drivers/char/watchdog/ib700wdt.c

   1 /*
   2  *      IB700 Single Board Computer WDT driver
   3  *
   4  *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>
   5  *
   6  *      Based on advantechwdt.c which is based on acquirewdt.c which
   7  *       is based on wdt.c.
   8  *
   9  *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
  10  *
  11  *      Based on acquirewdt.c which is based on wdt.c.
  12  *      Original copyright messages:
  13  *
  14  *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
  15  *                              http://www.redhat.com
  16  *
  17  *      This program is free software; you can redistribute it and/or
  18  *      modify it under the terms of the GNU General Public License
  19  *      as published by the Free Software Foundation; either version
  20  *      2 of the License, or (at your option) any later version.
  21  *
  22  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  23  *      warranty for any of this software. This material is provided
  24  *      "AS-IS" and at no charge.
  25  *
  26  *      (c) Copyright 1995    Alan Cox <alan@redhat.com>
  27  *
  28  *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  29  *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  30  *           Added timeout module option to override default
  31  *
  32  */
  33
  34 #include <linux/config.h>
  35 #include <linux/module.h>
  36 #include <linux/types.h>
  37 #include <linux/miscdevice.h>
  38 #include <linux/watchdog.h>
  39 #include <linux/ioport.h>
  40 #include <linux/notifier.h>
  41 #include <linux/fs.h>
  42 #include <linux/reboot.h>
  43 #include <linux/init.h>
  44 #include <linux/spinlock.h>
  45 #include <linux/moduleparam.h>
  46
  47 #include <asm/io.h>
  48 #include <asm/uaccess.h>
  49 #include <asm/system.h>
  50
  51 static unsigned long ibwdt_is_open;
  52 static spinlock_t ibwdt_lock;
  53 static char expect_close;
  54
  55 #define PFX "ib700wdt: "
  56
  57 /*
  58  *
  59  * Watchdog Timer Configuration
  60  *
  61  * The function of the watchdog timer is to reset the system
  62  * automatically and is defined at I/O port 0443H.  To enable the
  63  * watchdog timer and allow the system to reset, write I/O port 0443H.
  64  * To disable the timer, write I/O port 0441H for the system to stop the
  65  * watchdog function.  The timer has a tolerance of 20% for its
  66  * intervals.
  67  *
  68  * The following describes how the timer should be programmed.
  69  *
  70  * Enabling Watchdog:
  71  * MOV AX,000FH (Choose the values from 0 to F)
  72  * MOV DX,0443H
  73  * OUT DX,AX
  74  *
  75  * Disabling Watchdog:
  76  * MOV AX,000FH (Any value is fine.)
  77  * MOV DX,0441H
  78  * OUT DX,AX
  79  *
  80  * Watchdog timer control table:
  81  * Level   Value  Time/sec | Level Value Time/sec
  82  *   1       F       0     |   9     7      16
  83  *   2       E       2     |   10    6      18
  84  *   3       D       4     |   11    5      20
  85  *   4       C       6     |   12    4      22
  86  *   5       B       8     |   13    3      24
  87  *   6       A       10    |   14    2      26
  88  *   7       9       12    |   15    1      28
  89  *   8       8       14    |   16    0      30
  90  *
  91  */
  92
  93 static int wd_times[] = {
  94         30,     /* 0x0 */
  95         28,     /* 0x1 */
  96         26,     /* 0x2 */
  97         24,     /* 0x3 */
  98         22,     /* 0x4 */
  99         20,     /* 0x5 */
 100         18,     /* 0x6 */
 101         16,     /* 0x7 */
 102         14,     /* 0x8 */
 103         12,     /* 0x9 */
 104         10,     /* 0xA */
 105         8,      /* 0xB */
 106         6,      /* 0xC */
 107         4,      /* 0xD */
 108         2,      /* 0xE */
 109         0,      /* 0xF */
 110 };
 111
 112 #define WDT_STOP 0x441
 113 #define WDT_START 0x443
 114
 115 /* Default timeout */
 116 #define WD_TIMO 0               /* 30 seconds +/- 20%, from table */
 117
 118 static int wd_margin = WD_TIMO;
 119
 120 #ifdef CONFIG_WATCHDOG_NOWAYOUT
 121 static int nowayout = 1;
 122 #else
 123 static int nowayout = 0;
 124 #endif
 125
 126 module_param(nowayout, int, 0);
 127 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
 128
 129
 130 /*
 131  *      Kernel methods.
