/*
 * sma cpu5 watchdog driver
 *
 * Copyright (C) 2003 Heiko Ronsdorf <hero@ihg.uni-duisburg.de>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/module.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 <asm/io.h>
#include <asm/uaccess.h>

#include <linux/watchdog.h>

/* adjustable parameters */

static int verbose = 0;
static int port = 0x91;
static volatile int ticks = 10000;

#define PFX			"cpu5wdt: "

#define CPU5WDT_EXTENT          0x0A

#define CPU5WDT_STATUS_REG      0x00
#define CPU5WDT_TIME_A_REG      0x02
#define CPU5WDT_TIME_B_REG      0x03
#define CPU5WDT_MODE_REG        0x04
#define CPU5WDT_TRIGGER_REG     0x07
#define CPU5WDT_ENABLE_REG      0x08
#define CPU5WDT_RESET_REG       0x09

#define CPU5WDT_INTERVAL	(HZ/10+1)

/* some device data */

static struct {
	struct semaphore stop;
	volatile int running;
	struct timer_list timer;
	volatile int queue;
	int default_ticks;
	int min_ticks;
	unsigned long inuse;
} cpu5wdt_device;

/* generic helper functions */

static void cpu5wdt_trigger(unsigned long unused)
{
	if ( verbose > 2 )
		printk(KERN_DEBUG PFX "trigger at %i ticks\n", ticks);

	if( cpu5wdt_device.running )
		ticks--;

	/* keep watchdog alive */
	outb(1, port + CPU5WDT_TRIGGER_REG);

	/* requeue?? */
	if( cpu5wdt_device.queue && ticks ) {
		cpu5wdt_device.timer.expires = jiffies + CPU5WDT_INTERVAL;
		add_timer(&cpu5wdt_device.timer);
	}
	else {
		/* ticks doesn't matter anyway */
		up(&cpu5wdt_device.stop);
	}

}

static void cpu5wdt_reset(void)
{
	if ( ticks < cpu5wdt_device.min_ticks )
		cpu5wdt_device.min_ticks = ticks;

	ticks = cpu5wdt_device.default_ticks;

	if ( verbose )
		printk(KERN_DEBUG PFX "reset (%i ticks)\n", (int) ticks);

}

static void cpu5wdt_start(void)
{
	if ( !cpu5wdt_device.queue ) {
		cpu5wdt_device.queue = 1;
		outb(0, port + CPU5WDT_TIME_A_REG);  
		outb(0, port + CPU5WDT_TIME_B_REG);  
		outb(1, port + CPU5WDT_MODE_REG);
		outb(0, port + CPU5WDT_RESET_REG);
		outb(0, port + CPU5WDT_ENABLE_REG);
		cpu5wdt_device.timer.expires = jiffies + CPU5WDT_INTERVAL;
		add_timer(&cpu5wdt_device.timer);
	}
	/* if process dies, counter is not decremented */
	cpu5wdt_device.running++;
}

static int cpu5wdt_stop(void)
{
	if ( cpu5wdt_device.running )
		cpu5wdt_device.running = 0;

	ticks = cpu5wdt_device.default_ticks;

	if ( verbose )
		printk(KERN_CRIT PFX "stop not possible\n");

	return -EIO;
}

/* filesystem operations */

static int cpu5wdt_open(struct inode *inode, struct file *file)
{
	switch(iminor(inode)) {
		case WATCHDOG_MINOR:
			if ( test_and_set_bit(0, &cpu5wdt_device.inuse) )
				return -EBUSY;
			break;
		default:
			return -ENODEV;
	}
	return 0;

