drivers/watchdog/sbc60xxwdt.c

   1 /*
   2  *      60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
   3  *
   4  *      Based on acquirewdt.c by Alan Cox.
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  *
  11  *      The author does NOT admit liability nor provide warranty for
  12  *      any of this software. This material is provided "AS-IS" in
  13  *      the hope that it may be useful for others.
  14  *
  15  *      (c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
  16  *
  17  *           12/4 - 2000      [Initial revision]
  18  *           25/4 - 2000      Added /dev/watchdog support
  19  *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1"
  20  *                                      on success
  21  *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
  22  *                            fix possible wdt_is_open race
  23  *                            add CONFIG_WATCHDOG_NOWAYOUT support
  24  *                            remove lock_kernel/unlock_kernel pairs
  25  *                            added KERN_* to printk's
  26  *                            got rid of extraneous comments
  27  *                            changed watchdog_info to correctly reflect what
  28  *                            the driver offers
  29  *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
  30  *                            WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
  31  *                            WDIOC_SETOPTIONS ioctls
  32  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  33  *                            use module_param
  34  *                            made timeout (the emulated heartbeat) a
  35  *                            module_param
  36  *                            made the keepalive ping an internal subroutine
  37  *                            made wdt_stop and wdt_start module params
  38  *                            added extra printk's for startup problems
  39  *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
  40  *
  41  *
  42  *  This WDT driver is different from the other Linux WDT
  43  *  drivers in the following ways:
  44  *  *)  The driver will ping the watchdog by itself, because this
  45  *      particular WDT has a very short timeout (one second) and it
  46  *      would be insane to count on any userspace daemon always
  47  *      getting scheduled within that time frame.
  48  *
  49  */
  50
  51 #include <linux/module.h>
  52 #include <linux/moduleparam.h>
  53 #include <linux/types.h>
  54 #include <linux/timer.h>
  55 #include <linux/jiffies.h>
  56 #include <linux/miscdevice.h>
  57 #include <linux/watchdog.h>
  58 #include <linux/fs.h>
  59 #include <linux/ioport.h>
  60 #include <linux/notifier.h>
  61 #include <linux/reboot.h>
  62 #include <linux/init.h>
  63 #include <linux/io.h>
  64 #include <linux/uaccess.h>
  65
  66
  67 #define OUR_NAME "sbc60xxwdt"
  68 #define PFX OUR_NAME ": "
  69
  70 /*
  71  * You must set these - The driver cannot probe for the settings
  72  */
  73
  74 static int wdt_stop = 0x45;
  75 module_param(wdt_stop, int, 0);
  76 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  77
  78 static int wdt_start = 0x443;
  79 module_param(wdt_start, int, 0);
  80 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  81
  82 /*
  83  * The 60xx board can use watchdog timeout values from one second
  84  * to several minutes.  The default is one second, so if we reset
  85  * the watchdog every ~250ms we should be safe.
  86  */
  87
  88 #define WDT_INTERVAL (HZ/4+1)
  89
  90 /*
  91  * We must not require too good response from the userspace daemon.
  92  * Here we require the userspace daemon to send us a heartbeat
  93  * char to /dev/watchdog every 30 seconds.
  94  * If the daemon pulses us every 25 seconds, we can still afford
  95  * a 5 second scheduling delay on the (high priority) daemon. That
  96  * should be sufficient for a box under any load.
