linux/drivers/watchdog/it8712f_wdt.c
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   1/*
   2 *      IT8712F "Smart Guardian" Watchdog support
   3 *
   4 *      Copyright (c) 2006-2007 Jorge Boncompte - DTI2 <jorge@dti2.net>
   5 *
   6 *      Based on info and code taken from:
   7 *
   8 *      drivers/char/watchdog/scx200_wdt.c
   9 *      drivers/hwmon/it87.c
  10 *      IT8712F EC-LPC I/O Preliminary Specification 0.8.2
  11 *      IT8712F EC-LPC I/O Preliminary Specification 0.9.3
  12 *
  13 *      This program is free software; you can redistribute it and/or
  14 *      modify it under the terms of the GNU General Public License as
  15 *      published by the Free Software Foundation; either version 2 of the
  16 *      License, or (at your option) any later version.
  17 *
  18 *      The author(s) of this software shall not be held liable for damages
  19 *      of any nature resulting due to the use of this software. This
  20 *      software is provided AS-IS with no warranties.
  21 */
  22
  23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25#include <linux/module.h>
  26#include <linux/moduleparam.h>
  27#include <linux/init.h>
  28#include <linux/miscdevice.h>
  29#include <linux/watchdog.h>
  30#include <linux/notifier.h>
  31#include <linux/reboot.h>
  32#include <linux/fs.h>
  33#include <linux/spinlock.h>
  34#include <linux/uaccess.h>
  35#include <linux/io.h>
  36#include <linux/ioport.h>
  37
  38#define DEBUG
  39#define NAME "it8712f_wdt"
  40
  41MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
  42MODULE_DESCRIPTION("IT8712F Watchdog Driver");
  43MODULE_LICENSE("GPL");
  44MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  45
  46static int max_units = 255;
  47static int margin = 60;         /* in seconds */
  48module_param(margin, int, 0);
  49MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  50
  51static bool nowayout = WATCHDOG_NOWAYOUT;
  52module_param(nowayout, bool, 0);
  53MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  54
  55static unsigned long wdt_open;
  56static unsigned expect_close;
  57static unsigned char revision;
  58
  59/* Dog Food address - We use the game port address */
  60static unsigned short address;
  61
  62#define REG             0x2e    /* The register to read/write */
  63#define VAL             0x2f    /* The value to read/write */
  64
  65#define LDN             0x07    /* Register: Logical device select */
  66#define DEVID           0x20    /* Register: Device ID */
  67#define DEVREV          0x22    /* Register: Device Revision */
  68#define ACT_REG         0x30    /* LDN Register: Activation */
  69#define BASE_REG        0x60    /* LDN Register: Base address */
  70
  71#define IT8712F_DEVID   0x8712
  72
  73#define LDN_GPIO        0x07    /* GPIO and Watch Dog Timer */
  74#define LDN_GAME        0x09    /* Game Port */
  75
  76#define WDT_CONTROL     0x71    /* WDT Register: Control */
  77#define WDT_CONFIG      0x72    /* WDT Register: Configuration */
  78#define WDT_TIMEOUT     0x73    /* WDT Register: Timeout Value */
  79
  80#define WDT_RESET_GAME  0x10    /* Reset timer on read or write to game port */
  81#define WDT_RESET_KBD   0x20    /* Reset timer on keyboard interrupt */
  82#define WDT_RESET_MOUSE 0x40    /* Reset timer on mouse interrupt */
  83#define WDT_RESET_CIR   0x80    /* Reset timer on consumer IR interrupt */
  84
  85#define WDT_UNIT_SEC    0x80    /* If 0 in MINUTES */
  86
  87#define WDT_OUT_PWROK   0x10    /* Pulse PWROK on timeout */
  88#define WDT_OUT_KRST    0x40    /* Pulse reset on timeout */
  89
  90static int wdt_control_reg = WDT_RESET_GAME;
  91module_param(wdt_control_reg, int, 0);
  92MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
  93                "register. The default WDT_RESET_GAME resets the timer on "
  94                "game port reads that this driver generates. You can also "
  95                "use KBD, MOUSE or CIR if you have some external way to "
  96                "generate those interrupts.");
  97
  98static int superio_inb(int reg)
  99{
 100        outb(reg, REG);
 101        return inb(VAL);
 102}
 103
 104static void superio_outb(int val, int reg)
 105{
 106        outb(reg, REG);
 107        outb(val, VAL);
 108}
 109
 110static int superio_inw(int reg)
 111{
 112        int val;
 113        outb(reg++, REG);
 114        val = inb(VAL) << 8;
 115        outb(reg, REG);
 116        val |= inb(VAL);
 117        return val;
 118}
 119
 120static inline void superio_select(int ldn)
 121{
 122        outb(LDN, REG);
 123        outb(ldn, VAL);
 124}
 125
 126static inline int superio_enter(void)
 127{
 128        /*
 129         * Try to reserve REG and REG + 1 for exclusive access.
