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 #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/fs.h>
  40 #include <linux/init.h>
  41 #include <linux/spinlock.h>
  42 #include <linux/moduleparam.h>
  43 #include <linux/platform_device.h>
  44 #include <linux/io.h>
  45 #include <linux/uaccess.h>
  46
  47
  48 static struct platform_device *ibwdt_platform_device;
  49 static unsigned long ibwdt_is_open;
  50 static DEFINE_SPINLOCK(ibwdt_lock);
  51 static char expect_close;
  52
  53 /* Module information */
  54 #define DRV_NAME "ib700wdt"
  55 #define PFX DRV_NAME ": "
  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 #define WDT_STOP 0x441
  94 #define WDT_START 0x443
  95
  96 /* Default timeout */
  97 #define WATCHDOG_TIMEOUT 30             /* 30 seconds +/- 20% */
  98 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds */
  99 module_param(timeout, int, 0);
 100 MODULE_PARM_DESC(timeout,
 101         "Watchdog timeout in seconds. 0<= timeout <=30, default="
 102                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
 103
 104 static int nowayout = WATCHDOG_NOWAYOUT;
 105 module_param(nowayout, int, 0);
 106 MODULE_PARM_DESC(nowayout,
 107                 "Watchdog cannot be stopped once started (default="
 108                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 109
 110
 111 /*
 112  *      Watchdog Operations
 113  */
 114
 115 static void ibwdt_ping(void)
 116 {
 117         int wd_margin = 15 - ((timeout + 1) / 2);
 118
 119         spin_lock(&ibwdt_lock);
 120
 121         /* Write a watchdog value */
 122         outb_p(wd_margin, WDT_START);
 123
 124         spin_unlock(&ibwdt_lock);
 125 }
 126
 127 static void ibwdt_disable(void)
 128 {
 129         spin_lock(&ibwdt_lock);
 130         outb_p(0, WDT_STOP);
 131         spin_unlock(&ibwdt_lock);
 132 }
 133
 134 static int ibwdt_set_heartbeat(int t)
 135 {
 136         if (t < 0 || t > 30)
 137                 return -EINVAL;
 138
 139         timeout = t;
 140         return 0;
 141 }
 142
 143 /*
 144  *      /dev/watchdog handling
 145  */
 146
 147 static ssize_t ibwdt_write(struct file *file, const char __user *buf,
 148                                                 size_t count, loff_t *ppos)
 149 {
 150         if (count) {
 151                 if (!nowayout) {
 152                         size_t i;
 153
 154                         /* In case it was set long ago */
 155                         expect_close = 0;
 156
 157                         for (i = 0; i != count; i++) {
 158                                 char c;
 159                                 if (get_user(c, buf + i))
 160                                         return -EFAULT;
 161                                 if (c == 'V')
 162                                         expect_close = 42;
 163                         }
 164                 }
 165                 ibwdt_ping();
 166         }
 167         return count;
 168 }
 169
 170 static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 171 {
 172         int new_margin;
 173         void __user *argp = (void __user *)arg;
 174         int __user *p = argp;
 175
 176         static const struct watchdog_info ident = {
 177                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 178                                                         | WDIOF_MAGICCLOSE,
 179                 .firmware_version = 1,
 180                 .identity = "IB700 WDT",
 181         };
 182
 183         switch (cmd) {
 184         case WDIOC_GETSUPPORT:
 185                 if (copy_to_user(argp, &ident, sizeof(ident)))
 186                         return -EFAULT;
 187                 break;
 188
 189         case WDIOC_GETSTATUS:
 190         case WDIOC_GETBOOTSTATUS:
 191                 return put_user(0, p);
 192
 193         case WDIOC_SETOPTIONS:
 194         {
 195                 int options, retval = -EINVAL;
 196
 197                 if (get_user(options, p))
 198                         return -EFAULT;
 199
 200                 if (options & WDIOS_DISABLECARD) {
 201                         ibwdt_disable();
 202                         retval = 0;
 203                 }
 204                 if (options & WDIOS_ENABLECARD) {
 205                         ibwdt_ping();
 206                         retval = 0;
 207                 }
 208                 return retval;
 209         }
 210         case WDIOC_KEEPALIVE:
 211                 ibwdt_ping();
 212                 break;
 213
 214         case WDIOC_SETTIMEOUT:
 215                 if (get_user(new_margin, p))
