release/src-rt-6.x.4708/linux/linux-2.6.36/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 #include <asm/system.h>
  67
  68 #define OUR_NAME "sbc60xxwdt"
  69 #define PFX OUR_NAME ": "
  70
  71 /*
  72  * You must set these - The driver cannot probe for the settings
  73  */
  74
  75 static int wdt_stop = 0x45;
  76 module_param(wdt_stop, int, 0);
  77 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  78
  79 static int wdt_start = 0x443;
  80 module_param(wdt_start, int, 0);
  81 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  82
  83 /*
  84  * The 60xx board can use watchdog timeout values from one second
  85  * to several minutes.  The default is one second, so if we reset
  86  * the watchdog every ~250ms we should be safe.
  87  */
  88
  89 #define WDT_INTERVAL (HZ/4+1)
  90
  91 /*
  92  * We must not require too good response from the userspace daemon.
  93  * Here we require the userspace daemon to send us a heartbeat
  94  * char to /dev/watchdog every 30 seconds.
  95  * If the daemon pulses us every 25 seconds, we can still afford
  96  * a 5 second scheduling delay on the (high priority) daemon. That
  97  * should be sufficient for a box under any load.
  98  */
  99
 100 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
 101 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
 102                                            get seconds to wait for a ping */
 103 module_param(timeout, int, 0);
 104 MODULE_PARM_DESC(timeout,
 105         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 106                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 107
 108 static int nowayout = WATCHDOG_NOWAYOUT;
 109 module_param(nowayout, int, 0);
 110 MODULE_PARM_DESC(nowayout,
 111         "Watchdog cannot be stopped once started (default="
 112                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 113
 114 static void wdt_timer_ping(unsigned long);
 115 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 116 static unsigned long next_heartbeat;
 117 static unsigned long wdt_is_open;
 118 static char wdt_expect_close;
 119
 120 /*
 121  *      Whack the dog
 122  */
 123
 124 static void wdt_timer_ping(unsigned long data)
 125 {
 126         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 127          * we agree to ping the WDT
 128          */
 129         if (time_before(jiffies, next_heartbeat)) {
 130                 /* Ping the WDT by reading from wdt_start */
 131                 inb_p(wdt_start);
 132                 /* Re-set the timer interval */
 133                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 134         } else
 135                 printk(KERN_WARNING PFX
 136                         "Heartbeat lost! Will not ping the watchdog\n");
 137 }
 138
 139 /*
 140  * Utility routines
 141  */
 142
 143 static void wdt_startup(void)
 144 {
 145         next_heartbeat = jiffies + (timeout * HZ);
 146
 147         /* Start the timer */
 148         mod_timer(&timer, jiffies + WDT_INTERVAL);
 149         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 150 }
 151
 152 static void wdt_turnoff(void)
 153 {
 154         /* Stop the timer */
 155         del_timer(&timer);
 156         inb_p(wdt_stop);
 157         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 158 }
 159
 160 static void wdt_keepalive(void)
 161 {
 162         /* user land ping */
 163         next_heartbeat = jiffies + (timeout * HZ);
 164 }
 165
 166 /*
 167  * /dev/watchdog handling
 168  */
 169
 170 static ssize_t fop_write(struct file *file, const char __user *buf,
 171                                                 size_t count, loff_t *ppos)
 172 {
 173         /* See if we got the magic character 'V' and reload the timer */
 174         if (count) {
 175                 if (!nowayout) {
 176                         size_t ofs;
 177
 178                         /* note: just in case someone wrote the
 179                            magic character five months ago... */
 180                         wdt_expect_close = 0;
 181
 182                         /* scan to see whether or not we got the
 183                            magic character */
 184                         for (ofs = 0; ofs != count; ofs++) {
 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
 194                    return that favour */
 195                 wdt_keepalive();
 196         }
 197         return count;
 198 }
 199
 200 static int fop_open(struct inode *inode, struct file *file)
 201 {
 202         /* Just in case we're already talking to someone... */
 203         if (test_and_set_bit(0, &wdt_is_open))
 204                 return -EBUSY;
 205
 206         if (nowayout)
 207                 __module_get(THIS_MODULE);
 208
 209         /* Good, fire up the show */
 210         wdt_startup();
 211         return nonseekable_open(inode, file);
 212 }
 213
 214 static int fop_close(struct inode *inode, struct file *file)
 215 {
 216         if (wdt_expect_close == 42)
 217                 wdt_turnoff();
 218         else {
 219                 del_timer(&timer);
 220                 printk(KERN_CRIT PFX
 221                   "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 long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 229 {
