/*

   *	w83697hf/hg WDT driver

   *

   *	(c) Copyright 2006 Samuel Tardieu <sam@rfc1149.net>

   *	(c) Copyright 2006 Marcus Junker <junker@anduras.de>
   *

   *	Based on w83627hf_wdt.c which is based on advantechwdt.c
   *	which is based on wdt.c.

   *	Original copyright messages:
   *

   *	(c) Copyright 2003 Pádraig Brady <P@draigBrady.com>

   *
   *	(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 Marcus Junker nor ANDURAS AG admit liability nor provide
   *	warranty for any of this software. This material is provided
   *	"AS-IS" and at no charge.
   */
  
  #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 "w83697hf/hg WDT"

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

  #define WATCHDOG_EARLY_DISABLE 1	/* Disable until userland kicks in */

  
  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,
  		"w83697hf/hg WDT io port (default 0x2e, 0 = autodetect)");

  
  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) ")");

  static int early_disable = WATCHDOG_EARLY_DISABLE;
  module_param(early_disable, int, 0);

  MODULE_PARM_DESC(early_disable,
  	"Watchdog gets disabled at boot time (default="
  				__MODULE_STRING(WATCHDOG_EARLY_DISABLE) ")");

  /*
   *	Kernel methods.
   */

  #define W83697HF_EFER (wdt_io + 0)  /* Extended Function Enable Register */
  #define W83697HF_EFIR (wdt_io + 0)  /* Extended Function Index Register
  							(same as EFER) */
  #define W83697HF_EFDR (wdt_io + 1)  /* Extended Function Data Register */

  static inline void w83697hf_unlock(void)

  {

  	outb_p(0x87, W83697HF_EFER);	/* Enter extended function mode */
  	outb_p(0x87, W83697HF_EFER);	/* Again according to manual */

  }

  static inline void w83697hf_lock(void)

  {
  	outb_p(0xAA, W83697HF_EFER);	/* Leave extended function mode */
  }

  /*

   *	The three functions w83697hf_get_reg(), w83697hf_set_reg() and
   *	w83697hf_write_timeout() must be called with the device unlocked.

   */

  static unsigned char w83697hf_get_reg(unsigned char reg)

  {
  	outb_p(reg, W83697HF_EFIR);
  	return inb_p(W83697HF_EFDR);
  }

  static void w83697hf_set_reg(unsigned char reg, unsigned char data)

  {
  	outb_p(reg, W83697HF_EFIR);
  	outb_p(data, W83697HF_EFDR);
  }

  static void w83697hf_write_timeout(int timeout)

  {

  	/* Write Timeout counter to CRF4 */
  	w83697hf_set_reg(0xF4, timeout);

  }

  static void w83697hf_select_wdt(void)

  {
  	w83697hf_unlock();
  	w83697hf_set_reg(0x07, 0x08);	/* Switch to logic device 8 (GPIO2) */
  }

  static inline void w83697hf_deselect_wdt(void)

  {
  	w83697hf_lock();
  }

  static void w83697hf_init(void)

  {

  	unsigned char bbuf;

  	w83697hf_select_wdt();

  	bbuf = w83697hf_get_reg(0x29);
  	bbuf &= ~0x60;
  	bbuf |= 0x20;

  
  	/* Set pin 119 to WDTO# mode (= CR29, WDT0) */
  	w83697hf_set_reg(0x29, bbuf);

  	bbuf = w83697hf_get_reg(0xF3);
  	bbuf &= ~0x04;
  	w83697hf_set_reg(0xF3, bbuf);	/* Count mode is seconds */

  	w83697hf_deselect_wdt();

  }

  static void wdt_ping(void)

  {

  	spin_lock(&io_lock);

  	w83697hf_select_wdt();

  	w83697hf_write_timeout(timeout);

  	w83697hf_deselect_wdt();

  	spin_unlock(&io_lock);

  }

  static void wdt_enable(void)

