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/*

 * Watchdog driver for Kendin/Micrel KS8695.

 *

 * (C) 2007 Andrew Victor

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#include <linux/bitops.h>

#include <linux/errno.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/miscdevice.h>

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/platform_device.h>

#include <linux/types.h>

#include <linux/watchdog.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/arch/regs-timer.h>

#define WDT_DEFAULT_TIME        5       /* seconds */

#define WDT_MAX_TIME            171     /* seconds */

static int wdt_time = WDT_DEFAULT_TIME;

static int nowayout = WATCHDOG_NOWAYOUT;

module_param(wdt_time, int, 0);

MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")");

#ifdef CONFIG_WATCHDOG_NOWAYOUT

module_param(nowayout, int, 0);

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

#endif

static unsigned long ks8695wdt_busy;

/* ......................................................................... */

/*

 * Disable the watchdog.

 */

static void inline ks8695_wdt_stop(void)

{

        unsigned long tmcon;

        /* disable timer0 */

        tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);

        __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

}

/*

 * Enable and reset the watchdog.

 */

static void inline ks8695_wdt_start(void)

{

        unsigned long tmcon;

        unsigned long tval = wdt_time * CLOCK_TICK_RATE;

        /* disable timer0 */

        tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);

        __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

        /* program timer0 */

        __raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);

        /* re-enable timer0 */

        tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);

        __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

}

/*

 * Reload the watchdog timer.  (ie, pat the watchdog)

 */

static void inline ks8695_wdt_reload(void)

{

        unsigned long tmcon;

        /* disable, then re-enable timer0 */

        tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);

        __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

        __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

}

/*

 * Change the watchdog time interval.

 */

static int ks8695_wdt_settimeout(int new_time)

{

        /*

         * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz

         *

         * Since WDV is a 16-bit counter, the maximum period is

         * 65536 / 0.256 = 256 seconds.

         */

        if ((new_time <= 0) || (new_time > WDT_MAX_TIME))

                return -EINVAL;

        /* Set new watchdog time. It will be used when ks8695_wdt_start() is called. */

        wdt_time = new_time;

        return 0;

}

/* ......................................................................... */

/*

 * Watchdog device is opened, and watchdog starts running.

 */

static int ks8695_wdt_open(struct inode *inode, struct file *file)

{

        if (test_and_set_bit(0, &ks8695wdt_busy))

                return -EBUSY;

        ks8695_wdt_start();

        return nonseekable_open(inode, file);

}

/*

 * Close the watchdog device.

 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also

 *  disabled.

 */

static int ks8695_wdt_close(struct inode *inode, struct file *file)

{

        if (!nowayout)

                ks8695_wdt_stop();      /* Disable the watchdog when file is closed */

        clear_bit(0, &ks8695wdt_busy);

        return 0;

}

static struct watchdog_info ks8695_wdt_info = {

        .identity       = "ks8695 watchdog",

        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,

};

/*

 * Handle commands from user-space.

 */

static int ks8695_wdt_ioctl(struct inode *inode, struct file *file,

                unsigned int cmd, unsigned long arg)

{

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

        int __user *p = argp;

        int new_value;

        switch(cmd) {

                case WDIOC_KEEPALIVE:

                        ks8695_wdt_reload();    /* pat the watchdog */

                        return 0;

                case WDIOC_GETSUPPORT:

                        return copy_to_user(argp, &ks8695_wdt_info, sizeof(ks8695_wdt_info)) ? -EFAULT : 0;

                case WDIOC_SETTIMEOUT:

                        if (get_user(new_value, p))

                                return -EFAULT;

                        if (ks8695_wdt_settimeout(new_value))

                                return -EINVAL;

                        /* Enable new time value */

                        ks8695_wdt_start();

                        /* Return current value */

                        return put_user(wdt_time, p);

                case WDIOC_GETTIMEOUT:

                        return put_user(wdt_time, p);

                case WDIOC_GETSTATUS:

                case WDIOC_GETBOOTSTATUS:

                        return put_user(0, p);

                case WDIOC_SETOPTIONS:

                        if (get_user(new_value, p))

                                return -EFAULT;

                        if (new_value & WDIOS_DISABLECARD)

                                ks8695_wdt_stop();

                        if (new_value & WDIOS_ENABLECARD)

                                ks8695_wdt_start();

                        return 0;

                default:

                        return -ENOTTY;

        }

}

/*

 * Pat the watchdog whenever device is written to.

 */

static ssize_t ks8695_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)

{

        ks8695_wdt_reload();            /* pat the watchdog */

        return len;

}

/* ......................................................................... */

static const struct file_operations ks8695wdt_fops = {

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .ioctl          = ks8695_wdt_ioctl,

        .open           = ks8695_wdt_open,

        .release        = ks8695_wdt_close,

        .write          = ks8695_wdt_write,

};

static struct miscdevice ks8695wdt_miscdev = {

        .minor          = WATCHDOG_MINOR,

        .name           = "watchdog",

        .fops           = &ks8695wdt_fops,

};

static int __init ks8695wdt_probe(struct platform_device *pdev)

{

        int res;

        if (ks8695wdt_miscdev.parent)

                return -EBUSY;

        ks8695wdt_miscdev.parent = &pdev->dev;

        res = misc_register(&ks8695wdt_miscdev);

        if (res)

                return res;

        printk("KS8695 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : "");

        return 0;

}

static int __exit ks8695wdt_remove(struct platform_device *pdev)

{

        int res;

        res = misc_deregister(&ks8695wdt_miscdev);

        if (!res)

                ks8695wdt_miscdev.parent = NULL;

        return res;

}

static void ks8695wdt_shutdown(struct platform_device *pdev)

{

        ks8695_wdt_stop();

}

#ifdef CONFIG_PM

static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)

{

        ks8695_wdt_stop();

        return 0;

}

static int ks8695wdt_resume(struct platform_device *pdev)

{

        if (ks8695wdt_busy)

                ks8695_wdt_start();

        return 0;

}

#else

#define ks8695wdt_suspend NULL

#define ks8695wdt_resume        NULL

#endif

static struct platform_driver ks8695wdt_driver = {

        .probe          = ks8695wdt_probe,

        .remove         = __exit_p(ks8695wdt_remove),

        .shutdown       = ks8695wdt_shutdown,

        .suspend        = ks8695wdt_suspend,

        .resume         = ks8695wdt_resume,

        .driver         = {

                .name   = "ks8695_wdt",

                .owner  = THIS_MODULE,

        },

};

static int __init ks8695_wdt_init(void)

{

        /* Check that the heartbeat value is within range; if not reset to the default */

        if (ks8695_wdt_settimeout(wdt_time)) {

                ks8695_wdt_settimeout(WDT_DEFAULT_TIME);

                pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i, using %d\n", wdt_time, WDT_MAX_TIME);

        }

        return platform_driver_register(&ks8695wdt_driver);

}

static void __exit ks8695_wdt_exit(void)

{

        platform_driver_unregister(&ks8695wdt_driver);

}

module_init(ks8695_wdt_init);

module_exit(ks8695_wdt_exit);

MODULE_AUTHOR("Andrew Victor");

MODULE_DESCRIPTION("Watchdog driver for KS8695");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);