_tx_interrupts(port);
+		return;
+	}
+
+	if (txroom == 0)
+		return;
+
+	do {
+		c = xmit->buf[xmit->tail];
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		asc_out(port, ASC_TXBUF, c);
+		port->icount.tx++;
+		txroom--;
+	} while ((txroom > 0) && (!uart_circ_empty(xmit)));
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit))
+		asc_disable_tx_interrupts(port);
+}
+
+static void asc_receive_chars(struct uart_port *port)
+{
+	struct tty_port *tport = &port->state->port;
+	unsigned long status;
+	unsigned long c = 0;
+	char flag;
+
+	if (port->irq_wake)
+		pm_wakeup_event(tport->tty->dev, 0);
+
+	while ((status = asc_in(port, ASC_STA)) & ASC_STA_RBF) {
+		c = asc_in(port, ASC_RXBUF) | ASC_RXBUF_DUMMY_RX;
+		flag = TTY_NORMAL;
+		port->icount.rx++;
+
+		if ((c & (ASC_RXBUF_FE | ASC_RXBUF_PE)) ||
+			status & ASC_STA_OE) {
+
+			if (c & ASC_RXBUF_FE) {
+				if (c == ASC_RXBUF_FE) {
+					port->icount.brk++;
+					if (uart_handle_break(port))
+						continue;
+					c |= ASC_RXBUF_DUMMY_BE;
+				} else {
+					port->icount.frame++;
+				}
+			} else if (c & ASC_RXBUF_PE) {
+				port->icount.parity++;
+			}
+			/*
+			 * Reading any data from the RX FIFO clears the
+			 * overflow error condition.
+			 */
+			if (status & ASC_STA_OE) {
+				port->icount.overrun++;
+				c |= ASC_RXBUF_DUMMY_OE;
+			}
+
+			c &= port->read_status_mask;
+
+			if (c & ASC_RXBUF_DUMMY_BE)
+				flag = TTY_BREAK;
+			else if (c & ASC_RXBUF_PE)
+				flag = TTY_PARITY;
+			else if (c & ASC_RXBUF_FE)
+				flag = TTY_FRAME;
+		}
+
+		if (uart_handle_sysrq_char(port, c))
+			continue;
+
+		uart_insert_char(port, c, ASC_RXBUF_DUMMY_OE, c & 0xff, flag);
+	}
+
+	/* Tell the rest of the system the news. New characters! */
+	tty_flip_buffer_push(tport);
+}
+
+static irqreturn_t asc_interrupt(int irq, void *ptr)
+{
+	struct uart_port *port = ptr;
+	u32 status;
+
+	spin_lock(&port->lock);
+
+	status = asc_in(port, ASC_STA);
+
+	if (status & ASC_STA_RBF) {
+		/* Receive FIFO not empty */
+		asc_receive_chars(port);
+	}
+
+	if ((status & ASC_STA_THE) &&
+	    (asc_in(port, ASC_INTEN) & ASC_INTEN_THE)) {
+		/* Transmitter FIFO at least half empty */
+		asc_transmit_chars(port);
+	}
+
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * UART Functions
+ */
+
+static unsigned int asc_tx_empty(struct uart_port *port)
+{
+	return asc_txfifo_is_empty(port) ? TIOCSER_TEMT : 0;
+}
+
+static void asc_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	/*
+	 * This routine is used for seting signals of: DTR, DCD, CTS/RTS
+	 * We use ASC's hardware for CTS/RTS, so don't need any for that.
+	 * Some boards have DTR and DCD implemented using PIO pins,
+	 * code to do this should be hooked in here.