  {

  	spin_lock(&io_lock);
  	w83697hf_select_wdt();
  
  	w83697hf_write_timeout(timeout);
  	w83697hf_set_reg(0x30, 1);	/* Enable timer */
  
  	w83697hf_deselect_wdt();
  	spin_unlock(&io_lock);

  }

  static void wdt_disable(void)

  {

  	spin_lock(&io_lock);
  	w83697hf_select_wdt();
  
  	w83697hf_set_reg(0x30, 0);	/* Disable timer */
  	w83697hf_write_timeout(0);
  
  	w83697hf_deselect_wdt();
  	spin_unlock(&io_lock);

  }

  static unsigned char wdt_running(void)

  {
  	unsigned char t;
  
  	spin_lock(&io_lock);
  	w83697hf_select_wdt();
  
  	t = w83697hf_get_reg(0xF4);	/* Read timer */
  
  	w83697hf_deselect_wdt();
  	spin_unlock(&io_lock);
  
  	return t;
  }

  static int wdt_set_heartbeat(int t)

  {

  	if (t < 1 || t > 255)

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

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

  	static const struct watchdog_info ident = {
  		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
  							| WDIOF_MAGICCLOSE,

  		.firmware_version = 1,
  		.identity = "W83697HF 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_enable();

  			retval = 0;
  		}

  		return retval;

  	}

  	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);

  	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_enable();

  	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 w83697hf_check_wdt(void)

  {
  	if (!request_region(wdt_io, 2, WATCHDOG_NAME)) {

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

  		return -EIO;
  	}

  	printk(KERN_DEBUG PFX
  			"Looking for watchdog at address 0x%x
  ", wdt_io);

  	w83697hf_unlock();
  	if (w83697hf_get_reg(0x20) == 0x60) {

  		printk(KERN_INFO PFX
  			"watchdog found at address 0x%x
  ", wdt_io);

  		w83697hf_lock();
  		return 0;
  	}

  	/* Reprotect in case it was a compatible device */
  	w83697hf_lock();

  	printk(KERN_INFO PFX "watchdog not found at address 0x%x
  ", wdt_io);

  	release_region(wdt_io, 2);
  	return -EIO;
  }

  static int w83697hf_ioports[] = { 0x2e, 0x4e, 0x00 };

  static int __init wdt_init(void)

  {

  	int ret, i, found = 0;

  	printk(KERN_INFO PFX "WDT driver for W83697HF/HG initializing
  ");

  	if (wdt_io == 0) {
  		/* we will autodetect the W83697HF/HG watchdog */
  		for (i = 0; ((!found) && (w83697hf_ioports[i] != 0)); i++) {
  			wdt_io = w83697hf_ioports[i];

  			if (!w83697hf_check_wdt())

  				found++;
  		}
  	} else {

  		if (!w83697hf_check_wdt())

  			found++;

  	}

  	if (!found) {

  		printk(KERN_ERR PFX "No W83697HF/HG could be found
  ");

  		ret = -EIO;
  		goto out;
  	}

  	w83697hf_init();

  	if (early_disable) {
  		if (wdt_running())

  			printk(KERN_WARNING PFX "Stopping previously enabled "
  					"watchdog until userland kicks in
  ");

  		wdt_disable();
  	}

  	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);

  	}

  	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, 2);

  	goto out;
  }

  static void __exit wdt_exit(void)

  {
  	misc_deregister(&wdt_miscdev);
  	unregister_reboot_notifier(&wdt_notifier);

  	release_region(wdt_io, 2);

  }
  
  module_init(wdt_init);
  module_exit(wdt_exit);
  
  MODULE_LICENSE("GPL");

  MODULE_AUTHOR("Marcus Junker <junker@anduras.de>, "
  		"Samuel Tardieu <sam@rfc1149.net>");

  MODULE_DESCRIPTION("w83697hf/hg WDT driver");

  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);