drivers/watchdog/smsc37b787_wdt.c

   1 /*
   2  *      SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x
   3  *
   4  *      Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
   5  *      and some other existing drivers
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  *
  12  *      The authors do NOT admit liability nor provide warranty for
  13  *      any of this software. This material is provided "AS-IS" in
  14  *      the hope that it may be useful for others.
  15  *
  16  *      (C) Copyright 2003-2006  Sven Anders <anders@anduras.de>
  17  *
  18  *  History:
  19  *      2003 - Created version 1.0 for Linux 2.4.x.
  20  *      2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE
  21  *             features. Released version 1.1
  22  *
  23  *  Theory of operation:
  24  *
  25  *      A Watchdog Timer (WDT) is a hardware circuit that can
  26  *      reset the computer system in case of a software fault.
  27  *      You probably knew that already.
  28  *
  29  *      Usually a userspace daemon will notify the kernel WDT driver
  30  *      via the /dev/watchdog special device file that userspace is
  31  *      still alive, at regular intervals.  When such a notification
  32  *      occurs, the driver will usually tell the hardware watchdog
  33  *      that everything is in order, and that the watchdog should wait
  34  *      for yet another little while to reset the system.
  35  *      If userspace fails (RAM error, kernel bug, whatever), the
  36  *      notifications cease to occur, and the hardware watchdog will
  37  *      reset the system (causing a reboot) after the timeout occurs.
  38  *
  39  * Create device with:
  40  *  mknod /dev/watchdog c 10 130
  41  *
  42  * For an example userspace keep-alive daemon, see:
  43  *   Documentation/watchdog/wdt.txt
  44  */
  45
  46 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  47
  48 #include <linux/module.h>
  49 #include <linux/moduleparam.h>
  50 #include <linux/types.h>
  51 #include <linux/miscdevice.h>
  52 #include <linux/watchdog.h>
  53 #include <linux/delay.h>
  54 #include <linux/fs.h>
  55 #include <linux/ioport.h>
  56 #include <linux/notifier.h>
  57 #include <linux/reboot.h>
  58 #include <linux/init.h>
  59 #include <linux/spinlock.h>
  60 #include <linux/io.h>
  61 #include <linux/uaccess.h>
  62
  63
  64 /* enable support for minutes as units? */
  65 /* (does not always work correctly, so disabled by default!) */
  66 #define SMSC_SUPPORT_MINUTES
  67 #undef SMSC_SUPPORT_MINUTES
  68
  69 #define MAX_TIMEOUT     255
  70
  71 #define UNIT_SECOND     0
  72 #define UNIT_MINUTE     1
  73
  74 #define VERSION         "1.1"
  75
  76 #define IOPORT          0x3F0
  77 #define IOPORT_SIZE     2
  78 #define IODEV_NO        8
  79
  80 static int unit = UNIT_SECOND;  /* timer's unit */
  81 static int timeout = 60;        /* timeout value: default is 60 "units" */
  82 static unsigned long timer_enabled;   /* is the timer enabled? */
  83
  84 static char expect_close;       /* is the close expected? */
  85
  86 static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
  87
  88 static bool nowayout = WATCHDOG_NOWAYOUT;
  89
  90 /* -- Low level function ----------------------------------------*/
  91
  92 /* unlock the IO chip */
  93
  94 static inline void open_io_config(void)
  95 {
  96         outb(0x55, IOPORT);
  97         mdelay(1);
  98         outb(0x55, IOPORT);
  99 }
 100
 101 /* lock the IO chip */
 102 static inline void close_io_config(void)
 103 {
 104         outb(0xAA, IOPORT);
 105 }
 106
 107 /* select the IO device */
 108 static inline void select_io_device(unsigned char devno)
 109 {
