linux/drivers/watchdog/w83877f_wdt.c
<<
>>
Prefs
   1/*
   2 *      W83877F Computer Watchdog Timer driver
   3 *
   4 *      Based on acquirewdt.c by Alan Cox,
   5 *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
   6 *
   7 *      This program is free software; you can redistribute it and/or
   8 *      modify it under the terms of the GNU General Public License
   9 *      as published by the Free Software Foundation; either version
  10 *      2 of the License, or (at your option) any later version.
  11 *
  12 *      The authors do NOT admit liability nor provide warranty for
  13 *      any of this software. This material is provided "AS-IS" in
  14 *      the hope that it may be useful for others.
  15 *
  16 *      (c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
  17 *
  18 *           4/19 - 2001      [Initial revision]
  19 *           9/27 - 2001      Added spinlocking
  20 *           4/12 - 2002      [rob@osinvestor.com] Eliminate extra comments
  21 *                            Eliminate fop_read
  22 *                            Eliminate extra spin_unlock
  23 *                            Added KERN_* tags to printks
  24 *                            add CONFIG_WATCHDOG_NOWAYOUT support
  25 *                            fix possible wdt_is_open race
  26 *                            changed watchdog_info to correctly reflect what
  27 *                            the driver offers
  28 *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
  29 *                            WDIOC_SETTIMEOUT,
  30 *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
  31 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  32 *                            added extra printk's for startup problems
  33 *                            use module_param
  34 *                            made timeout (the emulated heartbeat) a
  35 *                            module_param
  36 *                            made the keepalive ping an internal subroutine
  37 *
  38 *  This WDT driver is different from most other Linux WDT
  39 *  drivers in that the driver will ping the watchdog by itself,
  40 *  because this particular WDT has a very short timeout (1.6
  41 *  seconds) and it would be insane to count on any userspace
  42 *  daemon always getting scheduled within that time frame.
  43 */
  44
  45#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  46
  47#include <linux/module.h>
  48#include <linux/moduleparam.h>
  49#include <linux/types.h>
  50#include <linux/timer.h>
  51#include <linux/jiffies.h>
  52#include <linux/miscdevice.h>
  53#include <linux/watchdog.h>
  54#include <linux/fs.h>
  55#include <linux/ioport.h>
  56#include <linux/notifier.h>
  57#include <linux/reboot.h>
  58#include <linux/init.h>
  59#include <linux/io.h>
  60#include <linux/uaccess.h>
  61
  62#define OUR_NAME "w83877f_wdt"
  63
  64#define ENABLE_W83877F_PORT 0x3F0
  65#define ENABLE_W83877F 0x87
  66#define DISABLE_W83877F 0xAA
  67#define WDT_PING 0x443
  68#define WDT_REGISTER 0x14
  69#define WDT_ENABLE 0x9C
  70#define WDT_DISABLE 0x8C
  71
  72/*
  73 * The W83877F seems to be fixed at 1.6s timeout (at least on the
  74 * EMACS PC-104 board I'm using). If we reset the watchdog every
  75 * ~250ms we should be safe.  */
  76
  77#define WDT_INTERVAL (HZ/4+1)
  78
  79/*
  80 * We must not require too good response from the userspace daemon.
  81 * Here we require the userspace daemon to send us a heartbeat
  82 * char to /dev/watchdog every 30 seconds.
