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@redhat.com>
  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         indydog_alive = 1;
  87         printk(KERN_INFO "Started watchdog timer.\n");
  88
  89         return nonseekable_open(inode, file);
  90 }
  91
  92 static int indydog_release(struct inode *inode, struct file *file)
  93 {
  94         /* Shut off the timer.
  95          * Lock it in if it's a module and we defined ...NOWAYOUT */
  96         if (!nowayout)
  97                 indydog_stop();         /* Turn the WDT off */
  98         clear_bit(0, &indydog_alive);
  99         return 0;
 100 }
 101
 102 static ssize_t indydog_write(struct file *file, const char *data,
 103                                                 size_t len, loff_t *ppos)
 104 {
 105         /* Refresh the timer. */
 106         if (len)
 107                 indydog_ping();
 108         return len;
 109 }
 110
 111 static long indydog_ioctl(struct file *file, unsigned int cmd,
 112                                                         unsigned long arg)
 113 {
 114         int options, retval = -EINVAL;
 115         static struct watchdog_info ident = {
 116                 .options                = WDIOF_KEEPALIVEPING |
 117                                           WDIOF_MAGICCLOSE,
 118                 .firmware_version       = 0,
 119                 .identity               = "Hardware Watchdog for SGI IP22",
 120         };
 121
 122         switch (cmd) {
 123         case WDIOC_GETSUPPORT:
 124                 if (copy_to_user((struct watchdog_info *)arg,
 125                                  &ident, sizeof(ident)))
 126                         return -EFAULT;
 127                 return 0;
 128         case WDIOC_GETSTATUS:
 129         case WDIOC_GETBOOTSTATUS:
 130                 return put_user(0, (int *)arg);
 131         case WDIOC_SETOPTIONS:
 132         {
 133                 if (get_user(options, (int *)arg))
 134                         return -EFAULT;
 135                 if (options & WDIOS_DISABLECARD) {
 136                         indydog_stop();
 137                         retval = 0;
 138                 }
 139                 if (options & WDIOS_ENABLECARD) {
 140                         indydog_start();
 141                         retval = 0;
 142                 }
 143                 return retval;
 144         }
 145         case WDIOC_KEEPALIVE:
 146                 indydog_ping();
 147                 return 0;
 148         case WDIOC_GETTIMEOUT:
 149                 return put_user(WATCHDOG_TIMEOUT, (int *)arg);
 150         default:
 151                 return -ENOTTY;
 152         }
 153 }
 154
 155 static int indydog_notify_sys(struct notifier_block *this,
 156                                         unsigned long code, void *unused)
 157 {
 158         if (code == SYS_DOWN || code == SYS_HALT)
 159                 indydog_stop();         /* Turn the WDT off */
 160
 161         return NOTIFY_DONE;
 162 }
 163
 164 static const struct file_operations indydog_fops = {
 165         .owner          = THIS_MODULE,
 166         .llseek         = no_llseek,
 167         .write          = indydog_write,
 168         .unlocked_ioctl = indydog_ioctl,
 169         .open           = indydog_open,
 170         .release        = indydog_release,
 171 };
 172
 173 static struct miscdevice indydog_miscdev = {
 174         .minor          = WATCHDOG_MINOR,
 175         .name           = "watchdog",
 176         .fops           = &indydog_fops,
 177 };
 178
 179 static struct notifier_block indydog_notifier = {
 180         .notifier_call = indydog_notify_sys,
 181 };
 182
 183 static char banner[] __initdata =
 184         KERN_INFO PFX "Hardware Watchdog Timer for SGI IP22: 0.3\n";
 185
 186 static int __init watchdog_init(void)
 187 {
 188         int ret;
 189
 190         spin_lock_init(&indydog_lock);
 191
 192         ret = register_reboot_notifier(&indydog_notifier);
 193         if (ret) {
 194                 printk(KERN_ERR PFX
 195                         "cannot register reboot notifier (err=%d)\n", ret);
 196                 return ret;
 197         }
 198
 199         ret = misc_register(&indydog_miscdev);
 200         if (ret) {
 201                 printk(KERN_ERR PFX
 202                         "cannot register miscdev on minor=%d (err=%d)\n",
 203                                                         WATCHDOG_MINOR, ret);
 204                 unregister_reboot_notifier(&indydog_notifier);
 205                 return ret;
 206         }
 207
 208         printk(banner);
 209
 210         return 0;
 211 }
 212
 213 static void __exit watchdog_exit(void)
 214 {
 215         misc_deregister(&indydog_miscdev);
 216         unregister_reboot_notifier(&indydog_notifier);
 217 }
 218
 219 module_init(watchdog_init);
 220 module_exit(watchdog_exit);
 221
 222 MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
 223 MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
 224 MODULE_LICENSE("GPL");
 225 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);