drivers/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@lxorguk.ukuu.org.uk>,
  15  *                                              All Rights Reserved.
  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@lxorguk.ukuu.org.uk>
  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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  35
  36 #include <linux/module.h>
  37 #include <linux/types.h>
  38 #include <linux/miscdevice.h>
  39 #include <linux/watchdog.h>
  40 #include <linux/ioport.h>
  41 #include <linux/fs.h>
  42 #include <linux/init.h>
  43 #include <linux/spinlock.h>
  44 #include <linux/moduleparam.h>
  45 #include <linux/platform_device.h>
  46 #include <linux/io.h>
  47 #include <linux/uaccess.h>
  48
  49 #include <asm/system.h>
  50
  51 static struct platform_device *ibwdt_platform_device;
  52 static unsigned long ibwdt_is_open;
  53 static DEFINE_SPINLOCK(ibwdt_lock);
  54 static char expect_close;
  55
  56 /* Module information */
  57 #define DRV_NAME "ib700wdt"
  58
  59 /*
  60  *
  61  * Watchdog Timer Configuration
  62  *
  63  * The function of the watchdog timer is to reset the system
  64  * automatically and is defined at I/O port 0443H.  To enable the
  65  * watchdog timer and allow the system to reset, write I/O port 0443H.
  66  * To disable the timer, write I/O port 0441H for the system to stop the
  67  * watchdog function.  The timer has a tolerance of 20% for its
  68  * intervals.
  69  *
  70  * The following describes how the timer should be programmed.
  71  *
  72  * Enabling Watchdog:
  73  * MOV AX,000FH (Choose the values from 0 to F)
  74  * MOV DX,0443H
  75  * OUT DX,AX
  76  *
  77  * Disabling Watchdog:
  78  * MOV AX,000FH (Any value is fine.)
  79  * MOV DX,0441H
  80  * OUT DX,AX
  81  *
  82  * Watchdog timer control table:
  83  * Level   Value  Time/sec | Level Value Time/sec
  84  *   1       F       0     |   9     7      16
  85  *   2       E       2     |   10    6      18
  86  *   3       D       4     |   11    5      20
  87  *   4       C       6     |   12    4      22
  88  *   5       B       8     |   13    3      24
  89  *   6       A       10    |   14    2      26
  90  *   7       9       12    |   15    1      28
  91  *   8       8       14    |   16    0      30
  92  *
  93  */
  94
  95 #define WDT_STOP 0x441
  96 #define WDT_START 0x443
  97
  98 /* Default timeout */
  99 #define WATCHDOG_TIMEOUT 30             /* 30 seconds +/- 20% */
 100 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds */
 101 module_param(timeout, int, 0);
 102 MODULE_PARM_DESC(timeout,
 103         "Watchdog timeout in seconds. 0<= timeout <=30, default="
 104                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
 105
 106 static bool nowayout = WATCHDOG_NOWAYOUT;
 107 module_param(nowayout, bool, 0);
 108 MODULE_PARM_DESC(nowayout,
 109                 "Watchdog cannot be stopped once started (default="
 110                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 111
 112
 113 /*
 114  *      Watchdog Operations
 115  */
 116
 117 static void ibwdt_ping(void)
 118 {
 119         int wd_margin = 15 - ((timeout + 1) / 2);
 120
 121         spin_lock(&ibwdt_lock);
 122
 123         /* Write a watchdog value */
 124         outb_p(wd_margin, WDT_START);
 125
 126         spin_unlock(&ibwdt_lock);
 127 }
 128
 129 static void ibwdt_disable(void)
 130 {
 131         spin_lock(&ibwdt_lock);
 132         outb_p(0, WDT_STOP);
 133         spin_unlock(&ibwdt_lock);
 134 }
 135
 136 static int ibwdt_set_heartbeat(int t)
 137 {
 138         if (t < 0 || t > 30)
 139                 return -EINVAL;
 140
 141         timeout = t;
 142         return 0;
 143 }
 144
 145 /*
 146  *      /dev/watchdog handling
 147  */
 148
 149 static ssize_t ibwdt_write(struct file *file, const char __user *buf,
 150                                                 size_t count, loff_t *ppos)
 151 {
 152         if (count) {
 153                 if (!nowayout) {
 154                         size_t i;
 155
 156                         /* In case it was set long ago */
 157                         expect_close = 0;
 158
 159                         for (i = 0; i != count; i++) {
 160                                 char c;
 161                                 if (get_user(c, buf + i))
 162                                         return -EFAULT;
 163                                 if (c == 'V')
 164                                         expect_close = 42;
 165                         }
 166                 }
 167                 ibwdt_ping();
 168         }
 169         return count;
 170 }
 171
 172 static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 173 {
 174         int new_margin;
 175         void __user *argp = (void __user *)arg;
 176         int __user *p = argp;
 177
 178         static const struct watchdog_info ident = {
 179                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 180                                                         | WDIOF_MAGICCLOSE,
 181                 .firmware_version = 1,
 182                 .identity = "IB700 WDT",
 183         };
 184
 185         switch (cmd) {
 186         case WDIOC_GETSUPPORT:
 187                 if (copy_to_user(argp, &ident, sizeof(ident)))
 188                         return -EFAULT;
 189                 break;
 190
 191         case WDIOC_GETSTATUS:
 192         case WDIOC_GETBOOTSTATUS:
 193                 return put_user(0, p);
 194
 195         case WDIOC_SETOPTIONS:
 196         {
 197                 int options, retval = -EINVAL;
 198
 199                 if (get_user(options, p))
 200                         return -EFAULT;
 201
 202                 if (options & WDIOS_DISABLECARD) {
 203                         ibwdt_disable();
