stmp3xxx_wdt.c

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/*
 * Watchdog driver for Freescale STMP37XX/STMP378X
 *
 * Author: Vitaly Wool <[email protected]>
 *
 * Copyright 2008 Freescale Semiconductor, Inc. All Rights Reserved.
 * Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/module.h>

#include <mach/platform.h>
#include <mach/regs-rtc.h>

#define DEFAULT_HEARTBEAT   19
#define MAX_HEARTBEAT       (0x10000000 >> 6)

/* missing bitmask in headers */
#define BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER     0x80000000

#define WDT_IN_USE      0
#define WDT_OK_TO_CLOSE     1

#define WDOG_COUNTER_RATE   1000 /* 1 kHz clock */

static DEFINE_SPINLOCK(stmp3xxx_wdt_io_lock);
static unsigned long wdt_status;
static const bool nowayout = WATCHDOG_NOWAYOUT;
static int heartbeat = DEFAULT_HEARTBEAT;
static unsigned long boot_status;

static void wdt_enable(u32 value)
{
    spin_lock(&stmp3xxx_wdt_io_lock);
    __raw_writel(value, REGS_RTC_BASE + HW_RTC_WATCHDOG);
    stmp3xxx_setl(BM_RTC_CTRL_WATCHDOGEN, REGS_RTC_BASE + HW_RTC_CTRL);
    stmp3xxx_setl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
            REGS_RTC_BASE + HW_RTC_PERSISTENT1);
    spin_unlock(&stmp3xxx_wdt_io_lock);
}

static void wdt_disable(void)
{
    spin_lock(&stmp3xxx_wdt_io_lock);
    stmp3xxx_clearl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
            REGS_RTC_BASE + HW_RTC_PERSISTENT1);
    stmp3xxx_clearl(BM_RTC_CTRL_WATCHDOGEN, REGS_RTC_BASE + HW_RTC_CTRL);
    spin_unlock(&stmp3xxx_wdt_io_lock);
}

static void wdt_ping(void)
{
    wdt_enable(heartbeat * WDOG_COUNTER_RATE);
}

static int stmp3xxx_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(WDT_IN_USE, &wdt_status))
        return -EBUSY;

    clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
    wdt_ping();

    return nonseekable_open(inode, file);
}

static ssize_t stmp3xxx_wdt_write(struct file *file, const char __user *data,
    size_t len, loff_t *ppos)
{
    if (len) {
        if (!nowayout) {
            size_t i;

            clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

            for (i = 0; i != len; i++) {
                char c;

                if (get_user(c, data + i))
                    return -EFAULT;
                if (c == 'V')
                    set_bit(WDT_OK_TO_CLOSE, &wdt_status);
            }
        }
        wdt_ping();
    }

    return len;
}

static const struct watchdog_info ident = {
    .options    = WDIOF_CARDRESET |
              WDIOF_MAGICCLOSE |
              WDIOF_SETTIMEOUT |
              WDIOF_KEEPALIVEPING,
    .identity   = "STMP3XXX Watchdog",
};

static long stmp3xxx_wdt_ioctl(struct file *file, unsigned int cmd,
    unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int new_heartbeat, opts;
    int ret = -ENOTTY;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
        break;

    case WDIOC_GETSTATUS:
        ret = put_user(0, p);
        break;

    case WDIOC_GETBOOTSTATUS:
        ret = put_user(boot_status, p);
        break;

    case WDIOC_SETOPTIONS:
        if (get_user(opts, p)) {
            ret = -EFAULT;
            break;
        }
        if (opts & WDIOS_DISABLECARD)
            wdt_disable();
        else if (opts & WDIOS_ENABLECARD)
            wdt_ping();
        else {
            pr_debug("%s: unknown option 0x%x\n", __func__, opts);
            ret = -EINVAL;
            break;
        }
        ret = 0;
        break;

    case WDIOC_KEEPALIVE:
        wdt_ping();
        ret = 0;
        break;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_heartbeat, p)) {
            ret = -EFAULT;
            break;
        }
        if (new_heartbeat <= 0 || new_heartbeat > MAX_HEARTBEAT) {
            ret = -EINVAL;
            break;
        }

