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 #ifdef CONFIG_WATCHDOG_NOWAYOUT
 102 static int nowayout = 1;
 103 #else
 104 static int nowayout = 0;
 105 #endif
 106
 107 module_param(nowayout, int, 0);
 108 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
 109
 110 static void wdt_timer_ping(unsigned long);
 111 static struct timer_list timer;
 112 static unsigned long next_heartbeat;
 113 static unsigned long wdt_is_open;
 114 static char wdt_expect_close;
 115
 116 /*
 117  *      Whack the dog
 118  */
 119
 120 static void wdt_timer_ping(unsigned long data)
 121 {
 122         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 123          * we agree to ping the WDT
 124          */
 125         if(time_before(jiffies, next_heartbeat))
 126         {
 127                 /* Ping the WDT by reading from wdt_start */
 128                 inb_p(wdt_start);
 129                 /* Re-set the timer interval */
 130                 timer.expires = jiffies + WDT_INTERVAL;
 131                 add_timer(&timer);
 132         } else {
 133                 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
 134         }
 135 }
 136
 137 /*
 138  * Utility routines
 139  */
 140
 141 static void wdt_startup(void)
 142 {
 143         next_heartbeat = jiffies + (timeout * HZ);
 144
 145         /* Start the timer */
 146         timer.expires = jiffies + WDT_INTERVAL;
 147         add_timer(&timer);
 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, size_t count, loff_t * ppos)
 170 {
 171         /* See if we got the magic character 'V' and reload the timer */
 172         if(count)
 173         {
 174                 if (!nowayout)
 175                 {
 176                         size_t ofs;
 177
 178                         /* note: just in case someone wrote the magic character
 179                          * five months ago... */
 180                         wdt_expect_close = 0;
 181
 182                         /* scan to see whether or not we got the magic character */
 183                         for(ofs = 0; ofs != count; ofs++)
 184                         {
 185                                 char c;
 186                                 if(get_user(c, buf+ofs))
 187                                         return -EFAULT;
 188                                 if(c == 'V')
 189                                         wdt_expect_close = 42;
 190                         }
 191                 }
 192
 193                 /* Well, anyhow someone wrote to us, we should 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         nonseekable_open(inode, file);
 202
 203         /* Just in case we're already talking to someone... */
 204         if(test_and_set_bit(0, &wdt_is_open))
 205                 return -EBUSY;
 206
 207         if (nowayout)
 208                 __module_get(THIS_MODULE);
 209
 210         /* Good, fire up the show */
 211         wdt_startup();
 212         return 0;
 213 }
 214
 215 static int fop_close(struct inode * inode, struct file * file)
 216 {
 217         if(wdt_expect_close == 42)
 218                 wdt_turnoff();
 219         else {
 220                 del_timer(&timer);
 221                 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 222         }
 223         clear_bit(0, &wdt_is_open);
 224         wdt_expect_close = 0;
 225         return 0;
 226 }
 227
 228 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 229         unsigned long arg)
 230 {
 231         void __user *argp = (void __user *)arg;
 232         int __user *p = argp;
 233         static struct watchdog_info ident=
 234         {
 235                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 236                 .firmware_version = 1,
 237                 .identity = "SBC60xx",
 238         };
 239
 240         switch(cmd)
 241         {
 242                 default:
 243                         return -ENOIOCTLCMD;
 244                 case WDIOC_GETSUPPORT:
 245                         return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
 246                 case WDIOC_GETSTATUS:
 247                 case WDIOC_GETBOOTSTATUS:
 248                         return put_user(0, p);
 249                 case WDIOC_KEEPALIVE:
 250                         wdt_keepalive();
 251                         return 0;
 252                 case WDIOC_SETOPTIONS:
 253                 {
 254                         int new_options, retval = -EINVAL;
 255
 256                         if(get_user(new_options, p))
 257                                 return -EFAULT;
 258
 259                         if(new_options & WDIOS_DISABLECARD) {
 260                                 wdt_turnoff();
 261                                 retval = 0;
 262                         }
 263
 264                         if(new_options & WDIOS_ENABLECARD) {
