bcm47xx_wdt.c

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/*
 *  Watchdog driver for Broadcom BCM47XX
 *
 *  Copyright (C) 2008 Aleksandar Radovanovic <[email protected]>
 *  Copyright (C) 2009 Matthieu CASTET <[email protected]>
 *
 *  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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/reboot.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/ssb/ssb_embedded.h>
#include <asm/mach-bcm47xx/bcm47xx.h>

#define DRV_NAME        "bcm47xx_wdt"

#define WDT_DEFAULT_TIME    30  /* seconds */
#define WDT_MAX_TIME        255 /* seconds */

static int wdt_time = WDT_DEFAULT_TIME;
static bool nowayout = WATCHDOG_NOWAYOUT;

module_param(wdt_time, int, 0);
MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
                __MODULE_STRING(WDT_DEFAULT_TIME) ")");

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

static unsigned long bcm47xx_wdt_busy;
static char expect_release;
static struct timer_list wdt_timer;
static atomic_t ticks;

static inline void bcm47xx_wdt_hw_start(void)
{
    /* this is 2,5s on 100Mhz clock  and 2s on 133 Mhz */
    switch (bcm47xx_bus_type) {
#ifdef CONFIG_BCM47XX_SSB
    case BCM47XX_BUS_TYPE_SSB:
        ssb_watchdog_timer_set(&bcm47xx_bus.ssb, 0xfffffff);
        break;
#endif
#ifdef CONFIG_BCM47XX_BCMA
    case BCM47XX_BUS_TYPE_BCMA:
        bcma_chipco_watchdog_timer_set(&bcm47xx_bus.bcma.bus.drv_cc,
                           0xfffffff);
        break;
#endif
    }
}

static inline int bcm47xx_wdt_hw_stop(void)
{
    switch (bcm47xx_bus_type) {
#ifdef CONFIG_BCM47XX_SSB
    case BCM47XX_BUS_TYPE_SSB:
        return ssb_watchdog_timer_set(&bcm47xx_bus.ssb, 0);
#endif
#ifdef CONFIG_BCM47XX_BCMA
    case BCM47XX_BUS_TYPE_BCMA:
        bcma_chipco_watchdog_timer_set(&bcm47xx_bus.bcma.bus.drv_cc, 0);
        return 0;
#endif
    }
    return -EINVAL;
}

static void bcm47xx_timer_tick(unsigned long unused)
{
    if (!atomic_dec_and_test(&ticks)) {
        bcm47xx_wdt_hw_start();
        mod_timer(&wdt_timer, jiffies + HZ);
    } else {
        pr_crit("Watchdog will fire soon!!!\n");
    }
}

static inline void bcm47xx_wdt_pet(void)
{
    atomic_set(&ticks, wdt_time);
}

static void bcm47xx_wdt_start(void)
{
    bcm47xx_wdt_pet();
    bcm47xx_timer_tick(0);
}

static void bcm47xx_wdt_pause(void)
{
    del_timer_sync(&wdt_timer);
    bcm47xx_wdt_hw_stop();
}

static void bcm47xx_wdt_stop(void)
{
    bcm47xx_wdt_pause();
}

static int bcm47xx_wdt_settimeout(int new_time)
{
    if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
        return -EINVAL;

    wdt_time = new_time;
    return 0;
}

static int bcm47xx_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &bcm47xx_wdt_busy))
        return -EBUSY;

    bcm47xx_wdt_start();
    return nonseekable_open(inode, file);
}

static int bcm47xx_wdt_release(struct inode *inode, struct file *file)
{
    if (expect_release == 42) {
        bcm47xx_wdt_stop();
    } else {
        pr_crit("Unexpected close, not stopping watchdog!\n");
        bcm47xx_wdt_start();
    }

    clear_bit(0, &bcm47xx_wdt_busy);
    expect_release = 0;
    return 0;
}

static ssize_t bcm47xx_wdt_write(struct file *file, const char __user *data,
                size_t len, loff_t *ppos)
{
    if (len) {
        if (!nowayout) {
            size_t i;

