linux/drivers/watchdog/sbc60xxwdt.c
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   1/*
   2 *      60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
   3 *
   4 *      Based on acquirewdt.c by Alan Cox.
   5 *
   6 *      This program is free software; you can redistribute it and/or
   7 *      modify it under the terms of the GNU General Public License
   8 *      as published by the Free Software Foundation; either version
   9 *      2 of the License, or (at your option) any later version.
  10 *
  11 *      The author does NOT admit liability nor provide warranty for
  12 *      any of this software. This material is provided "AS-IS" in
  13 *      the hope that it may be useful for others.
  14 *
  15 *      (c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
  16 *
  17 *           12/4 - 2000      [Initial revision]
  18 *           25/4 - 2000      Added /dev/watchdog support
  19 *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1"
  20 *                                      on success
  21 *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
  22 *                            fix possible wdt_is_open race
  23 *                            add CONFIG_WATCHDOG_NOWAYOUT support
  24 *                            remove lock_kernel/unlock_kernel pairs
  25 *                            added KERN_* to printk's
  26 *                            got rid of extraneous comments
  27 *                            changed watchdog_info to correctly reflect what
  28 *                            the driver offers
  29 *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
  30 *                            WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
  31 *                            WDIOC_SETOPTIONS ioctls
  32 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  33 *                            use module_param
  34 *                            made timeout (the emulated heartbeat) a
  35 *                            module_param
  36 *                            made the keepalive ping an internal subroutine
  37 *                            made wdt_stop and wdt_start module params
  38 *                            added extra printk's for startup problems
  39 *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
  40 *
  41 *
  42 *  This WDT driver is different from the other Linux WDT
  43 *  drivers in the following ways:
  44 *  *)  The driver will ping the watchdog by itself, because this
  45 *      particular WDT has a very short timeout (one second) and it
  46 *      would be insane to count on any userspace daemon always
  47 *      getting scheduled within that time frame.
  48 *
  49 */
  50
  51#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  52
  53#include <linux/module.h>
  54#include <linux/moduleparam.h>
  55#include <linux/types.h>
  56#include <linux/timer.h>
  57#include <linux/jiffies.h>
  58#include <linux/miscdevice.h>
  59#include <linux/watchdog.h>
  60#include <linux/fs.h>
  61#include <linux/ioport.h>
  62#include <linux/notifier.h>
  63#include <linux/reboot.h>
  64#include <linux/init.h>
  65#include <linux/io.h>
  66#include <linux/uaccess.h>
  67
  68
  69#define OUR_NAME "sbc60xxwdt"
  70#define PFX OUR_NAME ": "
  71
  72/*
  73 * You must set these - The driver cannot probe for the settings
  74 */
  75
  76static int wdt_stop = 0x45;
  77module_param(wdt_stop, int, 0);
  78MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  79
  80static int wdt_start = 0x443;
  81module_param(wdt_start, int, 0);
  82MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  83
  84/*
  85 * The 60xx board can use watchdog timeout values from one second
  86 * to several minutes.  The default is one second, so if we reset
  87 * the watchdog every ~250ms we should be safe.
  88 */
  89
  90#define WDT_INTERVAL (HZ/4+1)
  91
  92/*
  93 * We must not require too good response from the userspace daemon.
  94 * Here we require the userspace daemon to send us a heartbeat
  95 * char to /dev/watchdog every 30 seconds.
  96 * If the daemon pulses us every 25 seconds, we can still afford
  97 * a 5 second scheduling delay on the (high priority) daemon. That
  98 * should be sufficient for a box under any load.