 110         outb(0x07, IOPORT);
 111         outb(devno, IOPORT+1);
 112 }
 113
 114 /* write to the control register */
 115 static inline void write_io_cr(unsigned char reg, unsigned char data)
 116 {
 117         outb(reg, IOPORT);
 118         outb(data, IOPORT+1);
 119 }
 120
 121 /* read from the control register */
 122 static inline char read_io_cr(unsigned char reg)
 123 {
 124         outb(reg, IOPORT);
 125         return inb(IOPORT+1);
 126 }
 127
 128 /* -- Medium level functions ------------------------------------*/
 129
 130 static inline void gpio_bit12(unsigned char reg)
 131 {
 132         /* -- General Purpose I/O Bit 1.2 --
 133          * Bit 0,   In/Out: 0 = Output, 1 = Input
 134          * Bit 1,   Polarity: 0 = No Invert, 1 = Invert
 135          * Bit 2,   Group Enable Intr.: 0 = Disable, 1 = Enable
 136          * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17,
 137          *                           11 = Either Edge Triggered Intr. 2
 138          * Bit 5/6  (Reserved)
 139          * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
 140          */
 141         write_io_cr(0xE2, reg);
 142 }
 143
 144 static inline void gpio_bit13(unsigned char reg)
 145 {
 146         /* -- General Purpose I/O Bit 1.3 --
 147          * Bit 0,  In/Out: 0 = Output, 1 = Input
 148          * Bit 1,  Polarity: 0 = No Invert, 1 = Invert
 149          * Bit 2,  Group Enable Intr.: 0 = Disable, 1 = Enable
 150          * Bit 3,  Function select: 0 = GPI/O, 1 = LED
 151          * Bit 4-6 (Reserved)
 152          * Bit 7,  Output Type: 0 = Push Pull Bit, 1 = Open Drain
 153          */
 154         write_io_cr(0xE3, reg);
 155 }
 156
 157 static inline void wdt_timer_units(unsigned char new_units)
 158 {
 159         /* -- Watchdog timer units --
 160          * Bit 0-6 (Reserved)
 161          * Bit 7,  WDT Time-out Value Units Select
 162          *         (0 = Minutes, 1 = Seconds)
 163          */
 164         write_io_cr(0xF1, new_units);
 165 }
 166
 167 static inline void wdt_timeout_value(unsigned char new_timeout)
 168 {
 169         /* -- Watchdog Timer Time-out Value --
 170          * Bit 0-7 Binary coded units (0=Disabled, 1..255)
 171          */
 172         write_io_cr(0xF2, new_timeout);
 173 }
 174
 175 static inline void wdt_timer_conf(unsigned char conf)
 176 {
 177         /* -- Watchdog timer configuration --
 178          * Bit 0   Joystick enable: 0* = No Reset, 1 = Reset WDT upon
 179          *                                                      Gameport I/O
 180          * Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
 181          * Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
 182          * Bit 3   Reset the timer
 183          *         (Wrong in SMsC documentation? Given as: PowerLED Timout
 184          *                                                      Enabled)
 185          * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
 186          *            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
 187          */
 188         write_io_cr(0xF3, conf);
 189 }
 190
 191 static inline void wdt_timer_ctrl(unsigned char reg)
 192 {
 193         /* -- Watchdog timer control --
 194          * Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occurred
 195          * Bit 1   Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz
 196          * Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)
 197          * Bit 3   P20 Force Timeout enabled:
 198          *          0 = P20 activity does not generate the WD timeout event
 199          *          1 = P20 Allows rising edge of P20, from the keyboard
 200          *              controller, to force the WD timeout event.
