drivers/watchdog/w83877f_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      W83877F Computer Watchdog Timer driver
   4  *
   5  *      Based on acquirewdt.c by Alan Cox,
   6  *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
   7  *
   8  *      The authors do NOT admit liability nor provide warranty for
   9  *      any of this software. This material is provided "AS-IS" in
  10  *      the hope that it may be useful for others.
  11  *
  12  *      (c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
  13  *
  14  *           4/19 - 2001      [Initial revision]
  15  *           9/27 - 2001      Added spinlocking
  16  *           4/12 - 2002      [rob@osinvestor.com] Eliminate extra comments
  17  *                            Eliminate fop_read
  18  *                            Eliminate extra spin_unlock
  19  *                            Added KERN_* tags to printks
  20  *                            add CONFIG_WATCHDOG_NOWAYOUT support
  21  *                            fix possible wdt_is_open race
  22  *                            changed watchdog_info to correctly reflect what
  23  *                            the driver offers
  24  *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
  25  *                            WDIOC_SETTIMEOUT,
  26  *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
  27  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  28  *                            added extra printk's for startup problems
  29  *                            use module_param
  30  *                            made timeout (the emulated heartbeat) a
  31  *                            module_param
  32  *                            made the keepalive ping an internal subroutine
  33  *
  34  *  This WDT driver is different from most other Linux WDT
  35  *  drivers in that the driver will ping the watchdog by itself,
  36  *  because this particular WDT has a very short timeout (1.6
  37  *  seconds) and it would be insane to count on any userspace
  38  *  daemon always getting scheduled within that time frame.
  39  */
  40
  41 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  42
  43 #include <linux/module.h>
  44 #include <linux/moduleparam.h>
  45 #include <linux/types.h>
  46 #include <linux/timer.h>
  47 #include <linux/jiffies.h>
  48 #include <linux/miscdevice.h>
  49 #include <linux/watchdog.h>
  50 #include <linux/fs.h>
  51 #include <linux/ioport.h>
  52 #include <linux/notifier.h>
  53 #include <linux/reboot.h>
  54 #include <linux/init.h>
  55 #include <linux/io.h>
  56 #include <linux/uaccess.h>
  57
  58 #define OUR_NAME "w83877f_wdt"
  59
  60 #define ENABLE_W83877F_PORT 0x3F0
  61 #define ENABLE_W83877F 0x87
  62 #define DISABLE_W83877F 0xAA
  63 #define WDT_PING 0x443
  64 #define WDT_REGISTER 0x14
  65 #define WDT_ENABLE 0x9C
  66 #define WDT_DISABLE 0x8C
  67
  68 /*
  69  * The W83877F seems to be fixed at 1.6s timeout (at least on the
  70  * EMACS PC-104 board I'm using). If we reset the watchdog every
  71  * ~250ms we should be safe.  */
  72
  73 #define WDT_INTERVAL (HZ/4+1)
  74
  75 /*
  76  * We must not require too good response from the userspace daemon.
  77  * Here we require the userspace daemon to send us a heartbeat
  78  * char to /dev/watchdog every 30 seconds.