+	 */
+}
+
+static unsigned int asc_get_mctrl(struct uart_port *port)
+{
+	/*
+	 * This routine is used for geting signals of: DTR, DCD, DSR, RI,
+	 * and CTS/RTS
+	 */
+	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+}
+
+/* There are probably characters waiting to be transmitted. */
+static void asc_start_tx(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+
+	if (!uart_circ_empty(xmit))
+		asc_enable_tx_interrupts(port);
+}
+
+/* Transmit stop */
+static void asc_stop_tx(struct uart_port *port)
+{
+	asc_disable_tx_interrupts(port);
+}
+
+/* Receive stop */
+static void asc_stop_rx(struct uart_port *port)
+{
+	asc_disable_rx_interrupts(port);
+}
+
+/* Force modem status interrupts on */
+static void asc_enable_ms(struct uart_port *port)
+{
+	/* Nothing here yet .. */
+}
+
+/* Handle breaks - ignored by us */
+static void asc_break_ctl(struct uart_port *port, int break_state)
+{
+	/* Nothing here yet .. */
+}
+
+/*
+ * Enable port for reception.
+ */
+static int asc_startup(struct uart_port *port)
+{
+	if (request_irq(port->irq, asc_interrupt, IRQF_NO_SUSPEND,
+			asc_port_name(port), port)) {
+		dev_err(port->dev, "cannot allocate irq.\n");
+		return -ENODEV;
+	}
+
+	asc_transmit_chars(port);
+	asc_enable_rx_interrupts(port);
+
+	return 0;
+}
+
+static void asc_shutdown(struct uart_port *port)
+{
+	asc_disable_tx_interrupts(port);
+	asc_disable_rx_interrupts(port);
+	free_irq(port->irq, port);
+}
+
+static void asc_pm(struct uart_port *port, unsigned int state,
+		unsigned int oldstate)
+{
+	struct asc_port *ascport = to_asc_port(port);
+	unsigned long flags = 0;
+	u32 ctl;
+
+	switch (state) {
+	case UART_PM_STATE_ON:
+		clk_prepare_enable(ascport->clk);
+		break;
+	case UART_PM_STATE_OFF:
+		/*
+		 * Disable the ASC baud rate generator, which is as close as
+		 * we can come to turning it off. Note this is not called with
+		 * the port spinlock held.
+		 */
+		spin_lock_irqsave(&port->lock, flags);
+		ctl = asc_in(port, ASC_CTL) & ~ASC_CTL_RUN;
+		asc_out(port, ASC_CTL, ctl);
+		spin_unlock_irqrestore(&port->lock, flags);
+		clk_disable_unprepare(ascport->clk);
+		break;
+	}
+}
+
+static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
+			    struct ktermios *old)
+{
+	struct asc_port *ascport = to_asc_port(port);
+	unsigned int baud;
+	u32 ctrl_val;
+	tcflag_t cflag;
+	unsigned long flags;
+
+	/* Update termios to reflect hardware capabilities */
+	termios->c_cflag &= ~(CMSPAR |
+			 (ascport->hw_flow_control ? 0 : CRTSCTS));
+
+	port->uartclk = clk_get_rate(ascport->clk);
+
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
+	cflag = termios->c_cflag;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* read control register */
+	ctrl_val = asc_in(port, ASC_CTL);
+
+	/* stop serial port and reset value */
+	asc_out(port, ASC_CTL, (ctrl_val & ~ASC_CTL_RUN));
+	ctrl_val = ASC_CTL_RXENABLE | ASC_CTL_FIFOENABLE;
+
+	/* reset fifo rx & tx */
+	asc_out(port, ASC_TXRESET, 1);
+	asc_out(port, ASC_RXRESET, 1);
+
+	/* set character length */
+	if ((cflag & CSIZE) == CS7) {
+		ctrl_val |= ASC_CTL_MODE_7BIT_PAR;
+	} else {
+		ctrl_val |= (cflag & PARENB) ?  ASC_CTL_MODE_8BIT_PAR :
+						ASC_CTL_MODE_8BIT;
+	}
+
+	/* set stop bit */
+	ctrl_val |= (cflag & CSTOPB) ? ASC_CTL_STOP_2BIT : ASC_CTL_STOP_1BIT;
+
+	/* odd parity */
+	if (cflag & PARODD)
+		ctrl_val |= ASC_CTL_PARITYODD;
+
+	/* hardware flow control */
+	if ((cflag & CRTSCTS))
+		ctrl_val |= ASC_CTL_CTSENABLE;
+
+	if ((baud < 19200) && !ascport->force_m1) {
+		asc_out(port, ASC_BAUDRATE, (port->uartclk / (16 * baud)));
+	} else {
+		/*
+		 * MODE 1: recommended for high bit rates (above 19.2K)
+		 *
+		 *                   baudrate * 16 * 2^16
+		 * ASCBaudRate =   ------------------------
+		 *                          inputclock
+		 *
+		 * However to keep the maths inside 32bits we divide top and
+		 * bottom by 64. The +1 is to avoid a divide by zero if the
+		 * input clock rate is something unexpected.
