drivers/char/watchdog/acquirewdt.c

   1 /*
   2  *      Acquire Single Board Computer Watchdog Timer driver
   3  *
   4  *      Based on wdt.c. Original copyright messages:
   5  *
   6  *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
   7  *                              http://www.redhat.com
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  15  *      warranty for any of this software. This material is provided
  16  *      "AS-IS" and at no charge.
  17  *
  18  *      (c) Copyright 1995    Alan Cox <alan@redhat.com>
  19  *
  20  *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  21  *          Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  22  *          Can't add timeout - driver doesn't allow changing value
  23  */
  24
  25 /*
  26  *      Theory of Operation:
  27  *              The Watch-Dog Timer is provided to ensure that standalone
  28  *              Systems can always recover from catastrophic conditions that
  29  *              caused the CPU to crash. This condition may have occured by
  30  *              external EMI or a software bug. When the CPU stops working
  31  *              correctly, hardware on the board will either perform a hardware
  32  *              reset (cold boot) or a non-maskable interrupt (NMI) to bring the
  33  *              system back to a known state.
  34  *
  35  *              The Watch-Dog Timer is controlled by two I/O Ports.
  36  *                443 hex       - Read  - Enable or refresh the Watch-Dog Timer
  37  *                043 hex       - Read  - Disable the Watch-Dog Timer
  38  *
  39  *              To enable the Watch-Dog Timer, a read from I/O port 443h must
  40  *              be performed. This will enable and activate the countdown timer
  41  *              which will eventually time out and either reset the CPU or cause
  42  *              an NMI depending on the setting of a jumper. To ensure that this
  43  *              reset condition does not occur, the Watch-Dog Timer must be
  44  *              periodically refreshed by reading the same I/O port 443h.
  45  *              The Watch-Dog Timer is disabled by reading I/O port 043h.
  46  *
  47  *              The Watch-Dog Timer Time-Out Period is set via jumpers.
  48  *              It can be 1, 2, 10, 20, 110 or 220 seconds.
  49  */
  50
  51 #include <linux/module.h>
  52 #include <linux/moduleparam.h>
  53 #include <linux/types.h>
  54 #include <linux/miscdevice.h>
  55 #include <linux/watchdog.h>
  56 #include <linux/fs.h>
  57 #include <linux/ioport.h>
  58 #include <linux/notifier.h>
  59 #include <linux/reboot.h>
  60 #include <linux/init.h>
  61
  62 #include <asm/io.h>
  63 #include <asm/uaccess.h>
  64 #include <asm/system.h>
  65
  66 #define WATCHDOG_NAME "Acquire WDT"
  67 #define PFX WATCHDOG_NAME ": "
  68 #define WATCHDOG_HEARTBEAT 0    /* There is no way to see what the correct time-out period is */
  69
  70 static unsigned long acq_is_open;
  71 static char expect_close;
  72
  73 /*
  74  *      You must set these - there is no sane way to probe for this board.
  75  */
  76
  77 static int wdt_stop = 0x43;
  78 module_param(wdt_stop, int, 0);
  79 MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
  80
  81 static int wdt_start = 0x443;
  82 module_param(wdt_start, int, 0);
  83 MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
  84
  85 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  86 static int nowayout = 1;
  87 #else
  88 static int nowayout = 0;
  89 #endif
  90
  91 module_param(nowayout, int, 0);
  92 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  93
  94 /*
  95  *      Kernel methods.
  96  */
  97
  98 static void acq_keepalive(void)
  99 {
 100         /* Write a watchdog value */
 101         inb_p(wdt_start);
 102 }
 103
 104 static void acq_stop(void)
 105 {
 106         /* Turn the card off */
 107         inb_p(wdt_stop);
 108 }
 109
 110 /*
 111  *      /dev/watchdog handling.
