mrst_max3110.c

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/*
 *  mrst_max3110.c - spi uart protocol driver for Maxim 3110
 *
 * Copyright (c) 2008-2010, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

/*
 * Note:
 * 1. From Max3110 spec, the Rx FIFO has 8 words, while the Tx FIFO only has
 *    1 word. If SPI master controller doesn't support sclk frequency change,
 *    then the char need be sent out one by one with some delay
 *
 * 2. Currently only RX available interrupt is used, no need for waiting TXE
 *    interrupt for a low speed UART device
 */

#ifdef CONFIG_MAGIC_SYSRQ
#define SUPPORT_SYSRQ
#endif

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial_reg.h>

#include <linux/kthread.h>
#include <linux/spi/spi.h>

#include "mrst_max3110.h"

#define PR_FMT  "mrst_max3110: "

#define UART_TX_NEEDED 1
#define CON_TX_NEEDED  2
#define BIT_IRQ_PENDING    3

struct uart_max3110 {
    struct uart_port port;
    struct spi_device *spi;
    char name[SPI_NAME_SIZE];

    wait_queue_head_t wq;
    struct task_struct *main_thread;
    struct task_struct *read_thread;
    struct mutex thread_mutex;

    u32 baud;
    u16 cur_conf;
    u8 clock;
    u8 parity, word_7bits;
    u16 irq;

    unsigned long uart_flags;

    /* console related */
    struct circ_buf con_xmit;
};

/* global data structure, may need be removed */
static struct uart_max3110 *pmax;

static int receive_chars(struct uart_max3110 *max,
                unsigned short *str, int len);
static int max3110_read_multi(struct uart_max3110 *max);
static void max3110_con_receive(struct uart_max3110 *max);

static int max3110_write_then_read(struct uart_max3110 *max,
        const void *txbuf, void *rxbuf, unsigned len, int always_fast)
{
    struct spi_device *spi = max->spi;
    struct spi_message  message;
    struct spi_transfer x;
    int ret;

    spi_message_init(&message);
    memset(&x, 0, sizeof x);
    x.len = len;
    x.tx_buf = txbuf;
    x.rx_buf = rxbuf;
    spi_message_add_tail(&x, &message);

    if (always_fast)
        x.speed_hz = spi->max_speed_hz;
    else if (max->baud)
        x.speed_hz = max->baud;

    /* Do the i/o */
    ret = spi_sync(spi, &message);
    return ret;
}

/* Write a 16b word to the device */
static int max3110_out(struct uart_max3110 *max, const u16 out)
{
    void *buf;
    u16 *obuf, *ibuf;
    int ret;

    buf = kzalloc(8, GFP_KERNEL | GFP_DMA);
    if (!buf)
        return -ENOMEM;

    obuf = buf;
    ibuf = buf + 4;
    *obuf = out;
    ret = max3110_write_then_read(max, obuf, ibuf, 2, 1);
    if (ret) {
        pr_warning(PR_FMT "%s(): get err msg %d when sending 0x%x\n",
                __func__, ret, out);
        goto exit;
    }

    receive_chars(max, ibuf, 1);

exit:
    kfree(buf);
    return ret;
}

/*
 * This is usually used to read data from SPIC RX FIFO, which doesn't
 * need any delay like flushing character out.
 *
 * Return how many valide bytes are read back
 */
static int max3110_read_multi(struct uart_max3110 *max)
{
    void *buf;
    u16 *obuf, *ibuf;
    int ret, blen;

    blen = M3110_RX_FIFO_DEPTH * sizeof(u16);
    buf = kzalloc(blen * 2, GFP_KERNEL | GFP_DMA);
    if (!buf) {
        pr_warning(PR_FMT "%s(): fail to alloc dma buffer\n", __func__);
        return 0;
    }

