Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / tty / serial / st-asc.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * st-asc.c: ST Asynchronous serial controller (ASC) driver
 *
 * Copyright (C) 2003-2013 STMicroelectronics (R&D) Limited
 */

#include <linux/module.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/pinctrl/consumer.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/of.h>
#include <linux/of_platform.h>
#include <linux/serial_core.h>
#include <linux/clk.h>
#include <linux/gpio/consumer.h>

#define DRIVER_NAME "st-asc"
#define ASC_SERIAL_NAME "ttyAS"
#define ASC_FIFO_SIZE 16
#define ASC_MAX_PORTS 8

/* Pinctrl states */
#define DEFAULT         0
#define NO_HW_FLOWCTRL  1

struct asc_port {
        struct uart_port port;
        struct gpio_desc *rts;
        struct clk *clk;
        struct pinctrl *pinctrl;
        struct pinctrl_state *states[2];
        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)
{
#ifdef readl_relaxed
        return readl_relaxed(port->membase + offset);
#else
        return readl(port->membase + offset);
#endif
}

static inline void asc_out(struct uart_port *port, u32 offset, u32 value)
{
#ifdef writel_relaxed
        writel_relaxed(value, port->membase + offset);
#else
        writel(value, port->membase + offset);
#endif
}

/*
 * 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 u32 asc_txfifo_is_half_empty(struct uart_port *port)
{
        return asc_in(port, ASC_STA) & ASC_STA_THE;
}

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)
{
        u8 ch;

        uart_port_tx_limited(port, ch, asc_hw_txroom(port),
                true,
                asc_out(port, ASC_TXBUF, ch),
                ({}));
}

static void asc_receive_chars(struct uart_port *port)
{
        struct tty_port *tport = &port->state->port;
        unsigned long status, mode;
        unsigned long c = 0;
        u8 flag;
        bool ignore_pe = false;

        /*
         * Datasheet states: If the MODE field selects an 8-bit frame then
         * this [parity error] bit is undefined. Software should ignore this
         * bit when reading 8-bit frames.
         */
        mode = asc_in(port, ASC_CTL) & ASC_CTL_MODE_MSK;
        if (mode == ASC_CTL_MODE_8BIT || mode == ASC_CTL_MODE_8BIT_PAR)
                ignore_pe = true;

        if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
                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 (status & ASC_STA_OE || c & ASC_RXBUF_FE ||
                    (c & ASC_RXBUF_PE && !ignore_pe)) {

                        if (c & ASC_RXBUF_FE) {
                                if (c == (ASC_RXBUF_FE | ASC_RXBUF_DUMMY_RX)) {
                                        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 & 0xff))
                        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;

        uart_port_lock(port);

        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);
        }

        uart_port_unlock(port);

        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)
{
        struct asc_port *ascport = to_asc_port(port);

        /*
         * This routine is used for seting signals of: DTR, DCD, CTS and RTS.
         * We use ASC's hardware for CTS/RTS when hardware flow-control is
         * enabled, however if the RTS line is required for another purpose,
         * commonly controlled using HUP from userspace, then we need to toggle
         * it manually, using GPIO.
         *
         * Some boards also have DTR and DCD implemented using PIO pins, code to
         * do this should be hooked in here.
         */

        if (!ascport->rts)
                return;

        /* If HW flow-control is enabled, we can't fiddle with the RTS line */
        if (asc_in(port, ASC_CTL) & ASC_CTL_CTSENABLE)
                return;

        gpiod_set_value(ascport->rts, mctrl & TIOCM_RTS);
}

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 tty_port *tport = &port->state->port;

        if (!kfifo_is_empty(&tport->xmit_fifo))
                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);
}

/* 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, 0,
                        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;
        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.
                 */
                uart_port_lock_irqsave(port, &flags);
                ctl = asc_in(port, ASC_CTL) & ~ASC_CTL_RUN;
                asc_out(port, ASC_CTL, ctl);
                uart_port_unlock_irqrestore(port, flags);
                clk_disable_unprepare(ascport->clk);
                break;
        }
}

static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
                            const struct ktermios *old)
{
        struct asc_port *ascport = to_asc_port(port);
        bool manual_rts, toggle_rts = false;
        struct gpio_desc *gpiod;
        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;

        uart_port_lock_irqsave(port, &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;
                cflag |= PARENB;
        } else {
                ctrl_val |= (cflag & PARENB) ?  ASC_CTL_MODE_8BIT_PAR :
                                                ASC_CTL_MODE_8BIT;
                cflag &= ~CSIZE;
                cflag |= CS8;
        }
        termios->c_cflag = cflag;

        /* 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 flow-control selected, stop handling RTS manually */
                if (ascport->rts) {
                        toggle_rts = true;
                        manual_rts = false;
                }
        } else {
                /* If flow-control disabled, it's safe to handle RTS manually */
                if (!ascport->rts && ascport->states[NO_HW_FLOWCTRL])
                        manual_rts = toggle_rts = true;
        }