 112  */
 113
 114 static ssize_t acq_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 115 {
 116         /* See if we got the magic character 'V' and reload the timer */
 117         if(count) {
 118                 if (!nowayout) {
 119                         size_t i;
 120
 121                         /* note: just in case someone wrote the magic character
 122                          * five months ago... */
 123                         expect_close = 0;
 124
 125                         /* scan to see whether or not we got the magic character */
 126                         for (i = 0; i != count; i++) {
 127                                 char c;
 128                                 if (get_user(c, buf + i))
 129                                         return -EFAULT;
 130                                 if (c == 'V')
 131                                         expect_close = 42;
 132                         }
 133                 }
 134
 135                 /* Well, anyhow someone wrote to us, we should return that favour */
 136                 acq_keepalive();
 137         }
 138         return count;
 139 }
 140
 141 static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 142         unsigned long arg)
 143 {
 144         int options, retval = -EINVAL;
 145         void __user *argp = (void __user *)arg;
 146         int __user *p = argp;
 147         static struct watchdog_info ident =
 148         {
 149                 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 150                 .firmware_version = 1,
 151                 .identity = "Acquire WDT",
 152         };
 153
 154         switch(cmd)
 155         {
 156         case WDIOC_GETSUPPORT:
 157           return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 158
 159         case WDIOC_GETSTATUS:
 160         case WDIOC_GETBOOTSTATUS:
 161           return put_user(0, p);
 162
 163         case WDIOC_KEEPALIVE:
 164           acq_keepalive();
 165           return 0;
 166
 167         case WDIOC_GETTIMEOUT:
 168           return put_user(WATCHDOG_HEARTBEAT, p);
 169
 170         case WDIOC_SETOPTIONS:
 171         {
 172             if (get_user(options, p))
 173               return -EFAULT;
 174
 175             if (options & WDIOS_DISABLECARD)
 176             {
 177               acq_stop();
 178               retval = 0;
 179             }
 180
 181             if (options & WDIOS_ENABLECARD)
 182             {
 183               acq_keepalive();
 184               retval = 0;
 185             }
 186
 187             return retval;
 188         }
 189
 190         default:
 191           return -ENOIOCTLCMD;
 192         }
 193 }
 194
 195 static int acq_open(struct inode *inode, struct file *file)
 196 {
 197         if (test_and_set_bit(0, &acq_is_open))
 198                 return -EBUSY;
 199
 200         if (nowayout)
 201                 __module_get(THIS_MODULE);
 202
 203         /* Activate */
 204         acq_keepalive();
 205         return nonseekable_open(inode, file);
 206 }
 207
 208 static int acq_close(struct inode *inode, struct file *file)
 209 {
 210         if (expect_close == 42) {
 211                 acq_stop();
 212         } else {
 213                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 214                 acq_keepalive();
 215         }
 216         clear_bit(0, &acq_is_open);
 217         expect_close = 0;
 218         return 0;
 219 }
 220
 221 /*
 222  *      Notifier for system down
 223  */
 224
 225 static int acq_notify_sys(struct notifier_block *this, unsigned long code,
 226         void *unused)
 227 {
 228         if(code==SYS_DOWN || code==SYS_HALT) {
 229                 /* Turn the WDT off */
 230                 acq_stop();
 231         }
 232         return NOTIFY_DONE;
 233 }
 234
 235 /*
 236  *      Kernel Interfaces
 237  */
 238
 239 static struct file_operations acq_fops = {
 240         .owner          = THIS_MODULE,
 241         .llseek         = no_llseek,
 242         .write          = acq_write,
 243         .ioctl          = acq_ioctl,
 244         .open           = acq_open,
 245         .release        = acq_close,
 246 };
 247
 248 static struct miscdevice acq_miscdev=
 249 {
 250         .minor = WATCHDOG_MINOR,
 251         .name = "watchdog",
 252         .fops = &acq_fops,
 253 };
 254
 255 /*
 256  *      The WDT card needs to learn about soft shutdowns in order to
 257  *      turn the timebomb registers off.
 258  */
 259
 260 static struct notifier_block acq_notifier =
 261 {
 262         .notifier_call = acq_notify_sys,
 263 };
 264
 265 static int __init acq_init(void)
 266 {
 267         int ret;
 268
 269         printk(KERN_INFO "WDT driver for Acquire single board computer initialising.\n");
 270
 271         if (wdt_stop != wdt_start) {
 272                 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
 273                         printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
 274                                 wdt_stop);
 275                         ret = -EIO;
 276                         goto out;
 277                 }
 278         }
 279
 280         if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
 281                 printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
 282                         wdt_start);
 283                 ret = -EIO;
 284                 goto unreg_stop;
 285         }
 286
 287         ret = register_reboot_notifier(&acq_notifier);
 288         if (ret != 0) {
 289                 printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 290                         ret);
 291                 goto unreg_regions;
 292         }
 293
 294         ret = misc_register(&acq_miscdev);
 295         if (ret != 0) {
 296                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 297                         WATCHDOG_MINOR, ret);
 298                 goto unreg_reboot;
 299         }
 300
 301         printk (KERN_INFO PFX "initialized. (nowayout=%d)\n",
 302                 nowayout);
 303
 304         return 0;
 305
 306 unreg_reboot:
 307         unregister_reboot_notifier(&acq_notifier);
 308 unreg_regions:
 309         release_region(wdt_start, 1);
 310 unreg_stop:
 311         if (wdt_stop != wdt_start)
 312                 release_region(wdt_stop, 1);
 313 out:
 314         return ret;
 315 }
 316
 317 static void __exit acq_exit(void)
 318 {
 319         misc_deregister(&acq_miscdev);
 320         unregister_reboot_notifier(&acq_notifier);
 321         if(wdt_stop != wdt_start)
 322                 release_region(wdt_stop,1);
 323         release_region(wdt_start,1);
 324 }
 325
 326 module_init(acq_init);
 327 module_exit(acq_exit);
 328
 329 MODULE_AUTHOR("David Woodhouse");
 330 MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
 331 MODULE_LICENSE("GPL");
 332 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);