root/drivers/watchdog/wdt.c

DEFINITIONS

1. wdt_ctr_mode
2. wdt_ctr_load
3. wdt_start
4. wdt_stop
5. wdt_ping
6. wdt_set_heartbeat
7. wdt_get_status
8. wdt_get_temperature
9. wdt_decode_501
10. wdt_interrupt
11. wdt_write
12. wdt_ioctl
13. wdt_open
14. wdt_release
15. wdt_temp_read
16. wdt_temp_open
17. wdt_temp_release
18. wdt_notify_sys
19. wdt_exit
20. wdt_init

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      Industrial Computer Source WDT501 driver
   4  *
   5  *      (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   6  *                                              All Rights Reserved.
   7  *
   8  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
   9  *      warranty for any of this software. This material is provided
  10  *      "AS-IS" and at no charge.
  11  *
  12  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  13  *
  14  *      Release 0.10.
  15  *
  16  *      Fixes
  17  *              Dave Gregorich  :       Modularisation and minor bugs
  18  *              Alan Cox        :       Added the watchdog ioctl() stuff
  19  *              Alan Cox        :       Fixed the reboot problem (as noted by
  20  *                                      Matt Crocker).
  21  *              Alan Cox        :       Added wdt= boot option
  22  *              Alan Cox        :       Cleaned up copy/user stuff
  23  *              Tim Hockin      :       Added insmod parameters, comment
  24  *                                      cleanup, parameterized timeout
  25  *              Tigran Aivazian :       Restructured wdt_init() to handle
  26  *                                      failures
  27  *              Joel Becker     :       Added WDIOC_GET/SETTIMEOUT
  28  *              Matt Domsch     :       Added nowayout module option
  29  */
  30 
  31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  32 
  33 #include <linux/interrupt.h>
  34 #include <linux/module.h>
  35 #include <linux/moduleparam.h>
  36 #include <linux/types.h>
  37 #include <linux/miscdevice.h>
  38 #include <linux/watchdog.h>
  39 #include <linux/fs.h>
  40 #include <linux/ioport.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/init.h>
  44 #include <linux/io.h>
  45 #include <linux/uaccess.h>
  46 
  47 #include "wd501p.h"
  48 
  49 static unsigned long wdt_is_open;
  50 static char expect_close;
  51 
  52 /*
  53  *      Module parameters
  54  */
  55 
  56 #define WD_TIMO 60                      /* Default heartbeat = 60 seconds */
  57 
  58 static int heartbeat = WD_TIMO;
  59 static int wd_heartbeat;
  60 module_param(heartbeat, int, 0);
  61 MODULE_PARM_DESC(heartbeat,
  62         "Watchdog heartbeat in seconds. (0 < heartbeat < 65536, default="
  63                                 __MODULE_STRING(WD_TIMO) ")");
  64 
  65 static bool nowayout = WATCHDOG_NOWAYOUT;
  66 module_param(nowayout, bool, 0);
  67 MODULE_PARM_DESC(nowayout,
  68         "Watchdog cannot be stopped once started (default="
  69                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  70 
  71 /* You must set these - there is no sane way to probe for this board. */
  72 static int io = 0x240;
  73 static int irq = 11;
  74 
  75 static DEFINE_SPINLOCK(wdt_lock);
  76 
  77 module_param_hw(io, int, ioport, 0);
  78 MODULE_PARM_DESC(io, "WDT io port (default=0x240)");
  79 module_param_hw(irq, int, irq, 0);
  80 MODULE_PARM_DESC(irq, "WDT irq (default=11)");
  81 
  82 /* Support for the Fan Tachometer on the WDT501-P */
  83 static int tachometer;
  84 module_param(tachometer, int, 0);
  85 MODULE_PARM_DESC(tachometer,
  86                 "WDT501-P Fan Tachometer support (0=disable, default=0)");
  87 
  88 static int type = 500;
  89 module_param(type, int, 0);
  90 MODULE_PARM_DESC(type,
  91                 "WDT501-P Card type (500 or 501, default=500)");
  92 
  93 /*
  94  *      Programming support
  95  */
  96 
  97 static void wdt_ctr_mode(int ctr, int mode)
  98 {
  99         ctr <<= 6;
 100         ctr |= 0x30;
 101         ctr |= (mode << 1);
 102         outb_p(ctr, WDT_CR);
 103 }
 104 
 105 static void wdt_ctr_load(int ctr, int val)
 106 {
 107         outb_p(val&0xFF, WDT_COUNT0+ctr);
 108         outb_p(val>>8, WDT_COUNT0+ctr);
 109 }
 110 
 111 /**
 112  *      wdt_start:
 113  *
 114  *      Start the watchdog driver.