    /* tx/rx always have the same length */
    obuf = buf;
    ibuf = buf + blen;

    if (max3110_write_then_read(max, obuf, ibuf, blen, 1)) {
        kfree(buf);
        return 0;
    }

    ret = receive_chars(max, ibuf, M3110_RX_FIFO_DEPTH);

    kfree(buf);
    return ret;
}

static void serial_m3110_con_putchar(struct uart_port *port, int ch)
{
    struct uart_max3110 *max =
        container_of(port, struct uart_max3110, port);
    struct circ_buf *xmit = &max->con_xmit;

    if (uart_circ_chars_free(xmit)) {
        xmit->buf[xmit->head] = (char)ch;
        xmit->head = (xmit->head + 1) & (PAGE_SIZE - 1);
    }
}

/*
 * Print a string to the serial port trying not to disturb
 * any possible real use of the port...
 *
 *  The console_lock must be held when we get here.
 */
static void serial_m3110_con_write(struct console *co,
                const char *s, unsigned int count)
{
    if (!pmax)
        return;

    uart_console_write(&pmax->port, s, count, serial_m3110_con_putchar);

    if (!test_and_set_bit(CON_TX_NEEDED, &pmax->uart_flags))
        wake_up(&pmax->wq);
}

static int __init
serial_m3110_con_setup(struct console *co, char *options)
{
    struct uart_max3110 *max = pmax;
    int baud = 115200;
    int bits = 8;
    int parity = 'n';
    int flow = 'n';

    pr_info(PR_FMT "setting up console\n");

    if (co->index == -1)
        co->index = 0;

    if (!max) {
        pr_err(PR_FMT "pmax is NULL, return");
        return -ENODEV;
    }

    if (options)
        uart_parse_options(options, &baud, &parity, &bits, &flow);

    return uart_set_options(&max->port, co, baud, parity, bits, flow);
}

static struct tty_driver *serial_m3110_con_device(struct console *co,
                            int *index)
{
    struct uart_driver *p = co->data;
    *index = co->index;
    return p->tty_driver;
}

static struct uart_driver serial_m3110_reg;
static struct console serial_m3110_console = {
    .name       = "ttyS",
    .write      = serial_m3110_con_write,
    .device     = serial_m3110_con_device,
    .setup      = serial_m3110_con_setup,
    .flags      = CON_PRINTBUFFER,
    .index      = -1,
    .data       = &serial_m3110_reg,
};

static unsigned int serial_m3110_tx_empty(struct uart_port *port)
{
    return 1;
}

static void serial_m3110_stop_tx(struct uart_port *port)
{
    return;
}

/* stop_rx will be called in spin_lock env */
static void serial_m3110_stop_rx(struct uart_port *port)
{
    return;
}

#define WORDS_PER_XFER  128
static void send_circ_buf(struct uart_max3110 *max,
                struct circ_buf *xmit)
{
    void *buf;
    u16 *obuf, *ibuf;
    int i, len, blen, dma_size, left, ret = 0;


    dma_size = WORDS_PER_XFER * sizeof(u16) * 2;
    buf = kzalloc(dma_size, GFP_KERNEL | GFP_DMA);
    if (!buf)
        return;
    obuf = buf;
    ibuf = buf + dma_size/2;

    while (!uart_circ_empty(xmit)) {
        left = uart_circ_chars_pending(xmit);
        while (left) {
            len = min(left, WORDS_PER_XFER);
            blen = len * sizeof(u16);
            memset(ibuf, 0, blen);

            for (i = 0; i < len; i++) {
                obuf[i] = (u8)xmit->buf[xmit->tail] | WD_TAG;
                xmit->tail = (xmit->tail + 1) &
                        (UART_XMIT_SIZE - 1);
            }

            /* Fail to send msg to console is not very critical */

            ret = max3110_write_then_read(max, obuf, ibuf, blen, 0);
            if (ret)
                pr_warning(PR_FMT "%s(): get err msg %d\n",
                        __func__, ret);

            receive_chars(max, ibuf, len);

            max->port.icount.tx += len;
            left -= len;
        }
    }

    kfree(buf);
}

static void transmit_char(struct uart_max3110 *max)
{
    struct uart_port *port = &max->port;
    struct circ_buf *xmit = &port->state->xmit;

    if (uart_circ_empty(xmit) || uart_tx_stopped(port))
        return;

    send_circ_buf(max, xmit);

    if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
        uart_write_wakeup(port);

    if (uart_circ_empty(xmit))
        serial_m3110_stop_tx(port);
}

/*
 * This will be called by uart_write() and tty_write, can't
 * go to sleep
 */
static void serial_m3110_start_tx(struct uart_port *port)
{
    struct uart_max3110 *max =
        container_of(port, struct uart_max3110, port);

    if (!test_and_set_bit(UART_TX_NEEDED, &max->uart_flags))
        wake_up(&max->wq);
}

static int
receive_chars(struct uart_max3110 *max, unsigned short *str, int len)
{
    struct uart_port *port = &max->port;
    struct tty_struct *tty;
    char buf[M3110_RX_FIFO_DEPTH];
    int r, w, usable;

