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=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 104
 105 static void wdt_timer_ping(unsigned long);
 106 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 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                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 126         } else {
 127                 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
 128         }
 129 }
 130
 131 /*
 132  * Utility routines
 133  */
 134
 135 static void wdt_startup(void)
 136 {
 137         next_heartbeat = jiffies + (timeout * HZ);
 138
 139         /* Start the timer */
 140         mod_timer(&timer, jiffies + WDT_INTERVAL);
 141         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 142 }
 143
 144 static void wdt_turnoff(void)
 145 {
 146         /* Stop the timer */
 147         del_timer(&timer);
 148         inb_p(wdt_stop);
 149         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 150 }
 151
 152 static void wdt_keepalive(void)
 153 {
 154         /* user land ping */
 155         next_heartbeat = jiffies + (timeout * HZ);
 156 }
 157
 158 /*
 159  * /dev/watchdog handling
 160  */
 161
 162 static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
 163 {
 164         /* See if we got the magic character 'V' and reload the timer */
 165         if(count)
 166         {
 167                 if (!nowayout)
 168                 {
 169                         size_t ofs;
 170
 171                         /* note: just in case someone wrote the magic character
 172                          * five months ago... */
 173                         wdt_expect_close = 0;
 174
 175                         /* scan to see whether or not we got the magic character */
 176                         for(ofs = 0; ofs != count; ofs++)
 177                         {
 178                                 char c;
 179                                 if(get_user(c, buf+ofs))
 180                                         return -EFAULT;
 181                                 if(c == 'V')
 182                                         wdt_expect_close = 42;
 183                         }
 184                 }
 185
 186                 /* Well, anyhow someone wrote to us, we should return that favour */
 187                 wdt_keepalive();
 188         }
 189         return count;
 190 }
 191
 192 static int fop_open(struct inode * inode, struct file * file)
 193 {
 194         nonseekable_open(inode, file);
 195
 196         /* Just in case we're already talking to someone... */
 197         if(test_and_set_bit(0, &wdt_is_open))
 198                 return -EBUSY;
 199
 200         if (nowayout)
 201                 __module_get(THIS_MODULE);
 202
 203         /* Good, fire up the show */
 204         wdt_startup();
 205         return 0;
 206 }
 207
 208 static int fop_close(struct inode * inode, struct file * file)
 209 {
 210         if(wdt_expect_close == 42)
 211                 wdt_turnoff();
 212         else {
 213                 del_timer(&timer);
 214                 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 215         }
 216         clear_bit(0, &wdt_is_open);
 217         wdt_expect_close = 0;
 218         return 0;
 219 }
 220
 221 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 222         unsigned long arg)
 223 {
 224         void __user *argp = (void __user *)arg;
 225         int __user *p = argp;
 226         static struct watchdog_info ident=
 227         {
 228                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 229                 .firmware_version = 1,
 230                 .identity = "SBC60xx",
 231         };
 232
 233         switch(cmd)
 234         {
 235                 default:
 236                         return -ENOTTY;
 237                 case WDIOC_GETSUPPORT:
 238                         return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
 239                 case WDIOC_GETSTATUS:
 240                 case WDIOC_GETBOOTSTATUS:
 241                         return put_user(0, p);
 242                 case WDIOC_KEEPALIVE:
 243                         wdt_keepalive();
 244                         return 0;
 245                 case WDIOC_SETOPTIONS:
 246                 {
 247                         int new_options, retval = -EINVAL;
 248
 249                         if(get_user(new_options, p))
 250                                 return -EFAULT;
 251
 252                         if(new_options & WDIOS_DISABLECARD) {
 253                                 wdt_turnoff();
 254                                 retval = 0;
 255                         }
 256
 257                         if(new_options & WDIOS_ENABLECARD) {
 258                                 wdt_startup();
 259                                 retval = 0;
 260                         }
 261
 262                         return retval;
 263                 }
 264                 case WDIOC_SETTIMEOUT:
 265                 {
 266                         int new_timeout;
 267
 268                         if(get_user(new_timeout, p))
 269                                 return -EFAULT;
 270
 271                         if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 272                                 return -EINVAL;
 273
 274                         timeout = new_timeout;
 275                         wdt_keepalive();
 276                         /* Fall through */
 277                 }
 278                 case WDIOC_GETTIMEOUT:
 279                         return put_user(timeout, p);
 280         }
 281 }
 282
 283 static const struct file_operations wdt_fops = {
 284         .owner          = THIS_MODULE,
 285         .llseek         = no_llseek,
 286         .write          = fop_write,
 287         .open           = fop_open,
 288         .release        = fop_close,
 289         .ioctl          = fop_ioctl,
 290 };
 291
 292 static struct miscdevice wdt_miscdev = {
 293         .minor = WATCHDOG_MINOR,
 294         .name = "watchdog",
 295         .fops = &wdt_fops,
 296 };
 297
 298 /*
 299  *      Notifier for system down
 300  */
 301
 302 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 303         void *unused)
 304 {
 305         if(code==SYS_DOWN || code==SYS_HALT)
 306                 wdt_turnoff();
 307         return NOTIFY_DONE;
 308 }
 309
 310 /*
 311  *      The WDT needs to learn about soft shutdowns in order to
 312  *      turn the timebomb registers off.
 313  */
 314
 315 static struct notifier_block wdt_notifier=
 316 {
 317         .notifier_call = wdt_notify_sys,
 318 };
 319
 320 static void __exit sbc60xxwdt_unload(void)
 321 {
 322         wdt_turnoff();
 323
 324         /* Deregister */
 325         misc_deregister(&wdt_miscdev);
 326
 327         unregister_reboot_notifier(&wdt_notifier);
 328         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 329                 release_region(wdt_stop,1);
 330         release_region(wdt_start,1);
 331 }
 332
 333 static int __init sbc60xxwdt_init(void)
 334 {
 335         int rc = -EBUSY;
 336
 337         if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 338         {
 339                 timeout = WATCHDOG_TIMEOUT;
 340                 printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
 341                         timeout);
 342         }
 343
 344         if (!request_region(wdt_start, 1, "SBC 60XX WDT"))
 345         {
 346                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 347                         wdt_start);
 348                 rc = -EIO;
 349                 goto err_out;
 350         }
 351
 352         /* We cannot reserve 0x45 - the kernel already has! */
 353         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 354         {
 355                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT"))
 356                 {
 357                         printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 358                                 wdt_stop);
 359                         rc = -EIO;
 360                         goto err_out_region1;
 361                 }
 362         }
 363
 364         rc = misc_register(&wdt_miscdev);
 365         if (rc)
 366         {
 367                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 368                         wdt_miscdev.minor, rc);
 369                 goto err_out_region2;
 370         }
 371
 372         rc = register_reboot_notifier(&wdt_notifier);
 373         if (rc)
 374         {
 375                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 376                         rc);
 377                 goto err_out_miscdev;
 378         }
 379
 380         printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 381                 timeout, nowayout);
 382
 383         return 0;
 384
 385 err_out_miscdev:
 386         misc_deregister(&wdt_miscdev);
 387 err_out_region2:
 388         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 389                 release_region(wdt_stop,1);
 390 err_out_region1:
 391         release_region(wdt_start,1);
 392 err_out:
 393         return rc;
 394 }
 395
 396 module_init(sbc60xxwdt_init);
 397 module_exit(sbc60xxwdt_unload);
 398
 399 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 400 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 401 MODULE_LICENSE("GPL");
 402 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);