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
  60 #define OUR_NAME "w83877f_wdt"
  61 #define PFX OUR_NAME ": "
  62
  63 #define ENABLE_W83877F_PORT 0x3F0
  64 #define ENABLE_W83877F 0x87
  65 #define DISABLE_W83877F 0xAA
  66 #define WDT_PING 0x443
  67 #define WDT_REGISTER 0x14
  68 #define WDT_ENABLE 0x9C
  69 #define WDT_DISABLE 0x8C
  70
  71 /*
  72  * The W83877F seems to be fixed at 1.6s timeout (at least on the
  73  * EMACS PC-104 board I'm using). If we reset the watchdog every
  74  * ~250ms we should be safe.  */
  75
  76 #define WDT_INTERVAL (HZ/4+1)
  77
  78 /*
  79  * We must not require too good response from the userspace daemon.
  80  * Here we require the userspace daemon to send us a heartbeat
  81  * char to /dev/watchdog every 30 seconds.
  82  */
  83
  84 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  85 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  86 static int timeout = WATCHDOG_TIMEOUT;
  87 module_param(timeout, int, 0);
  88 MODULE_PARM_DESC(timeout,
  89         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  90                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  91
  92
  93 static int nowayout = WATCHDOG_NOWAYOUT;
  94 module_param(nowayout, int, 0);
  95 MODULE_PARM_DESC(nowayout,
  96                 "Watchdog cannot be stopped once started (default="
  97                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  98
  99 static void wdt_timer_ping(unsigned long);
 100 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 101 static unsigned long next_heartbeat;
 102 static unsigned long wdt_is_open;
 103 static char wdt_expect_close;
 104 static DEFINE_SPINLOCK(wdt_spinlock);
 105
 106 /*
 107  *      Whack the dog
 108  */
 109
 110 static void wdt_timer_ping(unsigned long data)
 111 {
 112         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 113          * we agree to ping the WDT
 114          */
 115         if (time_before(jiffies, next_heartbeat)) {
 116                 /* Ping the WDT */
 117                 spin_lock(&wdt_spinlock);
 118
 119                 /* Ping the WDT by reading from WDT_PING */
 120                 inb_p(WDT_PING);
 121
 122                 /* Re-set the timer interval */
 123                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 124
 125                 spin_unlock(&wdt_spinlock);
 126
 127         } else
 128                 printk(KERN_WARNING PFX
 129                         "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         printk(KERN_INFO PFX "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         printk(KERN_INFO PFX "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                 printk(KERN_CRIT PFX
 237                   "device file closed unexpectedly. Will not stop the WDT!\n");
 238         }
 239         clear_bit(0, &wdt_is_open);
 240         wdt_expect_close = 0;
 241         return 0;
 242 }
 243
 244 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 245 {
 246         void __user *argp = (void __user *)arg;
 247         int __user *p = argp;
 248         static const struct watchdog_info ident = {
 249                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 250                                                         | WDIOF_MAGICCLOSE,
 251                 .firmware_version = 1,
 252                 .identity = "W83877F",
 253         };
 254
 255         switch (cmd) {
 256         case WDIOC_GETSUPPORT:
 257                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 258         case WDIOC_GETSTATUS:
 259         case WDIOC_GETBOOTSTATUS:
 260                 return put_user(0, p);
 261         case WDIOC_SETOPTIONS:
 262         {
 263                 int new_options, retval = -EINVAL;
 264
 265                 if (get_user(new_options, p))
 266                         return -EFAULT;
 267
 268                 if (new_options & WDIOS_DISABLECARD) {
 269                         wdt_turnoff();
 270                         retval = 0;
 271                 }
 272
 273                 if (new_options & WDIOS_ENABLECARD) {
 274                         wdt_startup();
 275                         retval = 0;
 276                 }
 277
 278                 return retval;
 279         }
 280         case WDIOC_KEEPALIVE:
 281                 wdt_keepalive();
