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         u32 mc_ctrl0;
  45
  46         spin_lock(&indydog_lock);
  47         mc_ctrl0 = sgimc->cpuctrl0;
  48         mc_ctrl0 = sgimc->cpuctrl0 | SGIMC_CCTRL0_WDOG;
  49         sgimc->cpuctrl0 = mc_ctrl0;
  50         spin_unlock(&indydog_lock);
  51 }
  52
  53 static void indydog_stop(void)
  54 {
  55         u32 mc_ctrl0;
  56
  57         spin_lock(&indydog_lock);
  58
  59         mc_ctrl0 = sgimc->cpuctrl0;
  60         mc_ctrl0 &= ~SGIMC_CCTRL0_WDOG;
  61         sgimc->cpuctrl0 = mc_ctrl0;
  62         spin_unlock(&indydog_lock);
  63
  64         pr_info("Stopped watchdog timer\n");
  65 }
  66
  67 static void indydog_ping(void)
  68 {
  69         sgimc->watchdogt = 0;
  70 }
  71
  72 /*
  73  *      Allow only one person to hold it open
  74  */
  75 static int indydog_open(struct inode *inode, struct file *file)
  76 {
  77         if (test_and_set_bit(0, &indydog_alive))
  78                 return -EBUSY;
  79
  80         if (nowayout)
  81                 __module_get(THIS_MODULE);
  82
  83         /* Activate timer */
  84         indydog_start();
  85         indydog_ping();
  86
  87         pr_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 const struct watchdog_info ident = {
 116                 .options                = WDIOF_KEEPALIVEPING,
 117                 .firmware_version       = 0,
 118                 .identity               = "Hardware Watchdog for SGI IP22",
 119         };
 120
 121         switch (cmd) {
 122         case WDIOC_GETSUPPORT:
 123                 if (copy_to_user((struct watchdog_info *)arg,
 124                                  &ident, sizeof(ident)))
 125                         return -EFAULT;
 126                 return 0;
 127         case WDIOC_GETSTATUS:
 128         case WDIOC_GETBOOTSTATUS:
 129                 return put_user(0, (int *)arg);
 130         case WDIOC_SETOPTIONS:
 131         {
 132                 if (get_user(options, (int *)arg))
 133                         return -EFAULT;
 134                 if (options & WDIOS_DISABLECARD) {
 135                         indydog_stop();
 136                         retval = 0;
 137                 }
 138                 if (options & WDIOS_ENABLECARD) {
 139                         indydog_start();
 140                         retval = 0;
 141                 }
 142                 return retval;
 143         }
 144         case WDIOC_KEEPALIVE:
 145                 indydog_ping();
 146                 return 0;
 147         case WDIOC_GETTIMEOUT:
 148                 return put_user(WATCHDOG_TIMEOUT, (int *)arg);
 149         default:
 150                 return -ENOTTY;
 151         }
 152 }
 153
 154 static int indydog_notify_sys(struct notifier_block *this,
 155                                         unsigned long code, void *unused)
 156 {
 157         if (code == SYS_DOWN || code == SYS_HALT)
 158                 indydog_stop();         /* Turn the WDT off */
 159
 160         return NOTIFY_DONE;
 161 }
 162
 163 static const struct file_operations indydog_fops = {
 164         .owner          = THIS_MODULE,
 165         .llseek         = no_llseek,
 166         .write          = indydog_write,
 167         .unlocked_ioctl = indydog_ioctl,
 168         .open           = indydog_open,
 169         .release        = indydog_release,
 170 };
 171
 172 static struct miscdevice indydog_miscdev = {
 173         .minor          = WATCHDOG_MINOR,
 174         .name           = "watchdog",
 175         .fops           = &indydog_fops,
 176 };
 177
 178 static struct notifier_block indydog_notifier = {
 179         .notifier_call = indydog_notify_sys,
 180 };
 181
 182 static int __init watchdog_init(void)
 183 {
 184         int ret;
 185
 186         ret = register_reboot_notifier(&indydog_notifier);
 187         if (ret) {
 188                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 189                 return ret;
 190         }
 191
 192         ret = misc_register(&indydog_miscdev);
 193         if (ret) {
 194                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 195                        WATCHDOG_MINOR, ret);
 196                 unregister_reboot_notifier(&indydog_notifier);
 197                 return ret;
 198         }
 199
 200         pr_info("Hardware Watchdog Timer for SGI IP22: 0.3\n");
 201
 202         return 0;
 203 }
 204
 205 static void __exit watchdog_exit(void)
 206 {
 207         misc_deregister(&indydog_miscdev);
 208         unregister_reboot_notifier(&indydog_notifier);
 209 }
 210
 211 module_init(watchdog_init);
 212 module_exit(watchdog_exit);
 213
 214 MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
 215 MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
 216 MODULE_LICENSE("GPL");