 115  */
 116 
 117 static int wdt_start(void)
 118 {
 119         unsigned long flags;
 120         spin_lock_irqsave(&wdt_lock, flags);
 121         inb_p(WDT_DC);                  /* Disable watchdog */
 122         wdt_ctr_mode(0, 3);             /* Program CTR0 for Mode 3:
 123                                                 Square Wave Generator */
 124         wdt_ctr_mode(1, 2);             /* Program CTR1 for Mode 2:
 125                                                 Rate Generator */
 126         wdt_ctr_mode(2, 0);             /* Program CTR2 for Mode 0:
 127                                                 Pulse on Terminal Count */
 128         wdt_ctr_load(0, 8948);          /* Count at 100Hz */
 129         wdt_ctr_load(1, wd_heartbeat);  /* Heartbeat */
 130         wdt_ctr_load(2, 65535);         /* Length of reset pulse */
 131         outb_p(0, WDT_DC);              /* Enable watchdog */
 132         spin_unlock_irqrestore(&wdt_lock, flags);
 133         return 0;
 134 }
 135 
 136 /**
 137  *      wdt_stop:
 138  *
 139  *      Stop the watchdog driver.
 140  */
 141 
 142 static int wdt_stop(void)
 143 {
 144         unsigned long flags;
 145         spin_lock_irqsave(&wdt_lock, flags);
 146         /* Turn the card off */
 147         inb_p(WDT_DC);                  /* Disable watchdog */
 148         wdt_ctr_load(2, 0);             /* 0 length reset pulses now */
 149         spin_unlock_irqrestore(&wdt_lock, flags);
 150         return 0;
 151 }
 152 
 153 /**
 154  *      wdt_ping:
 155  *
 156  *      Reload counter one with the watchdog heartbeat. We don't bother
 157  *      reloading the cascade counter.
 158  */
 159 
 160 static void wdt_ping(void)
 161 {
 162         unsigned long flags;
 163         spin_lock_irqsave(&wdt_lock, flags);
 164         /* Write a watchdog value */
 165         inb_p(WDT_DC);                  /* Disable watchdog */
 166         wdt_ctr_mode(1, 2);             /* Re-Program CTR1 for Mode 2:
 167                                                         Rate Generator */
 168         wdt_ctr_load(1, wd_heartbeat);  /* Heartbeat */
 169         outb_p(0, WDT_DC);              /* Enable watchdog */
 170         spin_unlock_irqrestore(&wdt_lock, flags);
 171 }
 172 
 173 /**
 174  *      wdt_set_heartbeat:
 175  *      @t:             the new heartbeat value that needs to be set.
 176  *
 177  *      Set a new heartbeat value for the watchdog device. If the heartbeat
 178  *      value is incorrect we keep the old value and return -EINVAL. If
 179  *      successful we return 0.
 180  */
 181 
 182 static int wdt_set_heartbeat(int t)
 183 {
 184         if (t < 1 || t > 65535)
 185                 return -EINVAL;
 186 
 187         heartbeat = t;
 188         wd_heartbeat = t * 100;
 189         return 0;
 190 }
 191 
 192 /**
 193  *      wdt_get_status:
 194  *
 195  *      Extract the status information from a WDT watchdog device. There are
 196  *      several board variants so we have to know which bits are valid. Some
 197  *      bits default to one and some to zero in order to be maximally painful.
