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=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  91
  92 static void wdt_timer_ping(unsigned long);
  93 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
  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                 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
 130 static 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
 152 static 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
 164 static 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
 174 static void wdt_keepalive(void)
 175 {
 176         /* user land ping */
 177         next_heartbeat = jiffies + (timeout * HZ);
 178 }
 179
 180 /*
 181  * /dev/watchdog handling
 182  */
 183
 184 static 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
 214 static 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
 225 static 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
 238 static 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
 300 static 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
 309 static 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
 319 static 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
 332 static struct notifier_block wdt_notifier=
 333 {
 334         .notifier_call = wdt_notify_sys,
 335 };
 336
 337 static 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
 349 static int __init w83877f_wdt_init(void)
 350 {
 351         int rc = -EBUSY;
 352
 353         spin_lock_init(&wdt_spinlock);
 354
 355         if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 356         {
 357                 timeout = WATCHDOG_TIMEOUT;
 358                 printk(KERN_INFO PFX "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         {
 364                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 365                         ENABLE_W83877F_PORT);
 366                 rc = -EIO;
 367                 goto err_out;
 368         }
 369
 370         if (!request_region(WDT_PING, 1, "W8387FF WDT"))
 371         {
 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 = misc_register(&wdt_miscdev);
 379         if (rc)
 380         {
 381                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 382                         wdt_miscdev.minor, rc);
 383                 goto err_out_region2;
 384         }
 385
 386         rc = register_reboot_notifier(&wdt_notifier);
 387         if (rc)
 388         {
 389                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 390                         rc);
 391                 goto err_out_miscdev;
 392         }
 393
 394         printk(KERN_INFO PFX "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 395                 timeout, nowayout);
 396
 397         return 0;
 398
 399 err_out_miscdev:
 400         misc_deregister(&wdt_miscdev);
 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);