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#include <linux/module.h>
  52#include <linux/moduleparam.h>
  53#include <linux/types.h>
  54#include <linux/timer.h>
  55#include <linux/jiffies.h>
  56#include <linux/miscdevice.h>
  57#include <linux/watchdog.h>
  58#include <linux/fs.h>
  59#include <linux/ioport.h>
  60#include <linux/notifier.h>
  61#include <linux/reboot.h>
  62#include <linux/init.h>
  63#include <linux/io.h>
  64#include <linux/uaccess.h>
  65
  66#include <asm/system.h>
  67
  68#define OUR_NAME "sbc60xxwdt"
  69#define PFX OUR_NAME ": "
  70
  71/*
  72 * You must set these - The driver cannot probe for the settings
  73 */
  74
  75static int wdt_stop = 0x45;
  76module_param(wdt_stop, int, 0);
  77MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  78
  79static int wdt_start = 0x443;
  80module_param(wdt_start, int, 0);
  81MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  82
  83/*
  84 * The 60xx board can use watchdog timeout values from one second
  85 * to several minutes.  The default is one second, so if we reset
  86 * the watchdog every ~250ms we should be safe.
  87 */
  88
  89#define WDT_INTERVAL (HZ/4+1)
  90
  91/*
  92 * We must not require too good response from the userspace daemon.
  93 * Here we require the userspace daemon to send us a heartbeat
  94 * char to /dev/watchdog every 30 seconds.
  95 * If the daemon pulses us every 25 seconds, we can still afford
  96 * a 5 second scheduling delay on the (high priority) daemon. That
  97 * should be sufficient for a box under any load.
  98 */
  99
 100#define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
 101static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
 102                                           get seconds to wait for a ping */
 103module_param(timeout, int, 0);
 104MODULE_PARM_DESC(timeout,
 105        "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 106                                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 107
 108static int nowayout = WATCHDOG_NOWAYOUT;
 109module_param(nowayout, int, 0);
 110MODULE_PARM_DESC(nowayout,
 111        "Watchdog cannot be stopped once started (default="
 112                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 113
 114static void wdt_timer_ping(unsigned long);
 115static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 116static unsigned long next_heartbeat;
 117static unsigned long wdt_is_open;
 118static char wdt_expect_close;
 119
 120/*
 121 *      Whack the dog
 122 */
 123
 124static void wdt_timer_ping(unsigned long data)
 125{
 126        /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 127         * we agree to ping the WDT
 128         */
 129        if (time_before(jiffies, next_heartbeat)) {
 130                /* Ping the WDT by reading from wdt_start */
 131                inb_p(wdt_start);
 132                /* Re-set the timer interval */
 133                mod_timer(&timer, jiffies + WDT_INTERVAL);
 134        } else
 135                printk(KERN_WARNING PFX
 136                        "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        printk(KERN_INFO PFX "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        printk(KERN_INFO PFX "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                printk(KERN_CRIT PFX
 221                  "device file closed unexpectedly. Will not stop the WDT!\n");
 222        }
 223        clear_bit(0, &wdt_is_open);
 224        wdt_expect_close = 0;
 225        return 0;
 226}
 227
 228static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 229{
 230        void __user *argp = (void __user *)arg;
 231        int __user *p = argp;
 232        static const struct watchdog_info ident = {
 233                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 234                                                        WDIOF_MAGICCLOSE,
 235                .firmware_version = 1,
 236                .identity = "SBC60xx",
 237        };
 238
 239        switch (cmd) {
 240        case WDIOC_GETSUPPORT:
 241                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 242        case WDIOC_GETSTATUS:
 243        case WDIOC_GETBOOTSTATUS:
 244                return put_user(0, p);
 245        case WDIOC_SETOPTIONS:
 246        {
 247                int new_options, retval = -EINVAL;
 248                if (get_user(new_options, p))
 249                        return -EFAULT;
 250                if (new_options & WDIOS_DISABLECARD) {
 251                        wdt_turnoff();
 252                        retval = 0;
 253                }
 254                if (new_options & WDIOS_ENABLECARD) {
 255                        wdt_startup();
