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 static int nowayout = WATCHDOG_NOWAYOUT;
  86 module_param(nowayout, int, 0);
  87 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  88
  89 /*
  90  *      Kernel methods.
  91  */
  92
  93 static void acq_keepalive(void)
  94 {
  95         /* Write a watchdog value */
  96         inb_p(wdt_start);
  97 }
  98
  99 static void acq_stop(void)
 100 {
 101         /* Turn the card off */
 102         inb_p(wdt_stop);
 103 }
 104
 105 /*
 106  *      /dev/watchdog handling.
 107  */
 108
 109 static ssize_t acq_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 110 {
 111         /* See if we got the magic character 'V' and reload the timer */
 112         if(count) {
 113                 if (!nowayout) {
 114                         size_t i;
 115
 116                         /* note: just in case someone wrote the magic character
 117                          * five months ago... */
 118                         expect_close = 0;
 119
 120                         /* scan to see whether or not we got the magic character */
 121                         for (i = 0; i != count; i++) {
 122                                 char c;
 123                                 if (get_user(c, buf + i))
 124                                         return -EFAULT;
 125                                 if (c == 'V')
 126                                         expect_close = 42;
 127                         }
 128                 }
 129
 130                 /* Well, anyhow someone wrote to us, we should return that favour */
 131                 acq_keepalive();
 132         }
 133         return count;
 134 }
 135
 136 static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 137         unsigned long arg)
 138 {
 139         int options, retval = -EINVAL;
 140         void __user *argp = (void __user *)arg;
 141         int __user *p = argp;
 142         static struct watchdog_info ident =
 143         {
 144                 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 145                 .firmware_version = 1,
 146                 .identity = "Acquire WDT",
 147         };
 148
 149         switch(cmd)
 150         {
 151         case WDIOC_GETSUPPORT:
 152           return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 153
 154         case WDIOC_GETSTATUS:
 155         case WDIOC_GETBOOTSTATUS:
 156           return put_user(0, p);
 157
 158         case WDIOC_KEEPALIVE:
 159           acq_keepalive();
 160           return 0;
 161
 162         case WDIOC_GETTIMEOUT:
 163           return put_user(WATCHDOG_HEARTBEAT, p);
 164
 165         case WDIOC_SETOPTIONS:
 166         {
 167             if (get_user(options, p))
 168               return -EFAULT;
 169
 170             if (options & WDIOS_DISABLECARD)
 171             {
 172               acq_stop();
 173               retval = 0;
 174             }
 175
 176             if (options & WDIOS_ENABLECARD)
 177             {
 178               acq_keepalive();
 179               retval = 0;
 180             }
 181
 182             return retval;
 183         }
 184
 185         default:
 186           return -ENOTTY;
 187         }
 188 }
 189
 190 static int acq_open(struct inode *inode, struct file *file)
 191 {
 192         if (test_and_set_bit(0, &acq_is_open))
 193                 return -EBUSY;
 194
 195         if (nowayout)
 196                 __module_get(THIS_MODULE);
 197
 198         /* Activate */
 199         acq_keepalive();
 200         return nonseekable_open(inode, file);
 201 }
 202
 203 static int acq_close(struct inode *inode, struct file *file)
 204 {
 205         if (expect_close == 42) {
 206                 acq_stop();
 207         } else {
 208                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 209                 acq_keepalive();
 210         }
 211         clear_bit(0, &acq_is_open);
 212         expect_close = 0;
 213         return 0;
 214 }
 215
 216 /*
 217  *      Notifier for system down
 218  */
 219
 220 static int acq_notify_sys(struct notifier_block *this, unsigned long code,
 221         void *unused)
 222 {
 223         if(code==SYS_DOWN || code==SYS_HALT) {
 224                 /* Turn the WDT off */
 225                 acq_stop();
 226         }
 227         return NOTIFY_DONE;
 228 }
 229
 230 /*
 231  *      Kernel Interfaces
 232  */
 233
 234 static const struct file_operations acq_fops = {
 235         .owner          = THIS_MODULE,
 236         .llseek         = no_llseek,
 237         .write          = acq_write,
 238         .ioctl          = acq_ioctl,
 239         .open           = acq_open,
 240         .release        = acq_close,
 241 };
 242
 243 static struct miscdevice acq_miscdev=
 244 {
 245         .minor = WATCHDOG_MINOR,
 246         .name = "watchdog",
 247         .fops = &acq_fops,
 248 };
 249
 250 /*
 251  *      The WDT card needs to learn about soft shutdowns in order to
 252  *      turn the timebomb registers off.
 253  */
 254
 255 static struct notifier_block acq_notifier =
 256 {
 257         .notifier_call = acq_notify_sys,
 258 };
 259
 260 static int __init acq_init(void)
 261 {
 262         int ret;
 263
 264         printk(KERN_INFO "WDT driver for Acquire single board computer initialising.\n");
 265
 266         if (wdt_stop != wdt_start) {
 267                 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
 268                         printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
 269                                 wdt_stop);
 270                         ret = -EIO;
 271                         goto out;
 272                 }
 273         }
 274
 275         if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
 276                 printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
 277                         wdt_start);
 278                 ret = -EIO;
 279                 goto unreg_stop;
 280         }
 281
 282         ret = register_reboot_notifier(&acq_notifier);
 283         if (ret != 0) {
 284                 printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 285                         ret);
 286                 goto unreg_regions;
 287         }
 288
 289         ret = misc_register(&acq_miscdev);
 290         if (ret != 0) {
 291                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 292                         WATCHDOG_MINOR, ret);
 293                 goto unreg_reboot;
 294         }
 295
 296         printk (KERN_INFO PFX "initialized. (nowayout=%d)\n",
 297                 nowayout);
 298
 299         return 0;
 300
 301 unreg_reboot:
 302         unregister_reboot_notifier(&acq_notifier);
 303 unreg_regions:
 304         release_region(wdt_start, 1);
 305 unreg_stop:
 306         if (wdt_stop != wdt_start)
 307                 release_region(wdt_stop, 1);
 308 out:
 309         return ret;
 310 }
 311
 312 static void __exit acq_exit(void)
 313 {
 314         misc_deregister(&acq_miscdev);
 315         unregister_reboot_notifier(&acq_notifier);
 316         if(wdt_stop != wdt_start)
 317                 release_region(wdt_stop,1);
 318         release_region(wdt_start,1);
 319 }
 320
 321 module_init(acq_init);
 322 module_exit(acq_exit);
 323
 324 MODULE_AUTHOR("David Woodhouse");
 325 MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
 326 MODULE_LICENSE("GPL");
 327 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);