drivers/watchdog/sbc8360.c

   1 /*
   2  *      SBC8360 Watchdog driver
   3  *
   4  *      (c) Copyright 2005 Webcon, Inc.
   5  *
   6  *      Based on ib700wdt.c, which is based on advantechwdt.c which is based
   7  *      on acquirewdt.c which is based on wdt.c.
   8  *
   9  *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>
  10  *
  11  *      Based on advantechwdt.c which is based on acquirewdt.c which
  12  *      is based on wdt.c.
  13  *
  14  *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
  15  *
  16  *      Based on acquirewdt.c which is based on wdt.c.
  17  *      Original copyright messages:
  18  *
  19  *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  20  *                                              All Rights Reserved.
  21  *
  22  *      This program is free software; you can redistribute it and/or
  23  *      modify it under the terms of the GNU General Public License
  24  *      as published by the Free Software Foundation; either version
  25  *      2 of the License, or (at your option) any later version.
  26  *
  27  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  28  *      warranty for any of this software. This material is provided
  29  *      "AS-IS" and at no charge.
  30  *
  31  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  32  *
  33  *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  34  *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  35  *           Added timeout module option to override default
  36  *
  37  */
  38
  39 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  40
  41 #include <linux/module.h>
  42 #include <linux/types.h>
  43 #include <linux/miscdevice.h>
  44 #include <linux/watchdog.h>
  45 #include <linux/ioport.h>
  46 #include <linux/delay.h>
  47 #include <linux/notifier.h>
  48 #include <linux/fs.h>
  49 #include <linux/reboot.h>
  50 #include <linux/init.h>
  51 #include <linux/spinlock.h>
  52 #include <linux/moduleparam.h>
  53 #include <linux/io.h>
  54 #include <linux/uaccess.h>
  55
  56
  57 static unsigned long sbc8360_is_open;
  58 static char expect_close;
  59
  60 /*
  61  *
  62  * Watchdog Timer Configuration
  63  *
  64  * The function of the watchdog timer is to reset the system automatically
  65  * and is defined at I/O port 0120H and 0121H.  To enable the watchdog timer
  66  * and allow the system to reset, write appropriate values from the table
  67  * below to I/O port 0120H and 0121H.  To disable the timer, write a zero
  68  * value to I/O port 0121H for the system to stop the watchdog function.
  69  *
  70  * The following describes how the timer should be programmed (according to
  71  * the vendor documentation)
  72  *
  73  * Enabling Watchdog:
  74  * MOV AX,000AH (enable, phase I)
  75  * MOV DX,0120H
  76  * OUT DX,AX
  77  * MOV AX,000BH (enable, phase II)
  78  * MOV DX,0120H
  79  * OUT DX,AX
  80  * MOV AX,000nH (set multiplier n, from 1-4)
  81  * MOV DX,0120H
  82  * OUT DX,AX
  83  * MOV AX,000mH (set base timer m, from 0-F)
  84  * MOV DX,0121H
  85  * OUT DX,AX
  86  *
  87  * Reset timer:
  88  * MOV AX,000mH (same as set base timer, above)
  89  * MOV DX,0121H
  90  * OUT DX,AX
  91  *
  92  * Disabling Watchdog:
  93  * MOV AX,0000H (a zero value)
  94  * MOV DX,0120H
  95  * OUT DX,AX
  96  *
  97  * Watchdog timeout configuration values:
  98  *              N
  99  *      M |     1       2       3       4
 100  *      --|----------------------------------
 101  *      0 |     0.5s    5s      50s     100s
 102  *      1 |     1s      10s     100s    200s
 103  *      2 |     1.5s    15s     150s    300s
 104  *      3 |     2s      20s     200s    400s
 105  *      4 |     2.5s    25s     250s    500s
 106  *      5 |     3s      30s     300s    600s
 107  *      6 |     3.5s    35s     350s    700s
 108  *      7 |     4s      40s     400s    800s
 109  *      8 |     4.5s    45s     450s    900s
 110  *      9 |     5s      50s     500s    1000s
 111  *      A |     5.5s    55s     550s    1100s
