it8712f_wdt.c

Go to the documentation of this file.

/*
 *  IT8712F "Smart Guardian" Watchdog support
 *
 *  Copyright (c) 2006-2007 Jorge Boncompte - DTI2 <[email protected]>
 *
 *  Based on info and code taken from:
 *
 *  drivers/char/watchdog/scx200_wdt.c
 *  drivers/hwmon/it87.c
 *  IT8712F EC-LPC I/O Preliminary Specification 0.8.2
 *  IT8712F EC-LPC I/O Preliminary Specification 0.9.3
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation; either version 2 of the
 *  License, or (at your option) any later version.
 *
 *  The author(s) of this software shall not be held liable for damages
 *  of any nature resulting due to the use of this software. This
 *  software is provided AS-IS with no warranties.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/ioport.h>

#define DEBUG
#define NAME "it8712f_wdt"

MODULE_AUTHOR("Jorge Boncompte - DTI2 <[email protected]>");
MODULE_DESCRIPTION("IT8712F Watchdog Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

static int max_units = 255;
static int margin = 60;     /* in seconds */
module_param(margin, int, 0);
MODULE_PARM_DESC(margin, "Watchdog margin in seconds");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");

static unsigned long wdt_open;
static unsigned expect_close;
static unsigned char revision;

/* Dog Food address - We use the game port address */
static unsigned short address;

#define REG     0x2e    /* The register to read/write */
#define VAL     0x2f    /* The value to read/write */

#define LDN     0x07    /* Register: Logical device select */
#define DEVID       0x20    /* Register: Device ID */
#define DEVREV      0x22    /* Register: Device Revision */
#define ACT_REG     0x30    /* LDN Register: Activation */
#define BASE_REG    0x60    /* LDN Register: Base address */

#define IT8712F_DEVID   0x8712

#define LDN_GPIO    0x07    /* GPIO and Watch Dog Timer */
#define LDN_GAME    0x09    /* Game Port */

#define WDT_CONTROL 0x71    /* WDT Register: Control */
#define WDT_CONFIG  0x72    /* WDT Register: Configuration */
#define WDT_TIMEOUT 0x73    /* WDT Register: Timeout Value */

#define WDT_RESET_GAME  0x10    /* Reset timer on read or write to game port */
#define WDT_RESET_KBD   0x20    /* Reset timer on keyboard interrupt */
#define WDT_RESET_MOUSE 0x40    /* Reset timer on mouse interrupt */
#define WDT_RESET_CIR   0x80    /* Reset timer on consumer IR interrupt */

#define WDT_UNIT_SEC    0x80    /* If 0 in MINUTES */

#define WDT_OUT_PWROK   0x10    /* Pulse PWROK on timeout */
#define WDT_OUT_KRST    0x40    /* Pulse reset on timeout */

static int wdt_control_reg = WDT_RESET_GAME;
module_param(wdt_control_reg, int, 0);
MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
        "register. The default WDT_RESET_GAME resets the timer on "
        "game port reads that this driver generates. You can also "
        "use KBD, MOUSE or CIR if you have some external way to "
        "generate those interrupts.");

static int superio_inb(int reg)
{
    outb(reg, REG);
    return inb(VAL);
}

static void superio_outb(int val, int reg)
{
    outb(reg, REG);
    outb(val, VAL);
}

static int superio_inw(int reg)
{
    int val;
    outb(reg++, REG);
    val = inb(VAL) << 8;
    outb(reg, REG);
    val |= inb(VAL);
    return val;
}

static inline void superio_select(int ldn)
{
    outb(LDN, REG);
    outb(ldn, VAL);
}

static inline int superio_enter(void)
{
    /*
     * Try to reserve REG and REG + 1 for exclusive access.
     */
    if (!request_muxed_region(REG, 2, NAME))
        return -EBUSY;

    outb(0x87, REG);
    outb(0x01, REG);
    outb(0x55, REG);
    outb(0x55, REG);
    return 0;
}

static inline void superio_exit(void)
{
    outb(0x02, REG);
    outb(0x02, VAL);
    release_region(REG, 2);
}

static inline void it8712f_wdt_ping(void)
{
    if (wdt_control_reg & WDT_RESET_GAME)
        inb(address);
}

static void it8712f_wdt_update_margin(void)
{
    int config = WDT_OUT_KRST | WDT_OUT_PWROK;
    int units = margin;

    /* Switch to minutes precision if the configured margin
     * value does not fit within the register width.
     */
    if (units <= max_units) {
        config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
        pr_info("timer margin %d seconds\n", units);
    } else {
        units /= 60;
        pr_info("timer margin %d minutes\n", units);
    }
    superio_outb(config, WDT_CONFIG);

    if (revision >= 0x08)
        superio_outb(units >> 8, WDT_TIMEOUT + 1);
    superio_outb(units, WDT_TIMEOUT);
}

static int it8712f_wdt_get_status(void)
{
    if (superio_inb(WDT_CONTROL) & 0x01)
        return WDIOF_CARDRESET;
    else
        return 0;
}

static int it8712f_wdt_enable(void)
{
    int ret = superio_enter();
    if (ret)
        return ret;

    pr_debug("enabling watchdog timer\n");
    superio_select(LDN_GPIO);

    superio_outb(wdt_control_reg, WDT_CONTROL);

    it8712f_wdt_update_margin();

    superio_exit();

    it8712f_wdt_ping();

    return 0;
}

static int it8712f_wdt_disable(void)
{
    int ret = superio_enter();
    if (ret)
        return ret;

    pr_debug("disabling watchdog timer\n");
    superio_select(LDN_GPIO);