  83 */
  84
  85#define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  86/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  87static int timeout = WATCHDOG_TIMEOUT;
  88module_param(timeout, int, 0);
  89MODULE_PARM_DESC(timeout,
  90        "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  91                                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  92
  93
  94static bool nowayout = WATCHDOG_NOWAYOUT;
  95module_param(nowayout, bool, 0);
  96MODULE_PARM_DESC(nowayout,
  97                "Watchdog cannot be stopped once started (default="
  98                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  99
 100static void wdt_timer_ping(unsigned long);
 101static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 102static unsigned long next_heartbeat;
 103static unsigned long wdt_is_open;
 104static char wdt_expect_close;
 105static DEFINE_SPINLOCK(wdt_spinlock);
 106
 107/*
 108 *      Whack the dog
 109 */
 110
 111static void wdt_timer_ping(unsigned long data)
 112{
 113        /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 114         * we agree to ping the WDT
 115         */
 116        if (time_before(jiffies, next_heartbeat)) {
 117                /* Ping the WDT */
 118                spin_lock(&wdt_spinlock);
 119
 120                /* Ping the WDT by reading from WDT_PING */
 121                inb_p(WDT_PING);
 122
 123                /* Re-set the timer interval */
 124                mod_timer(&timer, jiffies + WDT_INTERVAL);
 125
 126                spin_unlock(&wdt_spinlock);
 127
 128        } else
 129                pr_warn("Heartbeat lost! Will not ping the watchdog\n");
 130}
 131
 132/*
 133 * Utility routines
 134 */
 135
 136static void wdt_change(int writeval)
 137{
 138        unsigned long flags;
 139        spin_lock_irqsave(&wdt_spinlock, flags);
 140
 141        /* buy some time */
 142        inb_p(WDT_PING);
 143
 144        /* make W83877F available */
 145        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 146        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 147
 148        /* enable watchdog */
 149        outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
 150        outb_p(writeval,        ENABLE_W83877F_PORT+1);
 151
 152        /* lock the W8387FF away */
 153        outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
 154
 155        spin_unlock_irqrestore(&wdt_spinlock, flags);
 156}
 157
 158static void wdt_startup(void)
 159{
 160        next_heartbeat = jiffies + (timeout * HZ);
 161
 162        /* Start the timer */
 163        mod_timer(&timer, jiffies + WDT_INTERVAL);
 164
 165        wdt_change(WDT_ENABLE);
 166
 167        pr_info("Watchdog timer is now enabled\n");
 168}
 169
 170static void wdt_turnoff(void)
 171{
 172        /* Stop the timer */
 173        del_timer(&timer);
 174
 175        wdt_change(WDT_DISABLE);
 176
 177        pr_info("Watchdog timer is now disabled...\n");
 178}
 179
 180static void wdt_keepalive(void)
 181{
 182        /* user land ping */
 183        next_heartbeat = jiffies + (timeout * HZ);
 184}
 185
 186/*
 187 * /dev/watchdog handling
 188 */
 189
 190static ssize_t fop_write(struct file *file, const char __user *buf,
 191                                                size_t count, loff_t *ppos)
 192{
 193        /* See if we got the magic character 'V' and reload the timer */
 194        if (count) {
 195                if (!nowayout) {
 196                        size_t ofs;
 197
 198                        /* note: just in case someone wrote the magic
 199                           character five months ago... */
 200                        wdt_expect_close = 0;
 201
 202                        /* scan to see whether or not we got the
 203                           magic character */
 204                        for (ofs = 0; ofs != count; ofs++) {
 205                                char c;
 206                                if (get_user(c, buf + ofs))
 207                                        return -EFAULT;
 208                                if (c == 'V')
 209                                        wdt_expect_close = 42;
 210                        }
 211                }
 212
 213                /* someone wrote to us, we should restart timer */
 214                wdt_keepalive();
 215        }
 216        return count;
 217}
 218
 219static int fop_open(struct inode *inode, struct file *file)
 220{
 221        /* Just in case we're already talking to someone... */
 222        if (test_and_set_bit(0, &wdt_is_open))
 223                return -EBUSY;
 224
 225        /* Good, fire up the show */
 226        wdt_startup();
 227        return nonseekable_open(inode, file);
 228}
 229
 230static int fop_close(struct inode *inode, struct file *file)
 231{
 232        if (wdt_expect_close == 42)
 233                wdt_turnoff();
 234        else {
 235                del_timer(&timer);
 236                pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
 237        }
 238        clear_bit(0, &wdt_is_open);
 239        wdt_expect_close = 0;
 240        return 0;
 241}
 242
 243static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 244{
 245        void __user *argp = (void __user *)arg;
