imx2_wdt.c

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/*
 * Watchdog driver for IMX2 and later processors
 *
 *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <[email protected]>
 *
 * some parts adapted by similar drivers from Darius Augulis and Vladimir
 * Zapolskiy, additional improvements by Wim Van Sebroeck.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
 *
 *          MX1:        MX2+:
 *          ----        -----
 * Registers:       32-bit      16-bit
 * Stopable timer:  Yes     No
 * Need to enable clk:  No      Yes
 * Halt on suspend: Manual      Can be automatic
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/clk.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <mach/hardware.h>

#define DRIVER_NAME "imx2-wdt"

#define IMX2_WDT_WCR        0x00        /* Control Register */
#define IMX2_WDT_WCR_WT     (0xFF << 8) /* -> Watchdog Timeout Field */
#define IMX2_WDT_WCR_WRE    (1 << 3)    /* -> WDOG Reset Enable */
#define IMX2_WDT_WCR_WDE    (1 << 2)    /* -> Watchdog Enable */

#define IMX2_WDT_WSR        0x02        /* Service Register */
#define IMX2_WDT_SEQ1       0x5555      /* -> service sequence 1 */
#define IMX2_WDT_SEQ2       0xAAAA      /* -> service sequence 2 */

#define IMX2_WDT_WRSR       0x04        /* Reset Status Register */
#define IMX2_WDT_WRSR_TOUT  (1 << 1)    /* -> Reset due to Timeout */

#define IMX2_WDT_MAX_TIME   128
#define IMX2_WDT_DEFAULT_TIME   60      /* in seconds */

#define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)

#define IMX2_WDT_STATUS_OPEN    0
#define IMX2_WDT_STATUS_STARTED 1
#define IMX2_WDT_EXPECT_CLOSE   2

static struct {
    struct clk *clk;
    void __iomem *base;
    unsigned timeout;
    unsigned long status;
    struct timer_list timer;    /* Pings the watchdog when closed */
} imx2_wdt;

static struct miscdevice imx2_wdt_miscdev;

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");


static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
                __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");

static const struct watchdog_info imx2_wdt_info = {
    .identity = "imx2+ watchdog",
    .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
};

static inline void imx2_wdt_setup(void)
{
    u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);

    /* Strip the old watchdog Time-Out value */
    val &= ~IMX2_WDT_WCR_WT;
    /* Generate reset if WDOG times out */
    val &= ~IMX2_WDT_WCR_WRE;
    /* Keep Watchdog Disabled */
    val &= ~IMX2_WDT_WCR_WDE;
    /* Set the watchdog's Time-Out value */
    val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);

    __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);

    /* enable the watchdog */
    val |= IMX2_WDT_WCR_WDE;
    __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
}

static inline void imx2_wdt_ping(void)
{
    __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
    __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
}

static void imx2_wdt_timer_ping(unsigned long arg)
{
    /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
    imx2_wdt_ping();
    mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
}

static void imx2_wdt_start(void)
{
    if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
        /* at our first start we enable clock and do initialisations */
        clk_prepare_enable(imx2_wdt.clk);

        imx2_wdt_setup();
    } else  /* delete the timer that pings the watchdog after close */
        del_timer_sync(&imx2_wdt.timer);

    /* Watchdog is enabled - time to reload the timeout value */
    imx2_wdt_ping();
}

static void imx2_wdt_stop(void)
{
    /* we don't need a clk_disable, it cannot be disabled once started.
     * We use a timer to ping the watchdog while /dev/watchdog is closed */
    imx2_wdt_timer_ping(0);
}

static void imx2_wdt_set_timeout(int new_timeout)
{
    u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);

    /* set the new timeout value in the WSR */
    val &= ~IMX2_WDT_WCR_WT;
    val |= WDOG_SEC_TO_COUNT(new_timeout);
    __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
}

static int imx2_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
        return -EBUSY;

    imx2_wdt_start();
    return nonseekable_open(inode, file);
}

static int imx2_wdt_close(struct inode *inode, struct file *file)
{
    if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
        imx2_wdt_stop();
    else {
        dev_crit(imx2_wdt_miscdev.parent,
            "Unexpected close: Expect reboot!\n");
        imx2_wdt_ping();
    }

    clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
    clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
    return 0;
}

static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int new_value;
    u16 val;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user(argp, &imx2_wdt_info,
            sizeof(struct watchdog_info)) ? -EFAULT : 0;

    case WDIOC_GETSTATUS:
        return put_user(0, p);

    case WDIOC_GETBOOTSTATUS:
        val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
        new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
        return put_user(new_value, p);

    case WDIOC_KEEPALIVE:
        imx2_wdt_ping();
        return 0;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_value, p))
            return -EFAULT;
        if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
            return -EINVAL;
        imx2_wdt_set_timeout(new_value);
        imx2_wdt.timeout = new_value;
        imx2_wdt_ping();