        heartbeat = new_heartbeat;
        wdt_ping();
        /* Fall through */

    case WDIOC_GETTIMEOUT:
        ret = put_user(heartbeat, p);
        break;
    }
    return ret;
}

static int stmp3xxx_wdt_release(struct inode *inode, struct file *file)
{
    int ret = 0;

    if (!nowayout) {
        if (!test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
            wdt_ping();
            pr_debug("%s: Device closed unexpectedly\n", __func__);
            ret = -EINVAL;
        } else {
            wdt_disable();
            clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
        }
    }
    clear_bit(WDT_IN_USE, &wdt_status);

    return ret;
}

static const struct file_operations stmp3xxx_wdt_fops = {
    .owner = THIS_MODULE,
    .llseek = no_llseek,
    .write = stmp3xxx_wdt_write,
    .unlocked_ioctl = stmp3xxx_wdt_ioctl,
    .open = stmp3xxx_wdt_open,
    .release = stmp3xxx_wdt_release,
};

static struct miscdevice stmp3xxx_wdt_miscdev = {
    .minor = WATCHDOG_MINOR,
    .name = "watchdog",
    .fops = &stmp3xxx_wdt_fops,
};

static int __devinit stmp3xxx_wdt_probe(struct platform_device *pdev)
{
    int ret = 0;

    if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
        heartbeat = DEFAULT_HEARTBEAT;

    boot_status = __raw_readl(REGS_RTC_BASE + HW_RTC_PERSISTENT1) &
            BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER;
    boot_status = !!boot_status;
    stmp3xxx_clearl(BV_RTC_PERSISTENT1_GENERAL__RTC_FORCE_UPDATER,
            REGS_RTC_BASE + HW_RTC_PERSISTENT1);
    wdt_disable();      /* disable for now */

    ret = misc_register(&stmp3xxx_wdt_miscdev);
    if (ret < 0) {
        dev_err(&pdev->dev, "cannot register misc device\n");
        return ret;
    }

    pr_info("initialized, heartbeat %d sec\n", heartbeat);

    return ret;
}

static int __devexit stmp3xxx_wdt_remove(struct platform_device *pdev)
{
    misc_deregister(&stmp3xxx_wdt_miscdev);
    return 0;
}

#ifdef CONFIG_PM
static int wdt_suspended;
static u32 wdt_saved_time;

static int stmp3xxx_wdt_suspend(struct platform_device *pdev,
                pm_message_t state)
{
    if (__raw_readl(REGS_RTC_BASE + HW_RTC_CTRL) &
        BM_RTC_CTRL_WATCHDOGEN) {
        wdt_suspended = 1;
        wdt_saved_time = __raw_readl(REGS_RTC_BASE + HW_RTC_WATCHDOG);
        wdt_disable();
    }
    return 0;
}

static int stmp3xxx_wdt_resume(struct platform_device *pdev)
{
    if (wdt_suspended) {
        wdt_enable(wdt_saved_time);
        wdt_suspended = 0;
    }
    return 0;
}
#else
#define stmp3xxx_wdt_suspend    NULL
#define stmp3xxx_wdt_resume NULL
#endif

static struct platform_driver platform_wdt_driver = {
    .driver = {
        .name = "stmp3xxx_wdt",
    },
    .probe = stmp3xxx_wdt_probe,
    .remove = __devexit_p(stmp3xxx_wdt_remove),
    .suspend = stmp3xxx_wdt_suspend,
    .resume = stmp3xxx_wdt_resume,
};

module_platform_driver(platform_wdt_driver);

MODULE_DESCRIPTION("STMP3XXX Watchdog Driver");
MODULE_LICENSE("GPL");

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
         "Watchdog heartbeat period in seconds from 1 to "
         __MODULE_STRING(MAX_HEARTBEAT) ", default "
         __MODULE_STRING(DEFAULT_HEARTBEAT));

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);