 216                         return -EFAULT;
 217                 if (ibwdt_set_heartbeat(new_margin))
 218                         return -EINVAL;
 219                 ibwdt_ping();
 220                 /* Fall */
 221
 222         case WDIOC_GETTIMEOUT:
 223                 return put_user(timeout, p);
 224
 225         default:
 226                 return -ENOTTY;
 227         }
 228         return 0;
 229 }
 230
 231 static int ibwdt_open(struct inode *inode, struct file *file)
 232 {
 233         if (test_and_set_bit(0, &ibwdt_is_open))
 234                 return -EBUSY;
 235         if (nowayout)
 236                 __module_get(THIS_MODULE);
 237
 238         /* Activate */
 239         ibwdt_ping();
 240         return nonseekable_open(inode, file);
 241 }
 242
 243 static int ibwdt_close(struct inode *inode, struct file *file)
 244 {
 245         if (expect_close == 42) {
 246                 ibwdt_disable();
 247         } else {
 248                 printk(KERN_CRIT PFX
 249                      "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 __devinit 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                 printk(KERN_ERR PFX "STOP method I/O %X is not available.\n",
 287                                                                 WDT_STOP);
 288                 res = -EIO;
 289                 goto out_nostopreg;
 290         }
 291 #endif
 292
 293         if (!request_region(WDT_START, 1, "IB700 WDT")) {
 294                 printk(KERN_ERR PFX "START method I/O %X is not available.\n",
 295                                                                 WDT_START);
 296                 res = -EIO;
 297                 goto out_nostartreg;
 298         }
 299
 300         /* Check that the heartbeat value is within it's range ;
 301          * if not reset to the default */
 302         if (ibwdt_set_heartbeat(timeout)) {
 303                 ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
 304                 printk(KERN_INFO PFX
 305                         "timeout value must be 0<=x<=30, using %d\n", timeout);
 306         }
 307
 308         res = misc_register(&ibwdt_miscdev);
 309         if (res) {
 310                 printk(KERN_ERR PFX "failed to register misc device\n");
 311                 goto out_nomisc;
 312         }
 313         return 0;
 314
 315 out_nomisc:
 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         return res;
 323 }
 324
 325 static int __devexit ibwdt_remove(struct platform_device *dev)
 326 {
 327         misc_deregister(&ibwdt_miscdev);
 328         release_region(WDT_START, 1);
 329 #if WDT_START != WDT_STOP
 330         release_region(WDT_STOP, 1);
 331 #endif
 332         return 0;
 333 }
 334
 335 static void ibwdt_shutdown(struct platform_device *dev)
 336 {
 337         /* Turn the WDT off if we have a soft shutdown */
 338         ibwdt_disable();
 339 }
 340
 341 static struct platform_driver ibwdt_driver = {
 342         .probe          = ibwdt_probe,
 343         .remove         = __devexit_p(ibwdt_remove),
 344         .shutdown       = ibwdt_shutdown,
 345         .driver         = {
 346                 .owner  = THIS_MODULE,
 347                 .name   = DRV_NAME,
 348         },
 349 };
 350
 351 static int __init ibwdt_init(void)
 352 {
 353         int err;
 354
 355         printk(KERN_INFO PFX
 356                 "WDT driver for IB700 single board computer initialising.\n");
 357
 358         err = platform_driver_register(&ibwdt_driver);
 359         if (err)
 360                 return err;
 361
 362         ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
 363                                                                 -1, NULL, 0);
 364         if (IS_ERR(ibwdt_platform_device)) {
 365                 err = PTR_ERR(ibwdt_platform_device);
 366                 goto unreg_platform_driver;
 367         }
 368
 369         return 0;
 370
 371 unreg_platform_driver:
 372         platform_driver_unregister(&ibwdt_driver);
 373         return err;
 374 }
 375
 376 static void __exit ibwdt_exit(void)
 377 {
 378         platform_device_unregister(ibwdt_platform_device);
 379         platform_driver_unregister(&ibwdt_driver);
 380         printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");
 381 }
 382
 383 module_init(ibwdt_init);
 384 module_exit(ibwdt_exit);
 385
 386 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 387 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 388 MODULE_LICENSE("GPL");
 389 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 390
 391 /* end of ib700wdt.c */