  99 */
 100
 101#define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
 102static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
 103                                           get seconds to wait for a ping */
 104module_param(timeout, int, 0);
 105MODULE_PARM_DESC(timeout,
 106        "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 107                                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 108
 109static bool nowayout = WATCHDOG_NOWAYOUT;
 110module_param(nowayout, bool, 0);
 111MODULE_PARM_DESC(nowayout,
 112        "Watchdog cannot be stopped once started (default="
 113                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 114
 115static void wdt_timer_ping(unsigned long);
 116static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 117static unsigned long next_heartbeat;
 118static unsigned long wdt_is_open;
 119static char wdt_expect_close;
 120
 121/*
 122 *      Whack the dog
 123 */
 124
 125static void wdt_timer_ping(unsigned long data)
 126{
 127        /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 128         * we agree to ping the WDT
 129         */
 130        if (time_before(jiffies, next_heartbeat)) {
 131                /* Ping the WDT by reading from wdt_start */
 132                inb_p(wdt_start);
 133                /* Re-set the timer interval */
 134                mod_timer(&timer, jiffies + WDT_INTERVAL);
 135        } else
 136                pr_warn("Heartbeat lost! Will not ping the watchdog\n");
 137}
 138
 139/*
 140 * Utility routines
 141 */
 142
 143static void wdt_startup(void)
 144{
 145        next_heartbeat = jiffies + (timeout * HZ);
 146
 147        /* Start the timer */
 148        mod_timer(&timer, jiffies + WDT_INTERVAL);
 149        pr_info("Watchdog timer is now enabled\n");
 150}
 151
 152static void wdt_turnoff(void)
 153{
 154        /* Stop the timer */
 155        del_timer(&timer);
 156        inb_p(wdt_stop);
 157        pr_info("Watchdog timer is now disabled...\n");
 158}
 159
 160static void wdt_keepalive(void)
 161{
 162        /* user land ping */
 163        next_heartbeat = jiffies + (timeout * HZ);
 164}
 165
 166/*
 167 * /dev/watchdog handling
 168 */
 169
 170static ssize_t fop_write(struct file *file, const char __user *buf,
 171                                                size_t count, loff_t *ppos)
 172{
 173        /* See if we got the magic character 'V' and reload the timer */
 174        if (count) {
 175                if (!nowayout) {
 176                        size_t ofs;
 177
 178                        /* note: just in case someone wrote the
 179                           magic character five months ago... */
 180                        wdt_expect_close = 0;
 181
 182                        /* scan to see whether or not we got the
 183                           magic character */
 184                        for (ofs = 0; ofs != count; ofs++) {
 185                                char c;
 186                                if (get_user(c, buf + ofs))
 187                                        return -EFAULT;
 188                                if (c == 'V')
 189                                        wdt_expect_close = 42;
 190                        }
 191                }
 192
 193                /* Well, anyhow someone wrote to us, we should
 194                   return that favour */
 195                wdt_keepalive();
 196        }
 197        return count;
 198}
 199
 200static int fop_open(struct inode *inode, struct file *file)
 201{
 202        /* Just in case we're already talking to someone... */
 203        if (test_and_set_bit(0, &wdt_is_open))
 204                return -EBUSY;
 205
 206        if (nowayout)
 207                __module_get(THIS_MODULE);
 208
 209        /* Good, fire up the show */
 210        wdt_startup();
 211        return nonseekable_open(inode, file);
 212}
 213
 214static int fop_close(struct inode *inode, struct file *file)
 215{
 216        if (wdt_expect_close == 42)
 217                wdt_turnoff();
 218        else {
 219                del_timer(&timer);
 220                pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
 221        }
 222        clear_bit(0, &wdt_is_open);
 223        wdt_expect_close = 0;
 224        return 0;
 225}
 226
 227static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 228{
 229        void __user *argp = (void __user *)arg;
 230        int __user *p = argp;
 231        static const struct watchdog_info ident = {
 232                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 233                                                        WDIOF_MAGICCLOSE,
 234                .firmware_version = 1,
 235                .identity = "SBC60xx",
 236        };
 237
 238        switch (cmd) {
 239        case WDIOC_GETSUPPORT:
 240                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 241        case WDIOC_GETSTATUS:
 242        case WDIOC_GETBOOTSTATUS:
 243                return put_user(0, p);
 244        case WDIOC_SETOPTIONS:
 245        {
 246                int new_options, retval = -EINVAL;
 247                if (get_user(new_options, p))
 248                        return -EFAULT;
 249                if (new_options & WDIOS_DISABLECARD) {
 250                        wdt_turnoff();
 251                        retval = 0;
 252                }
 253                if (new_options & WDIOS_ENABLECARD) {
 254                        wdt_startup();
 255                        retval = 0;
 256                }
 257                return retval;
 258        }
 259        case WDIOC_KEEPALIVE:
 260                wdt_keepalive();
 261                return 0;
 262        case WDIOC_SETTIMEOUT:
 263        {
 264                int new_timeout;
 265                if (get_user(new_timeout, p))
 266                        return -EFAULT;
 267                /* arbitrary upper limit */
 268                if (new_timeout < 1 || new_timeout > 3600)
 269                        return -EINVAL;
 270
 271                timeout = new_timeout;
 272                wdt_keepalive();
 273                /* Fall through */
 274        }
 275        case WDIOC_GETTIMEOUT:
 276                return put_user(timeout, p);
 277        default:
 278                return -ENOTTY;
 279        }
 280}
 281
 282static const struct file_operations wdt_fops = {
 283        .owner          = THIS_MODULE,
 284        .llseek         = no_llseek,
 285        .write          = fop_write,
 286        .open           = fop_open,
 287        .release        = fop_close,
 288        .unlocked_ioctl = fop_ioctl,
 289};
 290
 291static struct miscdevice wdt_miscdev = {
 292        .minor = WATCHDOG_MINOR,
 293        .name = "watchdog",
 294        .fops = &wdt_fops,
 295};
 296
 297/*
 298 *      Notifier for system down
 299 */
 300
 301static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 302        void *unused)
 303{
 304        if (code == SYS_DOWN || code == SYS_HALT)
 305                wdt_turnoff();
 306        return NOTIFY_DONE;
 307}
 308
 309/*
 310 *      The WDT needs to learn about soft shutdowns in order to
 311 *      turn the timebomb registers off.
 312 */
 313
 314static struct notifier_block wdt_notifier = {
 315        .notifier_call = wdt_notify_sys,
 316};
 317
 318static void __exit sbc60xxwdt_unload(void)
 319{
 320        wdt_turnoff();
 321
 322        /* Deregister */
 323        misc_deregister(&wdt_miscdev);
 324
 325        unregister_reboot_notifier(&wdt_notifier);
 326        if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 327                release_region(wdt_stop, 1);
 328        release_region(wdt_start, 1);
 329}
 330
 331static int __init sbc60xxwdt_init(void)
 332{
 333        int rc = -EBUSY;
 334
 335        if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 336                timeout = WATCHDOG_TIMEOUT;
 337                pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 338                        timeout);
 339        }
 340
 341        if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
 342                pr_err("I/O address 0x%04x already in use\n", wdt_start);
 343                rc = -EIO;
 344                goto err_out;
 345        }
 346
 347        /* We cannot reserve 0x45 - the kernel already has! */
 348        if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
 349                if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
 350                        pr_err("I/O address 0x%04x already in use\n", wdt_stop);
 351                        rc = -EIO;
 352                        goto err_out_region1;
 353                }
 354        }
 355
 356        rc = register_reboot_notifier(&wdt_notifier);
 357        if (rc) {
 358                pr_err("cannot register reboot notifier (err=%d)\n", rc);
 359                goto err_out_region2;
 360        }
 361
 362        rc = misc_register(&wdt_miscdev);
 363        if (rc) {
 364                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 365                       wdt_miscdev.minor, rc);
 366                goto err_out_reboot;
 367        }
 368        pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 369                timeout, nowayout);
 370
 371        return 0;
 372
 373err_out_reboot:
 374        unregister_reboot_notifier(&wdt_notifier);
 375err_out_region2:
 376        if (wdt_stop != 0x45 && wdt_stop != wdt_start)
 377                release_region(wdt_stop, 1);
 378err_out_region1:
 379        release_region(wdt_start, 1);
 380err_out:
 381        return rc;
 382}
 383
 384module_init(sbc60xxwdt_init);
 385module_exit(sbc60xxwdt_unload);
 386
 387MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 388MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 389MODULE_LICENSE("GPL");
 390MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 391
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