    /* If uart is not opened, just return */
    if (!port->state)
        return 0;

    tty = tty_port_tty_get(&port->state->port);
    if (!tty)
        return 0;

    for (r = 0, w = 0; r < len; r++) {
        if (str[r] & MAX3110_BREAK &&
            uart_handle_break(port))
            continue;

        if (str[r] & MAX3110_READ_DATA_AVAILABLE) {
            if (uart_handle_sysrq_char(port, str[r] & 0xff))
                continue;

            buf[w++] = str[r] & 0xff;
        }
    }

    if (!w) {
        tty_kref_put(tty);
        return 0;
    }

    for (r = 0; w; r += usable, w -= usable) {
        usable = tty_buffer_request_room(tty, w);
        if (usable) {
            tty_insert_flip_string(tty, buf + r, usable);
            port->icount.rx += usable;
        }
    }
    tty_flip_buffer_push(tty);
    tty_kref_put(tty);

    return r;
}

/*
 * This routine will be used in read_thread or RX IRQ handling,
 * it will first do one round buffer read(8 words), if there is some
 * valid RX data, will try to read 5 more rounds till all data
 * is read out.
 *
 * Use stack space as data buffer to save some system load, and chose
 * 504 Btyes as a threadhold to do a bulk push to upper tty layer when
 * receiving bulk data, a much bigger buffer may cause stack overflow
 */
static void max3110_con_receive(struct uart_max3110 *max)
{
    int loop = 1, num;

    do {
        num = max3110_read_multi(max);

        if (num) {
            loop = 5;
        }
    } while (--loop);
}

static int max3110_main_thread(void *_max)
{
    struct uart_max3110 *max = _max;
    wait_queue_head_t *wq = &max->wq;
    int ret = 0;
    struct circ_buf *xmit = &max->con_xmit;

    pr_info(PR_FMT "start main thread\n");

    do {
        wait_event_interruptible(*wq,
                max->uart_flags || kthread_should_stop());

        mutex_lock(&max->thread_mutex);

        if (test_and_clear_bit(BIT_IRQ_PENDING, &max->uart_flags))
            max3110_con_receive(max);

        /* first handle console output */
        if (test_and_clear_bit(CON_TX_NEEDED, &max->uart_flags))
            send_circ_buf(max, xmit);

        /* handle uart output */
        if (test_and_clear_bit(UART_TX_NEEDED, &max->uart_flags))
            transmit_char(max);

        mutex_unlock(&max->thread_mutex);

    } while (!kthread_should_stop());

    return ret;
}

static irqreturn_t serial_m3110_irq(int irq, void *dev_id)
{
    struct uart_max3110 *max = dev_id;

    /* max3110's irq is a falling edge, not level triggered,
     * so no need to disable the irq */

    if (!test_and_set_bit(BIT_IRQ_PENDING, &max->uart_flags))
        wake_up(&max->wq);

    return IRQ_HANDLED;
}

/* if don't use RX IRQ, then need a thread to polling read */
static int max3110_read_thread(void *_max)
{
    struct uart_max3110 *max = _max;

    pr_info(PR_FMT "start read thread\n");
    do {
        /*
         * If can't acquire the mutex, it means the main thread
         * is running which will also perform the rx job
         */
        if (mutex_trylock(&max->thread_mutex)) {
            max3110_con_receive(max);
            mutex_unlock(&max->thread_mutex);
        }

        set_current_state(TASK_INTERRUPTIBLE);
        schedule_timeout(HZ / 20);
    } while (!kthread_should_stop());

    return 0;
}

static int serial_m3110_startup(struct uart_port *port)
{
    struct uart_max3110 *max =
        container_of(port, struct uart_max3110, port);
    u16 config = 0;
    int ret = 0;

    if (port->line != 0) {
        pr_err(PR_FMT "uart port startup failed\n");
        return -1;
    }

