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 the driver offers
  27 *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT,
  28 *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
  29 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  30 *                            added extra printk's for startup problems
  31 *                            use module_param
  32 *                            made timeout (the emulated heartbeat) a module_param
  33 *                            made the keepalive ping an internal subroutine
  34 *
  35 *  This WDT driver is different from most other Linux WDT
  36 *  drivers in that the driver will ping the watchdog by itself,
  37 *  because this particular WDT has a very short timeout (1.6
  38 *  seconds) and it would be insane to count on any userspace
  39 *  daemon always getting scheduled within that time frame.
  40 */
  41
  42#include <linux/module.h>
  43#include <linux/moduleparam.h>
  44#include <linux/types.h>
  45#include <linux/timer.h>
  46#include <linux/jiffies.h>
  47#include <linux/miscdevice.h>
  48#include <linux/watchdog.h>
  49#include <linux/fs.h>
  50#include <linux/ioport.h>
  51#include <linux/notifier.h>
  52#include <linux/reboot.h>
  53#include <linux/init.h>
  54#include <asm/io.h>
  55#include <asm/uaccess.h>
  56#include <asm/system.h>
  57
  58#define OUR_NAME "w83877f_wdt"
  59#define PFX OUR_NAME ": "
  60
  61#define ENABLE_W83877F_PORT 0x3F0
  62#define ENABLE_W83877F 0x87
  63#define DISABLE_W83877F 0xAA
  64#define WDT_PING 0x443
  65#define WDT_REGISTER 0x14
  66#define WDT_ENABLE 0x9C
  67#define WDT_DISABLE 0x8C
  68
  69/*
  70 * The W83877F seems to be fixed at 1.6s timeout (at least on the
  71 * EMACS PC-104 board I'm using). If we reset the watchdog every
  72 * ~250ms we should be safe.  */
  73
  74#define WDT_INTERVAL (HZ/4+1)
  75
  76/*
  77 * We must not require too good response from the userspace daemon.
  78 * Here we require the userspace daemon to send us a heartbeat
  79 * char to /dev/watchdog every 30 seconds.
  80 */
  81
  82#define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  83static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  84module_param(timeout, int, 0);
  85MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  86
  87
  88static int nowayout = WATCHDOG_NOWAYOUT;
  89module_param(nowayout, int, 0);
  90MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  91
  92static void wdt_timer_ping(unsigned long);
  93static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
  94static unsigned long next_heartbeat;
  95static unsigned long wdt_is_open;
  96static char wdt_expect_close;
  97static DEFINE_SPINLOCK(wdt_spinlock);
  98
  99/*
 100 *      Whack the dog
 101 */
 102
 103static void wdt_timer_ping(unsigned long data)
 104{
 105        /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 106         * we agree to ping the WDT
 107         */
 108        if(time_before(jiffies, next_heartbeat))
 109        {
 110                /* Ping the WDT */
 111                spin_lock(&wdt_spinlock);
 112
 113                /* Ping the WDT by reading from WDT_PING */
 114                inb_p(WDT_PING);
 115
 116                /* Re-set the timer interval */
 117                mod_timer(&timer, jiffies + WDT_INTERVAL);
 118
 119                spin_unlock(&wdt_spinlock);
 120
 121        } else {
 122                printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
 123        }
 124}
 125
 126/*
 127 * Utility routines
 128 */
 129
 130static void wdt_change(int writeval)
 131{
 132        unsigned long flags;
 133        spin_lock_irqsave(&wdt_spinlock, flags);
 134
 135        /* buy some time */
 136        inb_p(WDT_PING);
 137
 138        /* make W83877F available */
 139        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 140        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 141
 142        /* enable watchdog */
 143        outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
 144        outb_p(writeval,        ENABLE_W83877F_PORT+1);
 145
 146        /* lock the W8387FF away */
 147        outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
 148
 149        spin_unlock_irqrestore(&wdt_spinlock, flags);
 150}
 151
 152static void wdt_startup(void)
 153{
 154        next_heartbeat = jiffies + (timeout * HZ);
 155
 156        /* Start the timer */
 157        mod_timer(&timer, jiffies + WDT_INTERVAL);
 158
 159        wdt_change(WDT_ENABLE);
 160
 161        printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 162}
 163
 164static void wdt_turnoff(void)
 165{
 166        /* Stop the timer */
 167        del_timer(&timer);
 168
 169        wdt_change(WDT_DISABLE);
 170
 171        printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 172}
 173
 174static void wdt_keepalive(void)
 175{
 176        /* user land ping */
 177        next_heartbeat = jiffies + (timeout * HZ);
 178}
 179
 180/*
 181 * /dev/watchdog handling
 182 */
 183
 184static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
 185{
 186        /* See if we got the magic character 'V' and reload the timer */
 187        if(count)
 188        {
 189                if (!nowayout)
 190                {
 191                        size_t ofs;
 192
 193                        /* note: just in case someone wrote the magic character
 194                         * five months ago... */
 195                        wdt_expect_close = 0;
 196
 197                        /* scan to see whether or not we got the magic character */
 198                        for(ofs = 0; ofs != count; ofs++)
 199                        {
 200                                char c;
 201                                if (get_user(c, buf + ofs))
 202                                        return -EFAULT;
 203                                if (c == 'V')
 204                                        wdt_expect_close = 42;
 205                        }
 206                }
