LXR linux/drivers/watchdog/w83877f

   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#include <linux/module.h>
  46#include <linux/moduleparam.h>
  47#include <linux/types.h>
  48#include <linux/timer.h>
  49#include <linux/jiffies.h>
  50#include <linux/miscdevice.h>
  51#include <linux/watchdog.h>
  52#include <linux/fs.h>
  53#include <linux/ioport.h>
  54#include <linux/notifier.h>
  55#include <linux/reboot.h>
  56#include <linux/init.h>
  57#include <linux/io.h>
  58#include <linux/uaccess.h>
  59#include <asm/system.h>
  60
  61#define OUR_NAME "w83877f_wdt"
  62#define PFX OUR_NAME ": "
  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 int nowayout = WATCHDOG_NOWAYOUT;
  95module_param(nowayout, int, 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                printk(KERN_WARNING PFX
 130                        "Heartbeat lost! Will not ping the watchdog\n");
 131}
 132
 133/*
 134 * Utility routines
 135 */
 136
 137static void wdt_change(int writeval)
 138{
 139        unsigned long flags;
 140        spin_lock_irqsave(&wdt_spinlock, flags);
 141
 142        /* buy some time */
 143        inb_p(WDT_PING);
 144
 145        /* make W83877F available */
 146        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 147        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 148
 149        /* enable watchdog */
 150        outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
 151        outb_p(writeval,        ENABLE_W83877F_PORT+1);
 152
 153        /* lock the W8387FF away */
 154        outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
 155
 156        spin_unlock_irqrestore(&wdt_spinlock, flags);
 157}
 158
 159static void wdt_startup(void)
 160{
 161        next_heartbeat = jiffies + (timeout * HZ);
 162
 163        /* Start the timer */
 164        mod_timer(&timer, jiffies + WDT_INTERVAL);
 165
 166        wdt_change(WDT_ENABLE);
 167
 168        printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 169}
 170
 171static void wdt_turnoff(void)
 172{
 173        /* Stop the timer */
 174        del_timer(&timer);
 175
 176        wdt_change(WDT_DISABLE);
 177
 178        printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 179}
 180
 181static void wdt_keepalive(void)
 182{
 183        /* user land ping */
 184        next_heartbeat = jiffies + (timeout * HZ);
 185}
 186
 187/*
 188 * /dev/watchdog handling
 189 */
 190
 191static ssize_t fop_write(struct file *file, const char __user *buf,
 192                                                size_t count, loff_t *ppos)
 193{
 194        /* See if we got the magic character 'V' and reload the timer */
 195        if (count) {
 196                if (!nowayout) {
 197                        size_t ofs;
 198
 199                        /* note: just in case someone wrote the magic
 200                           character five months ago... */
 201                        wdt_expect_close = 0;
 202
 203                        /* scan to see whether or not we got the
 204                           magic character */
 205                        for (ofs = 0; ofs != count; ofs++) {
 206                                char c;
 207                                if (get_user(c, buf + ofs))
 208                                        return -EFAULT;
 209                                if (c == 'V')
 210                                        wdt_expect_close = 42;
 211                        }
 212                }
 213
 214                /* someone wrote to us, we should restart timer */
 215                wdt_keepalive();
 216        }
 217        return count;
 218}
 219
 220static int fop_open(struct inode *inode, struct file *file)
 221{
 222        /* Just in case we're already talking to someone... */
 223        if (test_and_set_bit(0, &wdt_is_open))
 224                return -EBUSY;
 225
 226        /* Good, fire up the show */
 227        wdt_startup();
 228        return nonseekable_open(inode, file);
 229}
 230
 231static int fop_close(struct inode *inode, struct file *file)
 232{
 233        if (wdt_expect_close == 42)
 234                wdt_turnoff();
 235        else {
 236                del_timer(&timer);
 237                printk(KERN_CRIT PFX
 238                  "device file closed unexpectedly. Will not stop the WDT!\n");
 239        }
 240        clear_bit(0, &wdt_is_open);
 241        wdt_expect_close = 0;
 242        return 0;
 243}
 244
 245static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 246{
 247        void __user *argp = (void __user *)arg;
 248        int __user *p = argp;
 249        static const struct watchdog_info ident = {
 250                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 251                                                        | WDIOF_MAGICCLOSE,
 252                .firmware_version = 1,
 253                .identity = "W83877F",
 254        };
 255
 256        switch (cmd) {
 257        case WDIOC_GETSUPPORT:
 258                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 259        case WDIOC_GETSTATUS:
 260        case WDIOC_GETBOOTSTATUS:
 261                return put_user(0, p);
 262        case WDIOC_SETOPTIONS:
 263        {
 264                int new_options, retval = -EINVAL;
 265
 266                if (get_user(new_options, p))
 267                        return -EFAULT;
 268
 269                if (new_options & WDIOS_DISABLECARD) {
 270                        wdt_turnoff();
 271                        retval = 0;
 272                }
 273
 274                if (new_options & WDIOS_ENABLECARD) {
 275                        wdt_startup();
 276                        retval = 0;
 277                }
 278
 279                return retval;
 280        }
 281        case WDIOC_KEEPALIVE:
 282                wdt_keepalive();
 283                return 0;
 284        case WDIOC_SETTIMEOUT:
 285        {
 286                int new_timeout;
 287
 288                if (get_user(new_timeout, p))
 289                        return -EFAULT;
 290
 291                /* arbitrary upper limit */
 292                if (new_timeout < 1 || new_timeout > 3600)
 293                        return -EINVAL;
 294
 295                timeout = new_timeout;
 296                wdt_keepalive();
 297                /* Fall through */
 298        }
 299        case WDIOC_GETTIMEOUT:
 300                return put_user(timeout, p);
 301        default:
 302                return -ENOTTY;
 303        }
 304}
 305
 306static const struct file_operations wdt_fops = {
 307        .owner          = THIS_MODULE,
 308        .llseek         = no_llseek,
 309        .write          = fop_write,
 310        .open           = fop_open,
 311        .release        = fop_close,
 312        .unlocked_ioctl = fop_ioctl,
 313};
 314
 315static struct miscdevice wdt_miscdev = {
 316        .minor  = WATCHDOG_MINOR,
 317        .name   = "watchdog",
 318        .fops   = &wdt_fops,
 319};
 320
 321/*
 322 *      Notifier for system down
 323 */
 324
 325static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 326        void *unused)
 327{
 328        if (code == SYS_DOWN || code == SYS_HALT)
 329                wdt_turnoff();
 330        return NOTIFY_DONE;
 331}
 332
 333/*
 334 *      The WDT needs to learn about soft shutdowns in order to
 335 *      turn the timebomb registers off.
 336 */
 337
 338static struct notifier_block wdt_notifier = {
 339        .notifier_call = wdt_notify_sys,
 340};
 341
 342static void __exit w83877f_wdt_unload(void)
 343{
 344        wdt_turnoff();
 345
 346        /* Deregister */
 347        misc_deregister(&wdt_miscdev);
 348
 349        unregister_reboot_notifier(&wdt_notifier);
 350        release_region(WDT_PING, 1);
 351        release_region(ENABLE_W83877F_PORT, 2);
 352}
 353
 354static int __init w83877f_wdt_init(void)
 355{
 356        int rc = -EBUSY;
 357
 358        if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 359                timeout = WATCHDOG_TIMEOUT;
 360                printk(KERN_INFO PFX
 361                        "timeout value must be 1 <= x <= 3600, using %d\n",
 362                                                        timeout);
 363        }
 364
 365        if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
 366                printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 367                        ENABLE_W83877F_PORT);
 368                rc = -EIO;
 369                goto err_out;
 370        }
 371
 372        if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
 373                printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 374                        WDT_PING);
 375                rc = -EIO;
 376                goto err_out_region1;
 377        }
 378
 379        rc = register_reboot_notifier(&wdt_notifier);
 380        if (rc) {
 381                printk(KERN_ERR PFX
 382                        "cannot register reboot notifier (err=%d)\n", rc);
 383                goto err_out_region2;
 384        }
 385
 386        rc = misc_register(&wdt_miscdev);
 387        if (rc) {
 388                printk(KERN_ERR PFX
 389                        "cannot register miscdev on minor=%d (err=%d)\n",
 390                                                        wdt_miscdev.minor, rc);
 391                goto err_out_reboot;
 392        }
 393
 394        printk(KERN_INFO PFX
 395          "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 396                timeout, nowayout);
 397
 398        return 0;
 399
 400err_out_reboot:
 401        unregister_reboot_notifier(&wdt_notifier);
 402err_out_region2:
 403        release_region(WDT_PING, 1);
 404err_out_region1:
 405        release_region(ENABLE_W83877F_PORT, 2);
 406err_out:
 407        return rc;
 408}
 409
 410module_init(w83877f_wdt_init);
 411module_exit(w83877f_wdt_unload);
 412
 413MODULE_AUTHOR("Scott and Bill Jennings");
 414MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 415MODULE_LICENSE("GPL");
 416MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 417