LXR linux/drivers/watchdog/softdog.c

   1/*
   2 *      SoftDog:        A Software Watchdog Device
   3 *
   4 *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   5 *                                                      All Rights Reserved.
   6 *
   7 *      This program is free software; you can redistribute it and/or
   8 *      modify it under the terms of the GNU General Public License
   9 *      as published by the Free Software Foundation; either version
  10 *      2 of the License, or (at your option) any later version.
  11 *
  12 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  13 *      warranty for any of this software. This material is provided
  14 *      "AS-IS" and at no charge.
  15 *
  16 *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  17 *
  18 *      Software only watchdog driver. Unlike its big brother the WDT501P
  19 *      driver this won't always recover a failed machine.
  20 */
  21
  22#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  23
  24#include <linux/init.h>
  25#include <linux/jiffies.h>
  26#include <linux/kernel.h>
  27#include <linux/module.h>
  28#include <linux/moduleparam.h>
  29#include <linux/reboot.h>
  30#include <linux/timer.h>
  31#include <linux/types.h>
  32#include <linux/watchdog.h>
  33
  34#define TIMER_MARGIN    60              /* Default is 60 seconds */
  35static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
  36module_param(soft_margin, uint, 0);
  37MODULE_PARM_DESC(soft_margin,
  38        "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
  39                                        __MODULE_STRING(TIMER_MARGIN) ")");
  40
  41static bool nowayout = WATCHDOG_NOWAYOUT;
  42module_param(nowayout, bool, 0);
  43MODULE_PARM_DESC(nowayout,
  44                "Watchdog cannot be stopped once started (default="
  45                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  46
  47static int soft_noboot;
  48module_param(soft_noboot, int, 0);
  49MODULE_PARM_DESC(soft_noboot,
  50        "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
  51
  52static int soft_panic;
  53module_param(soft_panic, int, 0);
  54MODULE_PARM_DESC(soft_panic,
  55        "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
  56
  57static void softdog_fire(unsigned long data)
  58{
  59        module_put(THIS_MODULE);
  60        if (soft_noboot) {
  61                pr_crit("Triggered - Reboot ignored\n");
  62        } else if (soft_panic) {
  63                pr_crit("Initiating panic\n");
  64                panic("Software Watchdog Timer expired");
  65        } else {
  66                pr_crit("Initiating system reboot\n");
  67                emergency_restart();
  68                pr_crit("Reboot didn't ?????\n");
  69        }
  70}
  71
  72static struct timer_list softdog_ticktock =
  73                TIMER_INITIALIZER(softdog_fire, 0, 0);
  74
  75static int softdog_ping(struct watchdog_device *w)
  76{
  77        if (!mod_timer(&softdog_ticktock, jiffies + (w->timeout * HZ)))
  78                __module_get(THIS_MODULE);
  79        return 0;
  80}
  81
  82static int softdog_stop(struct watchdog_device *w)
  83{
  84        if (del_timer(&softdog_ticktock))
  85                module_put(THIS_MODULE);
  86
  87        return 0;
  88}
  89
  90static struct watchdog_info softdog_info = {
  91        .identity = "Software Watchdog",
  92        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  93};
  94
  95static struct watchdog_ops softdog_ops = {
  96        .owner = THIS_MODULE,
  97        .start = softdog_ping,
  98        .stop = softdog_stop,
  99};
 100
 101static struct watchdog_device softdog_dev = {
 102        .info = &softdog_info,
 103        .ops = &softdog_ops,
 104        .min_timeout = 1,
 105        .max_timeout = 65535,
 106        .timeout = TIMER_MARGIN,
 107};
 108
 109static int __init softdog_init(void)
 110{
 111        int ret;
 112
 113        watchdog_init_timeout(&softdog_dev, soft_margin, NULL);
 114        watchdog_set_nowayout(&softdog_dev, nowayout);
 115        watchdog_stop_on_reboot(&softdog_dev);
 116
 117        ret = watchdog_register_device(&softdog_dev);
 118        if (ret)
 119                return ret;
 120
 121        pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
 122                soft_noboot, softdog_dev.timeout, soft_panic, nowayout);
 123
 124        return 0;
 125}
 126module_init(softdog_init);
 127
 128static void __exit softdog_exit(void)
 129{
 130        watchdog_unregister_device(&softdog_dev);
 131}
 132module_exit(softdog_exit);
 133
 134MODULE_AUTHOR("Alan Cox");
 135MODULE_DESCRIPTION("Software Watchdog Device Driver");
 136MODULE_LICENSE("GPL");
 137