 198  *
 199  *      we then map the bits onto the status ioctl flags.
 200  */
 201 
 202 static int wdt_get_status(void)
 203 {
 204         unsigned char new_status;
 205         int status = 0;
 206         unsigned long flags;
 207 
 208         spin_lock_irqsave(&wdt_lock, flags);
 209         new_status = inb_p(WDT_SR);
 210         spin_unlock_irqrestore(&wdt_lock, flags);
 211 
 212         if (new_status & WDC_SR_ISOI0)
 213                 status |= WDIOF_EXTERN1;
 214         if (new_status & WDC_SR_ISII1)
 215                 status |= WDIOF_EXTERN2;
 216         if (type == 501) {
 217                 if (!(new_status & WDC_SR_TGOOD))
 218                         status |= WDIOF_OVERHEAT;
 219                 if (!(new_status & WDC_SR_PSUOVER))
 220                         status |= WDIOF_POWEROVER;
 221                 if (!(new_status & WDC_SR_PSUUNDR))
 222                         status |= WDIOF_POWERUNDER;
 223                 if (tachometer) {
 224                         if (!(new_status & WDC_SR_FANGOOD))
 225                                 status |= WDIOF_FANFAULT;
 226                 }
 227         }
 228         return status;
 229 }
 230 
 231 /**
 232  *      wdt_get_temperature:
 233  *
 234  *      Reports the temperature in degrees Fahrenheit. The API is in
 235  *      farenheit. It was designed by an imperial measurement luddite.
 236  */
 237 
 238 static int wdt_get_temperature(void)
 239 {
 240         unsigned short c;
 241         unsigned long flags;
 242 
 243         spin_lock_irqsave(&wdt_lock, flags);
 244         c = inb_p(WDT_RT);
 245         spin_unlock_irqrestore(&wdt_lock, flags);
 246         return (c * 11 / 15) + 7;
 247 }
 248 
 249 static void wdt_decode_501(int status)
 250 {
 251         if (!(status & WDC_SR_TGOOD))
 252                 pr_crit("Overheat alarm (%d)\n", inb_p(WDT_RT));
 253         if (!(status & WDC_SR_PSUOVER))
 254                 pr_crit("PSU over voltage\n");
 255         if (!(status & WDC_SR_PSUUNDR))
 256                 pr_crit("PSU under voltage\n");
 257 }
 258 
 259 /**
 260  *      wdt_interrupt:
 261  *      @irq:           Interrupt number
 262  *      @dev_id:        Unused as we don't allow multiple devices.
 263  *
 264  *      Handle an interrupt from the board. These are raised when the status
 265  *      map changes in what the board considers an interesting way. That means
 266  *      a failure condition occurring.
 267  */
 268 
 269 static irqreturn_t wdt_interrupt(int irq, void *dev_id)
 270 {
 271         /*
 272          *      Read the status register see what is up and
 273          *      then printk it.
 274          */
 275         unsigned char status;
 276 
 277         spin_lock(&wdt_lock);
 278         status = inb_p(WDT_SR);
 279 
 280         pr_crit("WDT status %d\n", status);
 281 
 282         if (type == 501) {
 283                 wdt_decode_501(status);
 284                 if (tachometer) {
 285                         if (!(status & WDC_SR_FANGOOD))
 286                                 pr_crit("Possible fan fault\n");
 287                 }
 288         }
 289         if (!(status & WDC_SR_WCCR)) {
 290 #ifdef SOFTWARE_REBOOT
 291 #ifdef ONLY_TESTING
 292                 pr_crit("Would Reboot\n");
 293 #else
 294                 pr_crit("Initiating system reboot\n");
 295                 emergency_restart();
 296 #endif
 297 #else
 298                 pr_crit("Reset in 5ms\n");
 299 #endif
 300         }
 301         spin_unlock(&wdt_lock);
 302         return IRQ_HANDLED;
 303 }
 304 
 305 
 306 /**
 307  *      wdt_write:
 308  *      @file: file handle to the watchdog
 309  *      @buf: buffer to write (unused as data does not matter here
 310  *      @count: count of bytes
 311  *      @ppos: pointer to the position to write. No seeks allowed
 312  *
 313  *      A write to a watchdog device is defined as a keepalive signal. Any
 314  *      write of data will do, as we we don't define content meaning.