+		 */
+		u32 counter = (baud * 16384) / ((port->uartclk / 64) + 1);
+		asc_out(port, ASC_BAUDRATE, counter);
+		ctrl_val |= ASC_CTL_BAUDMODE;
+	}
+
+	uart_update_timeout(port, cflag, baud);
+
+	ascport->port.read_status_mask = ASC_RXBUF_DUMMY_OE;
+	if (termios->c_iflag & INPCK)
+		ascport->port.read_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE;
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		ascport->port.read_status_mask |= ASC_RXBUF_DUMMY_BE;
+
+	/*
+	 * Characters to ignore
+	 */
+	ascport->port.ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		ascport->port.ignore_status_mask |= ASC_RXBUF_FE | ASC_RXBUF_PE;
+	if (termios->c_iflag & IGNBRK) {
+		ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_BE;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_OE;
+	}
+
+	/*
+	 * Ignore all characters if CREAD is not set.
+	 */
+	if (!(termios->c_cflag & CREAD))
+		ascport->port.ignore_status_mask |= ASC_RXBUF_DUMMY_RX;
+
+	/* Set the timeout */
+	asc_out(port, ASC_TIMEOUT, 20);
+
+	/* write final value and enable port */
+	asc_out(port, ASC_CTL, (ctrl_val | ASC_CTL_RUN));
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *asc_type(struct uart_port *port)
+{
+	return (port->type == PORT_ASC) ? DRIVER_NAME : NULL;
+}
+
+static void asc_release_port(struct uart_port *port)
+{
+}
+
+static int asc_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+/*
+ * Called when the port is opened, and UPF_BOOT_AUTOCONF flag is set
+ * Set type field if successful
+ */
+static void asc_config_port(struct uart_port *port, int flags)
+{
+	if ((flags & UART_CONFIG_TYPE))
+		port->type = PORT_ASC;
+}
+
+static int
+asc_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	/* No user changeable parameters */
+	return -EINVAL;
+}
+
+#ifdef CONFIG_CONSOLE_POLL
+/*
+ * Console polling routines for writing and reading from the uart while
+ * in an interrupt or debug context (i.e. kgdb).