    /* Disable all IRQ and config it to 115200, 8n1 */
    config = WC_TAG | WC_FIFO_ENABLE
            | WC_1_STOPBITS
            | WC_8BIT_WORD
            | WC_BAUD_DR2;

    /* as we use thread to handle tx/rx, need set low latency */
    port->state->port.tty->low_latency = 1;

    if (max->irq) {
        max->read_thread = NULL;
        ret = request_irq(max->irq, serial_m3110_irq,
                IRQ_TYPE_EDGE_FALLING, "max3110", max);
        if (ret) {
            max->irq = 0;
            pr_err(PR_FMT "unable to allocate IRQ, polling\n");
        }  else {
            /* Enable RX IRQ only */
            config |= WC_RXA_IRQ_ENABLE;
        }
    }

    if (max->irq == 0) {
        /* If IRQ is disabled, start a read thread for input data */
        max->read_thread =
            kthread_run(max3110_read_thread, max, "max3110_read");
        if (IS_ERR(max->read_thread)) {
            ret = PTR_ERR(max->read_thread);
            max->read_thread = NULL;
            pr_err(PR_FMT "Can't create read thread!\n");
            return ret;
        }
    }

    ret = max3110_out(max, config);
    if (ret) {
        if (max->irq)
            free_irq(max->irq, max);
        if (max->read_thread)
            kthread_stop(max->read_thread);
        max->read_thread = NULL;
        return ret;
    }

    max->cur_conf = config;
    return 0;
}

static void serial_m3110_shutdown(struct uart_port *port)
{
    struct uart_max3110 *max =
        container_of(port, struct uart_max3110, port);
    u16 config;

    if (max->read_thread) {
        kthread_stop(max->read_thread);
        max->read_thread = NULL;
    }

    if (max->irq)
        free_irq(max->irq, max);

    /* Disable interrupts from this port */
    config = WC_TAG | WC_SW_SHDI;
    max3110_out(max, config);
}

static void serial_m3110_release_port(struct uart_port *port)
{
}

static int serial_m3110_request_port(struct uart_port *port)
{
    return 0;
}

static void serial_m3110_config_port(struct uart_port *port, int flags)
{
    port->type = PORT_MAX3100;
}

static int
serial_m3110_verify_port(struct uart_port *port, struct serial_struct *ser)
{
    /* we don't want the core code to modify any port params */
    return -EINVAL;
}


static const char *serial_m3110_type(struct uart_port *port)
{
    struct uart_max3110 *max =
        container_of(port, struct uart_max3110, port);
    return max->name;
}

static void
serial_m3110_set_termios(struct uart_port *port, struct ktermios *termios,
               struct ktermios *old)
{
    struct uart_max3110 *max =
        container_of(port, struct uart_max3110, port);
    unsigned char cval;
    unsigned int baud, parity = 0;
    int clk_div = -1;
    u16 new_conf = max->cur_conf;

    switch (termios->c_cflag & CSIZE) {
    case CS7:
        cval = UART_LCR_WLEN7;
        new_conf |= WC_7BIT_WORD;
        break;
    default:
        /* We only support CS7 & CS8 */
        termios->c_cflag &= ~CSIZE;
        termios->c_cflag |= CS8;
    case CS8:
        cval = UART_LCR_WLEN8;
        new_conf |= WC_8BIT_WORD;
        break;
    }

    baud = uart_get_baud_rate(port, termios, old, 0, 230400);