 256                        retval = 0;
 257                }
 258                return retval;
 259        }
 260        case WDIOC_KEEPALIVE:
 261                wdt_keepalive();
 262                return 0;
 263        case WDIOC_SETTIMEOUT:
 264        {
 265                int new_timeout;
 266                if (get_user(new_timeout, p))
 267                        return -EFAULT;
 268                /* arbitrary upper limit */
 269                if (new_timeout < 1 || new_timeout > 3600)
 270                        return -EINVAL;
 271
 272                timeout = new_timeout;
 273                wdt_keepalive();
 274                /* Fall through */
 275        }
 276        case WDIOC_GETTIMEOUT:
 277                return put_user(timeout, p);
 278        default:
 279                return -ENOTTY;
 280        }
 281}
 282
 283static const struct file_operations wdt_fops = {
 284        .owner          = THIS_MODULE,
 285        .llseek         = no_llseek,
 286        .write          = fop_write,
 287        .open           = fop_open,
 288        .release        = fop_close,
 289        .unlocked_ioctl = fop_ioctl,
 290};
 291
 292static struct miscdevice wdt_miscdev = {
 293        .minor = WATCHDOG_MINOR,
 294        .name = "watchdog",
 295        .fops = &wdt_fops,
 296};
 297
 298/*
 299 *      Notifier for system down
 300 */
 301
 302static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 303        void *unused)
 304{
 305        if (code == SYS_DOWN || code == SYS_HALT)
 306                wdt_turnoff();
 307        return NOTIFY_DONE;
 308}
 309
 310/*
 311 *      The WDT needs to learn about soft shutdowns in order to
 312 *      turn the timebomb registers off.
 313 */
 314
 315static struct notifier_block wdt_notifier = {
 316        .notifier_call = wdt_notify_sys,
 317};
 318
 319static void __exit sbc60xxwdt_unload(void)
 320{
 321        wdt_turnoff();
 322
 323        /* Deregister */
 324        misc_deregister(&wdt_miscdev);
 325
 326        unregister_reboot_notifier(&wdt_notifier);
 327        if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 328                release_region(wdt_stop, 1);
 329        release_region(wdt_start, 1);
 330}
 331
 332static int __init sbc60xxwdt_init(void)
 333{
 334        int rc = -EBUSY;
 335
 336        if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 337                timeout = WATCHDOG_TIMEOUT;
 338                printk(KERN_INFO PFX
 339                        "timeout value must be 1 <= x <= 3600, using %d\n",
 340                                                                timeout);
 341        }
 342
 343        if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
 344                printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 345                        wdt_start);
 346                rc = -EIO;
 347                goto err_out;
 348        }
 349
 350        /* We cannot reserve 0x45 - the kernel already has! */
 351        if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
 352                if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
 353                        printk(KERN_ERR PFX
 354                                "I/O address 0x%04x already in use\n",
 355                                                        wdt_stop);
 356                        rc = -EIO;
 357                        goto err_out_region1;
 358                }
 359        }
 360
 361        rc = register_reboot_notifier(&wdt_notifier);
 362        if (rc) {
 363                printk(KERN_ERR PFX
 364                        "cannot register reboot notifier (err=%d)\n", rc);
 365                goto err_out_region2;
 366        }
 367
 368        rc = misc_register(&wdt_miscdev);
 369        if (rc) {
 370                printk(KERN_ERR PFX
 371                        "cannot register miscdev on minor=%d (err=%d)\n",
 372                                                wdt_miscdev.minor, rc);
 373                goto err_out_reboot;
 374        }
 375        printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 376                timeout, nowayout);
 377
 378        return 0;
 379
 380err_out_reboot:
 381        unregister_reboot_notifier(&wdt_notifier);
 382err_out_region2:
 383        if (wdt_stop != 0x45 && wdt_stop != wdt_start)
 384                release_region(wdt_stop, 1);
 385err_out_region1:
 386        release_region(wdt_start, 1);
 387err_out:
 388        return rc;
 389}
 390
 391module_init(sbc60xxwdt_init);
 392module_exit(sbc60xxwdt_unload);
 393
 394MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 395MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 396MODULE_LICENSE("GPL");
 397MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 398