+ */
+
+static int asc_get_poll_char(struct uart_port *port)
+{
+	if (!(asc_in(port, ASC_STA) & ASC_STA_RBF))
+		return NO_POLL_CHAR;
+
+	return asc_in(port, ASC_RXBUF);
+}
+
+static void asc_put_poll_char(struct uart_port *port, unsigned char c)
+{
+	while (asc_txfifo_is_full(port))
+		cpu_relax();
+	asc_out(port, ASC_TXBUF, c);
+}
+
+#endif /* CONFIG_CONSOLE_POLL */
+
+/*---------------------------------------------------------------------*/
+
+static struct uart_ops asc_uart_ops = {
+	.tx_empty	= asc_tx_empty,
+	.set_mctrl	= asc_set_mctrl,
+	.get_mctrl	= asc_get_mctrl,
+	.start_tx	= asc_start_tx,
+	.stop_tx	= asc_stop_tx,
+	.stop_rx	= asc_stop_rx,
+	.enable_ms	= asc_enable_ms,
+	.break_ctl	= asc_break_ctl,
+	.startup	= asc_startup,
+	.shutdown	= asc_shutdown,
+	.set_termios	= asc_set_termios,
+	.type		= asc_type,
+	.release_port	= asc_release_port,
+	.request_port	= asc_request_port,
+	.config_port	= asc_config_port,
+	.verify_port	= asc_verify_port,
+	.pm		= asc_pm,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_get_char = asc_get_poll_char,
+	.poll_put_char = asc_put_poll_char,
+#endif /* CONFIG_CONSOLE_POLL */
+};
+
+static int asc_init_port(struct asc_port *ascport,
+			  struct platform_device *pdev)
+{
+	struct uart_port *port = &ascport->port;
+	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	if (!res) {
+		dev_err(&pdev->dev, "Unable to get io resource\n");
+		return -ENODEV;
+	}
+
+	port->iotype	= UPIO_MEM;
+	port->flags	= UPF_BOOT_AUTOCONF;
+	port->ops	= &asc_uart_ops;
+	port->fifosize	= ASC_FIFO_SIZE;
+	port->dev	= &pdev->dev;
+	port->mapbase	= res->start;
+	port->irq	= platform_get_irq(pdev, 0);
+
+	port->membase = devm_request_and_ioremap(&pdev->dev, res);
+	if (!port->membase) {
+		dev_err(&pdev->dev, "Unable to request io memory\n");
+		return -ENODEV;
+	}
+
+	spin_lock_init(&port->lock);
+
+	ascport->clk = devm_clk_get(&pdev->dev, NULL);
+
+	if (WARN_ON(IS_ERR(ascport->clk)))
+		return -EINVAL;
+	/* ensure that clk rate is correct by enabling the clk */
+	clk_prepare_enable(ascport->clk);
+	ascport->port.uartclk = clk_get_rate(ascport->clk);
+	WARN_ON(ascport->port.uartclk == 0);
+	clk_disable_unprepare(ascport->clk);
+
+	return 0;
+}
+
+static struct asc_port *asc_of_get_asc_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, ASC_SERIAL_NAME);
+
+	if (id < 0)
+		id = 0;
+
+	if (WARN_ON(id >= ASC_MAX_PORTS))
+		return NULL;
+
+	asc_ports[id].hw_flow_control = of_property_read_bool(np,
+							"st,hw-flow-control");
+	asc_ports[id].force_m1 =  of_property_read_bool(np, "st,force_m1");
+	asc_ports[id].port.line = id;
+	return &asc_ports[id];
+}
+
+static struct of_device_id asc_match[] = {
+	{ .compatible = "st,asc", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, asc_match);
+
+static int asc_serial_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct asc_port *ascport;
+
+	ascport = asc_of_get_asc_port(pdev);
+	if (!ascport)
+		return -ENODEV;
+
+	ret = asc_init_port(ascport, pdev);
+	if (ret)
+		return ret;
+
+	ret = uart_add_one_port(&asc_uart_driver, &ascport->port);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, &ascport->port);
+
+	return 0;
+}
+
+static int asc_serial_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = platform_get_drvdata(pdev);
+
+	platform_set_drvdata(pdev, NULL);
+	return uart_remove_one_port(&asc_uart_driver, port);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int asc_serial_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+
+	return uart_suspend_port(&asc_uart_driver, port);
+}
+
+static int asc_serial_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+
+	return uart_resume_port(&asc_uart_driver, port);
+}
+
+#endif /* CONFIG_PM_SLEEP */
+
+/*----------------------------------------------------------------------*/
+
+#ifdef CONFIG_SERIAL_ST_ASC_CONSOLE
+static void asc_console_putchar(struct uart_port *port, int ch)
+{
+	unsigned int timeout = 1000000;
+
+	/* Wait for upto 1 second in case flow control is stopping us. */
+	while (--timeout && asc_txfifo_is_full(port))
+		udelay(1);
+
+	asc_out(port, ASC_TXBUF, ch);
+}
+
+/*
+ *  Print a string to the serial port trying not to disturb
+ *  any possible real use of the port...
