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/*

 * mpc83xx_wdt.c - MPC83xx watchdog userspace interface

 *

 * Authors: Dave Updegraff <dave@cray.org>

 *          Kumar Gala <galak@kernel.crashing.org>

 *              Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>

 *                              ..and from sc520_wdt

 *

 * Note: it appears that you can only actually ENABLE or DISABLE the thing

 * once after POR. Once enabled, you cannot disable, and vice versa.

 *

 * 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.

 */

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/miscdevice.h>

#include <linux/platform_device.h>

#include <linux/module.h>

#include <linux/watchdog.h>

#include <asm/io.h>

#include <asm/uaccess.h>

struct mpc83xx_wdt {

        __be32 res0;

        __be32 swcrr; /* System watchdog control register */

#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */

#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */

#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/

#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */

        __be32 swcnr; /* System watchdog count register */

        u8 res1[2];

        __be16 swsrr; /* System watchdog service register */

        u8 res2[0xF0];

};

static struct mpc83xx_wdt __iomem *wd_base;

static u16 timeout = 0xffff;

module_param(timeout, ushort, 0);

MODULE_PARM_DESC(timeout, "Watchdog timeout in ticks. (0<timeout<65536, default=65535");

static int reset = 1;

module_param(reset, bool, 0);

MODULE_PARM_DESC(reset, "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");

/*

 * We always prescale, but if someone really doesn't want to they can set this

 * to 0

 */

static int prescale = 1;

static unsigned int timeout_sec;

static unsigned long wdt_is_open;

static DEFINE_SPINLOCK(wdt_spinlock);

static void mpc83xx_wdt_keepalive(void)

{

        /* Ping the WDT */

        spin_lock(&wdt_spinlock);

        out_be16(&wd_base->swsrr, 0x556c);

        out_be16(&wd_base->swsrr, 0xaa39);

        spin_unlock(&wdt_spinlock);

}

static ssize_t mpc83xx_wdt_write(struct file *file, const char __user *buf,

                                 size_t count, loff_t *ppos)

{

        if (count)

                mpc83xx_wdt_keepalive();

        return count;

}

static int mpc83xx_wdt_open(struct inode *inode, struct file *file)

{

        u32 tmp = SWCRR_SWEN;

        if (test_and_set_bit(0, &wdt_is_open))

                return -EBUSY;

        /* Once we start the watchdog we can't stop it */

        __module_get(THIS_MODULE);

        /* Good, fire up the show */

        if (prescale)

                tmp |= SWCRR_SWPR;

        if (reset)

                tmp |= SWCRR_SWRI;

        tmp |= timeout << 16;

        out_be32(&wd_base->swcrr, tmp);

        return nonseekable_open(inode, file);

}

static int mpc83xx_wdt_release(struct inode *inode, struct file *file)

{

        printk(KERN_CRIT "Unexpected close, not stopping watchdog!\n");

        mpc83xx_wdt_keepalive();

        clear_bit(0, &wdt_is_open);

        return 0;

}

static int mpc83xx_wdt_ioctl(struct inode *inode, struct file *file,

                                unsigned int cmd, unsigned long arg)

{

        void __user *argp = (void __user *)arg;

        int __user *p = argp;

        static struct watchdog_info ident = {

                .options = WDIOF_KEEPALIVEPING,

                .firmware_version = 1,

                .identity = "MPC83xx",

        };

        switch (cmd) {

        case WDIOC_GETSUPPORT:

                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;

        case WDIOC_GETSTATUS:

        case WDIOC_GETBOOTSTATUS:

                return put_user(0, p);

        case WDIOC_KEEPALIVE:

                mpc83xx_wdt_keepalive();

                return 0;

        case WDIOC_GETTIMEOUT:

                return put_user(timeout_sec, p);

        default:

                return -ENOTTY;

        }

}

static const struct file_operations mpc83xx_wdt_fops = {

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .write          = mpc83xx_wdt_write,

        .ioctl          = mpc83xx_wdt_ioctl,

        .open           = mpc83xx_wdt_open,

        .release        = mpc83xx_wdt_release,

};

static struct miscdevice mpc83xx_wdt_miscdev = {

        .minor  = WATCHDOG_MINOR,

        .name   = "watchdog",

        .fops   = &mpc83xx_wdt_fops,

};

static int __devinit mpc83xx_wdt_probe(struct platform_device *dev)

{

        struct resource *r;

        int ret;

        unsigned int *freq = dev->dev.platform_data;

        /* get a pointer to the register memory */

        r = platform_get_resource(dev, IORESOURCE_MEM, 0);

        if (!r) {

                ret = -ENODEV;

                goto err_out;

        }

        wd_base = ioremap(r->start, sizeof (struct mpc83xx_wdt));

        if (wd_base == NULL) {

                ret = -ENOMEM;

                goto err_out;

        }

        ret = misc_register(&mpc83xx_wdt_miscdev);

        if (ret) {

                printk(KERN_ERR "cannot register miscdev on minor=%d "

                                "(err=%d)\n",

                                WATCHDOG_MINOR, ret);

                goto err_unmap;

        }

        /* Calculate the timeout in seconds */

        if (prescale)

                timeout_sec = (timeout * 0x10000) / (*freq);

        else

                timeout_sec = timeout / (*freq);

        printk(KERN_INFO "WDT driver for MPC83xx initialized. "

                "mode:%s timeout=%d (%d seconds)\n",

                reset ? "reset":"interrupt", timeout, timeout_sec);

        return 0;

err_unmap:

        iounmap(wd_base);

err_out:

        return ret;

}

static int __devexit mpc83xx_wdt_remove(struct platform_device *dev)

{

        misc_deregister(&mpc83xx_wdt_miscdev);

        iounmap(wd_base);

        return 0;

}

static struct platform_driver mpc83xx_wdt_driver = {

        .probe          = mpc83xx_wdt_probe,

        .remove         = __devexit_p(mpc83xx_wdt_remove),

        .driver         = {

                .name   = "mpc83xx_wdt",

        },

};

static int __init mpc83xx_wdt_init(void)

{

        return platform_driver_register(&mpc83xx_wdt_driver);

}

static void __exit mpc83xx_wdt_exit(void)

{

        platform_driver_unregister(&mpc83xx_wdt_driver);

}

module_init(mpc83xx_wdt_init);

module_exit(mpc83xx_wdt_exit);

MODULE_AUTHOR("Dave Updegraff, Kumar Gala");

MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx uProcessor");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);