drivers/char/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" on success
  20  *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
  21  *                            fix possible wdt_is_open race
  22  *                            add CONFIG_WATCHDOG_NOWAYOUT support
  23  *                            remove lock_kernel/unlock_kernel pairs
  24  *                            added KERN_* to printk's
  25  *                            got rid of extraneous comments
  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  *                            use module_param
  31  *                            made timeout (the emulated heartbeat) a module_param
  32  *                            made the keepalive ping an internal subroutine
  33  *                            made wdt_stop and wdt_start module params
  34  *                            added extra printk's for startup problems
  35  *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
  36  *
  37  *
  38  *  This WDT driver is different from the other Linux WDT
  39  *  drivers in the following ways:
  40  *  *)  The driver will ping the watchdog by itself, because this
  41  *      particular WDT has a very short timeout (one second) and it
  42  *      would be insane to count on any userspace daemon always
  43  *      getting scheduled within that time frame.
  44  *
  45  */
  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
  60 #include <asm/io.h>
  61 #include <asm/uaccess.h>
  62 #include <asm/system.h>
  63
  64 #define OUR_NAME "sbc60xxwdt"
  65 #define PFX OUR_NAME ": "
  66
  67 /*
  68  * You must set these - The driver cannot probe for the settings
  69  */
  70
  71 static int wdt_stop = 0x45;
  72 module_param(wdt_stop, int, 0);
  73 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  74
  75 static int wdt_start = 0x443;
  76 module_param(wdt_start, int, 0);
  77 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  78
  79 /*
  80  * The 60xx board can use watchdog timeout values from one second
  81  * to several minutes.  The default is one second, so if we reset
  82  * the watchdog every ~250ms we should be safe.
  83  */
  84
  85 #define WDT_INTERVAL (HZ/4+1)
  86
  87 /*
  88  * We must not require too good response from the userspace daemon.
  89  * Here we require the userspace daemon to send us a heartbeat
  90  * char to /dev/watchdog every 30 seconds.
  91  * If the daemon pulses us every 25 seconds, we can still afford
  92  * a 5 second scheduling delay on the (high priority) daemon. That
  93  * should be sufficient for a box under any load.
  94  */
  95
  96 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
  97 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  98 module_param(timeout, int, 0);
  99 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 100
 101 static int nowayout = WATCHDOG_NOWAYOUT;
 102 module_param(nowayout, int, 0);
 103 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
 104
 105 static void wdt_timer_ping(unsigned long);
 106 static struct timer_list timer;
 107 static unsigned long next_heartbeat;
 108 static unsigned long wdt_is_open;
 109 static char wdt_expect_close;
 110
 111 /*
 112  *      Whack the dog
 113  */
 114
 115 static void wdt_timer_ping(unsigned long data)
 116 {
 117         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 118          * we agree to ping the WDT
 119          */
 120         if(time_before(jiffies, next_heartbeat))
 121         {
 122                 /* Ping the WDT by reading from wdt_start */
 123                 inb_p(wdt_start);
 124                 /* Re-set the timer interval */
 125                 timer.expires = jiffies + WDT_INTERVAL;
 126                 add_timer(&timer);
 127         } else {
 128                 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
 129         }
 130 }
 131
 132 /*
 133  * Utility routines
 134  */
 135
 136 static void wdt_startup(void)
 137 {
 138         next_heartbeat = jiffies + (timeout * HZ);
 139
 140         /* Start the timer */
 141         timer.expires = jiffies + WDT_INTERVAL;
 142         add_timer(&timer);
 143         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 144 }
 145
 146 static void wdt_turnoff(void)
 147 {
 148         /* Stop the timer */
 149         del_timer(&timer);
 150         inb_p(wdt_stop);
 151         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 152 }
 153
 154 static void wdt_keepalive(void)
 155 {
 156         /* user land ping */
 157         next_heartbeat = jiffies + (timeout * HZ);
 158 }
 159
 160 /*
 161  * /dev/watchdog handling
 162  */
 163
 164 static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
 165 {
 166         /* See if we got the magic character 'V' and reload the timer */
 167         if(count)
 168         {
 169                 if (!nowayout)
 170                 {
 171                         size_t ofs;
 172
 173                         /* note: just in case someone wrote the magic character
 174                          * five months ago... */
 175                         wdt_expect_close = 0;
 176
 177                         /* scan to see whether or not we got the magic character */
 178                         for(ofs = 0; ofs != count; ofs++)
 179                         {
 180                                 char c;
 181                                 if(get_user(c, buf+ofs))
 182                                         return -EFAULT;
 183                                 if(c == 'V')
 184                                         wdt_expect_close = 42;
 185                         }
 186                 }
 187
 188                 /* Well, anyhow someone wrote to us, we should return that favour */
 189                 wdt_keepalive();
 190         }
 191         return count;
 192 }
 193
 194 static int fop_open(struct inode * inode, struct file * file)
 195 {
 196         nonseekable_open(inode, file);
 197
 198         /* Just in case we're already talking to someone... */
 199         if(test_and_set_bit(0, &wdt_is_open))
 200                 return -EBUSY;
 201
 202         if (nowayout)
 203                 __module_get(THIS_MODULE);
 204
 205         /* Good, fire up the show */
 206         wdt_startup();
 207         return 0;
 208 }
 209
 210 static int fop_close(struct inode * inode, struct file * file)
 211 {
