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 #include <linux/module.h>
  47 #include <linux/moduleparam.h>
  48 #include <linux/types.h>
  49 #include <linux/miscdevice.h>
  50 #include <linux/watchdog.h>
  51 #include <linux/delay.h>
  52 #include <linux/fs.h>
  53 #include <linux/ioport.h>
  54 #include <linux/notifier.h>
  55 #include <linux/reboot.h>
  56 #include <linux/init.h>
  57 #include <linux/spinlock.h>
  58 #include <linux/io.h>
  59 #include <linux/uaccess.h>
  60
  61 #include <asm/system.h>
  62
  63 /* enable support for minutes as units? */
  64 /* (does not always work correctly, so disabled by default!) */
  65 #define SMSC_SUPPORT_MINUTES
  66 #undef SMSC_SUPPORT_MINUTES
  67
  68 #define MAX_TIMEOUT     255
  69
  70 #define UNIT_SECOND     0
  71 #define UNIT_MINUTE     1
  72
  73 #define MODNAME         "smsc37b787_wdt: "
  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 int 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         printk(KERN_INFO MODNAME
 367                 "Watchdog enabled. Timeout set to %d %s.\n",
 368                 timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
 369
 370         return nonseekable_open(inode, file);
 371 }
 372
 373 /* close => shut off the timer */
 374
 375 static int wb_smsc_wdt_release(struct inode *inode, struct file *file)
 376 {
 377         /* Shut off the timer. */
 378
 379         if (expect_close == 42) {
 380                 wb_smsc_wdt_disable();
 381                 printk(KERN_INFO MODNAME
 382                                 "Watchdog disabled, sleeping again...\n");
 383         } else {
 384                 printk(KERN_CRIT MODNAME
 385                                 "Unexpected close, not stopping watchdog!\n");
 386                 wb_smsc_wdt_reset_timer();
 387         }
 388
 389         clear_bit(0, &timer_enabled);
 390         expect_close = 0;
 391         return 0;
 392 }
 393
 394 /* write => update the timer to keep the machine alive */
 395
 396 static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data,
 397                                  size_t len, loff_t *ppos)
 398 {
 399         /* See if we got the magic character 'V' and reload the timer */
 400         if (len) {
 401                 if (!nowayout) {
 402                         size_t i;
 403
 404                         /* reset expect flag */
 405                         expect_close = 0;
 406
 407                         /* scan to see whether or not we got the
 408                            magic character */
 409                         for (i = 0; i != len; i++) {
 410                                 char c;
 411                                 if (get_user(c, data + i))
 412                                         return -EFAULT;
 413                                 if (c == 'V')
 414                                         expect_close = 42;
 415                         }
 416                 }
 417
 418                 /* someone wrote to us, we should reload the timer */
 419                 wb_smsc_wdt_reset_timer();
 420         }
 421         return len;
 422 }
 423
 424 /* ioctl => control interface */
 425
 426 static long wb_smsc_wdt_ioctl(struct file *file,
 427                                         unsigned int cmd, unsigned long arg)
 428 {
 429         int new_timeout;
 430
 431         union {
 432                 struct watchdog_info __user *ident;
 433                 int __user *i;
 434         } uarg;
 435
 436         static const struct watchdog_info ident = {
 437                 .options =              WDIOF_KEEPALIVEPING |
 438                                         WDIOF_SETTIMEOUT |
 439                                         WDIOF_MAGICCLOSE,
 440                 .firmware_version =     0,
 441                 .identity =             "SMsC 37B787 Watchdog",
 442         };
 443
 444         uarg.i = (int __user *)arg;
 445
 446         switch (cmd) {
 447         case WDIOC_GETSUPPORT:
 448                 return copy_to_user(uarg.ident, &ident, sizeof(ident))
 449                                                                 ? -EFAULT : 0;
 450         case WDIOC_GETSTATUS:
 451                 return put_user(wb_smsc_wdt_status(), uarg.i);
 452         case WDIOC_GETBOOTSTATUS:
 453                 return put_user(0, uarg.i);
 454         case WDIOC_SETOPTIONS:
 455         {
 456                 int options, retval = -EINVAL;
 457
 458                 if (get_user(options, uarg.i))
 459                         return -EFAULT;
 460
 461                 if (options & WDIOS_DISABLECARD) {
 462                         wb_smsc_wdt_disable();
 463                         retval = 0;
 464                 }
 465                 if (options & WDIOS_ENABLECARD) {
 466                         wb_smsc_wdt_enable();
 467                         retval = 0;
 468                 }
 469                 return retval;
 470         }
 471         case WDIOC_KEEPALIVE:
 472                 wb_smsc_wdt_reset_timer();
 473                 return 0;
 474         case WDIOC_SETTIMEOUT:
 475                 if (get_user(new_timeout, uarg.i))
 476                         return -EFAULT;
 477                 /* the API states this is given in secs */
 478                 if (unit == UNIT_MINUTE)
 479                         new_timeout /= 60;
 480                 if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