        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
                 *
                 * To keep maths inside 64bits, we divide inputclock by 16.
                 */
                u64 dividend = (u64)baud * (1 << 16);

                do_div(dividend, port->uartclk / 16);
                asc_out(port, ASC_BAUDRATE, dividend);
                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 & (IGNBRK | 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));

        uart_port_unlock_irqrestore(port, flags);

        if (toggle_rts) {
                if (manual_rts) {
                        pinctrl_select_state(ascport->pinctrl,
                                             ascport->states[NO_HW_FLOWCTRL]);

                        gpiod = devm_gpiod_get(port->dev, "rts", GPIOD_OUT_LOW);
                        if (!IS_ERR(gpiod)) {
                                gpiod_set_consumer_name(gpiod,
                                                        port->dev->of_node->name);
                                ascport->rts = gpiod;
                        }
                } else {
                                devm_gpiod_put(port->dev, ascport->rts);
                                ascport->rts = NULL;
                                pinctrl_select_state(ascport->pinctrl,
                                                     ascport->states[DEFAULT]);
                }
        }
}

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_half_empty(port))
                cpu_relax();
        asc_out(port, ASC_TXBUF, c);
}

#endif /* CONFIG_CONSOLE_POLL */

/*---------------------------------------------------------------------*/

static const 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,
        .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;
        int ret;

        port->iotype    = UPIO_MEM;
        port->flags     = UPF_BOOT_AUTOCONF;
        port->ops       = &asc_uart_ops;
        port->fifosize  = ASC_FIFO_SIZE;
        port->dev       = &pdev->dev;
        port->irq       = platform_get_irq(pdev, 0);
        port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ST_ASC_CONSOLE);

        port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(port->membase))
                return PTR_ERR(port->membase);
        port->mapbase = res->start;

        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 */
        ret = clk_prepare_enable(ascport->clk);
        if (ret)
                return ret;
        ascport->port.uartclk = clk_get_rate(ascport->clk);
        WARN_ON(ascport->port.uartclk == 0);
        clk_disable_unprepare(ascport->clk);

        ascport->pinctrl = devm_pinctrl_get(&pdev->dev);
        if (IS_ERR(ascport->pinctrl)) {
                ret = PTR_ERR(ascport->pinctrl);
                dev_err(&pdev->dev, "Failed to get Pinctrl: %d\n", ret);
                return ret;
        }

        ascport->states[DEFAULT] =
                pinctrl_lookup_state(ascport->pinctrl, "default");
        if (IS_ERR(ascport->states[DEFAULT])) {
                ret = PTR_ERR(ascport->states[DEFAULT]);
                dev_err(&pdev->dev,
                        "Failed to look up Pinctrl state 'default': %d\n", ret);
                return ret;
        }

        /* "no-hw-flowctrl" state is optional */
        ascport->states[NO_HW_FLOWCTRL] =
                pinctrl_lookup_state(ascport->pinctrl, "no-hw-flowctrl");
        if (IS_ERR(ascport->states[NO_HW_FLOWCTRL]))
                ascport->states[NO_HW_FLOWCTRL] = NULL;

        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, "serial");
        if (id < 0)
                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,
                                                        "uart-has-rtscts");
        asc_ports[id].force_m1 =  of_property_read_bool(np, "st,force-m1");
        asc_ports[id].port.line = id;
        asc_ports[id].rts = NULL;

        return &asc_ports[id];
}

#ifdef CONFIG_OF
static const struct of_device_id asc_match[] = {
        { .compatible = "st,asc", },
        {},
};

MODULE_DEVICE_TABLE(of, asc_match);
#endif

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 void asc_serial_remove(struct platform_device *pdev)
{
        struct uart_port *port = platform_get_drvdata(pdev);

        uart_remove_one_port(&asc_uart_driver, port);
}

static int asc_serial_suspend(struct device *dev)
{
        struct uart_port *port = dev_get_drvdata(dev);

        return uart_suspend_port(&asc_uart_driver, port);
}

static int asc_serial_resume(struct device *dev)
{
        struct uart_port *port = dev_get_drvdata(dev);

        return uart_resume_port(&asc_uart_driver, port);
}

/*----------------------------------------------------------------------*/

#ifdef CONFIG_SERIAL_ST_ASC_CONSOLE
static void asc_console_putchar(struct uart_port *port, unsigned char ch)
{
        unsigned int timeout = 1000000;

        /* Wait for upto 1 second in case flow control is stopping us. */
        while (--timeout && !asc_txfifo_is_half_empty(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;

        if (port->sysrq)
                locked = 0; /* asc_interrupt has already claimed the lock */
        else if (oops_in_progress)
                locked = uart_port_trylock_irqsave(port, &flags);
        else
                uart_port_lock_irqsave(port, &flags);

        /*
         * 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)
                uart_port_unlock_irqrestore(port, flags);
}

static int asc_console_setup(struct console *co, char *options)
{
        struct asc_port *ascport;
        int baud = 115200;
        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.
         */
        if (ascport->port.mapbase == 0 || ascport->port.membase == NULL)
                return -ENXIO;

        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 DEFINE_SIMPLE_DEV_PM_OPS(asc_serial_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     = pm_sleep_ptr(&asc_serial_pm_ops),
                .of_match_table = of_match_ptr(asc_match),
        },
};

static int __init asc_init(void)
{
        int ret;
        static const char banner[] __initconst =
                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");