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 #include <asm/system.h>
  62
  63 #define OUR_NAME "w83877f_wdt"
  64
  65 #define ENABLE_W83877F_PORT 0x3F0
  66 #define ENABLE_W83877F 0x87
  67 #define DISABLE_W83877F 0xAA
  68 #define WDT_PING 0x443
  69 #define WDT_REGISTER 0x14
  70 #define WDT_ENABLE 0x9C
  71 #define WDT_DISABLE 0x8C
  72
  73 /*
  74  * The W83877F seems to be fixed at 1.6s timeout (at least on the
  75  * EMACS PC-104 board I'm using). If we reset the watchdog every
  76  * ~250ms we should be safe.  */
  77
  78 #define WDT_INTERVAL (HZ/4+1)
  79
  80 /*
  81  * We must not require too good response from the userspace daemon.
  82  * Here we require the userspace daemon to send us a heartbeat
  83  * char to /dev/watchdog every 30 seconds.
  84  */
  85
  86 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  87 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  88 static int timeout = WATCHDOG_TIMEOUT;
  89 module_param(timeout, int, 0);
  90 MODULE_PARM_DESC(timeout,
  91         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  92                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  93
  94
  95 static int nowayout = WATCHDOG_NOWAYOUT;
  96 module_param(nowayout, int, 0);
  97 MODULE_PARM_DESC(nowayout,
  98                 "Watchdog cannot be stopped once started (default="
  99                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 100
 101 static void wdt_timer_ping(unsigned long);
 102 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 103 static unsigned long next_heartbeat;
 104 static unsigned long wdt_is_open;
 105 static char wdt_expect_close;
 106 static DEFINE_SPINLOCK(wdt_spinlock);
 107
 108 /*
 109  *      Whack the dog
 110  */
 111
 112 static void wdt_timer_ping(unsigned long data)
 113 {
 114         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 115          * we agree to ping the WDT
 116          */
 117         if (time_before(jiffies, next_heartbeat)) {
 118                 /* Ping the WDT */
 119                 spin_lock(&wdt_spinlock);
 120
 121                 /* Ping the WDT by reading from WDT_PING */
 122                 inb_p(WDT_PING);
 123
 124                 /* Re-set the timer interval */
 125                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 126
 127                 spin_unlock(&wdt_spinlock);
 128
 129         } else
 130                 pr_warn("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         pr_info("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         pr_info("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                 pr_crit("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                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 360                         timeout);
 361         }
 362
 363         if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
 364                 pr_err("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                 pr_err("I/O address 0x%04x already in use\n", WDT_PING);
 372                 rc = -EIO;
 373                 goto err_out_region1;
 374         }
 375
 376         rc = register_reboot_notifier(&wdt_notifier);
 377         if (rc) {
 378                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 379                 goto err_out_region2;
 380         }
 381
 382         rc = misc_register(&wdt_miscdev);
 383         if (rc) {
 384                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 385                        wdt_miscdev.minor, rc);
 386                 goto err_out_reboot;
 387         }
 388
 389         pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 390                 timeout, nowayout);
 391
 392         return 0;
 393
 394 err_out_reboot:
 395         unregister_reboot_notifier(&wdt_notifier);
 396 err_out_region2:
 397         release_region(WDT_PING, 1);
 398 err_out_region1:
 399         release_region(ENABLE_W83877F_PORT, 2);
 400 err_out:
 401         return rc;
 402 }
 403
 404 module_init(w83877f_wdt_init);
 405 module_exit(w83877f_wdt_unload);
 406
 407 MODULE_AUTHOR("Scott and Bill Jennings");
 408 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 409 MODULE_LICENSE("GPL");
 410 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);