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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  52
  53 #include <linux/module.h>
  54 #include <linux/moduleparam.h>
  55 #include <linux/types.h>
  56 #include <linux/timer.h>
  57 #include <linux/jiffies.h>
  58 #include <linux/miscdevice.h>
  59 #include <linux/watchdog.h>
  60 #include <linux/fs.h>
  61 #include <linux/ioport.h>
  62 #include <linux/notifier.h>
  63 #include <linux/reboot.h>
  64 #include <linux/init.h>
  65 #include <linux/io.h>
  66 #include <linux/uaccess.h>
  67
  68 #include <asm/system.h>
  69
  70 #define OUR_NAME "sbc60xxwdt"
  71 #define PFX OUR_NAME ": "
  72
  73 /*
  74  * You must set these - The driver cannot probe for the settings
  75  */
  76
  77 static int wdt_stop = 0x45;
  78 module_param(wdt_stop, int, 0);
  79 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  80
  81 static int wdt_start = 0x443;
  82 module_param(wdt_start, int, 0);
  83 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  84
  85 /*
  86  * The 60xx board can use watchdog timeout values from one second
  87  * to several minutes.  The default is one second, so if we reset
  88  * the watchdog every ~250ms we should be safe.
  89  */
  90
  91 #define WDT_INTERVAL (HZ/4+1)
  92
  93 /*
  94  * We must not require too good response from the userspace daemon.
  95  * Here we require the userspace daemon to send us a heartbeat
  96  * char to /dev/watchdog every 30 seconds.
  97  * If the daemon pulses us every 25 seconds, we can still afford
  98  * a 5 second scheduling delay on the (high priority) daemon. That
  99  * should be sufficient for a box under any load.
 100  */
 101
 102 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
 103 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
 104                                            get seconds to wait for a ping */
 105 module_param(timeout, int, 0);
 106 MODULE_PARM_DESC(timeout,
 107         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 108                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 109
 110 static int nowayout = WATCHDOG_NOWAYOUT;
 111 module_param(nowayout, int, 0);
 112 MODULE_PARM_DESC(nowayout,
 113         "Watchdog cannot be stopped once started (default="
 114                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 115
 116 static void wdt_timer_ping(unsigned long);
 117 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 118 static unsigned long next_heartbeat;
 119 static unsigned long wdt_is_open;
 120 static char wdt_expect_close;
 121
 122 /*
 123  *      Whack the dog
 124  */
 125
 126 static void wdt_timer_ping(unsigned long data)
 127 {
 128         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 129          * we agree to ping the WDT
 130          */
 131         if (time_before(jiffies, next_heartbeat)) {
 132                 /* Ping the WDT by reading from wdt_start */
 133                 inb_p(wdt_start);
 134                 /* Re-set the timer interval */
 135                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 136         } else
 137                 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
 138 }
 139
 140 /*
 141  * Utility routines
 142  */
 143
 144 static void wdt_startup(void)
 145 {
 146         next_heartbeat = jiffies + (timeout * HZ);
 147
 148         /* Start the timer */
 149         mod_timer(&timer, jiffies + WDT_INTERVAL);
 150         pr_info("Watchdog timer is now enabled\n");
 151 }
 152
 153 static void wdt_turnoff(void)
 154 {
 155         /* Stop the timer */
 156         del_timer(&timer);
 157         inb_p(wdt_stop);
 158         pr_info("Watchdog timer is now disabled...\n");
 159 }
 160
 161 static void wdt_keepalive(void)
 162 {
 163         /* user land ping */
 164         next_heartbeat = jiffies + (timeout * HZ);
 165 }
 166
 167 /*
 168  * /dev/watchdog handling
 169  */
 170
 171 static ssize_t fop_write(struct file *file, const char __user *buf,
 172                                                 size_t count, loff_t *ppos)
 173 {
 174         /* See if we got the magic character 'V' and reload the timer */
 175         if (count) {
 176                 if (!nowayout) {
 177                         size_t ofs;
 178
 179                         /* note: just in case someone wrote the
 180                            magic character five months ago... */
 181                         wdt_expect_close = 0;
 182
 183                         /* scan to see whether or not we got the
 184                            magic character */
 185                         for (ofs = 0; ofs != count; ofs++) {
 186                                 char c;
 187                                 if (get_user(c, buf + ofs))
 188                                         return -EFAULT;
 189                                 if (c == 'V')
 190                                         wdt_expect_close = 42;
 191                         }
 192                 }
 193
 194                 /* Well, anyhow someone wrote to us, we should
 195                    return that favour */
 196                 wdt_keepalive();
 197         }
 198         return count;
 199 }
 200
 201 static int fop_open(struct inode *inode, struct file *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 nonseekable_open(inode, file);
 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                 pr_crit("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                 pr_info("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                 pr_err("I/O address 0x%04x already in use\n", wdt_start);
 344                 rc = -EIO;
 345                 goto err_out;
 346         }
 347
 348         /* We cannot reserve 0x45 - the kernel already has! */
 349         if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
 350                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
 351                         pr_err("I/O address 0x%04x already in use\n", wdt_stop);
 352                         rc = -EIO;
 353                         goto err_out_region1;
 354                 }
 355         }
 356
 357         rc = register_reboot_notifier(&wdt_notifier);
 358         if (rc) {
 359                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 360                 goto err_out_region2;
 361         }
 362
 363         rc = misc_register(&wdt_miscdev);
 364         if (rc) {
 365                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 366                        wdt_miscdev.minor, rc);
 367                 goto err_out_reboot;
 368         }
 369         pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 370                 timeout, nowayout);
 371
 372         return 0;
 373
 374 err_out_reboot:
 375         unregister_reboot_notifier(&wdt_notifier);
 376 err_out_region2:
 377         if (wdt_stop != 0x45 && wdt_stop != wdt_start)
 378                 release_region(wdt_stop, 1);
 379 err_out_region1:
 380         release_region(wdt_start, 1);
 381 err_out:
 382         return rc;
 383 }
 384
 385 module_init(sbc60xxwdt_init);
 386 module_exit(sbc60xxwdt_unload);
 387
 388 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 389 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 390 MODULE_LICENSE("GPL");
 391 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);