 112  *      B |     6s      60s     600s    1200s
 113  *      C |     6.5s    65s     650s    1300s
 114  *      D |     7s      70s     700s    1400s
 115  *      E |     7.5s    75s     750s    1500s
 116  *      F |     8s      80s     800s    1600s
 117  *
 118  * Another way to say the same things is:
 119  *  For N=1, Timeout = (M+1) * 0.5s
 120  *  For N=2, Timeout = (M+1) * 5s
 121  *  For N=3, Timeout = (M+1) * 50s
 122  *  For N=4, Timeout = (M+1) * 100s
 123  *
 124  */
 125
 126 static int wd_times[64][2] = {
 127         {0, 1},                 /* 0  = 0.5s */
 128         {1, 1},                 /* 1  = 1s   */
 129         {2, 1},                 /* 2  = 1.5s */
 130         {3, 1},                 /* 3  = 2s   */
 131         {4, 1},                 /* 4  = 2.5s */
 132         {5, 1},                 /* 5  = 3s   */
 133         {6, 1},                 /* 6  = 3.5s */
 134         {7, 1},                 /* 7  = 4s   */
 135         {8, 1},                 /* 8  = 4.5s */
 136         {9, 1},                 /* 9  = 5s   */
 137         {0xA, 1},               /* 10 = 5.5s */
 138         {0xB, 1},               /* 11 = 6s   */
 139         {0xC, 1},               /* 12 = 6.5s */
 140         {0xD, 1},               /* 13 = 7s   */
 141         {0xE, 1},               /* 14 = 7.5s */
 142         {0xF, 1},               /* 15 = 8s   */
 143         {0, 2},                 /* 16 = 5s  */
 144         {1, 2},                 /* 17 = 10s */
 145         {2, 2},                 /* 18 = 15s */
 146         {3, 2},                 /* 19 = 20s */
 147         {4, 2},                 /* 20 = 25s */
 148         {5, 2},                 /* 21 = 30s */
 149         {6, 2},                 /* 22 = 35s */
 150         {7, 2},                 /* 23 = 40s */
 151         {8, 2},                 /* 24 = 45s */
 152         {9, 2},                 /* 25 = 50s */
 153         {0xA, 2},               /* 26 = 55s */
 154         {0xB, 2},               /* 27 = 60s */
 155         {0xC, 2},               /* 28 = 65s */
 156         {0xD, 2},               /* 29 = 70s */
 157         {0xE, 2},               /* 30 = 75s */
 158         {0xF, 2},               /* 31 = 80s */
 159         {0, 3},                 /* 32 = 50s  */
 160         {1, 3},                 /* 33 = 100s */
 161         {2, 3},                 /* 34 = 150s */
 162         {3, 3},                 /* 35 = 200s */
 163         {4, 3},                 /* 36 = 250s */
 164         {5, 3},                 /* 37 = 300s */
 165         {6, 3},                 /* 38 = 350s */
 166         {7, 3},                 /* 39 = 400s */
 167         {8, 3},                 /* 40 = 450s */
 168         {9, 3},                 /* 41 = 500s */
 169         {0xA, 3},               /* 42 = 550s */
 170         {0xB, 3},               /* 43 = 600s */
 171         {0xC, 3},               /* 44 = 650s */
 172         {0xD, 3},               /* 45 = 700s */
 173         {0xE, 3},               /* 46 = 750s */
 174         {0xF, 3},               /* 47 = 800s */
 175         {0, 4},                 /* 48 = 100s */
 176         {1, 4},                 /* 49 = 200s */
 177         {2, 4},                 /* 50 = 300s */
 178         {3, 4},                 /* 51 = 400s */
 179         {4, 4},                 /* 52 = 500s */
 180         {5, 4},                 /* 53 = 600s */
 181         {6, 4},                 /* 54 = 700s */
 182         {7, 4},                 /* 55 = 800s */
 183         {8, 4},                 /* 56 = 900s */
 184         {9, 4},                 /* 57 = 1000s */
 185         {0xA, 4},               /* 58 = 1100s */
 186         {0xB, 4},               /* 59 = 1200s */
 187         {0xC, 4},               /* 60 = 1300s */
 188         {0xD, 4},               /* 61 = 1400s */
 189         {0xE, 4},               /* 62 = 1500s */
 190         {0xF, 4}                /* 63 = 1600s */
 191 };
 192
 193 #define SBC8360_ENABLE 0x120
 194 #define SBC8360_BASETIME 0x121
 195
 196 static int timeout = 27;