 481                         return -EINVAL;
 482                 timeout = new_timeout;
 483                 wb_smsc_wdt_set_timeout(timeout);
 484                 /* fall through and return the new timeout... */
 485         case WDIOC_GETTIMEOUT:
 486                 new_timeout = timeout;
 487                 if (unit == UNIT_MINUTE)
 488                         new_timeout *= 60;
 489                 return put_user(new_timeout, uarg.i);
 490         default:
 491                 return -ENOTTY;
 492         }
 493 }
 494
 495 /* -- Notifier funtions -----------------------------------------*/
 496
 497 static int wb_smsc_wdt_notify_sys(struct notifier_block *this,
 498                                         unsigned long code, void *unused)
 499 {
 500         if (code == SYS_DOWN || code == SYS_HALT) {
 501                 /* set timeout to 0, to avoid possible race-condition */
 502                 timeout = 0;
 503                 wb_smsc_wdt_disable();
 504         }
 505         return NOTIFY_DONE;
 506 }
 507
 508 /* -- Module's structures ---------------------------------------*/
 509
 510 static const struct file_operations wb_smsc_wdt_fops = {
 511         .owner    = THIS_MODULE,
 512         .llseek         = no_llseek,
 513         .write          = wb_smsc_wdt_write,
 514         .unlocked_ioctl = wb_smsc_wdt_ioctl,
 515         .open           = wb_smsc_wdt_open,
 516         .release        = wb_smsc_wdt_release,
 517 };
 518
 519 static struct notifier_block wb_smsc_wdt_notifier = {
 520         .notifier_call  = wb_smsc_wdt_notify_sys,
 521 };
 522
 523 static struct miscdevice wb_smsc_wdt_miscdev = {
 524         .minor          = WATCHDOG_MINOR,
 525         .name           = "watchdog",
 526         .fops           = &wb_smsc_wdt_fops,
 527 };
 528
 529 /* -- Module init functions -------------------------------------*/
 530
 531 /* module's "constructor" */
 532
 533 static int __init wb_smsc_wdt_init(void)
 534 {
 535         int ret;
 536
 537         printk(KERN_INFO "SMsC 37B787 watchdog component driver "
 538                                         VERSION " initialising...\n");
 539
 540         if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {
 541                 printk(KERN_ERR MODNAME "Unable to register IO port %#x\n",
 542                                                                 IOPORT);
 543                 ret = -EBUSY;
 544                 goto out_pnp;
 545         }
 546
 547         /* set new maximum, if it's too big */
 548         if (timeout > MAX_TIMEOUT)
 549                 timeout = MAX_TIMEOUT;
 550
 551         /* init the watchdog timer */
 552         wb_smsc_wdt_initialize();
 553
 554         ret = register_reboot_notifier(&wb_smsc_wdt_notifier);
 555         if (ret) {
 556                 printk(KERN_ERR MODNAME
 557                         "Unable to register reboot notifier err = %d\n", ret);
 558                 goto out_io;
 559         }
 560
 561         ret = misc_register(&wb_smsc_wdt_miscdev);
 562         if (ret) {
 563                 printk(KERN_ERR MODNAME
 564                         "Unable to register miscdev on minor %d\n",
 565                                                         WATCHDOG_MINOR);
 566                 goto out_rbt;
 567         }
 568
 569         /* output info */
 570         printk(KERN_INFO MODNAME "Timeout set to %d %s.\n",
 571                 timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
 572         printk(KERN_INFO MODNAME
 573                 "Watchdog initialized and sleeping (nowayout=%d)...\n",
 574                                                                 nowayout);
 575 out_clean:
 576         return ret;
 577
 578 out_rbt:
 579         unregister_reboot_notifier(&wb_smsc_wdt_notifier);
 580
 581 out_io:
 582         release_region(IOPORT, IOPORT_SIZE);
 583
 584 out_pnp:
 585         goto out_clean;
 586 }
 587
 588 /* module's "destructor" */
 589
 590 static void __exit wb_smsc_wdt_exit(void)
 591 {
 592         /* Stop the timer before we leave */
 593         if (!nowayout) {
 594                 wb_smsc_wdt_shutdown();
 595                 printk(KERN_INFO MODNAME "Watchdog disabled.\n");
 596         }
 597
 598         misc_deregister(&wb_smsc_wdt_miscdev);
 599         unregister_reboot_notifier(&wb_smsc_wdt_notifier);
 600         release_region(IOPORT, IOPORT_SIZE);
 601
 602         printk(KERN_INFO "SMsC 37B787 watchdog component driver removed.\n");
 603 }
 604
 605 module_init(wb_smsc_wdt_init);
 606 module_exit(wb_smsc_wdt_exit);
 607
 608 MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
 609 MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
 610                                                                 VERSION ")");
 611 MODULE_LICENSE("GPL");
 612
 613 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 614
 615 #ifdef SMSC_SUPPORT_MINUTES
 616 module_param(unit, int, 0);
 617 MODULE_PARM_DESC(unit,
 618                 "set unit to use, 0=seconds or 1=minutes, default is 0");
 619 #endif
 620
 621 module_param(timeout, int, 0);
 622 MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
 623
 624 module_param(nowayout, int, 0);
 625 MODULE_PARM_DESC(nowayout,
 626                 "Watchdog cannot be stopped once started (default="
 627                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");