    superio_outb(0, WDT_CONFIG);
    superio_outb(0, WDT_CONTROL);
    if (revision >= 0x08)
        superio_outb(0, WDT_TIMEOUT + 1);
    superio_outb(0, WDT_TIMEOUT);

    superio_exit();
    return 0;
}

static int it8712f_wdt_notify(struct notifier_block *this,
            unsigned long code, void *unused)
{
    if (code == SYS_HALT || code == SYS_POWER_OFF)
        if (!nowayout)
            it8712f_wdt_disable();

    return NOTIFY_DONE;
}

static struct notifier_block it8712f_wdt_notifier = {
    .notifier_call = it8712f_wdt_notify,
};

static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
                    size_t len, loff_t *ppos)
{
    /* check for a magic close character */
    if (len) {
        size_t i;

        it8712f_wdt_ping();

        expect_close = 0;
        for (i = 0; i < len; ++i) {
            char c;
            if (get_user(c, data + i))
                return -EFAULT;
            if (c == 'V')
                expect_close = 42;
        }
    }

    return len;
}

static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    static const struct watchdog_info ident = {
        .identity = "IT8712F Watchdog",
        .firmware_version = 1,
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
                        WDIOF_MAGICCLOSE,
    };
    int value;
    int ret;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            return -EFAULT;
        return 0;
    case WDIOC_GETSTATUS:
        ret = superio_enter();
        if (ret)
            return ret;
        superio_select(LDN_GPIO);

        value = it8712f_wdt_get_status();

        superio_exit();

        return put_user(value, p);
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);
    case WDIOC_KEEPALIVE:
        it8712f_wdt_ping();
        return 0;
    case WDIOC_SETTIMEOUT:
        if (get_user(value, p))
            return -EFAULT;
        if (value < 1)
            return -EINVAL;
        if (value > (max_units * 60))
            return -EINVAL;
        margin = value;
        ret = superio_enter();
        if (ret)
            return ret;
        superio_select(LDN_GPIO);

        it8712f_wdt_update_margin();

        superio_exit();
        it8712f_wdt_ping();
        /* Fall through */
    case WDIOC_GETTIMEOUT:
        if (put_user(margin, p))
            return -EFAULT;
        return 0;
    default:
        return -ENOTTY;
    }
}

static int it8712f_wdt_open(struct inode *inode, struct file *file)
{
    int ret;
    /* only allow one at a time */
    if (test_and_set_bit(0, &wdt_open))
        return -EBUSY;

    ret = it8712f_wdt_enable();
    if (ret)
        return ret;
    return nonseekable_open(inode, file);
}

static int it8712f_wdt_release(struct inode *inode, struct file *file)
{
    if (expect_close != 42) {
        pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
    } else if (!nowayout) {
        if (it8712f_wdt_disable())
            pr_warn("Watchdog disable failed\n");
    }
    expect_close = 0;
    clear_bit(0, &wdt_open);

    return 0;
}

static const struct file_operations it8712f_wdt_fops = {
    .owner = THIS_MODULE,
    .llseek = no_llseek,
    .write = it8712f_wdt_write,
    .unlocked_ioctl = it8712f_wdt_ioctl,
    .open = it8712f_wdt_open,
    .release = it8712f_wdt_release,
};

static struct miscdevice it8712f_wdt_miscdev = {
    .minor = WATCHDOG_MINOR,
    .name = "watchdog",
    .fops = &it8712f_wdt_fops,
};

static int __init it8712f_wdt_find(unsigned short *address)
{
    int err = -ENODEV;
    int chip_type;
    int ret = superio_enter();
    if (ret)
        return ret;

    chip_type = superio_inw(DEVID);
    if (chip_type != IT8712F_DEVID)
        goto exit;

    superio_select(LDN_GAME);
    superio_outb(1, ACT_REG);
    if (!(superio_inb(ACT_REG) & 0x01)) {
        pr_err("Device not activated, skipping\n");
        goto exit;
    }

    *address = superio_inw(BASE_REG);
    if (*address == 0) {
        pr_err("Base address not set, skipping\n");
        goto exit;
    }

    err = 0;
    revision = superio_inb(DEVREV) & 0x0f;

    /* Later revisions have 16-bit values per datasheet 0.9.1 */
    if (revision >= 0x08)
        max_units = 65535;

    if (margin > (max_units * 60))
        margin = (max_units * 60);

    pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
        chip_type, revision, *address);

exit:
    superio_exit();
    return err;
}

static int __init it8712f_wdt_init(void)
{
    int err = 0;

    if (it8712f_wdt_find(&address))
        return -ENODEV;

    if (!request_region(address, 1, "IT8712F Watchdog")) {
        pr_warn("watchdog I/O region busy\n");
        return -EBUSY;
    }

    err = it8712f_wdt_disable();
    if (err) {
        pr_err("unable to disable watchdog timer\n");
        goto out;
    }

    err = register_reboot_notifier(&it8712f_wdt_notifier);
    if (err) {
        pr_err("unable to register reboot notifier\n");
        goto out;
    }

    err = misc_register(&it8712f_wdt_miscdev);
    if (err) {
        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
               WATCHDOG_MINOR, err);
        goto reboot_out;
    }

    return 0;


reboot_out:
    unregister_reboot_notifier(&it8712f_wdt_notifier);
out:
    release_region(address, 1);
    return err;
}

static void __exit it8712f_wdt_exit(void)
{
    misc_deregister(&it8712f_wdt_miscdev);
    unregister_reboot_notifier(&it8712f_wdt_notifier);
    release_region(address, 1);
}

module_init(it8712f_wdt_init);
module_exit(it8712f_wdt_exit);