 201          * Bit 4   (Reserved)
 202          * -- Soft power management --
 203          * Bit 5   Stop Counter: 1 = Stop software power down counter
 204          *            set via register 0xB8, (self-cleaning)
 205          *            (Upon read: 0 = Counter running, 1 = Counter stopped)
 206          * Bit 6   Restart Counter: 1 = Restart software power down counter
 207          *            set via register 0xB8, (self-cleaning)
 208          * Bit 7   SPOFF: 1 = Force software power down (self-cleaning)
 209          */
 210         write_io_cr(0xF4, reg);
 211 }
 212
 213 /* -- Higher level functions ------------------------------------*/
 214
 215 /* initialize watchdog */
 216
 217 static void wb_smsc_wdt_initialize(void)
 218 {
 219         unsigned char old;
 220
 221         spin_lock(&io_lock);
 222         open_io_config();
 223         select_io_device(IODEV_NO);
 224
 225         /* enable the watchdog */
 226         gpio_bit13(0x08);  /* Select pin 80 = LED not GPIO */
 227         gpio_bit12(0x0A);  /* Set pin 79 = WDT not
 228                               GPIO/Output/Polarity=Invert */
 229         /* disable the timeout */
 230         wdt_timeout_value(0);
 231
 232         /* reset control register */
 233         wdt_timer_ctrl(0x00);
 234
 235         /* reset configuration register */
 236         wdt_timer_conf(0x00);
 237
 238         /* read old (timer units) register */
 239         old = read_io_cr(0xF1) & 0x7F;
 240         if (unit == UNIT_SECOND)
 241                 old |= 0x80;    /* set to seconds */
 242
 243         /* set the watchdog timer units */
 244         wdt_timer_units(old);
 245
 246         close_io_config();
 247         spin_unlock(&io_lock);
 248 }
 249
 250 /* shutdown the watchdog */
 251
 252 static void wb_smsc_wdt_shutdown(void)
 253 {
 254         spin_lock(&io_lock);
 255         open_io_config();
 256         select_io_device(IODEV_NO);
 257
 258         /* disable the watchdog */
 259         gpio_bit13(0x09);
 260         gpio_bit12(0x09);
 261
 262         /* reset watchdog config register */
 263         wdt_timer_conf(0x00);
 264
 265         /* reset watchdog control register */
 266         wdt_timer_ctrl(0x00);
 267
 268         /* disable timeout */
 269         wdt_timeout_value(0x00);
 270
 271         close_io_config();
 272         spin_unlock(&io_lock);
 273 }
 274
 275 /* set timeout => enable watchdog */
 276
 277 static void wb_smsc_wdt_set_timeout(unsigned char new_timeout)
 278 {
 279         spin_lock(&io_lock);
 280         open_io_config();
 281         select_io_device(IODEV_NO);
 282
 283         /* set Power LED to blink, if we enable the timeout */
 284         wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02);
 285
 286         /* set timeout value */
 287         wdt_timeout_value(new_timeout);
 288
 289         close_io_config();
 290         spin_unlock(&io_lock);
 291 }
 292
 293 /* get timeout */
 294
 295 static unsigned char wb_smsc_wdt_get_timeout(void)
 296 {
 297         unsigned char set_timeout;
 298
 299         spin_lock(&io_lock);
 300         open_io_config();
 301         select_io_device(IODEV_NO);
 302         set_timeout = read_io_cr(0xF2);
 303         close_io_config();
 304         spin_unlock(&io_lock);
 305
 306         return set_timeout;
 307 }
 308
 309 /* disable watchdog */
 310
 311 static void wb_smsc_wdt_disable(void)
 312 {
 313         /* set the timeout to 0 to disable the watchdog */
 314         wb_smsc_wdt_set_timeout(0);
 315 }
 316
 317 /* enable watchdog by setting the current timeout */
 318
 319 static void wb_smsc_wdt_enable(void)
 320 {
 321         /* set the current timeout... */
 322         wb_smsc_wdt_set_timeout(timeout);
 323 }
 324
 325 /* reset the timer */
 326
 327 static void wb_smsc_wdt_reset_timer(void)
 328 {
 329         spin_lock(&io_lock);
 330         open_io_config();
 331         select_io_device(IODEV_NO);
 332
 333         /* reset the timer */
 334         wdt_timeout_value(timeout);
 335         wdt_timer_conf(0x08);
 336
 337         close_io_config();
 338         spin_unlock(&io_lock);
 339 }
 340
 341 /* return, if the watchdog is enabled (timeout is set...) */
 342
 343 static int wb_smsc_wdt_status(void)
 344 {
 345         return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING;
 346 }
 347
 348
 349 /* -- File operations -------------------------------------------*/
 350
 351 /* open => enable watchdog and set initial timeout */
 352
 353 static int wb_smsc_wdt_open(struct inode *inode, struct file *file)
 354 {
 355         /* /dev/watchdog can only be opened once */
 356
 357         if (test_and_set_bit(0, &timer_enabled))
 358                 return -EBUSY;