+ */
+
+static void asc_console_write(struct console *co, const char *s, unsigned count)
+{
+	struct uart_port *port = &asc_ports[co->index].port;
+	unsigned long flags;
+	unsigned long timeout = 1000000;
+	int locked = 1;
+	u32 intenable;
+
+	local_irq_save(flags);
+	if (port->sysrq)
+		locked = 0; /* asc_interrupt has already claimed the lock */
+	else if (oops_in_progress)
+		locked = spin_trylock(&port->lock);
+	else
+		spin_lock(&port->lock);
+
+	/*
+	 * Disable interrupts so we don't get the IRQ line bouncing
+	 * up and down while interrupts are disabled.
+	 */
+	intenable = asc_in(port, ASC_INTEN);
+	asc_out(port, ASC_INTEN, 0);
+	(void)asc_in(port, ASC_INTEN);	/* Defeat bus write posting */
+
+	uart_console_write(port, s, count, asc_console_putchar);
+
+	while (--timeout && !asc_txfifo_is_empty(port))
+		udelay(1);
+
+	asc_out(port, ASC_INTEN, intenable);
+
+	if (locked)
+		spin_unlock(&port->lock);
+	local_irq_restore(flags);
+}
+
+static int asc_console_setup(struct console *co, char *options)
+{
+	struct asc_port *ascport;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index >= ASC_MAX_PORTS)
+		return -ENODEV;
+
+	ascport = &asc_ports[co->index];
+
+	/*
+	 * This driver does not support early console initialization
+	 * (use ARM early printk support instead), so we only expect
+	 * this to be called during the uart port registration when the
+	 * driver gets probed and the port should be mapped at that point.
+	 */
+	BUG_ON(ascport->port.mapbase == 0 || ascport->port.membase == NULL);
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(&ascport->port, co, baud, parity, bits, flow);
+}
+
+static struct console asc_console = {
+	.name		= ASC_SERIAL_NAME,
+	.device		= uart_console_device,
+	.write		= asc_console_write,
+	.setup		= asc_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &asc_uart_driver,
+};
+
+#define ASC_SERIAL_CONSOLE (&asc_console)
+
+#else
+#define ASC_SERIAL_CONSOLE NULL
+#endif /* CONFIG_SERIAL_ST_ASC_CONSOLE */
+
+static struct uart_driver asc_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= DRIVER_NAME,
+	.dev_name	= ASC_SERIAL_NAME,
+	.major		= 0,
+	.minor		= 0,
+	.nr		= ASC_MAX_PORTS,
+	.cons		= ASC_SERIAL_CONSOLE,
+};
+
+static const struct dev_pm_ops asc_serial_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(asc_serial_suspend, asc_serial_resume)
+};
+
+static struct platform_driver asc_serial_driver = {
+	.probe		= asc_serial_probe,
+	.remove		= asc_serial_remove,
+	.driver	= {
+		.name	= DRIVER_NAME,
+		.pm	= &asc_serial_pm_ops,
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(asc_match),
+	},
+};
+
+static int __init asc_init(void)
+{
+	int ret;
+	static char banner[] __initdata =
+		KERN_INFO "STMicroelectronics ASC driver initialized\n";
+
+	printk(banner);
+
+	ret = uart_register_driver(&asc_uart_driver);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&asc_serial_driver);
+	if (ret)
+		uart_unregister_driver(&asc_uart_driver);
+
+	return ret;
+}
+
+static void __exit asc_exit(void)
+{
+	platform_driver_unregister(&asc_serial_driver);
+	uart_unregister_driver(&asc_uart_driver);
+}
+
+module_init(asc_init);
+module_exit(asc_exit);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_AUTHOR("STMicroelectronics (R&D) Limited");
+MODULE_DESCRIPTION("STMicroelectronics ASC serial port driver");
+MODULE_LICENSE("GPL");