/*
 *	w83627hf WDT driver
 *
 *	(c) Copyright 2003 Pádraig Brady <P@draigBrady.com>
 *
 *	Based on advantechwdt.c which is based on wdt.c.
 *	Original copyright messages:
 *
 *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
 *
 *	(c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
 *				http://www.redhat.com
 *
 *	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 Alan Cox nor CymruNet Ltd. admit liability nor provide
 *	warranty for any of this software. This material is provided
 *	"AS-IS" and at no charge.
 *
 *	(c) Copyright 1995    Alan Cox <alan@redhat.com>
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>

#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>

#define WATCHDOG_NAME "w83627hf WDT"
#define PFX WATCHDOG_NAME ": "
#define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */

static unsigned long wdt_is_open;
static char expect_close;

/* You must set this - there is no sane way to probe for this board. */
static int wdt_io = 0x2E;
module_param(wdt_io, int, 0);
MODULE_PARM_DESC(wdt_io, "w83627hf WDT io port (default 0x2E)");

static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. 1<= timeout <=63, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ".");

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");

/*
 *	Kernel methods.
 */

#define WDT_EFER (wdt_io+0)   /* Extended Function Enable Registers */
#define WDT_EFIR (wdt_io+0)   /* Extended Function Index Register (same as EFER) */
#define WDT_EFDR (WDT_EFIR+1) /* Extended Function Data Register */

static void
w83627hf_select_wd_register(void)
{
	outb_p(0x87, WDT_EFER); /* Enter extended function mode */
	outb_p(0x87, WDT_EFER); /* Again according to manual */

	outb_p(0x07, WDT_EFER); /* point to logical device number reg */
	outb_p(0x08, WDT_EFDR); /* select logical device 8 (GPIO2) */
	outb_p(0x30, WDT_EFER); /* select CR30 */
	outb_p(0x01, WDT_EFDR); /* set bit 0 to activate GPIO2 */
}

static void
w83627hf_unselect_wd_register(void)
{
	outb_p(0xAA, WDT_EFER); /* Leave extended function mode */
}

/* tyan motherboards seem to set F5 to 0x4C ?
 * So explicitly init to appropriate value. */
static void
w83627hf_init(void)
{
	unsigned char t;

	w83627hf_select_wd_register();

	outb_p(0xF6, WDT_EFER); /* Select CRF6 */
	t=inb_p(WDT_EFDR);      /* read CRF6 */
	if (t != 0) {
		printk (KERN_INFO PFX "Watchdog already running. Resetting timeout to %d sec\n", timeout);
		outb_p(timeout, WDT_EFDR);    /* Write back to CRF6 */
	}
	outb_p(0xF5, WDT_EFER); /* Select CRF5 */
	t=inb_p(WDT_EFDR);      /* read CRF5 */
	t&=~0x0C;               /* set second mode & disable keyboard turning off watchdog */
	outb_p(t, WDT_EFDR);    /* Write back to CRF5 */

	w83627hf_unselect_wd_register();
}

static void
wdt_ctrl(int timeout)
{
	w83627hf_select_wd_register();

	outb_p(0xF6, WDT_EFER);    /* Select CRF6 */
	outb_p(timeout, WDT_EFDR); /* Write Timeout counter to CRF6 */

	w83627hf_unselect_wd_register();
}

static int
wdt_ping(void)
{
	wdt_ctrl(timeout);
	return 0;
}

static int
wdt_disable(void)
{
	wdt_ctrl(0);
	return 0;
}

static int
wdt_set_heartbeat(int t)
{
	if ((t < 1) || (t > 63))
		return -EINVAL;

	timeout = t;
	return 0;
}

static ssize_t
wdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
	if (count) {
		if (!nowayout) {
			size_t i;

			expect_close = 0;

			for (i = 0; i != count; i++) {
				char c;
				if (get_user(c, buf+i))
					return -EFAULT;
				if (c == 'V')
					expect_close = 42;
			}
		}
		wdt_ping();
	}
	return count;
}