 197 static int wd_margin = 0xB;
 198 static int wd_multiplier = 2;
 199 static bool nowayout = WATCHDOG_NOWAYOUT;
 200
 201 module_param(timeout, int, 0);
 202 MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
 203 module_param(nowayout, bool, 0);
 204 MODULE_PARM_DESC(nowayout,
 205                  "Watchdog cannot be stopped once started (default="
 206                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 207
 208 /*
 209  *      Kernel methods.
 210  */
 211
 212 /* Activate and pre-configure watchdog */
 213 static void sbc8360_activate(void)
 214 {
 215         /* Enable the watchdog */
 216         outb(0x0A, SBC8360_ENABLE);
 217         msleep_interruptible(100);
 218         outb(0x0B, SBC8360_ENABLE);
 219         msleep_interruptible(100);
 220         /* Set timeout multiplier */
 221         outb(wd_multiplier, SBC8360_ENABLE);
 222         msleep_interruptible(100);
 223         /* Nothing happens until first sbc8360_ping() */
 224 }
 225
 226 /* Kernel pings watchdog */
 227 static void sbc8360_ping(void)
 228 {
 229         /* Write the base timer register */
 230         outb(wd_margin, SBC8360_BASETIME);
 231 }
 232
 233 /* stop watchdog */
 234 static void sbc8360_stop(void)
 235 {
 236         /* De-activate the watchdog */
 237         outb(0, SBC8360_ENABLE);
 238 }
 239
 240 /* Userspace pings kernel driver, or requests clean close */
 241 static ssize_t sbc8360_write(struct file *file, const char __user *buf,
 242                              size_t count, loff_t *ppos)
 243 {
 244         if (count) {
 245                 if (!nowayout) {
 246                         size_t i;
 247
 248                         /* In case it was set long ago */
 249                         expect_close = 0;
 250
 251                         for (i = 0; i != count; i++) {
 252                                 char c;
 253                                 if (get_user(c, buf + i))
 254                                         return -EFAULT;
 255                                 if (c == 'V')
 256                                         expect_close = 42;
 257                         }
 258                 }
 259                 sbc8360_ping();
 260         }
 261         return count;
 262 }
 263
 264 static int sbc8360_open(struct inode *inode, struct file *file)
 265 {
 266         if (test_and_set_bit(0, &sbc8360_is_open))
 267                 return -EBUSY;
 268         if (nowayout)
 269                 __module_get(THIS_MODULE);
 270
 271         /* Activate and ping once to start the countdown */
 272         sbc8360_activate();
 273         sbc8360_ping();
 274         return nonseekable_open(inode, file);
 275 }
 276
 277 static int sbc8360_close(struct inode *inode, struct file *file)
 278 {
 279         if (expect_close == 42)
 280                 sbc8360_stop();
 281         else
 282                 pr_crit("SBC8360 device closed unexpectedly.  SBC8360 will not stop!\n");
 283
 284         clear_bit(0, &sbc8360_is_open);
 285         expect_close = 0;
 286         return 0;
 287 }
 288
 289 /*
 290  *      Notifier for system down
 291  */
 292
 293 static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code,
 294                               void *unused)
 295 {
 296         if (code == SYS_DOWN || code == SYS_HALT)
 297                 sbc8360_stop(); /* Disable the SBC8360 Watchdog */
 298
 299         return NOTIFY_DONE;
 300 }
 301
 302 /*
 303  *      Kernel Interfaces
 304  */
 305
 306 static const struct file_operations sbc8360_fops = {
 307         .owner = THIS_MODULE,
 308         .llseek = no_llseek,
 309         .write = sbc8360_write,
 310         .open = sbc8360_open,
 311         .release = sbc8360_close,
 312 };
 313
 314 static struct miscdevice sbc8360_miscdev = {
 315         .minor = WATCHDOG_MINOR,
 316         .name = "watchdog",
 317         .fops = &sbc8360_fops,
 318 };
 319
 320 /*
 321  *      The SBC8360 needs to learn about soft shutdowns in order to
 322  *      turn the timebomb registers off.