  97  */
  98
  99 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
 100 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
 101                                            get seconds to wait for a ping */
 102 module_param(timeout, int, 0);
 103 MODULE_PARM_DESC(timeout,
 104         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 105                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 106
 107 static int nowayout = WATCHDOG_NOWAYOUT;
 108 module_param(nowayout, int, 0);
 109 MODULE_PARM_DESC(nowayout,
 110         "Watchdog cannot be stopped once started (default="
 111                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 112
 113 static void wdt_timer_ping(unsigned long);
 114 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 115 static unsigned long next_heartbeat;
 116 static unsigned long wdt_is_open;
 117 static char wdt_expect_close;
 118
 119 /*
 120  *      Whack the dog
 121  */
 122
 123 static void wdt_timer_ping(unsigned long data)
 124 {
 125         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 126          * we agree to ping the WDT
 127          */
 128         if (time_before(jiffies, next_heartbeat)) {
 129                 /* Ping the WDT by reading from wdt_start */
 130                 inb_p(wdt_start);
 131                 /* Re-set the timer interval */
 132                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 133         } else
 134                 printk(KERN_WARNING PFX
 135                         "Heartbeat lost! Will not ping the watchdog\n");
 136 }
 137
 138 /*
 139  * Utility routines
 140  */
 141
 142 static void wdt_startup(void)
 143 {
 144         next_heartbeat = jiffies + (timeout * HZ);
 145
 146         /* Start the timer */
 147         mod_timer(&timer, jiffies + WDT_INTERVAL);
 148         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 149 }
 150
 151 static void wdt_turnoff(void)
 152 {
 153         /* Stop the timer */
 154         del_timer(&timer);
 155         inb_p(wdt_stop);
 156         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 157 }
 158
 159 static void wdt_keepalive(void)
 160 {
 161         /* user land ping */
 162         next_heartbeat = jiffies + (timeout * HZ);
 163 }
 164
 165 /*
 166  * /dev/watchdog handling
 167  */
 168
 169 static ssize_t fop_write(struct file *file, const char __user *buf,
 170                                                 size_t count, loff_t *ppos)
 171 {
 172         /* See if we got the magic character 'V' and reload the timer */
 173         if (count) {
 174                 if (!nowayout) {
 175                         size_t ofs;
 176
 177                         /* note: just in case someone wrote the
 178                            magic character five months ago... */
 179                         wdt_expect_close = 0;
 180
 181                         /* scan to see whether or not we got the
 182                            magic character */
 183                         for (ofs = 0; ofs != count; ofs++) {
 184                                 char c;
 185                                 if (get_user(c, buf + ofs))
 186                                         return -EFAULT;
 187                                 if (c == 'V')
 188                                         wdt_expect_close = 42;
 189                         }
 190                 }
 191
 192                 /* Well, anyhow someone wrote to us, we should
 193                    return that favour */
 194                 wdt_keepalive();
 195         }
 196         return count;
 197 }
 198
 199 static int fop_open(struct inode *inode, struct file *file)
 200 {
 201         /* Just in case we're already talking to someone... */
 202         if (test_and_set_bit(0, &wdt_is_open))
 203                 return -EBUSY;
 204
 205         if (nowayout)
 206                 __module_get(THIS_MODULE);
 207
 208         /* Good, fire up the show */
 209         wdt_startup();
 210         return nonseekable_open(inode, file);
 211 }
 212
 213 static int fop_close(struct inode *inode, struct file *file)
 214 {
 215         if (wdt_expect_close == 42)
 216                 wdt_turnoff();
 217         else {
 218                 del_timer(&timer);
 219                 printk(KERN_CRIT PFX
 220                   "device file closed unexpectedly. Will not stop the WDT!\n");
 221         }
 222         clear_bit(0, &wdt_is_open);
 223         wdt_expect_close = 0;
 224         return 0;
 225 }
 226
 227 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 228 {
 229         void __user *argp = (void __user *)arg;
 230         int __user *p = argp;
 231         static const struct watchdog_info ident = {
 232                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 233                                                         WDIOF_MAGICCLOSE,
 234                 .firmware_version = 1,
 235                 .identity = "SBC60xx",
 236         };
 237
 238         switch (cmd) {
 239         case WDIOC_GETSUPPORT:
 240                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 241         case WDIOC_GETSTATUS:
 242         case WDIOC_GETBOOTSTATUS:
 243                 return put_user(0, p);
 244         case WDIOC_SETOPTIONS:
 245         {
 246                 int new_options, retval = -EINVAL;
