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