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 static int nowayout = WATCHDOG_NOWAYOUT;
 121 module_param(nowayout, int, 0);
 122 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
 123
 124
 125 /*
 126  *      Kernel methods.
 127  */
 128
 129 static void
 130 ibwdt_ping(void)
 131 {
 132         /* Write a watchdog value */
 133         outb_p(wd_margin, WDT_START);
 134 }
 135
 136 static ssize_t
 137 ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 138 {
 139         if (count) {
 140                 if (!nowayout) {
 141                         size_t i;
 142
 143                         /* In case it was set long ago */
 144                         expect_close = 0;
 145
 146                         for (i = 0; i != count; i++) {
 147                                 char c;
 148                                 if (get_user(c, buf + i))
 149                                         return -EFAULT;
 150                                 if (c == 'V')
 151                                         expect_close = 42;
 152                         }
 153                 }
 154                 ibwdt_ping();
 155         }
 156         return count;
 157 }
 158
 159 static int
 160 ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 161           unsigned long arg)
 162 {
 163         int i, new_margin;
 164         void __user *argp = (void __user *)arg;
 165         int __user *p = argp;
 166
 167         static struct watchdog_info ident = {
 168                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 169                 .firmware_version = 1,
 170                 .identity = "IB700 WDT",
 171         };
 172
 173         switch (cmd) {
 174         case WDIOC_GETSUPPORT:
 175           if (copy_to_user(argp, &ident, sizeof(ident)))
 176             return -EFAULT;
 177           break;
 178
 179         case WDIOC_GETSTATUS:
 180           return put_user(0, p);
 181
 182         case WDIOC_KEEPALIVE:
 183           ibwdt_ping();
 184           break;
 185
 186         case WDIOC_SETTIMEOUT:
 187           if (get_user(new_margin, p))
 188                   return -EFAULT;
 189           if ((new_margin < 0) || (new_margin > 30))
 190                   return -EINVAL;
 191           for (i = 0x0F; i > -1; i--)
 192                   if (wd_times[i] > new_margin)
 193                           break;
 194           wd_margin = i;
 195           ibwdt_ping();
 196           /* Fall */
 197
 198         case WDIOC_GETTIMEOUT:
 199           return put_user(wd_times[wd_margin], p);
 200           break;
 201
 202         default:
 203           return -ENOIOCTLCMD;
 204         }
 205         return 0;
 206 }
 207
 208 static int
 209 ibwdt_open(struct inode *inode, struct file *file)
 210 {
 211         spin_lock(&ibwdt_lock);
 212         if (test_and_set_bit(0, &ibwdt_is_open)) {
 213                 spin_unlock(&ibwdt_lock);
 214                 return -EBUSY;
 215         }
 216         if (nowayout)
 217                 __module_get(THIS_MODULE);
 218
 219         /* Activate */
 220         ibwdt_ping();
 221         spin_unlock(&ibwdt_lock);
 222         return nonseekable_open(inode, file);
 223 }
 224
 225 static int
 226 ibwdt_close(struct inode *inode, struct file *file)
 227 {
 228         spin_lock(&ibwdt_lock);
 229         if (expect_close == 42)
 230                 outb_p(0, WDT_STOP);
 231         else
 232                 printk(KERN_CRIT PFX "WDT device closed unexpectedly.  WDT will not stop!\n");
 233
 234         clear_bit(0, &ibwdt_is_open);
 235         expect_close = 0;
 236         spin_unlock(&ibwdt_lock);
 237         return 0;
 238 }
 239
 240 /*
 241  *      Notifier for system down
 242  */
 243
 244 static int
 245 ibwdt_notify_sys(struct notifier_block *this, unsigned long code,
 246         void *unused)
 247 {
 248         if (code == SYS_DOWN || code == SYS_HALT) {
 249                 /* Turn the WDT off */
 250                 outb_p(0, WDT_STOP);
 251         }
 252         return NOTIFY_DONE;
 253 }
 254
 255 /*
 256  *      Kernel Interfaces
 257  */
 258
 259 static struct file_operations ibwdt_fops = {
 260         .owner          = THIS_MODULE,
 261         .llseek         = no_llseek,
 262         .write          = ibwdt_write,
 263         .ioctl          = ibwdt_ioctl,
 264         .open           = ibwdt_open,
 265         .release        = ibwdt_close,
 266 };
 267
 268 static struct miscdevice ibwdt_miscdev = {
 269         .minor = WATCHDOG_MINOR,
 270         .name = "watchdog",
 271         .fops = &ibwdt_fops,
 272 };
 273
 274 /*
 275  *      The WDT needs to learn about soft shutdowns in order to
 276  *      turn the timebomb registers off.
 277  */
 278
 279 static struct notifier_block ibwdt_notifier = {
 280         .notifier_call = ibwdt_notify_sys,
 281 };
 282
 283 static int __init ibwdt_init(void)
 284 {
 285         int res;
 286
 287         printk(KERN_INFO PFX "WDT driver for IB700 single board computer initialising.\n");
 288
 289         spin_lock_init(&ibwdt_lock);
 290         res = misc_register(&ibwdt_miscdev);
 291         if (res) {
 292                 printk (KERN_ERR PFX "failed to register misc device\n");
 293                 goto out_nomisc;
 294         }
 295
 296 #if WDT_START != WDT_STOP
 297         if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 298                 printk (KERN_ERR PFX "STOP method I/O %X is not available.\n", WDT_STOP);
 299                 res = -EIO;
 300                 goto out_nostopreg;
 301         }
 302 #endif
 303
 304         if (!request_region(WDT_START, 1, "IB700 WDT")) {
 305                 printk (KERN_ERR PFX "START method I/O %X is not available.\n", WDT_START);
 306                 res = -EIO;
 307                 goto out_nostartreg;
 308         }
 309         res = register_reboot_notifier(&ibwdt_notifier);
 310         if (res) {
 311                 printk (KERN_ERR PFX "Failed to register reboot notifier.\n");
 312                 goto out_noreboot;
 313         }
 314         return 0;
 315
 316 out_noreboot:
 317         release_region(WDT_START, 1);
 318 out_nostartreg:
 319 #if WDT_START != WDT_STOP
 320         release_region(WDT_STOP, 1);
 321 #endif
 322 out_nostopreg:
 323         misc_deregister(&ibwdt_miscdev);
 324 out_nomisc:
 325         return res;
 326 }
 327
 328 static void __exit
 329 ibwdt_exit(void)
 330 {
 331         misc_deregister(&ibwdt_miscdev);
 332         unregister_reboot_notifier(&ibwdt_notifier);
 333 #if WDT_START != WDT_STOP
 334         release_region(WDT_STOP,1);
 335 #endif
 336         release_region(WDT_START,1);
 337 }
 338
 339 module_init(ibwdt_init);
 340 module_exit(ibwdt_exit);
 341
 342 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 343 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 344 MODULE_LICENSE("GPL");
 345 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 346
 347 /* end of ib700wdt.c */