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
  69 #define OUR_NAME "sbc60xxwdt"
  70 #define PFX OUR_NAME ": "
  71
  72 /*
  73  * You must set these - The driver cannot probe for the settings
  74  */
  75
  76 static int wdt_stop = 0x45;
  77 module_param(wdt_stop, int, 0);
  78 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  79
  80 static int wdt_start = 0x443;
  81 module_param(wdt_start, int, 0);
  82 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  83
  84 /*
  85  * The 60xx board can use watchdog timeout values from one second
  86  * to several minutes.  The default is one second, so if we reset
  87  * the watchdog every ~250ms we should be safe.
  88  */
  89
  90 #define WDT_INTERVAL (HZ/4+1)
  91
  92 /*
  93  * We must not require too good response from the userspace daemon.
  94  * Here we require the userspace daemon to send us a heartbeat
  95  * char to /dev/watchdog every 30 seconds.
  96  * If the daemon pulses us every 25 seconds, we can still afford
  97  * a 5 second scheduling delay on the (high priority) daemon. That
  98  * should be sufficient for a box under any load.
  99  */
 100
 101 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
 102 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
 103                                            get seconds to wait for a ping */
 104 module_param(timeout, int, 0);
 105 MODULE_PARM_DESC(timeout,
 106         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
 107                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 108
 109 static bool nowayout = WATCHDOG_NOWAYOUT;
 110 module_param(nowayout, bool, 0);
 111 MODULE_PARM_DESC(nowayout,
 112         "Watchdog cannot be stopped once started (default="
 113                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 114
 115 static void wdt_timer_ping(struct timer_list *);
 116 static DEFINE_TIMER(timer, wdt_timer_ping);
 117 static unsigned long next_heartbeat;
 118 static unsigned long wdt_is_open;
 119 static char wdt_expect_close;
 120
 121 /*
 122  *      Whack the dog
 123  */
 124
 125 static void wdt_timer_ping(struct timer_list *unused)
 126 {
 127         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 128          * we agree to ping the WDT
 129          */
 130         if (time_before(jiffies, next_heartbeat)) {
 131                 /* Ping the WDT by reading from wdt_start */
 132                 inb_p(wdt_start);
 133                 /* Re-set the timer interval */
 134                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 135         } else
 136                 pr_warn("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         pr_info("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         pr_info("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                 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
 221         }
 222         clear_bit(0, &wdt_is_open);
 223         wdt_expect_close = 0;
 224         return 0;
 225 }
 226
 227 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 228 {
 229         void __user *argp = (void __user *)arg;
 230         int __user *p = argp;
 231         static const struct watchdog_info ident = {
 232                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 233                                                         WDIOF_MAGICCLOSE,
 234                 .firmware_version = 1,
 235                 .identity = "SBC60xx",
 236         };
 237
 238         switch (cmd) {
 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_SETOPTIONS:
 245         {
 246                 int new_options, retval = -EINVAL;
 247                 if (get_user(new_options, p))
 248                         return -EFAULT;
 249                 if (new_options & WDIOS_DISABLECARD) {
 250                         wdt_turnoff();
 251                         retval = 0;
 252                 }
 253                 if (new_options & WDIOS_ENABLECARD) {
 254                         wdt_startup();
 255                         retval = 0;
 256                 }
 257                 return retval;
 258         }
 259         case WDIOC_KEEPALIVE:
 260                 wdt_keepalive();
 261                 return 0;
 262         case WDIOC_SETTIMEOUT:
 263         {
 264                 int new_timeout;
 265                 if (get_user(new_timeout, p))
 266                         return -EFAULT;
 267                 /* arbitrary upper limit */
 268                 if (new_timeout < 1 || new_timeout > 3600)
 269                         return -EINVAL;
 270
 271                 timeout = new_timeout;
 272                 wdt_keepalive();
 273                 /* Fall through */
 274         }
 275         case WDIOC_GETTIMEOUT:
 276                 return put_user(timeout, p);
 277         default:
 278                 return -ENOTTY;
 279         }
 280 }
 281
 282 static const struct file_operations wdt_fops = {
 283         .owner          = THIS_MODULE,
 284         .llseek         = no_llseek,
 285         .write          = fop_write,
 286         .open           = fop_open,
 287         .release        = fop_close,
 288         .unlocked_ioctl = fop_ioctl,
 289 };
 290
 291 static struct miscdevice wdt_miscdev = {
 292         .minor = WATCHDOG_MINOR,
 293         .name = "watchdog",
 294         .fops = &wdt_fops,
 295 };
 296
 297 /*
 298  *      Notifier for system down
 299  */
 300
 301 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 302         void *unused)
 303 {
 304         if (code == SYS_DOWN || code == SYS_HALT)
 305                 wdt_turnoff();
 306         return NOTIFY_DONE;
 307 }
 308
 309 /*
 310  *      The WDT needs to learn about soft shutdowns in order to
 311  *      turn the timebomb registers off.
 312  */
 313
 314 static struct notifier_block wdt_notifier = {
 315         .notifier_call = wdt_notify_sys,
 316 };
 317
 318 static void __exit sbc60xxwdt_unload(void)
 319 {
 320         wdt_turnoff();
 321
 322         /* Deregister */
 323         misc_deregister(&wdt_miscdev);
 324
 325         unregister_reboot_notifier(&wdt_notifier);
 326         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 327                 release_region(wdt_stop, 1);
 328         release_region(wdt_start, 1);
 329 }
 330
 331 static int __init sbc60xxwdt_init(void)
 332 {
 333         int rc = -EBUSY;
 334
 335         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 336                 timeout = WATCHDOG_TIMEOUT;
 337                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 338                         timeout);
 339         }
 340
 341         if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
 342                 pr_err("I/O address 0x%04x already in use\n", wdt_start);
 343                 rc = -EIO;
 344                 goto err_out;
 345         }
 346
 347         /* We cannot reserve 0x45 - the kernel already has! */
 348         if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
 349                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
 350                         pr_err("I/O address 0x%04x already in use\n", wdt_stop);
 351                         rc = -EIO;
 352                         goto err_out_region1;
 353                 }
 354         }
 355
 356         rc = register_reboot_notifier(&wdt_notifier);
 357         if (rc) {
 358                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 359                 goto err_out_region2;
 360         }
 361
 362         rc = misc_register(&wdt_miscdev);
 363         if (rc) {
 364                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 365                        wdt_miscdev.minor, rc);
 366                 goto err_out_reboot;
 367         }
 368         pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 369                 timeout, nowayout);
 370
 371         return 0;
 372
 373 err_out_reboot:
 374         unregister_reboot_notifier(&wdt_notifier);
 375 err_out_region2:
 376         if (wdt_stop != 0x45 && wdt_stop != wdt_start)
 377                 release_region(wdt_stop, 1);
 378 err_out_region1:
 379         release_region(wdt_start, 1);
 380 err_out:
 381         return rc;
 382 }
 383
 384 module_init(sbc60xxwdt_init);
 385 module_exit(sbc60xxwdt_unload);
 386
 387 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 388 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 389 MODULE_LICENSE("GPL");