 230         void __user *argp = (void __user *)arg;
 231         int __user *p = argp;
 232         static const struct watchdog_info ident = {
 233                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 234                                                         WDIOF_MAGICCLOSE,
 235                 .firmware_version = 1,
 236                 .identity = "SBC60xx",
 237         };
 238
 239         switch (cmd) {
 240         case WDIOC_GETSUPPORT:
 241                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 242         case WDIOC_GETSTATUS:
 243         case WDIOC_GETBOOTSTATUS:
 244                 return put_user(0, p);
 245         case WDIOC_SETOPTIONS:
 246         {
 247                 int new_options, retval = -EINVAL;
 248                 if (get_user(new_options, p))
 249                         return -EFAULT;
 250                 if (new_options & WDIOS_DISABLECARD) {
 251                         wdt_turnoff();
 252                         retval = 0;
 253                 }
 254                 if (new_options & WDIOS_ENABLECARD) {
 255                         wdt_startup();
 256                         retval = 0;
 257                 }
 258                 return retval;
 259         }
 260         case WDIOC_KEEPALIVE:
 261                 wdt_keepalive();
 262                 return 0;
 263         case WDIOC_SETTIMEOUT:
 264         {
 265                 int new_timeout;
 266                 if (get_user(new_timeout, p))
 267                         return -EFAULT;
 268                 /* arbitrary upper limit */
 269                 if (new_timeout < 1 || new_timeout > 3600)
 270                         return -EINVAL;
 271
 272                 timeout = new_timeout;
 273                 wdt_keepalive();
 274                 /* Fall through */
 275         }
 276         case WDIOC_GETTIMEOUT:
 277                 return put_user(timeout, p);
 278         default:
 279                 return -ENOTTY;
 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         .unlocked_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         .notifier_call = wdt_notify_sys,
 317 };
 318
 319 static void __exit sbc60xxwdt_unload(void)
 320 {
 321         wdt_turnoff();
 322
 323         /* Deregister */
 324         misc_deregister(&wdt_miscdev);
 325
 326         unregister_reboot_notifier(&wdt_notifier);
 327         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 328                 release_region(wdt_stop, 1);
 329         release_region(wdt_start, 1);
 330 }
 331
 332 static int __init sbc60xxwdt_init(void)
 333 {
 334         int rc = -EBUSY;
 335
 336         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 337                 timeout = WATCHDOG_TIMEOUT;
 338                 printk(KERN_INFO PFX
 339                         "timeout value must be 1 <= x <= 3600, using %d\n",
 340                                                                 timeout);
 341         }
 342
 343         if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
 344                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 345                         wdt_start);
 346                 rc = -EIO;
 347                 goto err_out;
 348         }
 349
 350         /* We cannot reserve 0x45 - the kernel already has! */
 351         if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
 352                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
 353                         printk(KERN_ERR PFX
 354                                 "I/O address 0x%04x already in use\n",
 355                                                         wdt_stop);
 356                         rc = -EIO;
 357                         goto err_out_region1;
 358                 }
 359         }
 360
 361         rc = register_reboot_notifier(&wdt_notifier);
 362         if (rc) {
 363                 printk(KERN_ERR PFX
 364                         "cannot register reboot notifier (err=%d)\n", rc);
 365                 goto err_out_region2;
 366         }
 367
 368         rc = misc_register(&wdt_miscdev);
 369         if (rc) {
 370                 printk(KERN_ERR PFX
 371                         "cannot register miscdev on minor=%d (err=%d)\n",
 372                                                 wdt_miscdev.minor, rc);
 373                 goto err_out_reboot;
 374         }
 375         printk(KERN_INFO PFX
 376                 "WDT driver for 60XX single board computer initialised. "
 377                 "timeout=%d sec (nowayout=%d)\n", timeout, nowayout);
 378
 379         return 0;
 380
 381 err_out_reboot:
 382         unregister_reboot_notifier(&wdt_notifier);
 383 err_out_region2:
 384         if (wdt_stop != 0x45 && wdt_stop != wdt_start)
 385                 release_region(wdt_stop, 1);
 386 err_out_region1:
 387         release_region(wdt_start, 1);
 388 err_out:
 389         return rc;
 390 }
 391
 392 module_init(sbc60xxwdt_init);
 393 module_exit(sbc60xxwdt_unload);
 394
 395 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 396 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 397 MODULE_LICENSE("GPL");
 398 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);