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