/*

   *	w83627hf/thf WDT driver
   *
   *	(c) Copyright 2007 Vlad Drukker <vlad@storewiz.com>
   *		added support for W83627THF.

   *

   *	(c) Copyright 2003,2007 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@lxorguk.ukuu.org.uk>,
   *						All Rights Reserved.

   *
   *	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@lxorguk.ukuu.org.uk>

   */
  
  #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 <linux/spinlock.h>

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

  #include <asm/system.h>

  #define WATCHDOG_NAME "w83627hf/thf/hg/dhg WDT"

  #define PFX WATCHDOG_NAME ": "
  #define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */
  
  static unsigned long wdt_is_open;
  static char expect_close;

  static DEFINE_SPINLOCK(io_lock);

  
  /* 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/thf 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 <= 255, 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="
  				__MODULE_STRING(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)

  {

  	unsigned char c;

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

  	outb(0x20, WDT_EFER);	/* check chip version	*/

  	c = inb(WDT_EFDR);

  	if (c == 0x82) {	/* W83627THF		*/

  		outb_p(0x2b, WDT_EFER); /* select GPIO3 */
  		c = ((inb_p(WDT_EFDR) & 0xf7) | 0x04); /* select WDT0 */
  		outb_p(0x2b, WDT_EFER);
  		outb_p(c, WDT_EFDR);	/* set GPIO3 to WDT0 */

  	} else if (c == 0x88 || c == 0xa0) {	/* W83627EHF / W83627DHG */

  		outb_p(0x2d, WDT_EFER); /* select GPIO5 */
  		c = inb_p(WDT_EFDR) & ~0x01; /* PIN77 -> WDT0# */
  		outb_p(0x2d, WDT_EFER);
  		outb_p(c, WDT_EFDR); /* set GPIO5 to WDT0 */

  	}

  	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
  ",
  								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 */

  	t |= 0x02;		  /* enable the WDTO# output low pulse
  				    to the KBRST# pin (PIN60) */

  	outb_p(t, WDT_EFDR);    /* Write back to CRF5 */

  	outb_p(0xF7, WDT_EFER); /* Select CRF7 */

  	t = inb_p(WDT_EFDR);      /* read CRF7 */
  	t &= ~0xC0;               /* disable keyboard & mouse turning off
  				    watchdog */

  	outb_p(t, WDT_EFDR);    /* Write back to CRF7 */

  	w83627hf_unselect_wd_register();
  }

  static void wdt_set_time(int timeout)

  {

  	spin_lock(&io_lock);

  	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();

  
  	spin_unlock(&io_lock);

  }

  static int wdt_ping(void)

  {

  	wdt_set_time(timeout);

  	return 0;
  }

  static int wdt_disable(void)

  {

  	wdt_set_time(0);

  	return 0;
  }

  static int wdt_set_heartbeat(int t)

  {

  	if (t < 1 || t > 255)

  		return -EINVAL;

  	timeout = t;
  	return 0;
  }

  static int wdt_get_time(void)
  {
  	int timeleft;
  
  	spin_lock(&io_lock);
  
  	w83627hf_select_wd_register();
  
  	outb_p(0xF6, WDT_EFER);    /* Select CRF6 */
  	timeleft = inb_p(WDT_EFDR); /* Read Timeout counter to CRF6 */
  
  	w83627hf_unselect_wd_register();
  
  	spin_unlock(&io_lock);
  
  	return timeleft;
  }

  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 long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

  {
  	void __user *argp = (void __user *)arg;
  	int __user *p = argp;

  	int timeval;

  	static const 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_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;

  	}

  	case WDIOC_KEEPALIVE:
  		wdt_ping();
  		break;
  	case WDIOC_SETTIMEOUT:

  		if (get_user(timeval, p))

  			return -EFAULT;

  		if (wdt_set_heartbeat(timeval))

  			return -EINVAL;
  		wdt_ping();
  		/* Fall */
  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout, p);

  	case WDIOC_GETTIMELEFT:
  		timeval = wdt_get_time();
  		return put_user(timeval, p);

  	default:

  		return -ENOTTY;

  	}
  	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!
  ");

  		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)
  		wdt_disable();	/* Turn the WDT off */

  	return NOTIFY_DONE;
  }
  
  /*
   *	Kernel Interfaces
   */

  static const struct file_operations wdt_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= wdt_write,

  	.unlocked_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/THF/HG/DHG Super I/O chip initialising.
  ");

  
  	if (wdt_set_heartbeat(timeout)) {
  		wdt_set_heartbeat(WATCHDOG_TIMEOUT);

  		printk(KERN_INFO PFX
  		     "timeout value must be 1 <= timeout <= 255, using %d
  ",
  				WATCHDOG_TIMEOUT);

  	}
  
  	if (!request_region(wdt_io, 1, WATCHDOG_NAME)) {

  		printk(KERN_ERR PFX "I/O address 0x%04x already in use
  ",

  			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)
  ", ret);

  		goto unreg_regions;
  	}
  
  	ret = misc_register(&wdt_miscdev);
  	if (ret != 0) {

  		printk(KERN_ERR PFX
  			"cannot register miscdev on minor=%d (err=%d)
  ",
  							WATCHDOG_MINOR, ret);

  		goto unreg_reboot;
  	}

  	printk(KERN_INFO PFX
  			"initialized. timeout=%d sec (nowayout=%d)
  ",
  							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("w83627hf/thf WDT driver");

  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);