 315  */
 316 
 317 static ssize_t wdt_write(struct file *file, const char __user *buf,
 318                                                 size_t count, loff_t *ppos)
 319 {
 320         if (count) {
 321                 if (!nowayout) {
 322                         size_t i;
 323 
 324                         /* In case it was set long ago */
 325                         expect_close = 0;
 326 
 327                         for (i = 0; i != count; i++) {
 328                                 char c;
 329                                 if (get_user(c, buf + i))
 330                                         return -EFAULT;
 331                                 if (c == 'V')
 332                                         expect_close = 42;
 333                         }
 334                 }
 335                 wdt_ping();
 336         }
 337         return count;
 338 }
 339 
 340 /**
 341  *      wdt_ioctl:
 342  *      @file: file handle to the device
 343  *      @cmd: watchdog command
 344  *      @arg: argument pointer
 345  *
 346  *      The watchdog API defines a common set of functions for all watchdogs
 347  *      according to their available features. We only actually usefully support
 348  *      querying capabilities and current status.
 349  */
 350 
 351 static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 352 {
 353         void __user *argp = (void __user *)arg;
 354         int __user *p = argp;
 355         int new_heartbeat;
 356         int status;
 357 
 358         struct watchdog_info ident = {
 359                 .options =              WDIOF_SETTIMEOUT|
 360                                         WDIOF_MAGICCLOSE|
 361                                         WDIOF_KEEPALIVEPING,
 362                 .firmware_version =     1,
 363                 .identity =             "WDT500/501",
 364         };
 365 
 366         /* Add options according to the card we have */
 367         ident.options |= (WDIOF_EXTERN1|WDIOF_EXTERN2);
 368         if (type == 501) {
 369                 ident.options |= (WDIOF_OVERHEAT|WDIOF_POWERUNDER|
 370                                                         WDIOF_POWEROVER);
 371                 if (tachometer)
 372                         ident.options |= WDIOF_FANFAULT;
 373         }
 374 
 375         switch (cmd) {
 376         case WDIOC_GETSUPPORT:
 377                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 378         case WDIOC_GETSTATUS:
 379                 status = wdt_get_status();
 380                 return put_user(status, p);
 381         case WDIOC_GETBOOTSTATUS:
 382                 return put_user(0, p);
 383         case WDIOC_KEEPALIVE:
 384                 wdt_ping();
 385                 return 0;
 386         case WDIOC_SETTIMEOUT:
 387                 if (get_user(new_heartbeat, p))
 388                         return -EFAULT;
 389                 if (wdt_set_heartbeat(new_heartbeat))
 390                         return -EINVAL;
 391                 wdt_ping();
 392                 /* Fall through */
 393         case WDIOC_GETTIMEOUT:
 394                 return put_user(heartbeat, p);
 395         default:
 396                 return -ENOTTY;
 397         }
 398 }
 399 
 400 /**
 401  *      wdt_open:
 402  *      @inode: inode of device
 403  *      @file: file handle to device
 404  *
 405  *      The watchdog device has been opened. The watchdog device is single
 406  *      open and on opening we load the counters. Counter zero is a 100Hz
 407  *      cascade, into counter 1 which downcounts to reboot. When the counter
 408  *      triggers counter 2 downcounts the length of the reset pulse which
 409  *      set set to be as long as possible.