 247                 if (get_user(new_options, p))
 248                         return -EFAULT;
 249                 if (new_options & WDIOS_DISABLECARD) {
 250                         wdt_turnoff();
 251                         retval = 0;
 252                 }
 253                 if (new_options & WDIOS_ENABLECARD) {
 254                         wdt_startup();
 255                         retval = 0;
 256                 }
 257                 return retval;
 258         }
 259         case WDIOC_KEEPALIVE:
 260                 wdt_keepalive();
 261                 return 0;
 262         case WDIOC_SETTIMEOUT:
 263         {
 264                 int new_timeout;
 265                 if (get_user(new_timeout, p))
 266                         return -EFAULT;
 267                 /* arbitrary upper limit */
 268                 if (new_timeout < 1 || new_timeout > 3600)
 269                         return -EINVAL;
 270
 271                 timeout = new_timeout;
 272                 wdt_keepalive();
 273                 /* Fall through */
 274         }
 275         case WDIOC_GETTIMEOUT:
 276                 return put_user(timeout, p);
 277         default:
 278                 return -ENOTTY;
 279         }
 280 }
 281
 282 static const struct file_operations wdt_fops = {
 283         .owner          = THIS_MODULE,
 284         .llseek         = no_llseek,
 285         .write          = fop_write,
 286         .open           = fop_open,
 287         .release        = fop_close,
 288         .unlocked_ioctl = fop_ioctl,
 289 };
 290
 291 static struct miscdevice wdt_miscdev = {
 292         .minor = WATCHDOG_MINOR,
 293         .name = "watchdog",
 294         .fops = &wdt_fops,
 295 };
 296
 297 /*
 298  *      Notifier for system down
 299  */
 300
 301 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 302         void *unused)
 303 {
 304         if (code == SYS_DOWN || code == SYS_HALT)
 305                 wdt_turnoff();
 306         return NOTIFY_DONE;
 307 }
 308
 309 /*
 310  *      The WDT needs to learn about soft shutdowns in order to
 311  *      turn the timebomb registers off.
 312  */
 313
 314 static struct notifier_block wdt_notifier = {
 315         .notifier_call = wdt_notify_sys,
 316 };
 317
 318 static void __exit sbc60xxwdt_unload(void)
 319 {
 320         wdt_turnoff();
 321
 322         /* Deregister */
 323         misc_deregister(&wdt_miscdev);
 324
 325         unregister_reboot_notifier(&wdt_notifier);
 326         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 327                 release_region(wdt_stop, 1);
 328         release_region(wdt_start, 1);
 329 }
 330
 331 static int __init sbc60xxwdt_init(void)
 332 {
 333         int rc = -EBUSY;
 334
 335         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 336                 timeout = WATCHDOG_TIMEOUT;
 337                 printk(KERN_INFO PFX
 338                         "timeout value must be 1 <= x <= 3600, using %d\n",
 339                                                                 timeout);
 340         }
 341
 342         if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
 343                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 344                         wdt_start);
 345                 rc = -EIO;
 346                 goto err_out;
 347         }
 348
 349         /* We cannot reserve 0x45 - the kernel already has! */
 350         if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
 351                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
 352                         printk(KERN_ERR PFX
 353                                 "I/O address 0x%04x already in use\n",
 354                                                         wdt_stop);
 355                         rc = -EIO;
 356                         goto err_out_region1;
 357                 }
 358         }
 359
 360         rc = register_reboot_notifier(&wdt_notifier);
 361         if (rc) {
 362                 printk(KERN_ERR PFX
 363                         "cannot register reboot notifier (err=%d)\n", rc);
 364                 goto err_out_region2;
 365         }
 366
 367         rc = misc_register(&wdt_miscdev);
 368         if (rc) {
 369                 printk(KERN_ERR PFX
 370                         "cannot register miscdev on minor=%d (err=%d)\n",
 371                                                 wdt_miscdev.minor, rc);
 372                 goto err_out_reboot;
 373         }
 374         printk(KERN_INFO PFX
 375                 "WDT driver for 60XX single board computer initialised. "
 376                 "timeout=%d sec (nowayout=%d)\n", timeout, nowayout);
 377
 378         return 0;
 379
 380 err_out_reboot:
 381         unregister_reboot_notifier(&wdt_notifier);
 382 err_out_region2:
 383         if (wdt_stop != 0x45 && wdt_stop != wdt_start)
 384                 release_region(wdt_stop, 1);
 385 err_out_region1:
 386         release_region(wdt_start, 1);
 387 err_out:
 388         return rc;
 389 }
 390
 391 module_init(sbc60xxwdt_init);
 392 module_exit(sbc60xxwdt_unload);
 393
 394 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 395 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 396 MODULE_LICENSE("GPL");
 397 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);