}

static int cpu5wdt_release(struct inode *inode, struct file *file)
{
	if(iminor(inode)==WATCHDOG_MINOR) {
		clear_bit(0, &cpu5wdt_device.inuse);
	}
	return 0;
}

static int cpu5wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	unsigned int value;
	static struct watchdog_info ident =
	{
		.options = WDIOF_CARDRESET,
		.identity = "CPU5 WDT"
	};
  
	switch(cmd) {
		case WDIOC_KEEPALIVE:
			cpu5wdt_reset();
			break;
		case WDIOC_GETSTATUS:    
			value = inb(port + CPU5WDT_STATUS_REG); 
			value = (value >> 2) & 1;
			if ( copy_to_user((int *)arg, (int *)&value, sizeof(int)) )
				return -EFAULT;
			break;
		case WDIOC_GETSUPPORT:
			if ( copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)) )
				return -EFAULT;
			break;
		case WDIOC_SETOPTIONS:
			if ( copy_from_user(&value, (int *)arg, sizeof(int)) )
				return -EFAULT;
			switch(value) {
				case WDIOS_ENABLECARD:
					cpu5wdt_start();
					break;
				case WDIOS_DISABLECARD:
					return cpu5wdt_stop();
				default:
					return -EINVAL;
			}
			break;
		default:
    			return -EINVAL;
	}
	return 0;
}

static ssize_t cpu5wdt_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
	if ( !count )
		return -EIO;
	
	cpu5wdt_reset();
	return count;

}

static struct file_operations cpu5wdt_fops = {
	.owner		= THIS_MODULE,
	.ioctl		= cpu5wdt_ioctl,
	.open		= cpu5wdt_open,
	.write		= cpu5wdt_write,
	.release	= cpu5wdt_release,
};

static struct miscdevice cpu5wdt_misc = {
	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
	.fops	= &cpu5wdt_fops
};

/* init/exit function */

static int __devinit cpu5wdt_init(void)
{
	unsigned int val;
	int err;

	if ( verbose )
		printk(KERN_DEBUG PFX "port=0x%x, verbose=%i\n", port, verbose);

	if ( (err = misc_register(&cpu5wdt_misc)) < 0 ) {
		printk(KERN_ERR PFX "misc_register failed\n");
		goto no_misc;
	}

	if ( !request_region(port, CPU5WDT_EXTENT, PFX) ) {
		printk(KERN_ERR PFX "request_region failed\n");
		err = -EBUSY;
		goto no_port;
	}

	/* watchdog reboot? */
	val = inb(port + CPU5WDT_STATUS_REG); 
	val = (val >> 2) & 1;
	if ( !val )
		printk(KERN_INFO PFX "sorry, was my fault\n");

	init_MUTEX_LOCKED(&cpu5wdt_device.stop);
	cpu5wdt_device.queue = 0;
	cpu5wdt_device.min_ticks = ticks;

	clear_bit(0, &cpu5wdt_device.inuse);

	init_timer(&cpu5wdt_device.timer);
	cpu5wdt_device.timer.function = cpu5wdt_trigger;
	cpu5wdt_device.timer.data = 0;

	cpu5wdt_device.default_ticks = ticks;

	printk(KERN_INFO PFX "init success\n");

	return 0;

no_port:
	misc_deregister(&cpu5wdt_misc);
no_misc:
	return err;
}

static int __devinit cpu5wdt_init_module(void)
{
	return cpu5wdt_init();
}

static void __devexit cpu5wdt_exit(void)
{
	if ( cpu5wdt_device.queue ) {
		cpu5wdt_device.queue = 0;
		down(&cpu5wdt_device.stop);
	}

	misc_deregister(&cpu5wdt_misc);

	release_region(port, CPU5WDT_EXTENT);

}

static void __devexit cpu5wdt_exit_module(void)
{
	cpu5wdt_exit();
}

/* module entry points */

module_init(cpu5wdt_init_module);
module_exit(cpu5wdt_exit_module);

MODULE_AUTHOR("Heiko Ronsdorf <hero@ihg.uni-duisburg.de>");
MODULE_DESCRIPTION("sma cpu5 watchdog driver");
MODULE_SUPPORTED_DEVICE("sma cpu5 watchdog");
MODULE_LICENSE("GPL");

MODULE_PARM(port, "i");
MODULE_PARM_DESC(port, "base address of watchdog card, default is 0x91");

MODULE_PARM(verbose, "i");
MODULE_PARM_DESC(verbose, "be verbose, default is 0 (no)");

MODULE_PARM(ticks, "i");
MODULE_PARM_DESC(ticks, "count down ticks, default is 10000");