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/*

 * Watchdog driver for Atmel AT91RM9200 (Thunder)

 *

 *  Copyright (C) 2003 SAN People (Pty) Ltd

 *

 * 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/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/uaccess.h>

#include <asm/arch/at91_st.h>

#define WDT_DEFAULT_TIME        5       /* seconds */

#define WDT_MAX_TIME            256     /* 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 at91wdt_busy;

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

/*

 * Disable the watchdog.

 */

static void inline at91_wdt_stop(void)

{

        at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);

}

/*

 * Enable and reset the watchdog.

 */

static void inline at91_wdt_start(void)

{

        at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV));

        at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);

}

/*

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

 */

static void inline at91_wdt_reload(void)

{

        at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);

}

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

/*

 * Watchdog device is opened, and watchdog starts running.

 */

static int at91_wdt_open(struct inode *inode, struct file *file)

{

        if (test_and_set_bit(0, &at91wdt_busy))

                return -EBUSY;

        at91_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 at91_wdt_close(struct inode *inode, struct file *file)

{

        if (!nowayout)

                at91_wdt_stop();        /* Disable the watchdog when file is closed */

        clear_bit(0, &at91wdt_busy);

        return 0;

}

/*

 * Change the watchdog time interval.

 */

static int at91_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 at91_wdt_start() is called. */

        wdt_time = new_time;

        return 0;

}

static struct watchdog_info at91_wdt_info = {

        .identity       = "at91 watchdog",

        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,

};

/*

 * Handle commands from user-space.

 */

static int at91_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:

                        at91_wdt_reload();      /* pat the watchdog */

                        return 0;

                case WDIOC_GETSUPPORT:

                        return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0;

                case WDIOC_SETTIMEOUT:

                        if (get_user(new_value, p))

                                return -EFAULT;

                        if (at91_wdt_settimeout(new_value))

                                return -EINVAL;

                        /* Enable new time value */

                        at91_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)

                                at91_wdt_stop();

                        if (new_value & WDIOS_ENABLECARD)

                                at91_wdt_start();

                        return 0;

                default:

                        return -ENOTTY;

        }

}

/*

 * Pat the watchdog whenever device is written to.

 */

static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)

{

        at91_wdt_reload();              /* pat the watchdog */

        return len;

}

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

static const struct file_operations at91wdt_fops = {

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .ioctl          = at91_wdt_ioctl,

        .open           = at91_wdt_open,

        .release        = at91_wdt_close,

        .write          = at91_wdt_write,

};

static struct miscdevice at91wdt_miscdev = {

        .minor          = WATCHDOG_MINOR,

        .name           = "watchdog",

        .fops           = &at91wdt_fops,

};

static int __init at91wdt_probe(struct platform_device *pdev)

{

        int res;

        if (at91wdt_miscdev.parent)

                return -EBUSY;

        at91wdt_miscdev.parent = &pdev->dev;

        res = misc_register(&at91wdt_miscdev);

        if (res)

                return res;

        printk("AT91 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : "");

        return 0;

}

static int __exit at91wdt_remove(struct platform_device *pdev)

{

        int res;

        res = misc_deregister(&at91wdt_miscdev);

        if (!res)

                at91wdt_miscdev.parent = NULL;

        return res;

}

static void at91wdt_shutdown(struct platform_device *pdev)

{

        at91_wdt_stop();

}

#ifdef CONFIG_PM

static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)

{

        at91_wdt_stop();

        return 0;

}

static int at91wdt_resume(struct platform_device *pdev)

{

        if (at91wdt_busy)

                at91_wdt_start();

                return 0;

}

#else

#define at91wdt_suspend NULL

#define at91wdt_resume  NULL

#endif

static struct platform_driver at91wdt_driver = {

        .probe          = at91wdt_probe,

        .remove         = __exit_p(at91wdt_remove),

        .shutdown       = at91wdt_shutdown,

        .suspend        = at91wdt_suspend,

        .resume         = at91wdt_resume,

        .driver         = {

                .name   = "at91_wdt",

                .owner  = THIS_MODULE,

        },

};

static int __init at91_wdt_init(void)

{

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

        if (at91_wdt_settimeout(wdt_time)) {

                at91_wdt_settimeout(WDT_DEFAULT_TIME);

                pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time);

        }

        return platform_driver_register(&at91wdt_driver);

}

static void __exit at91_wdt_exit(void)

{

        platform_driver_unregister(&at91wdt_driver);

}

module_init(at91_wdt_init);

module_exit(at91_wdt_exit);

MODULE_AUTHOR("Andrew Victor");

MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);