 132  */
 133
 134 static void
 135 ibwdt_ping(void)
 136 {
 137         /* Write a watchdog value */
 138         outb_p(wd_margin, WDT_START);
 139 }
 140
 141 static ssize_t
 142 ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 143 {
 144         if (count) {
 145                 if (!nowayout) {
 146                         size_t i;
 147
 148                         /* In case it was set long ago */
 149                         expect_close = 0;
 150
 151                         for (i = 0; i != count; i++) {
 152                                 char c;
 153                                 if (get_user(c, buf + i))
 154                                         return -EFAULT;
 155                                 if (c == 'V')
 156                                         expect_close = 42;
 157                         }
 158                 }
 159                 ibwdt_ping();
 160         }
 161         return count;
 162 }
 163
 164 static int
 165 ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 166           unsigned long arg)
 167 {
 168         int i, new_margin;
 169         void __user *argp = (void __user *)arg;
 170         int __user *p = argp;
 171
 172         static struct watchdog_info ident = {
 173                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 174                 .firmware_version = 1,
 175                 .identity = "IB700 WDT",
 176         };
 177
 178         switch (cmd) {
 179         case WDIOC_GETSUPPORT:
 180           if (copy_to_user(argp, &ident, sizeof(ident)))
 181             return -EFAULT;
 182           break;
 183
 184         case WDIOC_GETSTATUS:
 185           return put_user(0, p);
 186
 187         case WDIOC_KEEPALIVE:
 188           ibwdt_ping();
 189           break;
 190
 191         case WDIOC_SETTIMEOUT:
 192           if (get_user(new_margin, p))
 193                   return -EFAULT;
 194           if ((new_margin < 0) || (new_margin > 30))
 195                   return -EINVAL;
 196           for (i = 0x0F; i > -1; i--)
 197                   if (wd_times[i] > new_margin)
 198                           break;
 199           wd_margin = i;
 200           ibwdt_ping();
 201           /* Fall */
 202
 203         case WDIOC_GETTIMEOUT:
 204           return put_user(wd_times[wd_margin], p);
 205           break;
 206
 207         default:
 208           return -ENOIOCTLCMD;
 209         }
 210         return 0;
 211 }
 212
 213 static int
 214 ibwdt_open(struct inode *inode, struct file *file)
 215 {
 216         spin_lock(&ibwdt_lock);
 217         if (test_and_set_bit(0, &ibwdt_is_open)) {
 218                 spin_unlock(&ibwdt_lock);
 219                 return -EBUSY;
 220         }
 221         if (nowayout)
 222                 __module_get(THIS_MODULE);
 223
 224         /* Activate */
 225         ibwdt_ping();
 226         spin_unlock(&ibwdt_lock);
 227         return nonseekable_open(inode, file);
 228 }
 229
 230 static int
 231 ibwdt_close(struct inode *inode, struct file *file)
 232 {
 233         spin_lock(&ibwdt_lock);
 234         if (expect_close == 42)
 235                 outb_p(0, WDT_STOP);
 236         else
 237                 printk(KERN_CRIT PFX "WDT device closed unexpectedly.  WDT will not stop!\n");
 238
 239         clear_bit(0, &ibwdt_is_open);
 240         expect_close = 0;
 241         spin_unlock(&ibwdt_lock);
 242         return 0;
 243 }
 244
 245 /*
 246  *      Notifier for system down
 247  */
 248
 249 static int
 250 ibwdt_notify_sys(struct notifier_block *this, unsigned long code,
 251         void *unused)
 252 {
 253         if (code == SYS_DOWN || code == SYS_HALT) {
 254                 /* Turn the WDT off */
 255                 outb_p(0, WDT_STOP);
 256         }
 257         return NOTIFY_DONE;
 258 }
 259
 260 /*
 261  *      Kernel Interfaces
 262  */
 263
 264 static struct file_operations ibwdt_fops = {
 265         .owner          = THIS_MODULE,
 266         .llseek         = no_llseek,
 267         .write          = ibwdt_write,
 268         .ioctl          = ibwdt_ioctl,
 269         .open           = ibwdt_open,
 270         .release        = ibwdt_close,
 271 };
 272
 273 static struct miscdevice ibwdt_miscdev = {
 274         .minor = WATCHDOG_MINOR,
 275         .name = "watchdog",
 276         .fops = &ibwdt_fops,
 277 };
 278
 279 /*
 280  *      The WDT needs to learn about soft shutdowns in order to
 281  *      turn the timebomb registers off.
 282  */
 283
 284 static struct notifier_block ibwdt_notifier = {
 285         .notifier_call = ibwdt_notify_sys,
 286 };
 287
 288 static int __init ibwdt_init(void)
 289 {
 290         int res;
 291
 292         printk(KERN_INFO PFX "WDT driver for IB700 single board computer initialising.\n");
 293
 294         spin_lock_init(&ibwdt_lock);
 295         res = misc_register(&ibwdt_miscdev);
 296         if (res) {
 297                 printk (KERN_ERR PFX "failed to register misc device\n");
 298                 goto out_nomisc;
 299         }
 300
 301 #if WDT_START != WDT_STOP
 302         if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 303                 printk (KERN_ERR PFX "STOP method I/O %X is not available.\n", WDT_STOP);
 304                 res = -EIO;
 305                 goto out_nostopreg;
 306         }
 307 #endif
 308
 309         if (!request_region(WDT_START, 1, "IB700 WDT")) {
 310                 printk (KERN_ERR PFX "START method I/O %X is not available.\n", WDT_START);
 311                 res = -EIO;
 312                 goto out_nostartreg;
 313         }
 314         res = register_reboot_notifier(&ibwdt_notifier);
 315         if (res) {
 316                 printk (KERN_ERR PFX "Failed to register reboot notifier.\n");
 317                 goto out_noreboot;
 318         }
 319         return 0;
 320
 321 out_noreboot:
 322         release_region(WDT_START, 1);
 323 out_nostartreg:
 324 #if WDT_START != WDT_STOP
 325         release_region(WDT_STOP, 1);
 326 #endif
 327 out_nostopreg:
 328         misc_deregister(&ibwdt_miscdev);
 329 out_nomisc:
 330         return res;
 331 }
 332
 333 static void __exit
 334 ibwdt_exit(void)
 335 {
 336         misc_deregister(&ibwdt_miscdev);
 337         unregister_reboot_notifier(&ibwdt_notifier);
 338 #if WDT_START != WDT_STOP
 339         release_region(WDT_STOP,1);
 340 #endif
 341         release_region(WDT_START,1);
 342 }
 343
 344 module_init(ibwdt_init);
 345 module_exit(ibwdt_exit);
 346
 347 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 348 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 349 MODULE_LICENSE("GPL");
 350 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 351
 352 /* end of ib700wdt.c */