LXR linux/drivers/watchdog/sbc8360.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 *      SBC8360 Watchdog driver
   4 *
   5 *      (c) Copyright 2005 Webcon, Inc.
   6 *
   7 *      Based on ib700wdt.c, which is based on advantechwdt.c which is based
   8 *      on acquirewdt.c which is based on wdt.c.
   9 *
  10 *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>
  11 *
  12 *      Based on advantechwdt.c which is based on acquirewdt.c which
  13 *      is based on wdt.c.
  14 *
  15 *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
  16 *
  17 *      Based on acquirewdt.c which is based on wdt.c.
  18 *      Original copyright messages:
  19 *
  20 *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  21 *                                              All Rights Reserved.
  22 *
  23 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  24 *      warranty for any of this software. This material is provided
  25 *      "AS-IS" and at no charge.
  26 *
  27 *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  28 *
  29 *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  30 *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  31 *           Added timeout module option to override default
  32 *
  33 */
  34
  35#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  36
  37#include <linux/module.h>
  38#include <linux/types.h>
  39#include <linux/miscdevice.h>
  40#include <linux/watchdog.h>
  41#include <linux/ioport.h>
  42#include <linux/delay.h>
  43#include <linux/notifier.h>
  44#include <linux/fs.h>
  45#include <linux/reboot.h>
  46#include <linux/init.h>
  47#include <linux/spinlock.h>
  48#include <linux/moduleparam.h>
  49#include <linux/io.h>
  50#include <linux/uaccess.h>
  51
  52
  53static unsigned long sbc8360_is_open;
  54static char expect_close;
  55
  56/*
  57 *
  58 * Watchdog Timer Configuration
  59 *
  60 * The function of the watchdog timer is to reset the system automatically
  61 * and is defined at I/O port 0120H and 0121H.  To enable the watchdog timer
  62 * and allow the system to reset, write appropriate values from the table
  63 * below to I/O port 0120H and 0121H.  To disable the timer, write a zero
  64 * value to I/O port 0121H for the system to stop the watchdog function.
  65 *
  66 * The following describes how the timer should be programmed (according to
  67 * the vendor documentation)
  68 *
  69 * Enabling Watchdog:
  70 * MOV AX,000AH (enable, phase I)
  71 * MOV DX,0120H
  72 * OUT DX,AX
  73 * MOV AX,000BH (enable, phase II)
  74 * MOV DX,0120H
  75 * OUT DX,AX
  76 * MOV AX,000nH (set multiplier n, from 1-4)
  77 * MOV DX,0120H
  78 * OUT DX,AX
  79 * MOV AX,000mH (set base timer m, from 0-F)
  80 * MOV DX,0121H
  81 * OUT DX,AX
  82 *
  83 * Reset timer:
  84 * MOV AX,000mH (same as set base timer, above)
  85 * MOV DX,0121H
  86 * OUT DX,AX
  87 *
  88 * Disabling Watchdog:
  89 * MOV AX,0000H (a zero value)
  90 * MOV DX,0120H
  91 * OUT DX,AX
  92 *
  93 * Watchdog timeout configuration values:
  94 *              N
  95 *      M |     1       2       3       4
  96 *      --|----------------------------------
  97 *      0 |     0.5s    5s      50s     100s
  98 *      1 |     1s      10s     100s    200s
  99 *      2 |     1.5s    15s     150s    300s
 100 *      3 |     2s      20s     200s    400s
 101 *      4 |     2.5s    25s     250s    500s
 102 *      5 |     3s      30s     300s    600s
 103 *      6 |     3.5s    35s     350s    700s
 104 *      7 |     4s      40s     400s    800s
 105 *      8 |     4.5s    45s     450s    900s
 106 *      9 |     5s      50s     500s    1000s
 107 *      A |     5.5s    55s     550s    1100s
 108 *      B |     6s      60s     600s    1200s
 109 *      C |     6.5s    65s     650s    1300s
 110 *      D |     7s      70s     700s    1400s
 111 *      E |     7.5s    75s     750s    1500s
 112 *      F |     8s      80s     800s    1600s
 113 *
 114 * Another way to say the same things is:
 115 *  For N=1, Timeout = (M+1) * 0.5s