static int
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_timeout;
	static struct watchdog_info ident = {
		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
		.firmware_version = 1,
		.identity = "W83627HF WDT",
	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
	  if (copy_to_user(argp, &ident, sizeof(ident)))
	    return -EFAULT;
	  break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
	  return put_user(0, p);

	case WDIOC_KEEPALIVE:
	  wdt_ping();
	  break;

	case WDIOC_SETTIMEOUT:
	  if (get_user(new_timeout, p))
		  return -EFAULT;
	  if (wdt_set_heartbeat(new_timeout))
		  return -EINVAL;
	  wdt_ping();
	  /* Fall */

	case WDIOC_GETTIMEOUT:
	  return put_user(timeout, p);

	case WDIOC_SETOPTIONS:
	{
	  int options, retval = -EINVAL;

	  if (get_user(options, p))
	    return -EFAULT;

	  if (options & WDIOS_DISABLECARD) {
	    wdt_disable();
	    retval = 0;
	  }

	  if (options & WDIOS_ENABLECARD) {
	    wdt_ping();
	    retval = 0;
	  }

	  return retval;
	}

	default:
	  return -ENOIOCTLCMD;
	}
	return 0;
}

static int
wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &wdt_is_open))
		return -EBUSY;
	/*
	 *	Activate
	 */

	wdt_ping();
	return nonseekable_open(inode, file);
}

static int
wdt_close(struct inode *inode, struct file *file)
{
	if (expect_close == 42) {
		wdt_disable();
	} else {
		printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
		wdt_ping();
	}
	expect_close = 0;
	clear_bit(0, &wdt_is_open);
	return 0;
}

/*
 *	Notifier for system down
 */

static int
wdt_notify_sys(struct notifier_block *this, unsigned long code,
	void *unused)
{
	if (code == SYS_DOWN || code == SYS_HALT) {
		/* Turn the WDT off */
		wdt_disable();
	}
	return NOTIFY_DONE;
}

/*
 *	Kernel Interfaces
 */

static struct file_operations wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= wdt_write,
	.ioctl		= wdt_ioctl,
	.open		= wdt_open,
	.release	= wdt_close,
};

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

/*
 *	The WDT needs to learn about soft shutdowns in order to
 *	turn the timebomb registers off.
 */

static struct notifier_block wdt_notifier = {
	.notifier_call = wdt_notify_sys,
};

static int __init
wdt_init(void)
{
	int ret;

	printk(KERN_INFO "WDT driver for the Winbond(TM) W83627HF Super I/O chip initialising.\n");

	if (wdt_set_heartbeat(timeout)) {
		wdt_set_heartbeat(WATCHDOG_TIMEOUT);
		printk (KERN_INFO PFX "timeout value must be 1<=timeout<=63, using %d\n",
			WATCHDOG_TIMEOUT);
	}

	if (!request_region(wdt_io, 1, WATCHDOG_NAME)) {
		printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
			wdt_io);
		ret = -EIO;
		goto out;
	}

	w83627hf_init();

	ret = register_reboot_notifier(&wdt_notifier);
	if (ret != 0) {
		printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
			ret);
		goto unreg_regions;
	}

	ret = misc_register(&wdt_miscdev);
	if (ret != 0) {
		printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
			WATCHDOG_MINOR, ret);
		goto unreg_reboot;
	}

	printk (KERN_INFO PFX "initialized. timeout=%d sec (nowayout=%d)\n",
		timeout, nowayout);

out:
	return ret;
unreg_reboot:
	unregister_reboot_notifier(&wdt_notifier);
unreg_regions:
	release_region(wdt_io, 1);
	goto out;
}

static void __exit
wdt_exit(void)
{
	misc_deregister(&wdt_miscdev);
	unregister_reboot_notifier(&wdt_notifier);
	release_region(wdt_io,1);
}

module_init(wdt_init);
module_exit(wdt_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pádraig Brady <P@draigBrady.com>");
MODULE_DESCRIPTION("w38627hf WDT driver");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);