    /* First calc the div for 1.8MHZ clock case */
    switch (baud) {
    case 300:
        clk_div = WC_BAUD_DR384;
        break;
    case 600:
        clk_div = WC_BAUD_DR192;
        break;
    case 1200:
        clk_div = WC_BAUD_DR96;
        break;
    case 2400:
        clk_div = WC_BAUD_DR48;
        break;
    case 4800:
        clk_div = WC_BAUD_DR24;
        break;
    case 9600:
        clk_div = WC_BAUD_DR12;
        break;
    case 19200:
        clk_div = WC_BAUD_DR6;
        break;
    case 38400:
        clk_div = WC_BAUD_DR3;
        break;
    case 57600:
        clk_div = WC_BAUD_DR2;
        break;
    case 115200:
        clk_div = WC_BAUD_DR1;
        break;
    case 230400:
        if (max->clock & MAX3110_HIGH_CLK)
            break;
    default:
        /* Pick the previous baud rate */
        baud = max->baud;
        clk_div = max->cur_conf & WC_BAUD_DIV_MASK;
        tty_termios_encode_baud_rate(termios, baud, baud);
    }

    if (max->clock & MAX3110_HIGH_CLK) {
        clk_div += 1;
        /* High clk version max3110 doesn't support B300 */
        if (baud == 300) {
            baud = 600;
            clk_div = WC_BAUD_DR384;
        }
        if (baud == 230400)
            clk_div = WC_BAUD_DR1;
        tty_termios_encode_baud_rate(termios, baud, baud);
    }

    new_conf = (new_conf & ~WC_BAUD_DIV_MASK) | clk_div;

    if (unlikely(termios->c_cflag & CMSPAR))
        termios->c_cflag &= ~CMSPAR;

    if (termios->c_cflag & CSTOPB)
        new_conf |= WC_2_STOPBITS;
    else
        new_conf &= ~WC_2_STOPBITS;

    if (termios->c_cflag & PARENB) {
        new_conf |= WC_PARITY_ENABLE;
        parity |= UART_LCR_PARITY;
    } else
        new_conf &= ~WC_PARITY_ENABLE;

    if (!(termios->c_cflag & PARODD))
        parity |= UART_LCR_EPAR;
    max->parity = parity;

    uart_update_timeout(port, termios->c_cflag, baud);

    new_conf |= WC_TAG;
    if (new_conf != max->cur_conf) {
        if (!max3110_out(max, new_conf)) {
            max->cur_conf = new_conf;
            max->baud = baud;
        }
    }
}

/* Don't handle hw handshaking */
static unsigned int serial_m3110_get_mctrl(struct uart_port *port)
{
    return TIOCM_DSR | TIOCM_CAR | TIOCM_DSR;
}

static void serial_m3110_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}

static void serial_m3110_break_ctl(struct uart_port *port, int break_state)
{
}

static void serial_m3110_pm(struct uart_port *port, unsigned int state,
            unsigned int oldstate)
{
}

static void serial_m3110_enable_ms(struct uart_port *port)
{
}

struct uart_ops serial_m3110_ops = {
    .tx_empty   = serial_m3110_tx_empty,
    .set_mctrl  = serial_m3110_set_mctrl,
    .get_mctrl  = serial_m3110_get_mctrl,
    .stop_tx    = serial_m3110_stop_tx,
    .start_tx   = serial_m3110_start_tx,
    .stop_rx    = serial_m3110_stop_rx,
    .enable_ms  = serial_m3110_enable_ms,
    .break_ctl  = serial_m3110_break_ctl,
    .startup    = serial_m3110_startup,
    .shutdown   = serial_m3110_shutdown,
    .set_termios    = serial_m3110_set_termios,
    .pm     = serial_m3110_pm,
    .type       = serial_m3110_type,
    .release_port   = serial_m3110_release_port,
    .request_port   = serial_m3110_request_port,
    .config_port    = serial_m3110_config_port,
    .verify_port    = serial_m3110_verify_port,
};

static struct uart_driver serial_m3110_reg = {
    .owner      = THIS_MODULE,
    .driver_name    = "MRST serial",
    .dev_name   = "ttyS",
    .major      = TTY_MAJOR,
    .minor      = 64,
    .nr     = 1,
    .cons       = &serial_m3110_console,
};

