drivers/watchdog/indydog.c

   1 /*
   2  *      IndyDog 0.3     A Hardware Watchdog Device for SGI IP22
   3  *
   4  *      (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>,
   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  *      based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
  13  */
  14
  15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  16
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/fs.h>
  22 #include <linux/mm.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/watchdog.h>
  25 #include <linux/notifier.h>
  26 #include <linux/reboot.h>
  27 #include <linux/init.h>
  28 #include <linux/uaccess.h>
  29 #include <asm/sgi/mc.h>
  30
  31 static unsigned long indydog_alive;
  32 static DEFINE_SPINLOCK(indydog_lock);
  33
  34 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
  35
  36 static bool nowayout = WATCHDOG_NOWAYOUT;
  37 module_param(nowayout, bool, 0);
  38 MODULE_PARM_DESC(nowayout,
  39                 "Watchdog cannot be stopped once started (default="
  40                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41
  42 static void indydog_start(void)
  43 {
  44         spin_lock(&indydog_lock);
  45         sgimc->cpuctrl0 |= SGIMC_CCTRL0_WDOG;
  46         spin_unlock(&indydog_lock);
  47 }
  48
  49 static void indydog_stop(void)
  50 {
  51         spin_lock(&indydog_lock);
  52         sgimc->cpuctrl0 &= ~SGIMC_CCTRL0_WDOG;
  53         spin_unlock(&indydog_lock);
  54
  55         pr_info("Stopped watchdog timer\n");
  56 }
  57
  58 static void indydog_ping(void)
  59 {
  60         sgimc->watchdogt = 0;
  61 }
  62
  63 /*
  64  *      Allow only one person to hold it open
  65  */
  66 static int indydog_open(struct inode *inode, struct file *file)
  67 {
  68         if (test_and_set_bit(0, &indydog_alive))
  69                 return -EBUSY;
  70
  71         if (nowayout)
  72                 __module_get(THIS_MODULE);
  73
  74         /* Activate timer */
  75         indydog_start();
  76         indydog_ping();
  77
  78         pr_info("Started watchdog timer\n");
  79
  80         return nonseekable_open(inode, file);
  81 }
  82
  83 static int indydog_release(struct inode *inode, struct file *file)
  84 {
  85         /* Shut off the timer.
  86          * Lock it in if it's a module and we defined ...NOWAYOUT */
  87         if (!nowayout)
  88                 indydog_stop();         /* Turn the WDT off */
  89         clear_bit(0, &indydog_alive);
  90         return 0;
  91 }
  92
  93 static ssize_t indydog_write(struct file *file, const char *data,
  94                                                 size_t len, loff_t *ppos)
  95 {
  96         /* Refresh the timer. */
  97         if (len)
  98                 indydog_ping();
  99         return len;
 100 }
 101
 102 static long indydog_ioctl(struct file *file, unsigned int cmd,
 103                                                         unsigned long arg)
 104 {
 105         int options, retval = -EINVAL;
 106         static const struct watchdog_info ident = {
 107                 .options                = WDIOF_KEEPALIVEPING,
 108                 .firmware_version       = 0,
 109                 .identity               = "Hardware Watchdog for SGI IP22",
 110         };
 111
 112         switch (cmd) {
 113         case WDIOC_GETSUPPORT:
 114                 if (copy_to_user((struct watchdog_info *)arg,
 115                                  &ident, sizeof(ident)))
 116                         return -EFAULT;
 117                 return 0;
 118         case WDIOC_GETSTATUS:
 119         case WDIOC_GETBOOTSTATUS:
 120                 return put_user(0, (int *)arg);
 121         case WDIOC_SETOPTIONS:
 122         {
 123                 if (get_user(options, (int *)arg))
 124                         return -EFAULT;
 125                 if (options & WDIOS_DISABLECARD) {
 126                         indydog_stop();
 127                         retval = 0;
 128                 }
 129                 if (options & WDIOS_ENABLECARD) {
 130                         indydog_start();
 131                         retval = 0;
 132                 }
 133                 return retval;
 134         }
 135         case WDIOC_KEEPALIVE:
 136                 indydog_ping();
 137                 return 0;
 138         case WDIOC_GETTIMEOUT:
 139                 return put_user(WATCHDOG_TIMEOUT, (int *)arg);
 140         default:
 141                 return -ENOTTY;
 142         }
 143 }
 144
 145 static int indydog_notify_sys(struct notifier_block *this,
 146                                         unsigned long code, void *unused)
 147 {
 148         if (code == SYS_DOWN || code == SYS_HALT)
 149                 indydog_stop();         /* Turn the WDT off */
 150
 151         return NOTIFY_DONE;
 152 }
 153
 154 static const struct file_operations indydog_fops = {
 155         .owner          = THIS_MODULE,
 156         .llseek         = no_llseek,
 157         .write          = indydog_write,
 158         .unlocked_ioctl = indydog_ioctl,
 159         .open           = indydog_open,
 160         .release        = indydog_release,
 161 };
 162
 163 static struct miscdevice indydog_miscdev = {
 164         .minor          = WATCHDOG_MINOR,
 165         .name           = "watchdog",
 166         .fops           = &indydog_fops,
 167 };
 168
 169 static struct notifier_block indydog_notifier = {
 170         .notifier_call = indydog_notify_sys,
 171 };
 172
 173 static int __init watchdog_init(void)
 174 {
 175         int ret;
 176
 177         ret = register_reboot_notifier(&indydog_notifier);
 178         if (ret) {
 179                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 180                 return ret;
 181         }
 182
 183         ret = misc_register(&indydog_miscdev);
 184         if (ret) {
 185                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 186                        WATCHDOG_MINOR, ret);
 187                 unregister_reboot_notifier(&indydog_notifier);
 188                 return ret;
 189         }
 190
 191         pr_info("Hardware Watchdog Timer for SGI IP22: 0.3\n");
 192
 193         return 0;
 194 }
 195
 196 static void __exit watchdog_exit(void)
 197 {
 198         misc_deregister(&indydog_miscdev);
 199         unregister_reboot_notifier(&indydog_notifier);
 200 }
 201
 202 module_init(watchdog_init);
 203 module_exit(watchdog_exit);
 204
 205 MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
 206 MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
 207 MODULE_LICENSE("GPL");