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 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/fs.h>
  20 #include <linux/mm.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/notifier.h>
  24 #include <linux/reboot.h>
  25 #include <linux/init.h>
  26 #include <linux/uaccess.h>
  27 #include <asm/sgi/mc.h>
  28
  29 #define PFX "indydog: "
  30 static unsigned long indydog_alive;
  31 static spinlock_t indydog_lock;
  32
  33 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
  34
  35 static int nowayout = WATCHDOG_NOWAYOUT;
  36 module_param(nowayout, int, 0);
  37 MODULE_PARM_DESC(nowayout,
  38                 "Watchdog cannot be stopped once started (default="
  39                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  40
  41 static void indydog_start(void)
  42 {
  43         u32 mc_ctrl0;
  44
  45         spin_lock(&indydog_lock);
  46         mc_ctrl0 = sgimc->cpuctrl0;
  47         mc_ctrl0 = sgimc->cpuctrl0 | SGIMC_CCTRL0_WDOG;
  48         sgimc->cpuctrl0 = mc_ctrl0;
  49         spin_unlock(&indydog_lock);
  50 }
  51
  52 static void indydog_stop(void)
  53 {
  54         u32 mc_ctrl0;
  55
  56         spin_lock(&indydog_lock);
  57
  58         mc_ctrl0 = sgimc->cpuctrl0;
  59         mc_ctrl0 &= ~SGIMC_CCTRL0_WDOG;
  60         sgimc->cpuctrl0 = mc_ctrl0;
  61         spin_unlock(&indydog_lock);
  62
  63         printk(KERN_INFO PFX "Stopped watchdog timer.\n");
  64 }
  65
  66 static void indydog_ping(void)
  67 {
  68         sgimc->watchdogt = 0;
  69 }
  70
  71 /*
  72  *      Allow only one person to hold it open
  73  */
  74 static int indydog_open(struct inode *inode, struct file *file)
  75 {
  76         if (test_and_set_bit(0, &indydog_alive))
  77                 return -EBUSY;
  78
  79         if (nowayout)
  80                 __module_get(THIS_MODULE);
  81
  82         /* Activate timer */
  83         indydog_start();
  84         indydog_ping();
  85
  86         printk(KERN_INFO "Started watchdog timer.\n");
  87
  88         return nonseekable_open(inode, file);
  89 }
  90
  91 static int indydog_release(struct inode *inode, struct file *file)
  92 {
  93         /* Shut off the timer.
  94          * Lock it in if it's a module and we defined ...NOWAYOUT */
  95         if (!nowayout)
  96                 indydog_stop();         /* Turn the WDT off */
  97         clear_bit(0, &indydog_alive);
  98         return 0;
  99 }
 100
 101 static ssize_t indydog_write(struct file *file, const char *data,
 102                                                 size_t len, loff_t *ppos)
 103 {
 104         /* Refresh the timer. */
 105         if (len)
 106                 indydog_ping();
 107         return len;
 108 }
 109
 110 static long indydog_ioctl(struct file *file, unsigned int cmd,
 111                                                         unsigned long arg)
 112 {
 113         int options, retval = -EINVAL;
 114         static const struct watchdog_info ident = {
 115                 .options                = WDIOF_KEEPALIVEPING,
 116                 .firmware_version       = 0,
 117                 .identity               = "Hardware Watchdog for SGI IP22",
 118         };
 119
 120         switch (cmd) {
 121         case WDIOC_GETSUPPORT:
 122                 if (copy_to_user((struct watchdog_info *)arg,
 123                                  &ident, sizeof(ident)))
 124                         return -EFAULT;
 125                 return 0;
 126         case WDIOC_GETSTATUS:
 127         case WDIOC_GETBOOTSTATUS:
 128                 return put_user(0, (int *)arg);
 129         case WDIOC_SETOPTIONS:
 130         {
 131                 if (get_user(options, (int *)arg))
 132                         return -EFAULT;
 133                 if (options & WDIOS_DISABLECARD) {
 134                         indydog_stop();
 135                         retval = 0;
 136                 }
 137                 if (options & WDIOS_ENABLECARD) {
 138                         indydog_start();
 139                         retval = 0;
 140                 }
 141                 return retval;
 142         }
 143         case WDIOC_KEEPALIVE:
 144                 indydog_ping();
 145                 return 0;
 146         case WDIOC_GETTIMEOUT:
 147                 return put_user(WATCHDOG_TIMEOUT, (int *)arg);
 148         default:
 149                 return -ENOTTY;
 150         }
 151 }
 152
 153 static int indydog_notify_sys(struct notifier_block *this,
 154                                         unsigned long code, void *unused)
 155 {
 156         if (code == SYS_DOWN || code == SYS_HALT)
 157                 indydog_stop();         /* Turn the WDT off */
 158
 159         return NOTIFY_DONE;
 160 }
 161
 162 static const struct file_operations indydog_fops = {
 163         .owner          = THIS_MODULE,
 164         .llseek         = no_llseek,
 165         .write          = indydog_write,
 166         .unlocked_ioctl = indydog_ioctl,
 167         .open           = indydog_open,
 168         .release        = indydog_release,
 169 };
 170
 171 static struct miscdevice indydog_miscdev = {
 172         .minor          = WATCHDOG_MINOR,
 173         .name           = "watchdog",
 174         .fops           = &indydog_fops,
 175 };
 176
 177 static struct notifier_block indydog_notifier = {
 178         .notifier_call = indydog_notify_sys,
 179 };
 180
 181 static char banner[] __initdata =
 182         KERN_INFO PFX "Hardware Watchdog Timer for SGI IP22: 0.3\n";
 183
 184 static int __init watchdog_init(void)
 185 {
 186         int ret;
 187
 188         spin_lock_init(&indydog_lock);
 189
 190         ret = register_reboot_notifier(&indydog_notifier);
 191         if (ret) {
 192                 printk(KERN_ERR PFX
 193                         "cannot register reboot notifier (err=%d)\n", ret);
 194                 return ret;
 195         }
 196
 197         ret = misc_register(&indydog_miscdev);
 198         if (ret) {
 199                 printk(KERN_ERR PFX
 200                         "cannot register miscdev on minor=%d (err=%d)\n",
 201                                                         WATCHDOG_MINOR, ret);
 202                 unregister_reboot_notifier(&indydog_notifier);
 203                 return ret;
 204         }
 205
 206         printk(banner);
 207
 208         return 0;
 209 }
 210
 211 static void __exit watchdog_exit(void)
 212 {
 213         misc_deregister(&indydog_miscdev);
 214         unregister_reboot_notifier(&indydog_notifier);
 215 }
 216
 217 module_init(watchdog_init);
 218 module_exit(watchdog_exit);
 219
 220 MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
 221 MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
 222 MODULE_LICENSE("GPL");
 223 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);