#ifdef CONFIG_PM
static int serial_m3110_suspend(struct spi_device *spi, pm_message_t state)
{
    struct uart_max3110 *max = spi_get_drvdata(spi);

    disable_irq(max->irq);
    uart_suspend_port(&serial_m3110_reg, &max->port);
    max3110_out(max, max->cur_conf | WC_SW_SHDI);
    return 0;
}

static int serial_m3110_resume(struct spi_device *spi)
{
    struct uart_max3110 *max = spi_get_drvdata(spi);

    max3110_out(max, max->cur_conf);
    uart_resume_port(&serial_m3110_reg, &max->port);
    enable_irq(max->irq);
    return 0;
}
#else
#define serial_m3110_suspend    NULL
#define serial_m3110_resume NULL
#endif

static int __devinit serial_m3110_probe(struct spi_device *spi)
{
    struct uart_max3110 *max;
    void *buffer;
    u16 res;
    int ret = 0;

    max = kzalloc(sizeof(*max), GFP_KERNEL);
    if (!max)
        return -ENOMEM;

    /* Set spi info */
    spi->bits_per_word = 16;
    max->clock = MAX3110_HIGH_CLK;

    spi_setup(spi);

    max->port.type = PORT_MAX3100;
    max->port.fifosize = 2;     /* Only have 16b buffer */
    max->port.ops = &serial_m3110_ops;
    max->port.line = 0;
    max->port.dev = &spi->dev;
    max->port.uartclk = 115200;

    max->spi = spi;
    strcpy(max->name, spi->modalias);
    max->irq = (u16)spi->irq;

    mutex_init(&max->thread_mutex);

    max->word_7bits = 0;
    max->parity = 0;
    max->baud = 0;

    max->cur_conf = 0;
    max->uart_flags = 0;

    /* Check if reading configuration register returns something sane */

    res = RC_TAG;
    ret = max3110_write_then_read(max, (u8 *)&res, (u8 *)&res, 2, 0);
    if (ret < 0 || res == 0 || res == 0xffff) {
        dev_dbg(&spi->dev, "MAX3111 deemed not present (conf reg %04x)",
                                    res);
        ret = -ENODEV;
        goto err_get_page;
    }

    buffer = (void *)__get_free_page(GFP_KERNEL);
    if (!buffer) {
        ret = -ENOMEM;
        goto err_get_page;
    }
    max->con_xmit.buf = buffer;
    max->con_xmit.head = 0;
    max->con_xmit.tail = 0;

    init_waitqueue_head(&max->wq);

    max->main_thread = kthread_run(max3110_main_thread,
                    max, "max3110_main");
    if (IS_ERR(max->main_thread)) {
        ret = PTR_ERR(max->main_thread);
        goto err_kthread;
    }

    spi_set_drvdata(spi, max);
    pmax = max;

    /* Give membase a psudo value to pass serial_core's check */
    max->port.membase = (void *)0xff110000;
    uart_add_one_port(&serial_m3110_reg, &max->port);

    return 0;

err_kthread:
    free_page((unsigned long)buffer);
err_get_page:
    kfree(max);
    return ret;
}

static int __devexit serial_m3110_remove(struct spi_device *dev)
{
    struct uart_max3110 *max = spi_get_drvdata(dev);

    if (!max)
        return 0;

    uart_remove_one_port(&serial_m3110_reg, &max->port);

    free_page((unsigned long)max->con_xmit.buf);

    if (max->main_thread)
        kthread_stop(max->main_thread);

    kfree(max);
    return 0;
}

static struct spi_driver uart_max3110_driver = {
    .driver = {
            .name   = "spi_max3111",
            .owner  = THIS_MODULE,
    },
    .probe      = serial_m3110_probe,
    .remove     = __devexit_p(serial_m3110_remove),
    .suspend    = serial_m3110_suspend,
    .resume     = serial_m3110_resume,
};

static int __init serial_m3110_init(void)
{
    int ret = 0;

    ret = uart_register_driver(&serial_m3110_reg);
    if (ret)
        return ret;

    ret = spi_register_driver(&uart_max3110_driver);
    if (ret)
        uart_unregister_driver(&serial_m3110_reg);

    return ret;
}

static void __exit serial_m3110_exit(void)
{
    spi_unregister_driver(&uart_max3110_driver);
    uart_unregister_driver(&serial_m3110_reg);
}

module_init(serial_m3110_init);
module_exit(serial_m3110_exit);

MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:max3110-uart");