        /* Fallthrough to return current value */
    case WDIOC_GETTIMEOUT:
        return put_user(imx2_wdt.timeout, p);

    default:
        return -ENOTTY;
    }
}

static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
                        size_t len, loff_t *ppos)
{
    size_t i;
    char c;

    if (len == 0)   /* Can we see this even ? */
        return 0;

    clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
    /* scan to see whether or not we got the magic character */
    for (i = 0; i != len; i++) {
        if (get_user(c, data + i))
            return -EFAULT;
        if (c == 'V')
            set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
    }

    imx2_wdt_ping();
    return len;
}

static const struct file_operations imx2_wdt_fops = {
    .owner = THIS_MODULE,
    .llseek = no_llseek,
    .unlocked_ioctl = imx2_wdt_ioctl,
    .open = imx2_wdt_open,
    .release = imx2_wdt_close,
    .write = imx2_wdt_write,
};

static struct miscdevice imx2_wdt_miscdev = {
    .minor = WATCHDOG_MINOR,
    .name = "watchdog",
    .fops = &imx2_wdt_fops,
};

static int __init imx2_wdt_probe(struct platform_device *pdev)
{
    int ret;
    struct resource *res;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res) {
        dev_err(&pdev->dev, "can't get device resources\n");
        return -ENODEV;
    }

    imx2_wdt.base = devm_request_and_ioremap(&pdev->dev, res);
    if (!imx2_wdt.base) {
        dev_err(&pdev->dev, "ioremap failed\n");
        return -ENOMEM;
    }

    imx2_wdt.clk = clk_get(&pdev->dev, NULL);
    if (IS_ERR(imx2_wdt.clk)) {
        dev_err(&pdev->dev, "can't get Watchdog clock\n");
        return PTR_ERR(imx2_wdt.clk);
    }

    imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
    if (imx2_wdt.timeout != timeout)
        dev_warn(&pdev->dev, "Initial timeout out of range! "
            "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);

    setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);

    imx2_wdt_miscdev.parent = &pdev->dev;
    ret = misc_register(&imx2_wdt_miscdev);
    if (ret)
        goto fail;

    dev_info(&pdev->dev,
        "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
                        imx2_wdt.timeout, nowayout);
    return 0;

fail:
    imx2_wdt_miscdev.parent = NULL;
    clk_put(imx2_wdt.clk);
    return ret;
}

static int __exit imx2_wdt_remove(struct platform_device *pdev)
{
    misc_deregister(&imx2_wdt_miscdev);

    if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
        del_timer_sync(&imx2_wdt.timer);

        dev_crit(imx2_wdt_miscdev.parent,
            "Device removed: Expect reboot!\n");
    } else
        clk_put(imx2_wdt.clk);

    imx2_wdt_miscdev.parent = NULL;
    return 0;
}

static void imx2_wdt_shutdown(struct platform_device *pdev)
{
    if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
        /* we are running, we need to delete the timer but will give
         * max timeout before reboot will take place */
        del_timer_sync(&imx2_wdt.timer);
        imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
        imx2_wdt_ping();

        dev_crit(imx2_wdt_miscdev.parent,
            "Device shutdown: Expect reboot!\n");
    }
}

static const struct of_device_id imx2_wdt_dt_ids[] = {
    { .compatible = "fsl,imx21-wdt", },
    { /* sentinel */ }
};

static struct platform_driver imx2_wdt_driver = {
    .remove     = __exit_p(imx2_wdt_remove),
    .shutdown   = imx2_wdt_shutdown,
    .driver     = {
        .name   = DRIVER_NAME,
        .owner  = THIS_MODULE,
        .of_match_table = imx2_wdt_dt_ids,
    },
};

static int __init imx2_wdt_init(void)
{
    return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
}
module_init(imx2_wdt_init);

static void __exit imx2_wdt_exit(void)
{
    platform_driver_unregister(&imx2_wdt_driver);
}
module_exit(imx2_wdt_exit);

MODULE_AUTHOR("Wolfram Sang");
MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:" DRIVER_NAME);