 359
 360         if (nowayout)
 361                 __module_get(THIS_MODULE);
 362
 363         /* Reload and activate timer */
 364         wb_smsc_wdt_enable();
 365
 366         pr_info("Watchdog enabled. Timeout set to %d %s\n",
 367                 timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
 368
 369         return nonseekable_open(inode, file);
 370 }
 371
 372 /* close => shut off the timer */
 373
 374 static int wb_smsc_wdt_release(struct inode *inode, struct file *file)
 375 {
 376         /* Shut off the timer. */
 377
 378         if (expect_close == 42) {
 379                 wb_smsc_wdt_disable();
 380                 pr_info("Watchdog disabled, sleeping again...\n");
 381         } else {
 382                 pr_crit("Unexpected close, not stopping watchdog!\n");
 383                 wb_smsc_wdt_reset_timer();
 384         }
 385
 386         clear_bit(0, &timer_enabled);
 387         expect_close = 0;
 388         return 0;
 389 }
 390
 391 /* write => update the timer to keep the machine alive */
 392
 393 static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data,
 394                                  size_t len, loff_t *ppos)
 395 {
 396         /* See if we got the magic character 'V' and reload the timer */
 397         if (len) {
 398                 if (!nowayout) {
 399                         size_t i;
 400
 401                         /* reset expect flag */
 402                         expect_close = 0;
 403
 404                         /* scan to see whether or not we got the
 405                            magic character */
 406                         for (i = 0; i != len; i++) {
 407                                 char c;
 408                                 if (get_user(c, data + i))
 409                                         return -EFAULT;
 410                                 if (c == 'V')
 411                                         expect_close = 42;
 412                         }
 413                 }
 414
 415                 /* someone wrote to us, we should reload the timer */
 416                 wb_smsc_wdt_reset_timer();
 417         }
 418         return len;
 419 }
 420
 421 /* ioctl => control interface */
 422
 423 static long wb_smsc_wdt_ioctl(struct file *file,
 424                                         unsigned int cmd, unsigned long arg)
 425 {
 426         int new_timeout;
 427
 428         union {
 429                 struct watchdog_info __user *ident;
 430                 int __user *i;
 431         } uarg;
 432
 433         static const struct watchdog_info ident = {
 434                 .options =              WDIOF_KEEPALIVEPING |
 435                                         WDIOF_SETTIMEOUT |
 436                                         WDIOF_MAGICCLOSE,
 437                 .firmware_version =     0,
 438                 .identity =             "SMsC 37B787 Watchdog",
 439         };
 440
 441         uarg.i = (int __user *)arg;
 442
 443         switch (cmd) {
 444         case WDIOC_GETSUPPORT:
 445                 return copy_to_user(uarg.ident, &ident, sizeof(ident))
 446                                                                 ? -EFAULT : 0;
 447         case WDIOC_GETSTATUS:
 448                 return put_user(wb_smsc_wdt_status(), uarg.i);
 449         case WDIOC_GETBOOTSTATUS:
 450                 return put_user(0, uarg.i);
 451         case WDIOC_SETOPTIONS:
 452         {
 453                 int options, retval = -EINVAL;
 454
 455                 if (get_user(options, uarg.i))
 456                         return -EFAULT;
 457
 458                 if (options & WDIOS_DISABLECARD) {
 459                         wb_smsc_wdt_disable();
 460                         retval = 0;
 461                 }
 462                 if (options & WDIOS_ENABLECARD) {
 463                         wb_smsc_wdt_enable();
 464                         retval = 0;
 465                 }
 466                 return retval;
 467         }
 468         case WDIOC_KEEPALIVE:
 469                 wb_smsc_wdt_reset_timer();
 470                 return 0;
 471         case WDIOC_SETTIMEOUT:
 472                 if (get_user(new_timeout, uarg.i))
 473                         return -EFAULT;
 474                 /* the API states this is given in secs */
 475                 if (unit == UNIT_MINUTE)
 476                         new_timeout /= 60;
 477                 if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
 478                         return -EINVAL;
 479                 timeout = new_timeout;
 480                 wb_smsc_wdt_set_timeout(timeout);
 481                 /* fall through and return the new timeout... */
 482         case WDIOC_GETTIMEOUT:
 483                 new_timeout = timeout;
 484                 if (unit == UNIT_MINUTE)
 485                         new_timeout *= 60;
 486                 return put_user(new_timeout, uarg.i);
 487         default:
 488                 return -ENOTTY;
 489         }
 490 }
 491
 492 /* -- Notifier funtions -----------------------------------------*/
 493
 494 static int wb_smsc_wdt_notify_sys(struct notifier_block *this,
 495                                         unsigned long code, void *unused)
 496 {
 497         if (code == SYS_DOWN || code == SYS_HALT) {
 498                 /* set timeout to 0, to avoid possible race-condition */
 499                 timeout = 0;
 500                 wb_smsc_wdt_disable();
 501         }
 502         return NOTIFY_DONE;
 503 }
 504
 505 /* -- Module's structures ---------------------------------------*/
 506
 507 static const struct file_operations wb_smsc_wdt_fops = {
 508         .owner    = THIS_MODULE,
 509         .llseek         = no_llseek,
 510         .write          = wb_smsc_wdt_write,
 511         .unlocked_ioctl = wb_smsc_wdt_ioctl,
 512         .open           = wb_smsc_wdt_open,
 513         .release        = wb_smsc_wdt_release,
 514 };
 515
 516 static struct notifier_block wb_smsc_wdt_notifier = {
 517         .notifier_call  = wb_smsc_wdt_notify_sys,
 518 };
 519
 520 static struct miscdevice wb_smsc_wdt_miscdev = {
 521         .minor          = WATCHDOG_MINOR,
 522         .name           = "watchdog",
 523         .fops           = &wb_smsc_wdt_fops,
 524 };
 525
 526 /* -- Module init functions -------------------------------------*/
 527
 528 /* module's "constructor" */
 529
 530 static int __init wb_smsc_wdt_init(void)
 531 {
 532         int ret;
 533
 534         pr_info("SMsC 37B787 watchdog component driver "
 535                 VERSION " initialising...\n");
 536
 537         if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {
 538                 pr_err("Unable to register IO port %#x\n", IOPORT);
 539                 ret = -EBUSY;
 540                 goto out_pnp;
 541         }
 542
 543         /* set new maximum, if it's too big */
 544         if (timeout > MAX_TIMEOUT)
 545                 timeout = MAX_TIMEOUT;
 546
 547         /* init the watchdog timer */
 548         wb_smsc_wdt_initialize();
 549
 550         ret = register_reboot_notifier(&wb_smsc_wdt_notifier);
 551         if (ret) {
 552                 pr_err("Unable to register reboot notifier err = %d\n", ret);
 553                 goto out_io;
 554         }
 555
 556         ret = misc_register(&wb_smsc_wdt_miscdev);
 557         if (ret) {
 558                 pr_err("Unable to register miscdev on minor %d\n",
 559                        WATCHDOG_MINOR);
 560                 goto out_rbt;
 561         }
 562
 563         /* output info */
 564         pr_info("Timeout set to %d %s\n",
 565                 timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
 566         pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n",
 567                 nowayout);
 568 out_clean:
 569         return ret;
 570
 571 out_rbt:
 572         unregister_reboot_notifier(&wb_smsc_wdt_notifier);
 573
 574 out_io:
 575         release_region(IOPORT, IOPORT_SIZE);
 576
 577 out_pnp:
 578         goto out_clean;
 579 }
 580
 581 /* module's "destructor" */
 582
 583 static void __exit wb_smsc_wdt_exit(void)
 584 {
 585         /* Stop the timer before we leave */
 586         if (!nowayout) {
 587                 wb_smsc_wdt_shutdown();
 588                 pr_info("Watchdog disabled\n");
 589         }
 590
 591         misc_deregister(&wb_smsc_wdt_miscdev);
 592         unregister_reboot_notifier(&wb_smsc_wdt_notifier);
 593         release_region(IOPORT, IOPORT_SIZE);
 594
 595         pr_info("SMsC 37B787 watchdog component driver removed\n");
 596 }
 597
 598 module_init(wb_smsc_wdt_init);
 599 module_exit(wb_smsc_wdt_exit);
 600
 601 MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
 602 MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
 603                                                                 VERSION ")");
 604 MODULE_LICENSE("GPL");
 605
 606 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 607
 608 #ifdef SMSC_SUPPORT_MINUTES
 609 module_param(unit, int, 0);
 610 MODULE_PARM_DESC(unit,
 611                 "set unit to use, 0=seconds or 1=minutes, default is 0");
 612 #endif
 613
 614 module_param(timeout, int, 0);
 615 MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
 616
 617 module_param(nowayout, bool, 0);
 618 MODULE_PARM_DESC(nowayout,
 619                 "Watchdog cannot be stopped once started (default="
 620                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");