w83697hf_wdt.c

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/*
 *  w83697hf/hg WDT driver
 *
 *  (c) Copyright 2006 Samuel Tardieu <[email protected]>
 *  (c) Copyright 2006 Marcus Junker <[email protected]>
 *
 *  Based on w83627hf_wdt.c which is based on advantechwdt.c
 *  which is based on wdt.c.
 *  Original copyright messages:
 *
 *  (c) Copyright 2003 Pádraig Brady <[email protected]>
 *
 *  (c) Copyright 2000-2001 Marek Michalkiewicz <[email protected]>
 *
 *  (c) Copyright 1996 Alan Cox <[email protected]>,
 *                      All Rights Reserved.
 *
 *  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.
 *
 *  Neither Marcus Junker nor ANDURAS AG admit liability nor provide
 *  warranty for any of this software. This material is provided
 *  "AS-IS" and at no charge.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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


#define WATCHDOG_NAME "w83697hf/hg WDT"
#define WATCHDOG_TIMEOUT 60     /* 60 sec default timeout */
#define WATCHDOG_EARLY_DISABLE 1    /* Disable until userland kicks in */

static unsigned long wdt_is_open;
static char expect_close;
static DEFINE_SPINLOCK(io_lock);

/* You must set this - there is no sane way to probe for this board. */
static int wdt_io = 0x2e;
module_param(wdt_io, int, 0);
MODULE_PARM_DESC(wdt_io,
        "w83697hf/hg WDT io port (default 0x2e, 0 = autodetect)");

static int timeout = WATCHDOG_TIMEOUT;  /* in seconds */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
    "Watchdog timeout in seconds. 1<= timeout <=255 (default="
                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
    "Watchdog cannot be stopped once started (default="
                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

static int early_disable = WATCHDOG_EARLY_DISABLE;
module_param(early_disable, int, 0);
MODULE_PARM_DESC(early_disable,
    "Watchdog gets disabled at boot time (default="
                __MODULE_STRING(WATCHDOG_EARLY_DISABLE) ")");

/*
 *  Kernel methods.
 */

#define W83697HF_EFER (wdt_io + 0)  /* Extended Function Enable Register */
#define W83697HF_EFIR (wdt_io + 0)  /* Extended Function Index Register
                            (same as EFER) */
#define W83697HF_EFDR (wdt_io + 1)  /* Extended Function Data Register */

static inline void w83697hf_unlock(void)
{
    outb_p(0x87, W83697HF_EFER);    /* Enter extended function mode */
    outb_p(0x87, W83697HF_EFER);    /* Again according to manual */
}

static inline void w83697hf_lock(void)
{
    outb_p(0xAA, W83697HF_EFER);    /* Leave extended function mode */
}

/*
 *  The three functions w83697hf_get_reg(), w83697hf_set_reg() and
 *  w83697hf_write_timeout() must be called with the device unlocked.
 */

static unsigned char w83697hf_get_reg(unsigned char reg)
{
    outb_p(reg, W83697HF_EFIR);
    return inb_p(W83697HF_EFDR);
}

static void w83697hf_set_reg(unsigned char reg, unsigned char data)
{
    outb_p(reg, W83697HF_EFIR);
    outb_p(data, W83697HF_EFDR);
}

static void w83697hf_write_timeout(int timeout)
{
    /* Write Timeout counter to CRF4 */
    w83697hf_set_reg(0xF4, timeout);
}

static void w83697hf_select_wdt(void)
{
    w83697hf_unlock();
    w83697hf_set_reg(0x07, 0x08);   /* Switch to logic device 8 (GPIO2) */
}

static inline void w83697hf_deselect_wdt(void)
{
    w83697hf_lock();
}

static void w83697hf_init(void)
{
    unsigned char bbuf;

    w83697hf_select_wdt();

    bbuf = w83697hf_get_reg(0x29);
    bbuf &= ~0x60;
    bbuf |= 0x20;

    /* Set pin 119 to WDTO# mode (= CR29, WDT0) */
    w83697hf_set_reg(0x29, bbuf);

    bbuf = w83697hf_get_reg(0xF3);
    bbuf &= ~0x04;
    w83697hf_set_reg(0xF3, bbuf);   /* Count mode is seconds */

    w83697hf_deselect_wdt();
}

static void wdt_ping(void)
{
    spin_lock(&io_lock);
    w83697hf_select_wdt();

    w83697hf_write_timeout(timeout);

    w83697hf_deselect_wdt();
    spin_unlock(&io_lock);
}

static void wdt_enable(void)
{
    spin_lock(&io_lock);
    w83697hf_select_wdt();

    w83697hf_write_timeout(timeout);
    w83697hf_set_reg(0x30, 1);  /* Enable timer */

    w83697hf_deselect_wdt();
    spin_unlock(&io_lock);
}

static void wdt_disable(void)
{
    spin_lock(&io_lock);
    w83697hf_select_wdt();

    w83697hf_set_reg(0x30, 0);  /* Disable timer */
    w83697hf_write_timeout(0);

    w83697hf_deselect_wdt();
    spin_unlock(&io_lock);
}

static unsigned char wdt_running(void)
{
    unsigned char t;

    spin_lock(&io_lock);
    w83697hf_select_wdt();

    t = w83697hf_get_reg(0xF4); /* Read timer */

    w83697hf_deselect_wdt();
    spin_unlock(&io_lock);

