pnx833x_wdt.c

Go to the documentation of this file.

/*
 *  PNX833x Hardware Watchdog Driver
 *  Copyright 2008 NXP Semiconductors
 *  Daniel Laird <[email protected]>
 *  Andre McCurdy <[email protected]>
 *
 *  Heavily based upon - IndyDog    0.3
 *  A Hardware Watchdog Device for SGI IP22
 *
 * (c) Copyright 2002 Guido Guenther <[email protected]>, All Rights Reserved.
 *
 * 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.
 *
 * based on softdog.c by Alan Cox <[email protected]>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <asm/mach-pnx833x/pnx833x.h>

#define WATCHDOG_TIMEOUT 30     /* 30 sec Maximum timeout */
#define WATCHDOG_COUNT_FREQUENCY 68000000U /* Watchdog counts at 68MHZ. */
#define PNX_WATCHDOG_TIMEOUT    (WATCHDOG_TIMEOUT * WATCHDOG_COUNT_FREQUENCY)
#define PNX_TIMEOUT_VALUE   2040000000U

#define PNX833X_CONFIG                      (0x07000U)
#define PNX833X_CONFIG_CPU_WATCHDOG         (0x54)
#define PNX833X_CONFIG_CPU_WATCHDOG_COMPARE (0x58)
#define PNX833X_CONFIG_CPU_COUNTERS_CONTROL (0x1c)

#define PNX833X_RESET                       (0x08000U)
#define PNX833X_RESET_CONFIG                (0x08)

static int pnx833x_wdt_alive;

/* Set default timeout in MHZ.*/
static int pnx833x_wdt_timeout = PNX_WATCHDOG_TIMEOUT;
module_param(pnx833x_wdt_timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in Mhz. (68Mhz clock), default="
            __MODULE_STRING(PNX_TIMEOUT_VALUE) "(30 seconds).");

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) ")");

#define START_DEFAULT   1
static int start_enabled = START_DEFAULT;
module_param(start_enabled, int, 0);
MODULE_PARM_DESC(start_enabled, "Watchdog is started on module insertion "
                "(default=" __MODULE_STRING(START_DEFAULT) ")");

static void pnx833x_wdt_start(void)
{
    /* Enable watchdog causing reset. */
    PNX833X_REG(PNX833X_RESET + PNX833X_RESET_CONFIG) |= 0x1;
    /* Set timeout.*/
    PNX833X_REG(PNX833X_CONFIG +
        PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
    /* Enable watchdog. */
    PNX833X_REG(PNX833X_CONFIG +
                PNX833X_CONFIG_CPU_COUNTERS_CONTROL) |= 0x1;

    pr_info("Started watchdog timer\n");
}

static void pnx833x_wdt_stop(void)
{
    /* Disable watchdog causing reset. */
    PNX833X_REG(PNX833X_RESET + PNX833X_CONFIG) &= 0xFFFFFFFE;
    /* Disable watchdog.*/
    PNX833X_REG(PNX833X_CONFIG +
            PNX833X_CONFIG_CPU_COUNTERS_CONTROL) &= 0xFFFFFFFE;

    pr_info("Stopped watchdog timer\n");
}

static void pnx833x_wdt_ping(void)
{
    PNX833X_REG(PNX833X_CONFIG +
        PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
}

/*
 *  Allow only one person to hold it open
 */
static int pnx833x_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &pnx833x_wdt_alive))
        return -EBUSY;

    if (nowayout)
        __module_get(THIS_MODULE);