  79  */
  80
  81 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  82 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  83 static int timeout = WATCHDOG_TIMEOUT;
  84 module_param(timeout, int, 0);
  85 MODULE_PARM_DESC(timeout,
  86         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  87                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  88
  89
  90 static bool nowayout = WATCHDOG_NOWAYOUT;
  91 module_param(nowayout, bool, 0);
  92 MODULE_PARM_DESC(nowayout,
  93                 "Watchdog cannot be stopped once started (default="
  94                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  95
  96 static void wdt_timer_ping(struct timer_list *);
  97 static DEFINE_TIMER(timer, wdt_timer_ping);
  98 static unsigned long next_heartbeat;
  99 static unsigned long wdt_is_open;
 100 static char wdt_expect_close;
 101 static DEFINE_SPINLOCK(wdt_spinlock);
 102
 103 /*
 104  *      Whack the dog
 105  */
 106
 107 static void wdt_timer_ping(struct timer_list *unused)
 108 {
 109         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 110          * we agree to ping the WDT
 111          */
 112         if (time_before(jiffies, next_heartbeat)) {
 113                 /* Ping the WDT */
 114                 spin_lock(&wdt_spinlock);
 115
 116                 /* Ping the WDT by reading from WDT_PING */
 117                 inb_p(WDT_PING);
 118
 119                 /* Re-set the timer interval */
 120                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 121
 122                 spin_unlock(&wdt_spinlock);
 123
 124         } else
 125                 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
 126 }
 127
 128 /*
 129  * Utility routines
 130  */
 131
 132 static void wdt_change(int writeval)
 133 {
 134         unsigned long flags;
 135         spin_lock_irqsave(&wdt_spinlock, flags);
 136
 137         /* buy some time */
 138         inb_p(WDT_PING);
 139
 140         /* make W83877F available */
 141         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 142         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 143
 144         /* enable watchdog */
 145         outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
 146         outb_p(writeval,        ENABLE_W83877F_PORT+1);
 147
 148         /* lock the W8387FF away */
 149         outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
 150
 151         spin_unlock_irqrestore(&wdt_spinlock, flags);
 152 }
 153
 154 static void wdt_startup(void)
 155 {
 156         next_heartbeat = jiffies + (timeout * HZ);
 157
 158         /* Start the timer */
 159         mod_timer(&timer, jiffies + WDT_INTERVAL);
 160
 161         wdt_change(WDT_ENABLE);
 162
 163         pr_info("Watchdog timer is now enabled\n");
 164 }
 165
 166 static void wdt_turnoff(void)
 167 {
 168         /* Stop the timer */
 169         del_timer_sync(&timer);
 170
 171         wdt_change(WDT_DISABLE);
 172
 173         pr_info("Watchdog timer is now disabled...\n");
 174 }
 175
 176 static void wdt_keepalive(void)
 177 {
 178         /* user land ping */
 179         next_heartbeat = jiffies + (timeout * HZ);
 180 }
 181
 182 /*
 183  * /dev/watchdog handling
 184  */
 185
 186 static ssize_t fop_write(struct file *file, const char __user *buf,
 187                                                 size_t count, loff_t *ppos)
 188 {
 189         /* See if we got the magic character 'V' and reload the timer */
 190         if (count) {
 191                 if (!nowayout) {
 192                         size_t ofs;
 193
 194                         /* note: just in case someone wrote the magic
 195                            character five months ago... */
 196                         wdt_expect_close = 0;
 197
 198                         /* scan to see whether or not we got the
 199                            magic character */
 200                         for (ofs = 0; ofs != count; ofs++) {
 201                                 char c;
 202                                 if (get_user(c, buf + ofs))
 203                                         return -EFAULT;
 204                                 if (c == 'V')
 205                                         wdt_expect_close = 42;
 206                         }
 207                 }
 208
 209                 /* someone wrote to us, we should restart timer */
 210                 wdt_keepalive();
 211         }
 212         return count;
 213 }
 214
 215 static int fop_open(struct inode *inode, struct file *file)
 216 {
 217         /* Just in case we're already talking to someone... */
 218         if (test_and_set_bit(0, &wdt_is_open))
 219                 return -EBUSY;
 220
 221         /* Good, fire up the show */
 222         wdt_startup();
 223         return stream_open(inode, file);
 224 }
 225
 226 static int fop_close(struct inode *inode, struct file *file)
 227 {
 228         if (wdt_expect_close == 42)
 229                 wdt_turnoff();
 230         else {
 231                 del_timer(&timer);
 232                 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
 233         }
 234         clear_bit(0, &wdt_is_open);
 235         wdt_expect_close = 0;
 236         return 0;
 237 }
 238
 239 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 240 {