 410  */
 411 
 412 static int wdt_open(struct inode *inode, struct file *file)
 413 {
 414         if (test_and_set_bit(0, &wdt_is_open))
 415                 return -EBUSY;
 416         /*
 417          *      Activate
 418          */
 419         wdt_start();
 420         return stream_open(inode, file);
 421 }
 422 
 423 /**
 424  *      wdt_release:
 425  *      @inode: inode to board
 426  *      @file: file handle to board
 427  *
 428  *      The watchdog has a configurable API. There is a religious dispute
 429  *      between people who want their watchdog to be able to shut down and
 430  *      those who want to be sure if the watchdog manager dies the machine
 431  *      reboots. In the former case we disable the counters, in the latter
 432  *      case you have to open it again very soon.
 433  */
 434 
 435 static int wdt_release(struct inode *inode, struct file *file)
 436 {
 437         if (expect_close == 42) {
 438                 wdt_stop();
 439                 clear_bit(0, &wdt_is_open);
 440         } else {
 441                 pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
 442                 wdt_ping();
 443         }
 444         expect_close = 0;
 445         return 0;
 446 }
 447 
 448 /**
 449  *      wdt_temp_read:
 450  *      @file: file handle to the watchdog board
 451  *      @buf: buffer to write 1 byte into
 452  *      @count: length of buffer
 453  *      @ptr: offset (no seek allowed)
 454  *
 455  *      Temp_read reports the temperature in degrees Fahrenheit. The API is in
 456  *      farenheit. It was designed by an imperial measurement luddite.
 457  */
 458 
 459 static ssize_t wdt_temp_read(struct file *file, char __user *buf,
 460                                                 size_t count, loff_t *ptr)
 461 {
 462         int temperature = wdt_get_temperature();
 463 
 464         if (copy_to_user(buf, &temperature, 1))
 465                 return -EFAULT;
 466 
 467         return 1;
 468 }
 469 
 470 /**
 471  *      wdt_temp_open:
 472  *      @inode: inode of device
 473  *      @file: file handle to device
 474  *
 475  *      The temperature device has been opened.
 476  */
 477 
 478 static int wdt_temp_open(struct inode *inode, struct file *file)
 479 {
 480         return stream_open(inode, file);
 481 }
 482 
 483 /**
 484  *      wdt_temp_release:
 485  *      @inode: inode to board
 486  *      @file: file handle to board
 487  *
 488  *      The temperature device has been closed.
 489  */
 490 
 491 static int wdt_temp_release(struct inode *inode, struct file *file)
 492 {
 493         return 0;
 494 }
 495 
 496 /**
 497  *      notify_sys:
 498  *      @this: our notifier block
 499  *      @code: the event being reported
 500  *      @unused: unused
 501  *
 502  *      Our notifier is called on system shutdowns. We want to turn the card
 503  *      off at reboot otherwise the machine will reboot again during memory
 504  *      test or worse yet during the following fsck. This would suck, in fact
 505  *      trust me - if it happens it does suck.
 506  */
 507 
 508 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 509         void *unused)
 510 {
 511         if (code == SYS_DOWN || code == SYS_HALT)
 512                 wdt_stop();
 513         return NOTIFY_DONE;
 514 }
 515 
 516 /*
 517  *      Kernel Interfaces
 518  */
 519 
 520 
 521 static const struct file_operations wdt_fops = {
 522         .owner          = THIS_MODULE,
 523         .llseek         = no_llseek,
 524         .write          = wdt_write,
 525         .unlocked_ioctl = wdt_ioctl,
 526         .open           = wdt_open,
 527         .release        = wdt_release,
 528 };
 529 
 530 static struct miscdevice wdt_miscdev = {
 531         .minor  = WATCHDOG_MINOR,
 532         .name   = "watchdog",
 533         .fops   = &wdt_fops,
 534 };
 535 
 536 static const struct file_operations wdt_temp_fops = {
 537         .owner          = THIS_MODULE,
 538         .llseek         = no_llseek,
 539         .read           = wdt_temp_read,
 540         .open           = wdt_temp_open,
 541         .release        = wdt_temp_release,
 542 };
 543 
 544 static struct miscdevice temp_miscdev = {
 545         .minor  = TEMP_MINOR,
 546         .name   = "temperature",
 547         .fops   = &wdt_temp_fops,
 548 };
 549 
 550 /*
 551  *      The WDT card needs to learn about soft shutdowns in order to
 552  *      turn the timebomb registers off.