            expect_release = 0;

            for (i = 0; i != len; i++) {
                char c;
                if (get_user(c, data + i))
                    return -EFAULT;
                if (c == 'V')
                    expect_release = 42;
            }
        }
        bcm47xx_wdt_pet();
    }
    return len;
}

static const struct watchdog_info bcm47xx_wdt_info = {
    .identity   = DRV_NAME,
    .options    = WDIOF_SETTIMEOUT |
                WDIOF_KEEPALIVEPING |
                WDIOF_MAGICCLOSE,
};

static long bcm47xx_wdt_ioctl(struct file *file,
                    unsigned int cmd, unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int new_value, retval = -EINVAL;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user(argp, &bcm47xx_wdt_info,
                sizeof(bcm47xx_wdt_info)) ? -EFAULT : 0;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);

    case WDIOC_SETOPTIONS:
        if (get_user(new_value, p))
            return -EFAULT;

        if (new_value & WDIOS_DISABLECARD) {
            bcm47xx_wdt_stop();
            retval = 0;
        }

        if (new_value & WDIOS_ENABLECARD) {
            bcm47xx_wdt_start();
            retval = 0;
        }

        return retval;

    case WDIOC_KEEPALIVE:
        bcm47xx_wdt_pet();
        return 0;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_value, p))
            return -EFAULT;

        if (bcm47xx_wdt_settimeout(new_value))
            return -EINVAL;

        bcm47xx_wdt_pet();

    case WDIOC_GETTIMEOUT:
        return put_user(wdt_time, p);

    default:
        return -ENOTTY;
    }
}

static int bcm47xx_wdt_notify_sys(struct notifier_block *this,
    unsigned long code, void *unused)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        bcm47xx_wdt_stop();
    return NOTIFY_DONE;
}

static const struct file_operations bcm47xx_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .unlocked_ioctl = bcm47xx_wdt_ioctl,
    .open       = bcm47xx_wdt_open,
    .release    = bcm47xx_wdt_release,
    .write      = bcm47xx_wdt_write,
};

static struct miscdevice bcm47xx_wdt_miscdev = {
    .minor      = WATCHDOG_MINOR,
    .name       = "watchdog",
    .fops       = &bcm47xx_wdt_fops,
};

static struct notifier_block bcm47xx_wdt_notifier = {
    .notifier_call = bcm47xx_wdt_notify_sys,
};

static int __init bcm47xx_wdt_init(void)
{
    int ret;

    if (bcm47xx_wdt_hw_stop() < 0)
        return -ENODEV;

    setup_timer(&wdt_timer, bcm47xx_timer_tick, 0L);

    if (bcm47xx_wdt_settimeout(wdt_time)) {
        bcm47xx_wdt_settimeout(WDT_DEFAULT_TIME);
        pr_info("wdt_time value must be 0 < wdt_time < %d, using %d\n",
            (WDT_MAX_TIME + 1), wdt_time);
    }

    ret = register_reboot_notifier(&bcm47xx_wdt_notifier);
    if (ret)
        return ret;

    ret = misc_register(&bcm47xx_wdt_miscdev);
    if (ret) {
        unregister_reboot_notifier(&bcm47xx_wdt_notifier);
        return ret;
    }

    pr_info("BCM47xx Watchdog Timer enabled (%d seconds%s)\n",
        wdt_time, nowayout ? ", nowayout" : "");
    return 0;
}

static void __exit bcm47xx_wdt_exit(void)
{
    if (!nowayout)
        bcm47xx_wdt_stop();

    misc_deregister(&bcm47xx_wdt_miscdev);

    unregister_reboot_notifier(&bcm47xx_wdt_notifier);
}

module_init(bcm47xx_wdt_init);
module_exit(bcm47xx_wdt_exit);

MODULE_AUTHOR("Aleksandar Radovanovic");
MODULE_DESCRIPTION("Watchdog driver for Broadcom BCM47xx");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);