drivers/watchdog/w83877f_wdt.c

   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 */
  87 static int timeout = WATCHDOG_TIMEOUT;
  88 module_param(timeout, int, 0);
  89 MODULE_PARM_DESC(timeout,
  90         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  91                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  92
  93
  94 static int nowayout = WATCHDOG_NOWAYOUT;
  95 module_param(nowayout, int, 0);
  96 MODULE_PARM_DESC(nowayout,
  97                 "Watchdog cannot be stopped once started (default="
  98                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  99
 100 static void wdt_timer_ping(unsigned long);
 101 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 102 static unsigned long next_heartbeat;
 103 static unsigned long wdt_is_open;
 104 static char wdt_expect_close;
 105 static DEFINE_SPINLOCK(wdt_spinlock);
 106
 107 /*
 108  *      Whack the dog
 109  */
 110
 111 static 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
 137 static 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
 159 static 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
 171 static 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
 181 static void wdt_keepalive(void)
 182 {
 183         /* user land ping */
 184         next_heartbeat = jiffies + (timeout * HZ);
 185 }
 186
 187 /*
 188  * /dev/watchdog handling
 189  */
 190
 191 static 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
 220 static 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
 231 static 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
 245 static 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
 306 static 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
 315 static 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
 325 static 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
 338 static struct notifier_block wdt_notifier = {
 339         .notifier_call = wdt_notify_sys,
 340 };
 341
 342 static 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
 354 static 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
 400 err_out_reboot:
 401         unregister_reboot_notifier(&wdt_notifier);
 402 err_out_region2:
 403         release_region(WDT_PING, 1);
 404 err_out_region1:
 405         release_region(ENABLE_W83877F_PORT, 2);
 406 err_out:
 407         return rc;
 408 }
 409
 410 module_init(w83877f_wdt_init);
 411 module_exit(w83877f_wdt_unload);
 412
 413 MODULE_AUTHOR("Scott and Bill Jennings");
 414 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 415 MODULE_LICENSE("GPL");
 416 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);