/*
 *      Driver for the MTX-1 Watchdog.
 *
 *      (C) Copyright 2005 4G Systems <info@4g-systems.biz>, All Rights Reserved.
 *                              http://www.4g-systems.biz
 *
 * 	(C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org>
 *
 *      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 Michael Stickel nor 4G Systems admit liability nor provide
 *      warranty for any of this software. This material is provided
 *      "AS-IS" and at no charge.
 *
 *      (c) Copyright 2005    4G Systems <info@4g-systems.biz>
 *
 *      Release 0.01.
 *      Author: Michael Stickel  michael.stickel@4g-systems.biz
 *
 *      Release 0.02.
 *	Author: Florian Fainelli florian@openwrt.org
 *		use the Linux watchdog/timer APIs
 *
 *      The Watchdog is configured to reset the MTX-1
 *      if it is not triggered for 100 seconds.
 *      It should not be triggered more often than 1.6 seconds.
 *
 *      A timer triggers the watchdog every 5 seconds, until
 *      it is opened for the first time. After the first open
 *      it MUST be triggered every 2..95 seconds.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <linux/completion.h>
#include <linux/jiffies.h>
#include <linux/watchdog.h>
#include <asm/io.h>
#include <asm/uaccess.h>

#include <asm/mach-au1x00/au1000.h>

#define MTX1_WDT_INTERVAL	(5 * HZ)

static int ticks = 100 * HZ;

static struct {
	struct completion stop;
	volatile int running;
	struct timer_list timer;
	volatile int queue;
	int default_ticks;
	unsigned long inuse;
} mtx1_wdt_device;

static void mtx1_wdt_trigger(unsigned long unused)
{
	u32 tmp;

	if (mtx1_wdt_device.running)
		ticks--;
	/*
	 * toggle GPIO2_15
	 */
	tmp = au_readl(GPIO2_DIR);
	tmp = (tmp & ~(1<<15)) | ((~tmp) & (1<<15));
	au_writel (tmp, GPIO2_DIR);

	if (mtx1_wdt_device.queue && ticks)
		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
	else {
		complete(&mtx1_wdt_device.stop);
	}
}

static void mtx1_wdt_reset(void)
{
	ticks = mtx1_wdt_device.default_ticks;
}


static void mtx1_wdt_start(void)
{
	if (!mtx1_wdt_device.queue) {
		mtx1_wdt_device.queue = 1;
		au_writel (au_readl(GPIO2_DIR) | (u32)(1<<15), GPIO2_DIR);
		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
	}
	mtx1_wdt_device.running++;
}

static int mtx1_wdt_stop(void)
{
	if (mtx1_wdt_device.queue) {
		mtx1_wdt_device.queue = 0;
		au_writel (au_readl(GPIO2_DIR) & ~((u32)(1<<15)), GPIO2_DIR);
	}

	ticks = mtx1_wdt_device.default_ticks;

	return 0;
}

/* Filesystem functions */

static int mtx1_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
		return -EBUSY;

	return nonseekable_open(inode, file);
}


static int mtx1_wdt_release(struct inode *inode, struct file *file)
{
	clear_bit(0, &mtx1_wdt_device.inuse);
	return 0;
}

static int mtx1_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	unsigned int value;
	static struct watchdog_info ident =
	{
		.options = WDIOF_CARDRESET,
		.identity = "MTX-1 WDT",
	};

	switch(cmd) {
		case WDIOC_KEEPALIVE:
			mtx1_wdt_reset();
			break;
		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			if ( copy_to_user(argp, &value, sizeof(int)) )
				return -EFAULT;
			break;
		case WDIOC_GETSUPPORT:
			if ( copy_to_user(argp, &ident, sizeof(ident)) )
				return -EFAULT;
			break;
		case WDIOC_SETOPTIONS:
			if ( copy_from_user(&value, argp, sizeof(int)) )
				return -EFAULT;
			switch(value) {
				case WDIOS_ENABLECARD:
					mtx1_wdt_start();
					break;
				case WDIOS_DISABLECARD:
					return mtx1_wdt_stop();
				default:
					return -EINVAL;
			}
			break;
		default:
			return -ENOTTY;
	}
	return 0;
}


static ssize_t mtx1_wdt_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
	if (!count)
		return -EIO;

	mtx1_wdt_reset();
	return count;
}

static const struct file_operations mtx1_wdt_fops = {
	.owner 		= THIS_MODULE,
	.llseek		= no_llseek,
	.ioctl		= mtx1_wdt_ioctl,
	.open 		= mtx1_wdt_open,
	.write 		= mtx1_wdt_write,
	.release 	= mtx1_wdt_release
};


static struct miscdevice mtx1_wdt_misc = {
	.minor 	= WATCHDOG_MINOR,
	.name 	= "watchdog",
	.fops 	= &mtx1_wdt_fops
};


static int __init mtx1_wdt_init(void)
{
	int ret;

	if ((ret = misc_register(&mtx1_wdt_misc)) < 0) {
		printk(KERN_ERR " mtx-1_wdt : failed to register\n");
		return ret;
	}

	init_completion(&mtx1_wdt_device.stop);
	mtx1_wdt_device.queue = 0;

	clear_bit(0, &mtx1_wdt_device.inuse);

	setup_timer(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0L);

	mtx1_wdt_device.default_ticks = ticks;

	mtx1_wdt_start();

	printk(KERN_INFO "MTX-1 Watchdog driver\n");

	return 0;
}

static void __exit mtx1_wdt_exit(void)
{
	if (mtx1_wdt_device.queue) {
		mtx1_wdt_device.queue = 0;
		wait_for_completion(&mtx1_wdt_device.stop);
	}
	misc_deregister(&mtx1_wdt_misc);
}

module_init(mtx1_wdt_init);
module_exit(mtx1_wdt_exit);

MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
MODULE_LICENSE("GPL");