drivers/char/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>, All Rights Reserved.
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  *
  11  *      based on softdog.c by Alan Cox <alan@redhat.com>
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/fs.h>
  19 #include <linux/mm.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/watchdog.h>
  22 #include <linux/notifier.h>
  23 #include <linux/reboot.h>
  24 #include <linux/init.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/sgi/mc.h>
  27
  28 #define PFX "indydog: "
  29 static int indydog_alive;
  30
  31 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
  32
  33 static int nowayout = WATCHDOG_NOWAYOUT;
  34 module_param(nowayout, int, 0);
  35 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  36
  37 static void indydog_start(void)
  38 {
  39         u32 mc_ctrl0 = sgimc->cpuctrl0;
  40
  41         mc_ctrl0 = sgimc->cpuctrl0 | SGIMC_CCTRL0_WDOG;
  42         sgimc->cpuctrl0 = mc_ctrl0;
  43 }
  44
  45 static void indydog_stop(void)
  46 {
  47         u32 mc_ctrl0 = sgimc->cpuctrl0;
  48
  49         mc_ctrl0 &= ~SGIMC_CCTRL0_WDOG;
  50         sgimc->cpuctrl0 = mc_ctrl0;
  51
  52         printk(KERN_INFO PFX "Stopped watchdog timer.\n");
  53 }
  54
  55 static void indydog_ping(void)
  56 {
  57         sgimc->watchdogt = 0;
  58 }
  59
  60 /*
  61  *      Allow only one person to hold it open
  62  */
  63 static int indydog_open(struct inode *inode, struct file *file)
  64 {
  65         if (indydog_alive)
  66                 return -EBUSY;
  67
  68         if (nowayout)
  69                 __module_get(THIS_MODULE);
  70
  71         /* Activate timer */
  72         indydog_start();
  73         indydog_ping();
  74
  75         indydog_alive = 1;
  76         printk(KERN_INFO "Started watchdog timer.\n");
  77
  78         return nonseekable_open(inode, file);
  79 }
  80
  81 static int indydog_release(struct inode *inode, struct file *file)
  82 {
  83         /* Shut off the timer.
  84          * Lock it in if it's a module and we defined ...NOWAYOUT */
  85         if (!nowayout)
  86                 indydog_stop();         /* Turn the WDT off */
  87
  88         indydog_alive = 0;
  89
  90         return 0;
  91 }
  92
  93 static ssize_t indydog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  94 {
  95         /* Refresh the timer. */
  96         if (len) {
  97                 indydog_ping();
  98         }
  99         return len;
 100 }
 101
 102 static int indydog_ioctl(struct inode *inode, struct file *file,
 103         unsigned int cmd, unsigned long arg)
 104 {
 105         int options, retval = -EINVAL;
 106         static struct watchdog_info ident = {
 107                 .options                = WDIOF_KEEPALIVEPING |
 108                                           WDIOF_MAGICCLOSE,
 109                 .firmware_version       = 0,
 110                 .identity               = "Hardware Watchdog for SGI IP22",
 111         };
 112
 113         switch (cmd) {
 114                 default:
 115                         return -ENOTTY;
 116                 case WDIOC_GETSUPPORT:
 117                         if (copy_to_user((struct watchdog_info *)arg,
 118                                          &ident, sizeof(ident)))
 119                                 return -EFAULT;
 120                         return 0;
 121                 case WDIOC_GETSTATUS:
 122                 case WDIOC_GETBOOTSTATUS:
 123                         return put_user(0,(int *)arg);
 124                 case WDIOC_KEEPALIVE:
 125                         indydog_ping();
 126                         return 0;
 127                 case WDIOC_GETTIMEOUT:
 128                         return put_user(WATCHDOG_TIMEOUT,(int *)arg);
 129                 case WDIOC_SETOPTIONS:
 130                 {
 131                         if (get_user(options, (int *)arg))
 132                                 return -EFAULT;
 133
 134                         if (options & WDIOS_DISABLECARD) {
 135                                 indydog_stop();
 136                                 retval = 0;
 137                         }
 138
 139                         if (options & WDIOS_ENABLECARD) {
 140                                 indydog_start();
 141                                 retval = 0;
 142                         }
 143
 144                         return retval;
 145                 }
 146         }
 147 }
 148
 149 static int indydog_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
 150 {
 151         if (code == SYS_DOWN || code == SYS_HALT)
 152                 indydog_stop();         /* Turn the WDT off */
 153
 154         return NOTIFY_DONE;
 155 }
 156
 157 static const struct file_operations indydog_fops = {
 158         .owner          = THIS_MODULE,
 159         .llseek         = no_llseek,
 160         .write          = indydog_write,
 161         .ioctl          = indydog_ioctl,
 162         .open           = indydog_open,
 163         .release        = indydog_release,
 164 };
 165
 166 static struct miscdevice indydog_miscdev = {
 167         .minor          = WATCHDOG_MINOR,
 168         .name           = "watchdog",
 169         .fops           = &indydog_fops,
 170 };
 171
 172 static struct notifier_block indydog_notifier = {
 173         .notifier_call = indydog_notify_sys,
 174 };
 175
 176 static char banner[] __initdata =
 177         KERN_INFO PFX "Hardware Watchdog Timer for SGI IP22: 0.3\n";
 178
 179 static int __init watchdog_init(void)
 180 {
 181         int ret;
 182
 183         ret = register_reboot_notifier(&indydog_notifier);
 184         if (ret) {
 185                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 186                         ret);
 187                 return ret;
 188         }
 189
 190         ret = misc_register(&indydog_miscdev);
 191         if (ret) {
 192                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 193                         WATCHDOG_MINOR, ret);
 194                 unregister_reboot_notifier(&indydog_notifier);
 195                 return ret;
 196         }
 197
 198         printk(banner);
 199
 200         return 0;
 201 }
 202
 203 static void __exit watchdog_exit(void)
 204 {
 205         misc_deregister(&indydog_miscdev);
 206         unregister_reboot_notifier(&indydog_notifier);
 207 }
 208
 209 module_init(watchdog_init);
 210 module_exit(watchdog_exit);
 211
 212 MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
 213 MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
 214 MODULE_LICENSE("GPL");
 215 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);