 116 *  For N=2, Timeout = (M+1) * 5s
 117 *  For N=3, Timeout = (M+1) * 50s
 118 *  For N=4, Timeout = (M+1) * 100s
 119 *
 120 */
 121
 122static int wd_times[64][2] = {
 123        {0, 1},                 /* 0  = 0.5s */
 124        {1, 1},                 /* 1  = 1s   */
 125        {2, 1},                 /* 2  = 1.5s */
 126        {3, 1},                 /* 3  = 2s   */
 127        {4, 1},                 /* 4  = 2.5s */
 128        {5, 1},                 /* 5  = 3s   */
 129        {6, 1},                 /* 6  = 3.5s */
 130        {7, 1},                 /* 7  = 4s   */
 131        {8, 1},                 /* 8  = 4.5s */
 132        {9, 1},                 /* 9  = 5s   */
 133        {0xA, 1},               /* 10 = 5.5s */
 134        {0xB, 1},               /* 11 = 6s   */
 135        {0xC, 1},               /* 12 = 6.5s */
 136        {0xD, 1},               /* 13 = 7s   */
 137        {0xE, 1},               /* 14 = 7.5s */
 138        {0xF, 1},               /* 15 = 8s   */
 139        {0, 2},                 /* 16 = 5s  */
 140        {1, 2},                 /* 17 = 10s */
 141        {2, 2},                 /* 18 = 15s */
 142        {3, 2},                 /* 19 = 20s */
 143        {4, 2},                 /* 20 = 25s */
 144        {5, 2},                 /* 21 = 30s */
 145        {6, 2},                 /* 22 = 35s */
 146        {7, 2},                 /* 23 = 40s */
 147        {8, 2},                 /* 24 = 45s */
 148        {9, 2},                 /* 25 = 50s */
 149        {0xA, 2},               /* 26 = 55s */
 150        {0xB, 2},               /* 27 = 60s */
 151        {0xC, 2},               /* 28 = 65s */
 152        {0xD, 2},               /* 29 = 70s */
 153        {0xE, 2},               /* 30 = 75s */
 154        {0xF, 2},               /* 31 = 80s */
 155        {0, 3},                 /* 32 = 50s  */
 156        {1, 3},                 /* 33 = 100s */
 157        {2, 3},                 /* 34 = 150s */
 158        {3, 3},                 /* 35 = 200s */
 159        {4, 3},                 /* 36 = 250s */
 160        {5, 3},                 /* 37 = 300s */
 161        {6, 3},                 /* 38 = 350s */
 162        {7, 3},                 /* 39 = 400s */
 163        {8, 3},                 /* 40 = 450s */
 164        {9, 3},                 /* 41 = 500s */
 165        {0xA, 3},               /* 42 = 550s */
 166        {0xB, 3},               /* 43 = 600s */
 167        {0xC, 3},               /* 44 = 650s */
 168        {0xD, 3},               /* 45 = 700s */
 169        {0xE, 3},               /* 46 = 750s */
 170        {0xF, 3},               /* 47 = 800s */
 171        {0, 4},                 /* 48 = 100s */
 172        {1, 4},                 /* 49 = 200s */
 173        {2, 4},                 /* 50 = 300s */
 174        {3, 4},                 /* 51 = 400s */
 175        {4, 4},                 /* 52 = 500s */
 176        {5, 4},                 /* 53 = 600s */
 177        {6, 4},                 /* 54 = 700s */
 178        {7, 4},                 /* 55 = 800s */
 179        {8, 4},                 /* 56 = 900s */
 180        {9, 4},                 /* 57 = 1000s */
 181        {0xA, 4},               /* 58 = 1100s */
 182        {0xB, 4},               /* 59 = 1200s */
 183        {0xC, 4},               /* 60 = 1300s */
 184        {0xD, 4},               /* 61 = 1400s */
 185        {0xE, 4},               /* 62 = 1500s */
 186        {0xF, 4}                /* 63 = 1600s */
 187};
 188
 189#define SBC8360_ENABLE 0x120
 190#define SBC8360_BASETIME 0x121
 191
 192static int timeout = 27;
 193static int wd_margin = 0xB;
 194static int wd_multiplier = 2;
 195static bool nowayout = WATCHDOG_NOWAYOUT;
 196
 197module_param(timeout, int, 0);
 198MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
 199module_param(nowayout, bool, 0);
 200MODULE_PARM_DESC(nowayout,
 201                 "Watchdog cannot be stopped once started (default="
 202                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 203
 204/*
 205 *      Kernel methods.