 207
 208                /* someone wrote to us, we should restart timer */
 209                wdt_keepalive();
 210        }
 211        return count;
 212}
 213
 214static int fop_open(struct inode * inode, struct file * file)
 215{
 216        /* Just in case we're already talking to someone... */
 217        if(test_and_set_bit(0, &wdt_is_open))
 218                return -EBUSY;
 219
 220        /* Good, fire up the show */
 221        wdt_startup();
 222        return nonseekable_open(inode, file);
 223}
 224
 225static int fop_close(struct inode * inode, struct file * file)
 226{
 227        if(wdt_expect_close == 42)
 228                wdt_turnoff();
 229        else {
 230                del_timer(&timer);
 231                printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 232        }
 233        clear_bit(0, &wdt_is_open);
 234        wdt_expect_close = 0;
 235        return 0;
 236}
 237
 238static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 239        unsigned long arg)
 240{
 241        void __user *argp = (void __user *)arg;
 242        int __user *p = argp;
 243        static struct watchdog_info ident=
 244        {
 245                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 246                .firmware_version = 1,
 247                .identity = "W83877F",
 248        };
 249
 250        switch(cmd)
 251        {
 252                default:
 253                        return -ENOTTY;
 254                case WDIOC_GETSUPPORT:
 255                        return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
 256                case WDIOC_GETSTATUS:
 257                case WDIOC_GETBOOTSTATUS:
 258                        return put_user(0, p);
 259                case WDIOC_KEEPALIVE:
 260                        wdt_keepalive();
 261                        return 0;
 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_SETTIMEOUT:
 282                {
 283                        int new_timeout;
 284
 285                        if(get_user(new_timeout, p))
 286                                return -EFAULT;
 287
 288                        if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 289                                return -EINVAL;
 290
 291                        timeout = new_timeout;
 292                        wdt_keepalive();
 293                        /* Fall through */
 294                }
 295                case WDIOC_GETTIMEOUT:
 296                        return put_user(timeout, p);
 297        }
 298}
 299
 300static const struct file_operations wdt_fops = {
 301        .owner          = THIS_MODULE,
 302        .llseek         = no_llseek,
 303        .write          = fop_write,
 304        .open           = fop_open,
 305        .release        = fop_close,
 306        .ioctl          = fop_ioctl,
 307};
 308
 309static struct miscdevice wdt_miscdev = {
 310        .minor  = WATCHDOG_MINOR,
 311        .name   = "watchdog",
 312        .fops   = &wdt_fops,
 313};
 314
 315/*
 316 *      Notifier for system down
 317 */
 318
 319static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 320        void *unused)
 321{
 322        if(code==SYS_DOWN || code==SYS_HALT)
 323                wdt_turnoff();
 324        return NOTIFY_DONE;
 325}
 326
 327/*
 328 *      The WDT needs to learn about soft shutdowns in order to
 329 *      turn the timebomb registers off.
 330 */
 331
 332static struct notifier_block wdt_notifier=
 333{
 334        .notifier_call = wdt_notify_sys,
 335};
 336
 337static void __exit w83877f_wdt_unload(void)
 338{
 339        wdt_turnoff();
 340
 341        /* Deregister */
 342        misc_deregister(&wdt_miscdev);
 343
 344        unregister_reboot_notifier(&wdt_notifier);
 345        release_region(WDT_PING,1);
 346        release_region(ENABLE_W83877F_PORT,2);
 347}
 348
 349static int __init w83877f_wdt_init(void)
 350{
 351        int rc = -EBUSY;
 352
 353        if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 354        {
 355                timeout = WATCHDOG_TIMEOUT;
 356                printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
 357                        timeout);
 358        }
 359
 360        if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT"))
 361        {
 362                printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 363                        ENABLE_W83877F_PORT);
 364                rc = -EIO;
 365                goto err_out;
 366        }
 367
 368        if (!request_region(WDT_PING, 1, "W8387FF WDT"))
 369        {
 370                printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 371                        WDT_PING);
 372                rc = -EIO;
 373                goto err_out_region1;
 374        }
 375
 376        rc = misc_register(&wdt_miscdev);
 377        if (rc)
 378        {
 379                printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 380                        wdt_miscdev.minor, rc);
 381                goto err_out_region2;
 382        }
 383
 384        rc = register_reboot_notifier(&wdt_notifier);
 385        if (rc)
 386        {
 387                printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 388                        rc);
 389                goto err_out_miscdev;
 390        }
 391
 392        printk(KERN_INFO PFX "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 393                timeout, nowayout);
 394
 395        return 0;
 396
 397err_out_miscdev:
 398        misc_deregister(&wdt_miscdev);
 399err_out_region2:
 400        release_region(WDT_PING,1);
 401err_out_region1:
 402        release_region(ENABLE_W83877F_PORT,2);
 403err_out:
 404        return rc;
 405}
 406
 407module_init(w83877f_wdt_init);
 408module_exit(w83877f_wdt_unload);
 409
 410MODULE_AUTHOR("Scott and Bill Jennings");
 411MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 412MODULE_LICENSE("GPL");
 413MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 414