linux/drivers/watchdog/smsc37b787_wdt.c
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   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
  80static int unit = UNIT_SECOND;  /* timer's unit */
  81static int timeout = 60;        /* timeout value: default is 60 "units" */
  82static unsigned long timer_enabled;   /* is the timer enabled? */
  83
  84static char expect_close;       /* is the close expected? */
  85
  86static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
  87
  88static bool nowayout = WATCHDOG_NOWAYOUT;
  89
  90/* -- Low level function ----------------------------------------*/
  91
  92/* unlock the IO chip */
  93
  94static 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 */
 102static inline void close_io_config(void)
 103{
 104        outb(0xAA, IOPORT);
 105}
 106
 107/* select the IO device */
 108static 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 */
 115static 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 */
 122static 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
 130static 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
 144static 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
 157static 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
 167static 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
 175static 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
 191static 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
 217static 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
 252static 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
 277static 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
 295static 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
 311static 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
 319static 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
 327static 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
 343static 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
 353static 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
 374static 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
 393static 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
 423static 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
 494static 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
 507static 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
 516static struct notifier_block wb_smsc_wdt_notifier = {
 517        .notifier_call  = wb_smsc_wdt_notify_sys,
 518};
 519
 520static 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
 530static 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);
 568out_clean:
 569        return ret;
 570
 571out_rbt:
 572        unregister_reboot_notifier(&wb_smsc_wdt_notifier);
 573
 574out_io:
 575        release_region(IOPORT, IOPORT_SIZE);
 576
 577out_pnp:
 578        goto out_clean;
 579}
 580
 581/* module's "destructor" */
 582
 583static 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
 598module_init(wb_smsc_wdt_init);
 599module_exit(wb_smsc_wdt_exit);
 600
 601MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
 602MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
 603                                                                VERSION ")");
 604MODULE_LICENSE("GPL");
 605
 606MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 607
 608#ifdef SMSC_SUPPORT_MINUTES
 609module_param(unit, int, 0);
 610MODULE_PARM_DESC(unit,
 611                "set unit to use, 0=seconds or 1=minutes, default is 0");
 612#endif
 613
 614module_param(timeout, int, 0);
 615MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
 616
 617module_param(nowayout, bool, 0);
 618MODULE_PARM_DESC(nowayout,
 619                "Watchdog cannot be stopped once started (default="
 620                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 621
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