 241         void __user *argp = (void __user *)arg;
 242         int __user *p = argp;
 243         static const struct watchdog_info ident = {
 244                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 245                                                         | WDIOF_MAGICCLOSE,
 246                 .firmware_version = 1,
 247                 .identity = "W83877F",
 248         };
 249
 250         switch (cmd) {
 251         case WDIOC_GETSUPPORT:
 252                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 253         case WDIOC_GETSTATUS:
 254         case WDIOC_GETBOOTSTATUS:
 255                 return put_user(0, p);
 256         case WDIOC_SETOPTIONS:
 257         {
 258                 int new_options, retval = -EINVAL;
 259
 260                 if (get_user(new_options, p))
 261                         return -EFAULT;
 262
 263                 if (new_options & WDIOS_DISABLECARD) {
 264                         wdt_turnoff();
 265                         retval = 0;
 266                 }
 267
 268                 if (new_options & WDIOS_ENABLECARD) {
 269                         wdt_startup();
 270                         retval = 0;
 271                 }
 272
 273                 return retval;
 274         }
 275         case WDIOC_KEEPALIVE:
 276                 wdt_keepalive();
 277                 return 0;
 278         case WDIOC_SETTIMEOUT:
 279         {
 280                 int new_timeout;
 281
 282                 if (get_user(new_timeout, p))
 283                         return -EFAULT;
 284
 285                 /* arbitrary upper limit */
 286                 if (new_timeout < 1 || new_timeout > 3600)
 287                         return -EINVAL;
 288
 289                 timeout = new_timeout;
 290                 wdt_keepalive();
 291         }
 292                 fallthrough;
 293         case WDIOC_GETTIMEOUT:
 294                 return put_user(timeout, p);
 295         default:
 296                 return -ENOTTY;
 297         }
 298 }
 299
 300 static const struct file_operations wdt_fops = {
 301         .owner          = THIS_MODULE,
 302         .llseek         = no_llseek,
 303         .write          = fop_write,
 304         .open           = fop_open,
 305         .release        = fop_close,
 306         .unlocked_ioctl = fop_ioctl,
 307         .compat_ioctl   = compat_ptr_ioctl,
 308 };
 309
 310 static struct miscdevice wdt_miscdev = {
 311         .minor  = WATCHDOG_MINOR,
 312         .name   = "watchdog",
 313         .fops   = &wdt_fops,
 314 };
 315
 316 /*
 317  *      Notifier for system down
 318  */
 319
 320 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 321         void *unused)
 322 {
 323         if (code == SYS_DOWN || code == SYS_HALT)
 324                 wdt_turnoff();
 325         return NOTIFY_DONE;
 326 }
 327
 328 /*
 329  *      The WDT needs to learn about soft shutdowns in order to
 330  *      turn the timebomb registers off.
 331  */
 332
 333 static struct notifier_block wdt_notifier = {
 334         .notifier_call = wdt_notify_sys,
 335 };
 336
 337 static void __exit w83877f_wdt_unload(void)
 338 {
 339         wdt_turnoff();
 340
 341         /* Deregister */
 342         misc_deregister(&wdt_miscdev);
 343
 344         unregister_reboot_notifier(&wdt_notifier);
 345         release_region(WDT_PING, 1);
 346         release_region(ENABLE_W83877F_PORT, 2);
 347 }
 348
 349 static int __init w83877f_wdt_init(void)
 350 {
 351         int rc = -EBUSY;
 352
 353         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 354                 timeout = WATCHDOG_TIMEOUT;
 355                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 356                         timeout);
 357         }
 358
 359         if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
 360                 pr_err("I/O address 0x%04x already in use\n",
 361                        ENABLE_W83877F_PORT);
 362                 rc = -EIO;
 363                 goto err_out;
 364         }
 365
 366         if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
 367                 pr_err("I/O address 0x%04x already in use\n", WDT_PING);
 368                 rc = -EIO;
 369                 goto err_out_region1;
 370         }
 371
 372         rc = register_reboot_notifier(&wdt_notifier);
 373         if (rc) {
 374                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 375                 goto err_out_region2;
 376         }
 377
 378         rc = misc_register(&wdt_miscdev);
 379         if (rc) {
 380                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 381                        wdt_miscdev.minor, rc);
 382                 goto err_out_reboot;
 383         }
 384
 385         pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 386                 timeout, nowayout);
 387
 388         return 0;
 389
 390 err_out_reboot:
 391         unregister_reboot_notifier(&wdt_notifier);
 392 err_out_region2:
 393         release_region(WDT_PING, 1);
 394 err_out_region1:
 395         release_region(ENABLE_W83877F_PORT, 2);
 396 err_out:
 397         return rc;
 398 }
 399
 400 module_init(w83877f_wdt_init);
 401 module_exit(w83877f_wdt_unload);
 402
 403 MODULE_AUTHOR("Scott and Bill Jennings");
 404 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 405 MODULE_LICENSE("GPL");