 130         */
 131        if (!request_muxed_region(REG, 2, NAME))
 132                return -EBUSY;
 133
 134        outb(0x87, REG);
 135        outb(0x01, REG);
 136        outb(0x55, REG);
 137        outb(0x55, REG);
 138        return 0;
 139}
 140
 141static inline void superio_exit(void)
 142{
 143        outb(0x02, REG);
 144        outb(0x02, VAL);
 145        release_region(REG, 2);
 146}
 147
 148static inline void it8712f_wdt_ping(void)
 149{
 150        if (wdt_control_reg & WDT_RESET_GAME)
 151                inb(address);
 152}
 153
 154static void it8712f_wdt_update_margin(void)
 155{
 156        int config = WDT_OUT_KRST | WDT_OUT_PWROK;
 157        int units = margin;
 158
 159        /* Switch to minutes precision if the configured margin
 160         * value does not fit within the register width.
 161         */
 162        if (units <= max_units) {
 163                config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
 164                pr_info("timer margin %d seconds\n", units);
 165        } else {
 166                units /= 60;
 167                pr_info("timer margin %d minutes\n", units);
 168        }
 169        superio_outb(config, WDT_CONFIG);
 170
 171        if (revision >= 0x08)
 172                superio_outb(units >> 8, WDT_TIMEOUT + 1);
 173        superio_outb(units, WDT_TIMEOUT);
 174}
 175
 176static int it8712f_wdt_get_status(void)
 177{
 178        if (superio_inb(WDT_CONTROL) & 0x01)
 179                return WDIOF_CARDRESET;
 180        else
 181                return 0;
 182}
 183
 184static int it8712f_wdt_enable(void)
 185{
 186        int ret = superio_enter();
 187        if (ret)
 188                return ret;
 189
 190        pr_debug("enabling watchdog timer\n");
 191        superio_select(LDN_GPIO);
 192
 193        superio_outb(wdt_control_reg, WDT_CONTROL);
 194
 195        it8712f_wdt_update_margin();
 196
 197        superio_exit();
 198
 199        it8712f_wdt_ping();
 200
 201        return 0;
 202}
 203
 204static int it8712f_wdt_disable(void)
 205{
 206        int ret = superio_enter();
 207        if (ret)
 208                return ret;
 209
 210        pr_debug("disabling watchdog timer\n");
 211        superio_select(LDN_GPIO);
 212
 213        superio_outb(0, WDT_CONFIG);
 214        superio_outb(0, WDT_CONTROL);
 215        if (revision >= 0x08)
 216                superio_outb(0, WDT_TIMEOUT + 1);
 217        superio_outb(0, WDT_TIMEOUT);
 218
 219        superio_exit();
 220        return 0;
 221}
 222
 223static int it8712f_wdt_notify(struct notifier_block *this,
 224                    unsigned long code, void *unused)
 225{
 226        if (code == SYS_HALT || code == SYS_POWER_OFF)
 227                if (!nowayout)
 228                        it8712f_wdt_disable();
 229
 230        return NOTIFY_DONE;
 231}
 232
 233static struct notifier_block it8712f_wdt_notifier = {
 234        .notifier_call = it8712f_wdt_notify,
 235};
 236
 237static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
 238                                        size_t len, loff_t *ppos)
 239{
 240        /* check for a magic close character */
 241        if (len) {
 242                size_t i;
 243
 244                it8712f_wdt_ping();
 245
 246                expect_close = 0;
 247                for (i = 0; i < len; ++i) {
 248                        char c;
 249                        if (get_user(c, data + i))
 250                                return -EFAULT;
 251                        if (c == 'V')
 252                                expect_close = 42;
 253                }
 254        }
 255
 256        return len;
 257}
 258
 259static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
 260                                                        unsigned long arg)
 261{
 262        void __user *argp = (void __user *)arg;
 263        int __user *p = argp;
 264        static const struct watchdog_info ident = {
 265                .identity = "IT8712F Watchdog",
 266                .firmware_version = 1,
 267                .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 268                                                WDIOF_MAGICCLOSE,
 269        };
 270        int value;
 271        int ret;
 272
 273        switch (cmd) {
 274        case WDIOC_GETSUPPORT:
 275                if (copy_to_user(argp, &ident, sizeof(ident)))
 276                        return -EFAULT;
 277                return 0;
 278        case WDIOC_GETSTATUS:
 279                ret = superio_enter();
 280                if (ret)
 281                        return ret;
 282                superio_select(LDN_GPIO);
 283
 284                value = it8712f_wdt_get_status();
 285
 286                superio_exit();
 287
 288                return put_user(value, p);
 289        case WDIOC_GETBOOTSTATUS:
 290                return put_user(0, p);
 291        case WDIOC_KEEPALIVE:
 292                it8712f_wdt_ping();
 293                return 0;
 294        case WDIOC_SETTIMEOUT:
 295                if (get_user(value, p))
 296                        return -EFAULT;
 297                if (value < 1)
 298                        return -EINVAL;
 299                if (value > (max_units * 60))
 300                        return -EINVAL;
 301                margin = value;
 302                ret = superio_enter();
 303                if (ret)
 304                        return ret;
 305                superio_select(LDN_GPIO);
 306
 307                it8712f_wdt_update_margin();
 308
 309                superio_exit();
 310                it8712f_wdt_ping();
 311                /* Fall through */
 312        case WDIOC_GETTIMEOUT:
 313                if (put_user(margin, p))
 314                        return -EFAULT;
 315                return 0;
 316        default:
 317                return -ENOTTY;
 318        }
 319}
 320
 321static int it8712f_wdt_open(struct inode *inode, struct file *file)
 322{
 323        int ret;
 324        /* only allow one at a time */
 325        if (test_and_set_bit(0, &wdt_open))
 326                return -EBUSY;
 327
 328        ret = it8712f_wdt_enable();
 329        if (ret)
 330                return ret;
 331        return nonseekable_open(inode, file);
 332}
 333
 334static int it8712f_wdt_release(struct inode *inode, struct file *file)
 335{
 336        if (expect_close != 42) {
 337                pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 338        } else if (!nowayout) {
 339                if (it8712f_wdt_disable())
 340                        pr_warn("Watchdog disable failed\n");
 341        }
 342        expect_close = 0;
 343        clear_bit(0, &wdt_open);
 344
 345        return 0;
 346}
 347
 348static const struct file_operations it8712f_wdt_fops = {
 349        .owner = THIS_MODULE,
 350        .llseek = no_llseek,
 351        .write = it8712f_wdt_write,
 352        .unlocked_ioctl = it8712f_wdt_ioctl,
 353        .open = it8712f_wdt_open,
 354        .release = it8712f_wdt_release,
 355};
 356
 357static struct miscdevice it8712f_wdt_miscdev = {
 358        .minor = WATCHDOG_MINOR,
 359        .name = "watchdog",
 360        .fops = &it8712f_wdt_fops,
 361};
 362
 363static int __init it8712f_wdt_find(unsigned short *address)
 364{
 365        int err = -ENODEV;
 366        int chip_type;
 367        int ret = superio_enter();
 368        if (ret)
 369                return ret;
 370
 371        chip_type = superio_inw(DEVID);
 372        if (chip_type != IT8712F_DEVID)
 373                goto exit;
 374
 375        superio_select(LDN_GAME);
 376        superio_outb(1, ACT_REG);
 377        if (!(superio_inb(ACT_REG) & 0x01)) {
 378                pr_err("Device not activated, skipping\n");
 379                goto exit;
 380        }
 381
 382        *address = superio_inw(BASE_REG);
 383        if (*address == 0) {
 384                pr_err("Base address not set, skipping\n");
 385                goto exit;
 386        }
 387
 388        err = 0;
 389        revision = superio_inb(DEVREV) & 0x0f;
 390
 391        /* Later revisions have 16-bit values per datasheet 0.9.1 */
 392        if (revision >= 0x08)
 393                max_units = 65535;
 394
 395        if (margin > (max_units * 60))
 396                margin = (max_units * 60);
 397
 398        pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
 399                chip_type, revision, *address);
 400
 401exit:
 402        superio_exit();
 403        return err;
 404}
 405
 406static int __init it8712f_wdt_init(void)
 407{
 408        int err = 0;
 409
 410        if (it8712f_wdt_find(&address))
 411                return -ENODEV;
 412
 413        if (!request_region(address, 1, "IT8712F Watchdog")) {
 414                pr_warn("watchdog I/O region busy\n");
 415                return -EBUSY;
 416        }
 417
 418        err = it8712f_wdt_disable();
 419        if (err) {
 420                pr_err("unable to disable watchdog timer\n");
 421                goto out;
 422        }
 423
 424        err = register_reboot_notifier(&it8712f_wdt_notifier);
 425        if (err) {
 426                pr_err("unable to register reboot notifier\n");
 427                goto out;
 428        }
 429
 430        err = misc_register(&it8712f_wdt_miscdev);
 431        if (err) {
 432                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 433                       WATCHDOG_MINOR, err);
 434                goto reboot_out;
 435        }
 436
 437        return 0;
 438
 439
 440reboot_out:
 441        unregister_reboot_notifier(&it8712f_wdt_notifier);
 442out:
 443        release_region(address, 1);
 444        return err;
 445}
 446
 447static void __exit it8712f_wdt_exit(void)
 448{
 449        misc_deregister(&it8712f_wdt_miscdev);
 450        unregister_reboot_notifier(&it8712f_wdt_notifier);
 451        release_region(address, 1);
 452}
 453
 454module_init(it8712f_wdt_init);
 455module_exit(it8712f_wdt_exit);
 456
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