 212         if(wdt_expect_close == 42)
 213                 wdt_turnoff();
 214         else {
 215                 del_timer(&timer);
 216                 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 217         }
 218         clear_bit(0, &wdt_is_open);
 219         wdt_expect_close = 0;
 220         return 0;
 221 }
 222
 223 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 224         unsigned long arg)
 225 {
 226         void __user *argp = (void __user *)arg;
 227         int __user *p = argp;
 228         static struct watchdog_info ident=
 229         {
 230                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 231                 .firmware_version = 1,
 232                 .identity = "SBC60xx",
 233         };
 234
 235         switch(cmd)
 236         {
 237                 default:
 238                         return -ENOTTY;
 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_KEEPALIVE:
 245                         wdt_keepalive();
 246                         return 0;
 247                 case WDIOC_SETOPTIONS:
 248                 {
 249                         int new_options, retval = -EINVAL;
 250
 251                         if(get_user(new_options, p))
 252                                 return -EFAULT;
 253
 254                         if(new_options & WDIOS_DISABLECARD) {
 255                                 wdt_turnoff();
 256                                 retval = 0;
 257                         }
 258
 259                         if(new_options & WDIOS_ENABLECARD) {
 260                                 wdt_startup();
 261                                 retval = 0;
 262                         }
 263
 264                         return retval;
 265                 }
 266                 case WDIOC_SETTIMEOUT:
 267                 {
 268                         int new_timeout;
 269
 270                         if(get_user(new_timeout, p))
 271                                 return -EFAULT;
 272
 273                         if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 274                                 return -EINVAL;
 275
 276                         timeout = new_timeout;
 277                         wdt_keepalive();
 278                         /* Fall through */
 279                 }
 280                 case WDIOC_GETTIMEOUT:
 281                         return put_user(timeout, p);
 282         }
 283 }
 284
 285 static const struct file_operations wdt_fops = {
 286         .owner          = THIS_MODULE,
 287         .llseek         = no_llseek,
 288         .write          = fop_write,
 289         .open           = fop_open,
 290         .release        = fop_close,
 291         .ioctl          = fop_ioctl,
 292 };
 293
 294 static struct miscdevice wdt_miscdev = {
 295         .minor = WATCHDOG_MINOR,
 296         .name = "watchdog",
 297         .fops = &wdt_fops,
 298 };
 299
 300 /*
 301  *      Notifier for system down
 302  */
 303
 304 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 305         void *unused)
 306 {
 307         if(code==SYS_DOWN || code==SYS_HALT)
 308                 wdt_turnoff();
 309         return NOTIFY_DONE;
 310 }
 311
 312 /*
 313  *      The WDT needs to learn about soft shutdowns in order to
 314  *      turn the timebomb registers off.
 315  */
 316
 317 static struct notifier_block wdt_notifier=
 318 {
 319         .notifier_call = wdt_notify_sys,
 320 };
 321
 322 static void __exit sbc60xxwdt_unload(void)
 323 {
 324         wdt_turnoff();
 325
 326         /* Deregister */
 327         misc_deregister(&wdt_miscdev);
 328
 329         unregister_reboot_notifier(&wdt_notifier);
 330         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 331                 release_region(wdt_stop,1);
 332         release_region(wdt_start,1);
 333 }
 334
 335 static int __init sbc60xxwdt_init(void)
 336 {
 337         int rc = -EBUSY;
 338
 339         if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 340         {
 341                 timeout = WATCHDOG_TIMEOUT;
 342                 printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
 343                         timeout);
 344         }
 345
 346         if (!request_region(wdt_start, 1, "SBC 60XX WDT"))
 347         {
 348                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 349                         wdt_start);
 350                 rc = -EIO;
 351                 goto err_out;
 352         }
 353
 354         /* We cannot reserve 0x45 - the kernel already has! */
 355         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 356         {
 357                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT"))
 358                 {
 359                         printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 360                                 wdt_stop);
 361                         rc = -EIO;
 362                         goto err_out_region1;
 363                 }
 364         }
 365
 366         init_timer(&timer);
 367         timer.function = wdt_timer_ping;
 368         timer.data = 0;
 369
 370         rc = misc_register(&wdt_miscdev);
 371         if (rc)
 372         {
 373                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 374                         wdt_miscdev.minor, rc);
 375                 goto err_out_region2;
 376         }
 377
 378         rc = register_reboot_notifier(&wdt_notifier);
 379         if (rc)
 380         {
 381                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 382                         rc);
 383                 goto err_out_miscdev;
 384         }
 385
 386         printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 387                 timeout, nowayout);
 388
 389         return 0;
 390
 391 err_out_miscdev:
 392         misc_deregister(&wdt_miscdev);
 393 err_out_region2:
 394         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 395                 release_region(wdt_stop,1);
 396 err_out_region1:
 397         release_region(wdt_start,1);
 398 err_out:
 399         return rc;
 400 }
 401
 402 module_init(sbc60xxwdt_init);
 403 module_exit(sbc60xxwdt_unload);
 404
 405 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 406 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 407 MODULE_LICENSE("GPL");
 408 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);