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/module.h>
  35 #include <linux/types.h>
  36 #include <linux/miscdevice.h>
  37 #include <linux/watchdog.h>
  38 #include <linux/ioport.h>
  39 #include <linux/notifier.h>
  40 #include <linux/fs.h>
  41 #include <linux/reboot.h>
  42 #include <linux/init.h>
  43 #include <linux/spinlock.h>
  44 #include <linux/moduleparam.h>
  45
  46 #include <asm/io.h>
  47 #include <asm/uaccess.h>
  48 #include <asm/system.h>
  49
  50 static unsigned long ibwdt_is_open;
  51 static spinlock_t ibwdt_lock;
  52 static char expect_close;
  53
  54 #define PFX "ib700wdt: "
  55
  56 /*
  57  *
  58  * Watchdog Timer Configuration
  59  *
  60  * The function of the watchdog timer is to reset the system
  61  * automatically and is defined at I/O port 0443H.  To enable the
  62  * watchdog timer and allow the system to reset, write I/O port 0443H.
  63  * To disable the timer, write I/O port 0441H for the system to stop the
  64  * watchdog function.  The timer has a tolerance of 20% for its
  65  * intervals.
  66  *
  67  * The following describes how the timer should be programmed.
  68  *
  69  * Enabling Watchdog:
  70  * MOV AX,000FH (Choose the values from 0 to F)
  71  * MOV DX,0443H
  72  * OUT DX,AX
  73  *
  74  * Disabling Watchdog:
  75  * MOV AX,000FH (Any value is fine.)
  76  * MOV DX,0441H
  77  * OUT DX,AX
  78  *
  79  * Watchdog timer control table:
  80  * Level   Value  Time/sec | Level Value Time/sec
  81  *   1       F       0     |   9     7      16
  82  *   2       E       2     |   10    6      18
  83  *   3       D       4     |   11    5      20
  84  *   4       C       6     |   12    4      22
  85  *   5       B       8     |   13    3      24
  86  *   6       A       10    |   14    2      26
  87  *   7       9       12    |   15    1      28
  88  *   8       8       14    |   16    0      30
  89  *
  90  */
  91
  92 static int wd_times[] = {
  93         30,     /* 0x0 */
  94         28,     /* 0x1 */
  95         26,     /* 0x2 */
  96         24,     /* 0x3 */
  97         22,     /* 0x4 */
  98         20,     /* 0x5 */
  99         18,     /* 0x6 */
 100         16,     /* 0x7 */
 101         14,     /* 0x8 */
 102         12,     /* 0x9 */
 103         10,     /* 0xA */
 104         8,      /* 0xB */
 105         6,      /* 0xC */
 106         4,      /* 0xD */
 107         2,      /* 0xE */
 108         0,      /* 0xF */
 109 };
 110
 111 #define WDT_STOP 0x441
 112 #define WDT_START 0x443
 113
 114 /* Default timeout */
 115 #define WD_TIMO 0               /* 30 seconds +/- 20%, from table */
 116
 117 static int wd_margin = WD_TIMO;
 118
 119 static int nowayout = WATCHDOG_NOWAYOUT;
 120 module_param(nowayout, int, 0);
 121 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 122
 123
 124 /*
 125  *      Watchdog Operations
 126  */
 127
 128 static void
 129 ibwdt_ping(void)
 130 {
 131         /* Write a watchdog value */
 132         outb_p(wd_margin, WDT_START);
 133 }
 134
 135 static void
 136 ibwdt_disable(void)
 137 {
 138         outb_p(0, WDT_STOP);
 139 }
 140
 141 static int
 142 ibwdt_set_heartbeat(int t)
 143 {
 144         int i;
 145
 146         if ((t < 0) || (t > 30))
 147                 return -EINVAL;
 148
 149         for (i = 0x0F; i > -1; i--)
 150                 if (wd_times[i] > t)
 151                         break;
 152         wd_margin = i;
 153         return 0;
 154 }
 155
 156 /*
 157  *      /dev/watchdog handling
 158  */
 159
 160 static ssize_t
 161 ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 162 {
 163         if (count) {
 164                 if (!nowayout) {
 165                         size_t i;
 166
 167                         /* In case it was set long ago */
 168                         expect_close = 0;
 169
 170                         for (i = 0; i != count; i++) {
 171                                 char c;
 172                                 if (get_user(c, buf + i))
 173                                         return -EFAULT;
 174                                 if (c == 'V')
 175                                         expect_close = 42;
 176                         }
 177                 }
 178                 ibwdt_ping();
 179         }
 180         return count;
 181 }
 182
 183 static int
 184 ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 185           unsigned long arg)
 186 {
 187         int new_margin;
 188         void __user *argp = (void __user *)arg;
 189         int __user *p = argp;
 190
 191         static struct watchdog_info ident = {
 192                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 193                 .firmware_version = 1,
 194                 .identity = "IB700 WDT",
 195         };
 196
 197         switch (cmd) {
 198         case WDIOC_GETSUPPORT:
 199           if (copy_to_user(argp, &ident, sizeof(ident)))
 200             return -EFAULT;
