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