 553  */
 554 
 555 static struct notifier_block wdt_notifier = {
 556         .notifier_call = wdt_notify_sys,
 557 };
 558 
 559 /**
 560  *      cleanup_module:
 561  *
 562  *      Unload the watchdog. You cannot do this with any file handles open.
 563  *      If your watchdog is set to continue ticking on close and you unload
 564  *      it, well it keeps ticking. We won't get the interrupt but the board
 565  *      will not touch PC memory so all is fine. You just have to load a new
 566  *      module in 60 seconds or reboot.
 567  */
 568 
 569 static void __exit wdt_exit(void)
 570 {
 571         misc_deregister(&wdt_miscdev);
 572         if (type == 501)
 573                 misc_deregister(&temp_miscdev);
 574         unregister_reboot_notifier(&wdt_notifier);
 575         free_irq(irq, NULL);
 576         release_region(io, 8);
 577 }
 578 
 579 /**
 580  *      wdt_init:
 581  *
 582  *      Set up the WDT watchdog board. All we have to do is grab the
 583  *      resources we require and bitch if anyone beat us to them.
 584  *      The open() function will actually kick the board off.
 585  */
 586 
 587 static int __init wdt_init(void)
 588 {
 589         int ret;
 590 
 591         if (type != 500 && type != 501) {
 592                 pr_err("unknown card type '%d'\n", type);
 593                 return -ENODEV;
 594         }
 595 
 596         /* Check that the heartbeat value is within it's range;
 597            if not reset to the default */
 598         if (wdt_set_heartbeat(heartbeat)) {
 599                 wdt_set_heartbeat(WD_TIMO);
 600                 pr_info("heartbeat value must be 0 < heartbeat < 65536, using %d\n",
 601                         WD_TIMO);
 602         }
 603 
 604         if (!request_region(io, 8, "wdt501p")) {
 605                 pr_err("I/O address 0x%04x already in use\n", io);
 606                 ret = -EBUSY;
 607                 goto out;
 608         }
 609 
 610         ret = request_irq(irq, wdt_interrupt, 0, "wdt501p", NULL);
 611         if (ret) {
 612                 pr_err("IRQ %d is not free\n", irq);
 613                 goto outreg;
 614         }
 615 
 616         ret = register_reboot_notifier(&wdt_notifier);
 617         if (ret) {
 618                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 619                 goto outirq;
 620         }
 621 
 622         if (type == 501) {
 623                 ret = misc_register(&temp_miscdev);
 624                 if (ret) {
 625                         pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 626                                TEMP_MINOR, ret);
 627                         goto outrbt;
 628                 }
 629         }
 630 
 631         ret = misc_register(&wdt_miscdev);
 632         if (ret) {
 633                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 634                        WATCHDOG_MINOR, ret);
 635                 goto outmisc;
 636         }
 637 
 638         pr_info("WDT500/501-P driver 0.10 at 0x%04x (Interrupt %d). heartbeat=%d sec (nowayout=%d)\n",
 639                 io, irq, heartbeat, nowayout);
 640         if (type == 501)
 641                 pr_info("Fan Tachometer is %s\n",
 642                         tachometer ? "Enabled" : "Disabled");
 643         return 0;
 644 
 645 outmisc:
 646         if (type == 501)
 647                 misc_deregister(&temp_miscdev);
 648 outrbt:
 649         unregister_reboot_notifier(&wdt_notifier);
 650 outirq:
 651         free_irq(irq, NULL);
 652 outreg:
 653         release_region(io, 8);
 654 out:
 655         return ret;
 656 }
 657 
 658 module_init(wdt_init);
 659 module_exit(wdt_exit);
 660 
 661 MODULE_AUTHOR("Alan Cox");
 662 MODULE_DESCRIPTION("Driver for ISA ICS watchdog cards (WDT500/501)");
 663 MODULE_LICENSE("GPL");