linux/drivers/watchdog/sbc8360.c
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   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
  57static unsigned long sbc8360_is_open;
  58static 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
 126static 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
 196static int timeout = 27;
 197static int wd_margin = 0xB;
 198static int wd_multiplier = 2;
 199static bool nowayout = WATCHDOG_NOWAYOUT;
 200
 201module_param(timeout, int, 0);
 202MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
 203module_param(nowayout, bool, 0);
 204MODULE_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 */
 213static 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 */
 227static void sbc8360_ping(void)
 228{
 229        /* Write the base timer register */
 230        outb(wd_margin, SBC8360_BASETIME);
 231}
 232
 233/* stop watchdog */
 234static 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 */
 241static 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
 264static 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
 277static 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
 293static 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
 306static 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
 314static 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
 325static struct notifier_block sbc8360_notifier = {
 326        .notifier_call = sbc8360_notify_sys,
 327};
 328
 329static 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
 382out_nomisc:
 383        unregister_reboot_notifier(&sbc8360_notifier);
 384out_noreboot:
 385        release_region(SBC8360_BASETIME, 1);
 386out_nobasetimereg:
 387        release_region(SBC8360_ENABLE, 1);
 388out:
 389        return res;
 390}
 391
 392static 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
 400module_init(sbc8360_init);
 401module_exit(sbc8360_exit);
 402
 403MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>");
 404MODULE_DESCRIPTION("SBC8360 watchdog driver");
 405MODULE_LICENSE("GPL");
 406MODULE_VERSION("1.01");
 407MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 408
 409/* end of sbc8360.c */
 410
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