 201           break;
 202
 203         case WDIOC_GETSTATUS:
 204           return put_user(0, p);
 205
 206         case WDIOC_KEEPALIVE:
 207           ibwdt_ping();
 208           break;
 209
 210         case WDIOC_SETTIMEOUT:
 211           if (get_user(new_margin, p))
 212                   return -EFAULT;
 213           if (ibwdt_set_heartbeat(new_margin))
 214                   return -EINVAL;
 215           ibwdt_ping();
 216           /* Fall */
 217
 218         case WDIOC_GETTIMEOUT:
 219           return put_user(wd_times[wd_margin], p);
 220           break;
 221
 222         default:
 223           return -ENOTTY;
 224         }
 225         return 0;
 226 }
 227
 228 static int
 229 ibwdt_open(struct inode *inode, struct file *file)
 230 {
 231         spin_lock(&ibwdt_lock);
 232         if (test_and_set_bit(0, &ibwdt_is_open)) {
 233                 spin_unlock(&ibwdt_lock);
 234                 return -EBUSY;
 235         }
 236         if (nowayout)
 237                 __module_get(THIS_MODULE);
 238
 239         /* Activate */
 240         ibwdt_ping();
 241         spin_unlock(&ibwdt_lock);
 242         return nonseekable_open(inode, file);
 243 }
 244
 245 static int
 246 ibwdt_close(struct inode *inode, struct file *file)
 247 {
 248         spin_lock(&ibwdt_lock);
 249         if (expect_close == 42)
 250                 ibwdt_disable();
 251         else
 252                 printk(KERN_CRIT PFX "WDT device closed unexpectedly.  WDT will not stop!\n");
 253
 254         clear_bit(0, &ibwdt_is_open);
 255         expect_close = 0;
 256         spin_unlock(&ibwdt_lock);
 257         return 0;
 258 }
 259
 260 /*
 261  *      Notifier for system down
 262  */
 263
 264 static int
 265 ibwdt_notify_sys(struct notifier_block *this, unsigned long code,
 266         void *unused)
 267 {
 268         if (code == SYS_DOWN || code == SYS_HALT) {
 269                 /* Turn the WDT off */
 270                 ibwdt_disable();
 271         }
 272         return NOTIFY_DONE;
 273 }
 274
 275 /*
 276  *      Kernel Interfaces
 277  */
 278
 279 static const struct file_operations ibwdt_fops = {
 280         .owner          = THIS_MODULE,
 281         .llseek         = no_llseek,
 282         .write          = ibwdt_write,
 283         .ioctl          = ibwdt_ioctl,
 284         .open           = ibwdt_open,
 285         .release        = ibwdt_close,
 286 };
 287
 288 static struct miscdevice ibwdt_miscdev = {
 289         .minor = WATCHDOG_MINOR,
 290         .name = "watchdog",
 291         .fops = &ibwdt_fops,
 292 };
 293
 294 /*
 295  *      The WDT needs to learn about soft shutdowns in order to
 296  *      turn the timebomb registers off.
 297  */
 298
 299 static struct notifier_block ibwdt_notifier = {
 300         .notifier_call = ibwdt_notify_sys,
 301 };
 302
 303 static int __init ibwdt_init(void)
 304 {
 305         int res;
 306
 307         printk(KERN_INFO PFX "WDT driver for IB700 single board computer initialising.\n");
 308
 309         spin_lock_init(&ibwdt_lock);
 310         res = misc_register(&ibwdt_miscdev);
 311         if (res) {
 312                 printk (KERN_ERR PFX "failed to register misc device\n");
 313                 goto out_nomisc;
 314         }
 315
 316 #if WDT_START != WDT_STOP
 317         if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 318                 printk (KERN_ERR PFX "STOP method I/O %X is not available.\n", WDT_STOP);
 319                 res = -EIO;
 320                 goto out_nostopreg;
 321         }
 322 #endif
 323
 324         if (!request_region(WDT_START, 1, "IB700 WDT")) {
 325                 printk (KERN_ERR PFX "START method I/O %X is not available.\n", WDT_START);
 326                 res = -EIO;
 327                 goto out_nostartreg;
 328         }
 329         res = register_reboot_notifier(&ibwdt_notifier);
 330         if (res) {
 331                 printk (KERN_ERR PFX "Failed to register reboot notifier.\n");
 332                 goto out_noreboot;
 333         }
 334         return 0;
 335
 336 out_noreboot:
 337         release_region(WDT_START, 1);
 338 out_nostartreg:
 339 #if WDT_START != WDT_STOP
 340         release_region(WDT_STOP, 1);
 341 #endif
 342 out_nostopreg:
 343         misc_deregister(&ibwdt_miscdev);
 344 out_nomisc:
 345         return res;
 346 }
 347
 348 static void __exit
 349 ibwdt_exit(void)
 350 {
 351         misc_deregister(&ibwdt_miscdev);
 352         unregister_reboot_notifier(&ibwdt_notifier);
 353 #if WDT_START != WDT_STOP
 354         release_region(WDT_STOP,1);
 355 #endif
 356         release_region(WDT_START,1);
 357 }
 358
 359 module_init(ibwdt_init);
 360 module_exit(ibwdt_exit);
 361
 362 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 363 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 364 MODULE_LICENSE("GPL");
 365 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 366
 367 /* end of ib700wdt.c */