 323  */
 324
 325 static struct notifier_block sbc8360_notifier = {
 326         .notifier_call = sbc8360_notify_sys,
 327 };
 328
 329 static int __init sbc8360_init(void)
 330 {
 331         int res;
 332         unsigned long int mseconds = 60000;
 333
 334         if (timeout < 0 || timeout > 63) {
 335                 pr_err("Invalid timeout index (must be 0-63)\n");
 336                 res = -EINVAL;
 337                 goto out;
 338         }
 339
 340         if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) {
 341                 pr_err("ENABLE method I/O %X is not available\n",
 342                        SBC8360_ENABLE);
 343                 res = -EIO;
 344                 goto out;
 345         }
 346         if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) {
 347                 pr_err("BASETIME method I/O %X is not available\n",
 348                        SBC8360_BASETIME);
 349                 res = -EIO;
 350                 goto out_nobasetimereg;
 351         }
 352
 353         res = register_reboot_notifier(&sbc8360_notifier);
 354         if (res) {
 355                 pr_err("Failed to register reboot notifier\n");
 356                 goto out_noreboot;
 357         }
 358
 359         res = misc_register(&sbc8360_miscdev);
 360         if (res) {
 361                 pr_err("failed to register misc device\n");
 362                 goto out_nomisc;
 363         }
 364
 365         wd_margin = wd_times[timeout][0];
 366         wd_multiplier = wd_times[timeout][1];
 367
 368         if (wd_multiplier == 1)
 369                 mseconds = (wd_margin + 1) * 500;
 370         else if (wd_multiplier == 2)
 371                 mseconds = (wd_margin + 1) * 5000;
 372         else if (wd_multiplier == 3)
 373                 mseconds = (wd_margin + 1) * 50000;
 374         else if (wd_multiplier == 4)
 375                 mseconds = (wd_margin + 1) * 100000;
 376
 377         /* My kingdom for the ability to print "0.5 seconds" in the kernel! */
 378         pr_info("Timeout set at %ld ms\n", mseconds);
 379
 380         return 0;
 381
 382 out_nomisc:
 383         unregister_reboot_notifier(&sbc8360_notifier);
 384 out_noreboot:
 385         release_region(SBC8360_BASETIME, 1);
 386 out_nobasetimereg:
 387         release_region(SBC8360_ENABLE, 1);
 388 out:
 389         return res;
 390 }
 391
 392 static void __exit sbc8360_exit(void)
 393 {
 394         misc_deregister(&sbc8360_miscdev);
 395         unregister_reboot_notifier(&sbc8360_notifier);
 396         release_region(SBC8360_ENABLE, 1);
 397         release_region(SBC8360_BASETIME, 1);
 398 }
 399
 400 module_init(sbc8360_init);
 401 module_exit(sbc8360_exit);
 402
 403 MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>");
 404 MODULE_DESCRIPTION("SBC8360 watchdog driver");
 405 MODULE_LICENSE("GPL");
 406 MODULE_VERSION("1.01");
 407
 408 /* end of sbc8360.c */