 246        int __user *p = argp;
 247        static const struct watchdog_info ident = {
 248                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 249                                                        | WDIOF_MAGICCLOSE,
 250                .firmware_version = 1,
 251                .identity = "W83877F",
 252        };
 253
 254        switch (cmd) {
 255        case WDIOC_GETSUPPORT:
 256                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 257        case WDIOC_GETSTATUS:
 258        case WDIOC_GETBOOTSTATUS:
 259                return put_user(0, p);
 260        case WDIOC_SETOPTIONS:
 261        {
 262                int new_options, retval = -EINVAL;
 263
 264                if (get_user(new_options, p))
 265                        return -EFAULT;
 266
 267                if (new_options & WDIOS_DISABLECARD) {
 268                        wdt_turnoff();
 269                        retval = 0;
 270                }
 271
 272                if (new_options & WDIOS_ENABLECARD) {
 273                        wdt_startup();
 274                        retval = 0;
 275                }
 276
 277                return retval;
 278        }
 279        case WDIOC_KEEPALIVE:
 280                wdt_keepalive();
 281                return 0;
 282        case WDIOC_SETTIMEOUT:
 283        {
 284                int new_timeout;
 285
 286                if (get_user(new_timeout, p))
 287                        return -EFAULT;
 288
 289                /* arbitrary upper limit */
 290                if (new_timeout < 1 || new_timeout > 3600)
 291                        return -EINVAL;
 292
 293                timeout = new_timeout;
 294                wdt_keepalive();
 295                /* Fall through */
 296        }
 297        case WDIOC_GETTIMEOUT:
 298                return put_user(timeout, p);
 299        default:
 300                return -ENOTTY;
 301        }
 302}
 303
 304static const struct file_operations wdt_fops = {
 305        .owner          = THIS_MODULE,
 306        .llseek         = no_llseek,
 307        .write          = fop_write,
 308        .open           = fop_open,
 309        .release        = fop_close,
 310        .unlocked_ioctl = fop_ioctl,
 311};
 312
 313static struct miscdevice wdt_miscdev = {
 314        .minor  = WATCHDOG_MINOR,
 315        .name   = "watchdog",
 316        .fops   = &wdt_fops,
 317};
 318
 319/*
 320 *      Notifier for system down
 321 */
 322
 323static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 324        void *unused)
 325{
 326        if (code == SYS_DOWN || code == SYS_HALT)
 327                wdt_turnoff();
 328        return NOTIFY_DONE;
 329}
 330
 331/*
 332 *      The WDT needs to learn about soft shutdowns in order to
 333 *      turn the timebomb registers off.
 334 */
 335
 336static struct notifier_block wdt_notifier = {
 337        .notifier_call = wdt_notify_sys,
 338};
 339
 340static void __exit w83877f_wdt_unload(void)
 341{
 342        wdt_turnoff();
 343
 344        /* Deregister */
 345        misc_deregister(&wdt_miscdev);
 346
 347        unregister_reboot_notifier(&wdt_notifier);
 348        release_region(WDT_PING, 1);
 349        release_region(ENABLE_W83877F_PORT, 2);
 350}
 351
 352static int __init w83877f_wdt_init(void)
 353{
 354        int rc = -EBUSY;
 355
 356        if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 357                timeout = WATCHDOG_TIMEOUT;
 358                pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 359                        timeout);
 360        }
 361
 362        if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
 363                pr_err("I/O address 0x%04x already in use\n",
 364                       ENABLE_W83877F_PORT);
 365                rc = -EIO;
 366                goto err_out;
 367        }
 368
 369        if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
 370                pr_err("I/O address 0x%04x already in use\n", WDT_PING);
 371                rc = -EIO;
 372                goto err_out_region1;
 373        }
 374
 375        rc = register_reboot_notifier(&wdt_notifier);
 376        if (rc) {
 377                pr_err("cannot register reboot notifier (err=%d)\n", rc);
 378                goto err_out_region2;
 379        }
 380
 381        rc = misc_register(&wdt_miscdev);
 382        if (rc) {
 383                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 384                       wdt_miscdev.minor, rc);
 385                goto err_out_reboot;
 386        }
 387
 388        pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 389                timeout, nowayout);
 390
 391        return 0;
 392
 393err_out_reboot:
 394        unregister_reboot_notifier(&wdt_notifier);
 395err_out_region2:
 396        release_region(WDT_PING, 1);
 397err_out_region1:
 398        release_region(ENABLE_W83877F_PORT, 2);
 399err_out:
 400        return rc;
 401}
 402
 403module_init(w83877f_wdt_init);
 404module_exit(w83877f_wdt_unload);
 405
 406MODULE_AUTHOR("Scott and Bill Jennings");
 407MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 408MODULE_LICENSE("GPL");
 409MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 410
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.