 206 */
 207
 208/* Activate and pre-configure watchdog */
 209static void sbc8360_activate(void)
 210{
 211        /* Enable the watchdog */
 212        outb(0x0A, SBC8360_ENABLE);
 213        msleep_interruptible(100);
 214        outb(0x0B, SBC8360_ENABLE);
 215        msleep_interruptible(100);
 216        /* Set timeout multiplier */
 217        outb(wd_multiplier, SBC8360_ENABLE);
 218        msleep_interruptible(100);
 219        /* Nothing happens until first sbc8360_ping() */
 220}
 221
 222/* Kernel pings watchdog */
 223static void sbc8360_ping(void)
 224{
 225        /* Write the base timer register */
 226        outb(wd_margin, SBC8360_BASETIME);
 227}
 228
 229/* stop watchdog */
 230static void sbc8360_stop(void)
 231{
 232        /* De-activate the watchdog */
 233        outb(0, SBC8360_ENABLE);
 234}
 235
 236/* Userspace pings kernel driver, or requests clean close */
 237static ssize_t sbc8360_write(struct file *file, const char __user *buf,
 238                             size_t count, loff_t *ppos)
 239{
 240        if (count) {
 241                if (!nowayout) {
 242                        size_t i;
 243
 244                        /* In case it was set long ago */
 245                        expect_close = 0;
 246
 247                        for (i = 0; i != count; i++) {
 248                                char c;
 249                                if (get_user(c, buf + i))
 250                                        return -EFAULT;
 251                                if (c == 'V')
 252                                        expect_close = 42;
 253                        }
 254                }
 255                sbc8360_ping();
 256        }
 257        return count;
 258}
 259
 260static int sbc8360_open(struct inode *inode, struct file *file)
 261{
 262        if (test_and_set_bit(0, &sbc8360_is_open))
 263                return -EBUSY;
 264        if (nowayout)
 265                __module_get(THIS_MODULE);
 266
 267        /* Activate and ping once to start the countdown */
 268        sbc8360_activate();
 269        sbc8360_ping();
 270        return stream_open(inode, file);
 271}
 272
 273static int sbc8360_close(struct inode *inode, struct file *file)
 274{
 275        if (expect_close == 42)
 276                sbc8360_stop();
 277        else
 278                pr_crit("SBC8360 device closed unexpectedly.  SBC8360 will not stop!\n");
 279
 280        clear_bit(0, &sbc8360_is_open);
 281        expect_close = 0;
 282        return 0;
 283}
 284
 285/*
 286 *      Notifier for system down
 287 */
 288
 289static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code,
 290                              void *unused)
 291{
 292        if (code == SYS_DOWN || code == SYS_HALT)
 293                sbc8360_stop(); /* Disable the SBC8360 Watchdog */
 294
 295        return NOTIFY_DONE;
 296}
 297
 298/*
 299 *      Kernel Interfaces
 300 */
 301
 302static const struct file_operations sbc8360_fops = {
 303        .owner = THIS_MODULE,
 304        .llseek = no_llseek,
 305        .write = sbc8360_write,
 306        .open = sbc8360_open,
 307        .release = sbc8360_close,
 308};
 309
 310static struct miscdevice sbc8360_miscdev = {
 311        .minor = WATCHDOG_MINOR,
 312        .name = "watchdog",
 313        .fops = &sbc8360_fops,
 314};
 315
 316/*
 317 *      The SBC8360 needs to learn about soft shutdowns in order to
 318 *      turn the timebomb registers off.
 319 */
 320
 321static struct notifier_block sbc8360_notifier = {
 322        .notifier_call = sbc8360_notify_sys,
 323};
 324
 325static int __init sbc8360_init(void)
 326{
 327        int res;
 328        unsigned long int mseconds = 60000;
 329
 330        if (timeout < 0 || timeout > 63) {
 331                pr_err("Invalid timeout index (must be 0-63)\n");
 332                res = -EINVAL;
 333                goto out;
 334        }
 335
 336        if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) {
 337                pr_err("ENABLE method I/O %X is not available\n",
 338                       SBC8360_ENABLE);
 339                res = -EIO;
 340                goto out;
 341        }
 342        if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) {
 343                pr_err("BASETIME method I/O %X is not available\n",
 344                       SBC8360_BASETIME);
 345                res = -EIO;
 346                goto out_nobasetimereg;
 347        }
 348
 349        res = register_reboot_notifier(&sbc8360_notifier);
 350        if (res) {
 351                pr_err("Failed to register reboot notifier\n");
 352                goto out_noreboot;
 353        }
 354
 355        res = misc_register(&sbc8360_miscdev);
 356        if (res) {
 357                pr_err("failed to register misc device\n");
 358                goto out_nomisc;
 359        }
 360
 361        wd_margin = wd_times[timeout][0];
 362        wd_multiplier = wd_times[timeout][1];
 363
 364        if (wd_multiplier == 1)
 365                mseconds = (wd_margin + 1) * 500;
 366        else if (wd_multiplier == 2)
 367                mseconds = (wd_margin + 1) * 5000;
 368        else if (wd_multiplier == 3)
 369                mseconds = (wd_margin + 1) * 50000;
 370        else if (wd_multiplier == 4)
 371                mseconds = (wd_margin + 1) * 100000;
 372
 373        /* My kingdom for the ability to print "0.5 seconds" in the kernel! */
 374        pr_info("Timeout set at %ld ms\n", mseconds);
 375
 376        return 0;
 377
 378out_nomisc:
 379        unregister_reboot_notifier(&sbc8360_notifier);
 380out_noreboot:
 381        release_region(SBC8360_BASETIME, 1);
 382out_nobasetimereg:
 383        release_region(SBC8360_ENABLE, 1);
 384out:
 385        return res;
 386}
 387
 388static void __exit sbc8360_exit(void)
 389{
 390        misc_deregister(&sbc8360_miscdev);
 391        unregister_reboot_notifier(&sbc8360_notifier);
 392        release_region(SBC8360_ENABLE, 1);
 393        release_region(SBC8360_BASETIME, 1);
 394}
 395
 396module_init(sbc8360_init);
 397module_exit(sbc8360_exit);
 398
 399MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>");
 400MODULE_DESCRIPTION("SBC8360 watchdog driver");
 401MODULE_LICENSE("GPL");
 402MODULE_VERSION("1.01");
 403
 404/* end of sbc8360.c */
 405