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=CONFIG_WATCHDOG_NOWAYOUT)");
 122
 123
 124 /*
 125  *      Kernel methods.
 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 ssize_t
 136 ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 137 {
 138         if (count) {
 139                 if (!nowayout) {
 140                         size_t i;
 141
 142                         /* In case it was set long ago */
 143                         expect_close = 0;
 144
 145                         for (i = 0; i != count; i++) {
 146                                 char c;
 147                                 if (get_user(c, buf + i))
 148                                         return -EFAULT;
 149                                 if (c == 'V')
 150                                         expect_close = 42;
 151                         }
 152                 }
 153                 ibwdt_ping();
 154         }
 155         return count;
 156 }
 157
 158 static int
 159 ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 160           unsigned long arg)
 161 {
 162         int i, new_margin;
 163         void __user *argp = (void __user *)arg;
 164         int __user *p = argp;
 165
 166         static struct watchdog_info ident = {
 167                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 168                 .firmware_version = 1,
 169                 .identity = "IB700 WDT",
 170         };
 171
 172         switch (cmd) {
 173         case WDIOC_GETSUPPORT:
 174           if (copy_to_user(argp, &ident, sizeof(ident)))
 175             return -EFAULT;
 176           break;
 177
 178         case WDIOC_GETSTATUS:
 179           return put_user(0, p);
 180
 181         case WDIOC_KEEPALIVE:
 182           ibwdt_ping();
 183           break;
 184
 185         case WDIOC_SETTIMEOUT:
 186           if (get_user(new_margin, p))
 187                   return -EFAULT;
 188           if ((new_margin < 0) || (new_margin > 30))
 189                   return -EINVAL;
 190           for (i = 0x0F; i > -1; i--)
 191                   if (wd_times[i] > new_margin)
 192                           break;
 193           wd_margin = i;
 194           ibwdt_ping();
 195           /* Fall */
 196
 197         case WDIOC_GETTIMEOUT:
 198           return put_user(wd_times[wd_margin], p);
 199           break;
 200
 201         default:
 202           return -ENOTTY;
 203         }
 204         return 0;
 205 }
 206
 207 static int
 208 ibwdt_open(struct inode *inode, struct file *file)
 209 {
 210         spin_lock(&ibwdt_lock);
 211         if (test_and_set_bit(0, &ibwdt_is_open)) {
 212                 spin_unlock(&ibwdt_lock);
 213                 return -EBUSY;
 214         }
 215         if (nowayout)
 216                 __module_get(THIS_MODULE);
 217
 218         /* Activate */
 219         ibwdt_ping();
 220         spin_unlock(&ibwdt_lock);
 221         return nonseekable_open(inode, file);
 222 }
 223
 224 static int
 225 ibwdt_close(struct inode *inode, struct file *file)
 226 {
 227         spin_lock(&ibwdt_lock);
 228         if (expect_close == 42)
 229                 outb_p(0, WDT_STOP);
 230         else
 231                 printk(KERN_CRIT PFX "WDT device closed unexpectedly.  WDT will not stop!\n");
 232
 233         clear_bit(0, &ibwdt_is_open);
 234         expect_close = 0;
 235         spin_unlock(&ibwdt_lock);
 236         return 0;
 237 }
 238
 239 /*
 240  *      Notifier for system down
 241  */
 242
 243 static int
 244 ibwdt_notify_sys(struct notifier_block *this, unsigned long code,
 245         void *unused)
 246 {
 247         if (code == SYS_DOWN || code == SYS_HALT) {
 248                 /* Turn the WDT off */
 249                 outb_p(0, WDT_STOP);
 250         }
 251         return NOTIFY_DONE;
 252 }
 253
 254 /*
 255  *      Kernel Interfaces
 256  */
 257
 258 static const struct file_operations ibwdt_fops = {
 259         .owner          = THIS_MODULE,
 260         .llseek         = no_llseek,
 261         .write          = ibwdt_write,
 262         .ioctl          = ibwdt_ioctl,
 263         .open           = ibwdt_open,
 264         .release        = ibwdt_close,
 265 };
 266
 267 static struct miscdevice ibwdt_miscdev = {
 268         .minor = WATCHDOG_MINOR,
 269         .name = "watchdog",
 270         .fops = &ibwdt_fops,
 271 };
 272
 273 /*
 274  *      The WDT needs to learn about soft shutdowns in order to
 275  *      turn the timebomb registers off.
 276  */
 277
 278 static struct notifier_block ibwdt_notifier = {
 279         .notifier_call = ibwdt_notify_sys,
 280 };
 281
 282 static int __init ibwdt_init(void)
 283 {
 284         int res;
 285
 286         printk(KERN_INFO PFX "WDT driver for IB700 single board computer initialising.\n");
 287
 288         spin_lock_init(&ibwdt_lock);
 289         res = misc_register(&ibwdt_miscdev);
 290         if (res) {
 291                 printk (KERN_ERR PFX "failed to register misc device\n");
 292                 goto out_nomisc;
 293         }
 294
 295 #if WDT_START != WDT_STOP
 296         if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 297                 printk (KERN_ERR PFX "STOP method I/O %X is not available.\n", WDT_STOP);
 298                 res = -EIO;
 299                 goto out_nostopreg;
 300         }
 301 #endif
 302
 303         if (!request_region(WDT_START, 1, "IB700 WDT")) {
 304                 printk (KERN_ERR PFX "START method I/O %X is not available.\n", WDT_START);
 305                 res = -EIO;
 306                 goto out_nostartreg;
 307         }
 308         res = register_reboot_notifier(&ibwdt_notifier);
 309         if (res) {
 310                 printk (KERN_ERR PFX "Failed to register reboot notifier.\n");
 311                 goto out_noreboot;
 312         }
 313         return 0;
 314
 315 out_noreboot:
 316         release_region(WDT_START, 1);
 317 out_nostartreg:
 318 #if WDT_START != WDT_STOP
 319         release_region(WDT_STOP, 1);
 320 #endif
 321 out_nostopreg:
 322         misc_deregister(&ibwdt_miscdev);
 323 out_nomisc:
 324         return res;
 325 }
 326
 327 static void __exit
 328 ibwdt_exit(void)
 329 {
 330         misc_deregister(&ibwdt_miscdev);
 331         unregister_reboot_notifier(&ibwdt_notifier);
 332 #if WDT_START != WDT_STOP
 333         release_region(WDT_STOP,1);
 334 #endif
 335         release_region(WDT_START,1);
 336 }
 337
 338 module_init(ibwdt_init);
 339 module_exit(ibwdt_exit);
 340
 341 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 342 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 343 MODULE_LICENSE("GPL");
 344 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 345
 346 /* end of ib700wdt.c */