drivers/char/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 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 */
  83 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  84 module_param(timeout, int, 0);
  85 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  86
  87
  88 static int nowayout = WATCHDOG_NOWAYOUT;
  89 module_param(nowayout, int, 0);
  90 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  91
  92 static void wdt_timer_ping(unsigned long);
  93 static struct timer_list timer;
  94 static unsigned long next_heartbeat;
  95 static unsigned long wdt_is_open;
  96 static char wdt_expect_close;
  97 static spinlock_t wdt_spinlock;
  98
  99 /*
 100  *      Whack the dog
 101  */
 102
 103 static 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                 timer.expires = jiffies + WDT_INTERVAL;
 118                 add_timer(&timer);
 119
 120                 spin_unlock(&wdt_spinlock);
 121
 122         } else {
 123                 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
 124         }
 125 }
 126
 127 /*
 128  * Utility routines
 129  */
 130
 131 static void wdt_change(int writeval)
 132 {
 133         unsigned long flags;
 134         spin_lock_irqsave(&wdt_spinlock, flags);
 135
 136         /* buy some time */
 137         inb_p(WDT_PING);
 138
 139         /* make W83877F available */
 140         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 141         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 142
 143         /* enable watchdog */
 144         outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
 145         outb_p(writeval,        ENABLE_W83877F_PORT+1);
 146
 147         /* lock the W8387FF away */
 148         outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
 149
 150         spin_unlock_irqrestore(&wdt_spinlock, flags);
 151 }
 152
 153 static void wdt_startup(void)
 154 {
 155         next_heartbeat = jiffies + (timeout * HZ);
 156
 157         /* Start the timer */
 158         timer.expires = jiffies + WDT_INTERVAL;
 159         add_timer(&timer);
 160
 161         wdt_change(WDT_ENABLE);
 162
 163         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 164 }
 165
 166 static void wdt_turnoff(void)
 167 {
 168         /* Stop the timer */
 169         del_timer(&timer);
 170
 171         wdt_change(WDT_DISABLE);
 172
 173         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 174 }
 175
 176 static void wdt_keepalive(void)
 177 {
 178         /* user land ping */
 179         next_heartbeat = jiffies + (timeout * HZ);
 180 }
 181
 182 /*
 183  * /dev/watchdog handling
 184  */
 185
 186 static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
 187 {
 188         /* See if we got the magic character 'V' and reload the timer */
 189         if(count)
 190         {
 191                 if (!nowayout)
 192                 {
 193                         size_t ofs;
 194
 195                         /* note: just in case someone wrote the magic character
 196                          * five months ago... */
 197                         wdt_expect_close = 0;
 198
 199                         /* scan to see whether or not we got the magic character */
 200                         for(ofs = 0; ofs != count; ofs++)
 201                         {
 202                                 char c;
 203                                 if (get_user(c, buf + ofs))
 204                                         return -EFAULT;
 205                                 if (c == 'V')
 206                                         wdt_expect_close = 42;
 207                         }
 208                 }
 209
 210                 /* someone wrote to us, we should restart timer */
 211                 wdt_keepalive();
 212         }
 213         return count;
 214 }
 215
 216 static int fop_open(struct inode * inode, struct file * file)
 217 {
 218         /* Just in case we're already talking to someone... */
 219         if(test_and_set_bit(0, &wdt_is_open))
 220                 return -EBUSY;
 221
 222         /* Good, fire up the show */
 223         wdt_startup();
 224         return nonseekable_open(inode, file);
 225 }
 226
 227 static int fop_close(struct inode * inode, struct file * file)
 228 {
 229         if(wdt_expect_close == 42)
 230                 wdt_turnoff();
 231         else {
 232                 del_timer(&timer);
 233                 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 234         }
 235         clear_bit(0, &wdt_is_open);
 236         wdt_expect_close = 0;
 237         return 0;
 238 }
 239
 240 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 241         unsigned long arg)
 242 {
 243         void __user *argp = (void __user *)arg;
 244         int __user *p = argp;
 245         static struct watchdog_info ident=
 246         {