 204                         retval = 0;
 205                 }
 206                 if (options & WDIOS_ENABLECARD) {
 207                         ibwdt_ping();
 208                         retval = 0;
 209                 }
 210                 return retval;
 211         }
 212         case WDIOC_KEEPALIVE:
 213                 ibwdt_ping();
 214                 break;
 215
 216         case WDIOC_SETTIMEOUT:
 217                 if (get_user(new_margin, p))
 218                         return -EFAULT;
 219                 if (ibwdt_set_heartbeat(new_margin))
 220                         return -EINVAL;
 221                 ibwdt_ping();
 222                 /* Fall */
 223
 224         case WDIOC_GETTIMEOUT:
 225                 return put_user(timeout, p);
 226
 227         default:
 228                 return -ENOTTY;
 229         }
 230         return 0;
 231 }
 232
 233 static int ibwdt_open(struct inode *inode, struct file *file)
 234 {
 235         if (test_and_set_bit(0, &ibwdt_is_open))
 236                 return -EBUSY;
 237         if (nowayout)
 238                 __module_get(THIS_MODULE);
 239
 240         /* Activate */
 241         ibwdt_ping();
 242         return nonseekable_open(inode, file);
 243 }
 244
 245 static int ibwdt_close(struct inode *inode, struct file *file)
 246 {
 247         if (expect_close == 42) {
 248                 ibwdt_disable();
 249         } else {
 250                 pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
 251                 ibwdt_ping();
 252         }
 253         clear_bit(0, &ibwdt_is_open);
 254         expect_close = 0;
 255         return 0;
 256 }
 257
 258 /*
 259  *      Kernel Interfaces
 260  */
 261
 262 static const struct file_operations ibwdt_fops = {
 263         .owner          = THIS_MODULE,
 264         .llseek         = no_llseek,
 265         .write          = ibwdt_write,
 266         .unlocked_ioctl = ibwdt_ioctl,
 267         .open           = ibwdt_open,
 268         .release        = ibwdt_close,
 269 };
 270
 271 static struct miscdevice ibwdt_miscdev = {
 272         .minor = WATCHDOG_MINOR,
 273         .name = "watchdog",
 274         .fops = &ibwdt_fops,
 275 };
 276
 277 /*
 278  *      Init & exit routines
 279  */
 280
 281 static int __devinit ibwdt_probe(struct platform_device *dev)
 282 {
 283         int res;
 284
 285 #if WDT_START != WDT_STOP
 286         if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 287                 pr_err("STOP method I/O %X is not available\n", WDT_STOP);
 288                 res = -EIO;
 289                 goto out_nostopreg;
 290         }
 291 #endif
 292
 293         if (!request_region(WDT_START, 1, "IB700 WDT")) {
 294                 pr_err("START method I/O %X is not available\n", WDT_START);
 295                 res = -EIO;
 296                 goto out_nostartreg;
 297         }
 298
 299         /* Check that the heartbeat value is within it's range ;
 300          * if not reset to the default */
 301         if (ibwdt_set_heartbeat(timeout)) {
 302                 ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
 303                 pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
 304         }
 305
 306         res = misc_register(&ibwdt_miscdev);
 307         if (res) {
 308                 pr_err("failed to register misc device\n");
 309                 goto out_nomisc;
 310         }
 311         return 0;
 312
 313 out_nomisc:
 314         release_region(WDT_START, 1);
 315 out_nostartreg:
 316 #if WDT_START != WDT_STOP
 317         release_region(WDT_STOP, 1);
 318 #endif
 319 out_nostopreg:
 320         return res;
 321 }
 322
 323 static int __devexit ibwdt_remove(struct platform_device *dev)
 324 {
 325         misc_deregister(&ibwdt_miscdev);
 326         release_region(WDT_START, 1);
 327 #if WDT_START != WDT_STOP
 328         release_region(WDT_STOP, 1);
 329 #endif
 330         return 0;
 331 }
 332
 333 static void ibwdt_shutdown(struct platform_device *dev)
 334 {
 335         /* Turn the WDT off if we have a soft shutdown */
 336         ibwdt_disable();
 337 }
 338
 339 static struct platform_driver ibwdt_driver = {
 340         .probe          = ibwdt_probe,
 341         .remove         = __devexit_p(ibwdt_remove),
 342         .shutdown       = ibwdt_shutdown,
 343         .driver         = {
 344                 .owner  = THIS_MODULE,
 345                 .name   = DRV_NAME,
 346         },
 347 };
 348
 349 static int __init ibwdt_init(void)
 350 {
 351         int err;
 352
 353         pr_info("WDT driver for IB700 single board computer initialising\n");
 354
 355         err = platform_driver_register(&ibwdt_driver);
 356         if (err)
 357                 return err;
 358
 359         ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
 360                                                                 -1, NULL, 0);
 361         if (IS_ERR(ibwdt_platform_device)) {
 362                 err = PTR_ERR(ibwdt_platform_device);
 363                 goto unreg_platform_driver;
 364         }
 365
 366         return 0;
 367
 368 unreg_platform_driver:
 369         platform_driver_unregister(&ibwdt_driver);
 370         return err;
 371 }
 372
 373 static void __exit ibwdt_exit(void)
 374 {
 375         platform_device_unregister(ibwdt_platform_device);
 376         platform_driver_unregister(&ibwdt_driver);
 377         pr_info("Watchdog Module Unloaded\n");
 378 }
 379
 380 module_init(ibwdt_init);
 381 module_exit(ibwdt_exit);
 382
 383 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 384 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 385 MODULE_LICENSE("GPL");
 386 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 387
 388 /* end of ib700wdt.c */