 265                                 wdt_startup();
 266                                 retval = 0;
 267                         }
 268
 269                         return retval;
 270                 }
 271                 case WDIOC_SETTIMEOUT:
 272                 {
 273                         int new_timeout;
 274
 275                         if(get_user(new_timeout, p))
 276                                 return -EFAULT;
 277
 278                         if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 279                                 return -EINVAL;
 280
 281                         timeout = new_timeout;
 282                         wdt_keepalive();
 283                         /* Fall through */
 284                 }
 285                 case WDIOC_GETTIMEOUT:
 286                         return put_user(timeout, p);
 287         }
 288 }
 289
 290 static struct file_operations wdt_fops = {
 291         .owner          = THIS_MODULE,
 292         .llseek         = no_llseek,
 293         .write          = fop_write,
 294         .open           = fop_open,
 295         .release        = fop_close,
 296         .ioctl          = fop_ioctl,
 297 };
 298
 299 static struct miscdevice wdt_miscdev = {
 300         .minor = WATCHDOG_MINOR,
 301         .name = "watchdog",
 302         .fops = &wdt_fops,
 303 };
 304
 305 /*
 306  *      Notifier for system down
 307  */
 308
 309 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 310         void *unused)
 311 {
 312         if(code==SYS_DOWN || code==SYS_HALT)
 313                 wdt_turnoff();
 314         return NOTIFY_DONE;
 315 }
 316
 317 /*
 318  *      The WDT needs to learn about soft shutdowns in order to
 319  *      turn the timebomb registers off.
 320  */
 321
 322 static struct notifier_block wdt_notifier=
 323 {
 324         .notifier_call = wdt_notify_sys,
 325 };
 326
 327 static void __exit sbc60xxwdt_unload(void)
 328 {
 329         wdt_turnoff();
 330
 331         /* Deregister */
 332         misc_deregister(&wdt_miscdev);
 333
 334         unregister_reboot_notifier(&wdt_notifier);
 335         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 336                 release_region(wdt_stop,1);
 337         release_region(wdt_start,1);
 338 }
 339
 340 static int __init sbc60xxwdt_init(void)
 341 {
 342         int rc = -EBUSY;
 343
 344         if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 345         {
 346                 timeout = WATCHDOG_TIMEOUT;
 347                 printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
 348                         timeout);
 349         }
 350
 351         if (!request_region(wdt_start, 1, "SBC 60XX WDT"))
 352         {
 353                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 354                         wdt_start);
 355                 rc = -EIO;
 356                 goto err_out;
 357         }
 358
 359         /* We cannot reserve 0x45 - the kernel already has! */
 360         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 361         {
 362                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT"))
 363                 {
 364                         printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 365                                 wdt_stop);
 366                         rc = -EIO;
 367                         goto err_out_region1;
 368                 }
 369         }
 370
 371         init_timer(&timer);
 372         timer.function = wdt_timer_ping;
 373         timer.data = 0;
 374
 375         rc = misc_register(&wdt_miscdev);
 376         if (rc)
 377         {
 378                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 379                         wdt_miscdev.minor, rc);
 380                 goto err_out_region2;
 381         }
 382
 383         rc = register_reboot_notifier(&wdt_notifier);
 384         if (rc)
 385         {
 386                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 387                         rc);
 388                 goto err_out_miscdev;
 389         }
 390
 391         printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 392                 timeout, nowayout);
 393
 394         return 0;
 395
 396 err_out_miscdev:
 397         misc_deregister(&wdt_miscdev);
 398 err_out_region2:
 399         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 400                 release_region(wdt_stop,1);
 401 err_out_region1:
 402         release_region(wdt_start,1);
 403 err_out:
 404         return rc;
 405 }
 406
 407 module_init(sbc60xxwdt_init);
 408 module_exit(sbc60xxwdt_unload);
 409
 410 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 411 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 412 MODULE_LICENSE("GPL");
 413 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);