 247                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 248                 .firmware_version = 1,
 249                 .identity = "W83877F",
 250         };
 251
 252         switch(cmd)
 253         {
 254                 default:
 255                         return -ENOTTY;
 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_KEEPALIVE:
 262                         wdt_keepalive();
 263                         return 0;
 264                 case WDIOC_SETOPTIONS:
 265                 {
 266                         int new_options, retval = -EINVAL;
 267
 268                         if(get_user(new_options, p))
 269                                 return -EFAULT;
 270
 271                         if(new_options & WDIOS_DISABLECARD) {
 272                                 wdt_turnoff();
 273                                 retval = 0;
 274                         }
 275
 276                         if(new_options & WDIOS_ENABLECARD) {
 277                                 wdt_startup();
 278                                 retval = 0;
 279                         }
 280
 281                         return retval;
 282                 }
 283                 case WDIOC_SETTIMEOUT:
 284                 {
 285                         int new_timeout;
 286
 287                         if(get_user(new_timeout, p))
 288                                 return -EFAULT;
 289
 290                         if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 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         }
 300 }
 301
 302 static const struct file_operations wdt_fops = {
 303         .owner          = THIS_MODULE,
 304         .llseek         = no_llseek,
 305         .write          = fop_write,
 306         .open           = fop_open,
 307         .release        = fop_close,
 308         .ioctl          = fop_ioctl,
 309 };
 310
 311 static struct miscdevice wdt_miscdev = {
 312         .minor  = WATCHDOG_MINOR,
 313         .name   = "watchdog",
 314         .fops   = &wdt_fops,
 315 };
 316
 317 /*
 318  *      Notifier for system down
 319  */
 320
 321 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 322         void *unused)
 323 {
 324         if(code==SYS_DOWN || code==SYS_HALT)
 325                 wdt_turnoff();
 326         return NOTIFY_DONE;
 327 }
 328
 329 /*
 330  *      The WDT needs to learn about soft shutdowns in order to
 331  *      turn the timebomb registers off.
 332  */
 333
 334 static struct notifier_block wdt_notifier=
 335 {
 336         .notifier_call = wdt_notify_sys,
 337 };
 338
 339 static void __exit w83877f_wdt_unload(void)
 340 {
 341         wdt_turnoff();
 342
 343         /* Deregister */
 344         misc_deregister(&wdt_miscdev);
 345
 346         unregister_reboot_notifier(&wdt_notifier);
 347         release_region(WDT_PING,1);
 348         release_region(ENABLE_W83877F_PORT,2);
 349 }
 350
 351 static int __init w83877f_wdt_init(void)
 352 {
 353         int rc = -EBUSY;
 354
 355         spin_lock_init(&wdt_spinlock);
 356
 357         if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 358         {
 359                 timeout = WATCHDOG_TIMEOUT;
 360                 printk(KERN_INFO PFX "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         {
 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         {
 374                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 375                         WDT_PING);
 376                 rc = -EIO;
 377                 goto err_out_region1;
 378         }
 379
 380         init_timer(&timer);
 381         timer.function = wdt_timer_ping;
 382         timer.data = 0;
 383
 384         rc = misc_register(&wdt_miscdev);
 385         if (rc)
 386         {
 387                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 388                         wdt_miscdev.minor, rc);
 389                 goto err_out_region2;
 390         }
 391
 392         rc = register_reboot_notifier(&wdt_notifier);
 393         if (rc)
 394         {
 395                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 396                         rc);
 397                 goto err_out_miscdev;
 398         }
 399
 400         printk(KERN_INFO PFX "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 401                 timeout, nowayout);
 402
 403         return 0;
 404
 405 err_out_miscdev:
 406         misc_deregister(&wdt_miscdev);
 407 err_out_region2:
 408         release_region(WDT_PING,1);
 409 err_out_region1:
 410         release_region(ENABLE_W83877F_PORT,2);
 411 err_out:
 412         return rc;
 413 }
 414
 415 module_init(w83877f_wdt_init);
 416 module_exit(w83877f_wdt_unload);
 417
 418 MODULE_AUTHOR("Scott and Bill Jennings");
 419 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 420 MODULE_LICENSE("GPL");
 421 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);