 282                 return 0;
 283         case WDIOC_SETTIMEOUT:
 284         {
 285                 int new_timeout;
 286
 287                 if (get_user(new_timeout, p))
 288                         return -EFAULT;
 289
 290                 /* arbitrary upper limit */
 291                 if (new_timeout < 1 || new_timeout > 3600)
 292                         return -EINVAL;
 293
 294                 timeout = new_timeout;
 295                 wdt_keepalive();
 296                 /* Fall through */
 297         }
 298         case WDIOC_GETTIMEOUT:
 299                 return put_user(timeout, p);
 300         default:
 301                 return -ENOTTY;
 302         }
 303 }
 304
 305 static const struct file_operations wdt_fops = {
 306         .owner          = THIS_MODULE,
 307         .llseek         = no_llseek,
 308         .write          = fop_write,
 309         .open           = fop_open,
 310         .release        = fop_close,
 311         .unlocked_ioctl = fop_ioctl,
 312 };
 313
 314 static struct miscdevice wdt_miscdev = {
 315         .minor  = WATCHDOG_MINOR,
 316         .name   = "watchdog",
 317         .fops   = &wdt_fops,
 318 };
 319
 320 /*
 321  *      Notifier for system down
 322  */
 323
 324 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 325         void *unused)
 326 {
 327         if (code == SYS_DOWN || code == SYS_HALT)
 328                 wdt_turnoff();
 329         return NOTIFY_DONE;
 330 }
 331
 332 /*
 333  *      The WDT needs to learn about soft shutdowns in order to
 334  *      turn the timebomb registers off.
 335  */
 336
 337 static struct notifier_block wdt_notifier = {
 338         .notifier_call = wdt_notify_sys,
 339 };
 340
 341 static void __exit w83877f_wdt_unload(void)
 342 {
 343         wdt_turnoff();
 344
 345         /* Deregister */
 346         misc_deregister(&wdt_miscdev);
 347
 348         unregister_reboot_notifier(&wdt_notifier);
 349         release_region(WDT_PING, 1);
 350         release_region(ENABLE_W83877F_PORT, 2);
 351 }
 352
 353 static int __init w83877f_wdt_init(void)
 354 {
 355         int rc = -EBUSY;
 356
 357         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 358                 timeout = WATCHDOG_TIMEOUT;
 359                 printk(KERN_INFO PFX
 360                         "timeout value must be 1 <= x <= 3600, using %d\n",
 361                                                         timeout);
 362         }
 363
 364         if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
 365                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 366                         ENABLE_W83877F_PORT);
 367                 rc = -EIO;
 368                 goto err_out;
 369         }
 370
 371         if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
 372                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 373                         WDT_PING);
 374                 rc = -EIO;
 375                 goto err_out_region1;
 376         }
 377
 378         rc = register_reboot_notifier(&wdt_notifier);
 379         if (rc) {
 380                 printk(KERN_ERR PFX
 381                         "cannot register reboot notifier (err=%d)\n", rc);
 382                 goto err_out_region2;
 383         }
 384
 385         rc = misc_register(&wdt_miscdev);
 386         if (rc) {
 387                 printk(KERN_ERR PFX
 388                         "cannot register miscdev on minor=%d (err=%d)\n",
 389                                                         wdt_miscdev.minor, rc);
 390                 goto err_out_reboot;
 391         }
 392
 393         printk(KERN_INFO PFX
 394           "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 395                 timeout, nowayout);
 396
 397         return 0;
 398
 399 err_out_reboot:
 400         unregister_reboot_notifier(&wdt_notifier);
 401 err_out_region2:
 402         release_region(WDT_PING, 1);
 403 err_out_region1:
 404         release_region(ENABLE_W83877F_PORT, 2);
 405 err_out:
 406         return rc;
 407 }
 408
 409 module_init(w83877f_wdt_init);
 410 module_exit(w83877f_wdt_unload);
 411
 412 MODULE_AUTHOR("Scott and Bill Jennings");
 413 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 414 MODULE_LICENSE("GPL");
 415 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);