    return t;
}

static int wdt_set_heartbeat(int t)
{
    if (t < 1 || t > 255)
        return -EINVAL;

    timeout = t;
    return 0;
}

static ssize_t wdt_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
    if (count) {
        if (!nowayout) {
            size_t i;

            expect_close = 0;

            for (i = 0; i != count; i++) {
                char c;
                if (get_user(c, buf + i))
                    return -EFAULT;
                if (c == 'V')
                    expect_close = 42;
            }
        }
        wdt_ping();
    }
    return count;
}

static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int new_timeout;
    static const struct watchdog_info ident = {
        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
                            | WDIOF_MAGICCLOSE,
        .firmware_version = 1,
        .identity = "W83697HF WDT",
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            return -EFAULT;
        break;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);

    case WDIOC_SETOPTIONS:
    {
        int options, retval = -EINVAL;

        if (get_user(options, p))
            return -EFAULT;

        if (options & WDIOS_DISABLECARD) {
            wdt_disable();
            retval = 0;
        }

        if (options & WDIOS_ENABLECARD) {
            wdt_enable();
            retval = 0;
        }

        return retval;
    }

    case WDIOC_KEEPALIVE:
        wdt_ping();
        break;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_timeout, p))
            return -EFAULT;
        if (wdt_set_heartbeat(new_timeout))
            return -EINVAL;
        wdt_ping();
        /* Fall */

    case WDIOC_GETTIMEOUT:
        return put_user(timeout, p);

    default:
        return -ENOTTY;
    }
    return 0;
}

static int wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &wdt_is_open))
        return -EBUSY;
    /*
     *  Activate
     */

    wdt_enable();
    return nonseekable_open(inode, file);
}

static int wdt_close(struct inode *inode, struct file *file)
{
    if (expect_close == 42)
        wdt_disable();
    else {
        pr_crit("Unexpected close, not stopping watchdog!\n");
        wdt_ping();
    }
    expect_close = 0;
    clear_bit(0, &wdt_is_open);
    return 0;
}

/*
 *  Notifier for system down
 */

static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
    void *unused)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        wdt_disable();  /* Turn the WDT off */

    return NOTIFY_DONE;
}

/*
 *  Kernel Interfaces
 */

static const struct file_operations wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = wdt_write,
    .unlocked_ioctl = wdt_ioctl,
    .open       = wdt_open,
    .release    = wdt_close,
};

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

/*
 *  The WDT needs to learn about soft shutdowns in order to
 *  turn the timebomb registers off.
 */

static struct notifier_block wdt_notifier = {
    .notifier_call = wdt_notify_sys,
};

static int w83697hf_check_wdt(void)
{
    if (!request_region(wdt_io, 2, WATCHDOG_NAME)) {
        pr_err("I/O address 0x%x already in use\n", wdt_io);
        return -EIO;
    }

    pr_debug("Looking for watchdog at address 0x%x\n", wdt_io);
    w83697hf_unlock();
    if (w83697hf_get_reg(0x20) == 0x60) {
        pr_info("watchdog found at address 0x%x\n", wdt_io);
        w83697hf_lock();
        return 0;
    }
    /* Reprotect in case it was a compatible device */
    w83697hf_lock();

    pr_info("watchdog not found at address 0x%x\n", wdt_io);
    release_region(wdt_io, 2);
    return -EIO;
}

static int w83697hf_ioports[] = { 0x2e, 0x4e, 0x00 };

static int __init wdt_init(void)
{
    int ret, i, found = 0;

    pr_info("WDT driver for W83697HF/HG initializing\n");

    if (wdt_io == 0) {
        /* we will autodetect the W83697HF/HG watchdog */
        for (i = 0; ((!found) && (w83697hf_ioports[i] != 0)); i++) {
            wdt_io = w83697hf_ioports[i];
            if (!w83697hf_check_wdt())
                found++;
        }
    } else {
        if (!w83697hf_check_wdt())
            found++;
    }

    if (!found) {
        pr_err("No W83697HF/HG could be found\n");
        ret = -EIO;
        goto out;
    }

    w83697hf_init();
    if (early_disable) {
        if (wdt_running())
            pr_warn("Stopping previously enabled watchdog until userland kicks in\n");
        wdt_disable();
    }

    if (wdt_set_heartbeat(timeout)) {
        wdt_set_heartbeat(WATCHDOG_TIMEOUT);
        pr_info("timeout value must be 1 <= timeout <= 255, using %d\n",
            WATCHDOG_TIMEOUT);
    }

    ret = register_reboot_notifier(&wdt_notifier);
    if (ret != 0) {
        pr_err("cannot register reboot notifier (err=%d)\n", ret);
        goto unreg_regions;
    }

    ret = misc_register(&wdt_miscdev);
    if (ret != 0) {
        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
               WATCHDOG_MINOR, ret);
        goto unreg_reboot;
    }

    pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
        timeout, nowayout);

out:
    return ret;
unreg_reboot:
    unregister_reboot_notifier(&wdt_notifier);
unreg_regions:
    release_region(wdt_io, 2);
    goto out;
}

static void __exit wdt_exit(void)
{
    misc_deregister(&wdt_miscdev);
    unregister_reboot_notifier(&wdt_notifier);
    release_region(wdt_io, 2);
}

module_init(wdt_init);
module_exit(wdt_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marcus Junker <[email protected]>, "
        "Samuel Tardieu <[email protected]>");
MODULE_DESCRIPTION("w83697hf/hg WDT driver");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);