    /* Activate timer */
    if (!start_enabled)
        pnx833x_wdt_start();

    pnx833x_wdt_ping();

    pr_info("Started watchdog timer\n");

    return nonseekable_open(inode, file);
}

static int pnx833x_wdt_release(struct inode *inode, struct file *file)
{
    /* Shut off the timer.
     * Lock it in if it's a module and we defined ...NOWAYOUT */
    if (!nowayout)
        pnx833x_wdt_stop(); /* Turn the WDT off */

    clear_bit(0, &pnx833x_wdt_alive);
    return 0;
}

static ssize_t pnx833x_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
{
    /* Refresh the timer. */
    if (len)
        pnx833x_wdt_ping();

    return len;
}

static long pnx833x_wdt_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    int options, new_timeout = 0;
    uint32_t timeout, timeout_left = 0;

    static const struct watchdog_info ident = {
        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
        .firmware_version = 0,
        .identity = "Hardware Watchdog for PNX833x",
    };

    switch (cmd) {
    default:
        return -ENOTTY;

    case WDIOC_GETSUPPORT:
        if (copy_to_user((struct watchdog_info *)arg,
                 &ident, sizeof(ident)))
            return -EFAULT;
        return 0;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, (int *)arg);

    case WDIOC_SETOPTIONS:
        if (get_user(options, (int *)arg))
            return -EFAULT;

        if (options & WDIOS_DISABLECARD)
            pnx833x_wdt_stop();

        if (options & WDIOS_ENABLECARD)
            pnx833x_wdt_start();

        return 0;

    case WDIOC_KEEPALIVE:
        pnx833x_wdt_ping();
        return 0;

    case WDIOC_SETTIMEOUT:
    {
        if (get_user(new_timeout, (int *)arg))
            return -EFAULT;

        pnx833x_wdt_timeout = new_timeout;
        PNX833X_REG(PNX833X_CONFIG +
            PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = new_timeout;
        return put_user(new_timeout, (int *)arg);
    }

    case WDIOC_GETTIMEOUT:
        timeout = PNX833X_REG(PNX833X_CONFIG +
                    PNX833X_CONFIG_CPU_WATCHDOG_COMPARE);
        return put_user(timeout, (int *)arg);

    case WDIOC_GETTIMELEFT:
        timeout_left = PNX833X_REG(PNX833X_CONFIG +
                        PNX833X_CONFIG_CPU_WATCHDOG);
        return put_user(timeout_left, (int *)arg);

    }
}

static int pnx833x_wdt_notify_sys(struct notifier_block *this,
                    unsigned long code, void *unused)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        pnx833x_wdt_stop(); /* Turn the WDT off */

    return NOTIFY_DONE;
}

static const struct file_operations pnx833x_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = pnx833x_wdt_write,
    .unlocked_ioctl = pnx833x_wdt_ioctl,
    .open       = pnx833x_wdt_open,
    .release    = pnx833x_wdt_release,
};

static struct miscdevice pnx833x_wdt_miscdev = {
    .minor      = WATCHDOG_MINOR,
    .name       = "watchdog",
    .fops       = &pnx833x_wdt_fops,
};

static struct notifier_block pnx833x_wdt_notifier = {
    .notifier_call = pnx833x_wdt_notify_sys,
};

static int __init watchdog_init(void)
{
    int ret, cause;

    /* Lets check the reason for the reset.*/
    cause = PNX833X_REG(PNX833X_RESET);
    /*If bit 31 is set then watchdog was cause of reset.*/
    if (cause & 0x80000000) {
        pr_info("The system was previously reset due to the watchdog firing - please investigate...\n");
    }

    ret = register_reboot_notifier(&pnx833x_wdt_notifier);
    if (ret) {
        pr_err("cannot register reboot notifier (err=%d)\n", ret);
        return ret;
    }

    ret = misc_register(&pnx833x_wdt_miscdev);
    if (ret) {
        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
               WATCHDOG_MINOR, ret);
        unregister_reboot_notifier(&pnx833x_wdt_notifier);
        return ret;
    }

    pr_info("Hardware Watchdog Timer for PNX833x: Version 0.1\n");

    if (start_enabled)
        pnx833x_wdt_start();

    return 0;
}

static void __exit watchdog_exit(void)
{
    misc_deregister(&pnx833x_wdt_miscdev);
    unregister_reboot_notifier(&pnx833x_wdt_notifier);
}

module_init(watchdog_init);
module_exit(watchdog_exit);

MODULE_AUTHOR("Daniel Laird/Andre McCurdy");
MODULE_DESCRIPTION("Hardware Watchdog Device for PNX833x");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);