/*

   *	Wdt977	0.04:	A Watchdog Device for Netwinder W83977AF chip

   *
   *	(c) Copyright 1998 Rebel.com (Woody Suwalski <woody@netwinder.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.
   *
   *			-----------------------
   *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
   *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
   *	19-Dec-2001 Woody Suwalski: Netwinder fixes, ioctl interface
   *	06-Jan-2002 Woody Suwalski: For compatibility, convert all timeouts
   *				    from minutes to seconds.
   *      07-Jul-2003 Daniele Bellucci: Audit return code of misc_register in
   *                                    nwwatchdog_init.

   *      25-Oct-2005 Woody Suwalski: Convert addresses to #defs, add spinlocks

   *				    remove limitiation to be used on
   *				    Netwinders only

   */
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>

  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/miscdevice.h>
  #include <linux/init.h>

  #include <linux/ioport.h>

  #include <linux/watchdog.h>
  #include <linux/notifier.h>
  #include <linux/reboot.h>

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

  #include <asm/system.h>
  #include <asm/mach-types.h>

  #define WATCHDOG_VERSION  "0.04"
  #define WATCHDOG_NAME     "Wdt977"
  #define PFX WATCHDOG_NAME ": "
  #define DRIVER_VERSION    WATCHDOG_NAME " driver, v" WATCHDOG_VERSION "
  "
  
  #define IO_INDEX_PORT	0x370		/* on some systems it can be 0x3F0 */

  #define IO_DATA_PORT	(IO_INDEX_PORT + 1)

  
  #define UNLOCK_DATA	0x87
  #define LOCK_DATA	0xAA
  #define DEVICE_REGISTER	0x07

  
  #define	DEFAULT_TIMEOUT	60			/* default timeout in seconds */
  
  static	int timeout = DEFAULT_TIMEOUT;
  static	int timeoutM;				/* timeout in minutes */
  static	unsigned long timer_alive;
  static	int testmode;
  static	char expect_close;

  static	DEFINE_SPINLOCK(spinlock);

  
  module_param(timeout, int, 0);

  MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (60..15300, default="

  				__MODULE_STRING(DEFAULT_TIMEOUT) ")");

  module_param(testmode, int, 0);

  MODULE_PARM_DESC(testmode, "Watchdog testmode (1 = no reboot), default=0");

  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) ")");

  
  /*
   * Start the watchdog
   */
  
  static int wdt977_start(void)
  {

  	unsigned long flags;
  
  	spin_lock_irqsave(&spinlock, flags);

  	/* unlock the SuperIO chip */

  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);
  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);

  
  	/* select device Aux2 (device=8) and set watchdog regs F2, F3 and F4
  	 * F2 has the timeout in minutes
  	 * F3 could be set to the POWER LED blink (with GP17 set to PowerLed)
  	 *   at timeout, and to reset timer on kbd/mouse activity (not impl.)
  	 * F4 is used to just clear the TIMEOUT'ed state (bit 0)
  	 */

  	outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
  	outb_p(0x08, IO_DATA_PORT);
  	outb_p(0xF2, IO_INDEX_PORT);
  	outb_p(timeoutM, IO_DATA_PORT);
  	outb_p(0xF3, IO_INDEX_PORT);

  	outb_p(0x00, IO_DATA_PORT);	/* another setting is 0E for
  					   kbd/mouse/LED */

  	outb_p(0xF4, IO_INDEX_PORT);
  	outb_p(0x00, IO_DATA_PORT);

  	/* At last select device Aux1 (dev=7) and set GP16 as a
  	 * watchdog output. In test mode watch the bit 1 on F4 to
  	 * indicate "triggered"
  	 */
  	if (!testmode) {

  		outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
  		outb_p(0x07, IO_DATA_PORT);
  		outb_p(0xE6, IO_INDEX_PORT);
  		outb_p(0x08, IO_DATA_PORT);

  	}
  
  	/* lock the SuperIO chip */

  	outb_p(LOCK_DATA, IO_INDEX_PORT);

  	spin_unlock_irqrestore(&spinlock, flags);

  	printk(KERN_INFO PFX "activated.
  ");
  
  	return 0;
  }
  
  /*
   * Stop the watchdog
   */
  
  static int wdt977_stop(void)
  {

  	unsigned long flags;
  	spin_lock_irqsave(&spinlock, flags);

  	/* unlock the SuperIO chip */

  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);
  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);

  
  	/* select device Aux2 (device=8) and set watchdog regs F2,F3 and F4
  	* F3 is reset to its default state
  	* F4 can clear the TIMEOUT'ed state (bit 0) - back to default
  	* We can not use GP17 as a PowerLed, as we use its usage as a RedLed
  	*/

  	outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
  	outb_p(0x08, IO_DATA_PORT);
  	outb_p(0xF2, IO_INDEX_PORT);
  	outb_p(0xFF, IO_DATA_PORT);
  	outb_p(0xF3, IO_INDEX_PORT);
  	outb_p(0x00, IO_DATA_PORT);
  	outb_p(0xF4, IO_INDEX_PORT);
  	outb_p(0x00, IO_DATA_PORT);
  	outb_p(0xF2, IO_INDEX_PORT);
  	outb_p(0x00, IO_DATA_PORT);

  	/* at last select device Aux1 (dev=7) and set
  	   GP16 as a watchdog output */

  	outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
  	outb_p(0x07, IO_DATA_PORT);
  	outb_p(0xE6, IO_INDEX_PORT);
  	outb_p(0x08, IO_DATA_PORT);

  
  	/* lock the SuperIO chip */

  	outb_p(LOCK_DATA, IO_INDEX_PORT);

  	spin_unlock_irqrestore(&spinlock, flags);

  	printk(KERN_INFO PFX "shutdown.
  ");
  
  	return 0;
  }
  
  /*
   * Send a keepalive ping to the watchdog
   * This is done by simply re-writing the timeout to reg. 0xF2
   */
  
  static int wdt977_keepalive(void)
  {

  	unsigned long flags;
  	spin_lock_irqsave(&spinlock, flags);

  	/* unlock the SuperIO chip */

  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);
  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);

  
  	/* select device Aux2 (device=8) and kicks watchdog reg F2 */
  	/* F2 has the timeout in minutes */

  	outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
  	outb_p(0x08, IO_DATA_PORT);
  	outb_p(0xF2, IO_INDEX_PORT);
  	outb_p(timeoutM, IO_DATA_PORT);

  
  	/* lock the SuperIO chip */

  	outb_p(LOCK_DATA, IO_INDEX_PORT);
  	spin_unlock_irqrestore(&spinlock, flags);

  
  	return 0;
  }
  
  /*
   * Set the watchdog timeout value
   */
  
  static int wdt977_set_timeout(int t)
  {
  	int tmrval;
  
  	/* convert seconds to minutes, rounding up */
  	tmrval = (t + 59) / 60;
  
  	if (machine_is_netwinder()) {

  		/* we have a hw bug somewhere, so each 977 minute is actually
  		 * only 30sec. This limits the max timeout to half of device
  		 * max of 255 minutes...

  		 */
  		tmrval += tmrval;
  	}

  	if (tmrval < 1 || tmrval > 255)

  		return -EINVAL;

  	/* timeout is the timeout in seconds, timeoutM is
  	   the timeout in minutes) */

  	timeout = t;
  	timeoutM = tmrval;
  	return 0;
  }
  
  /*
   * Get the watchdog status
   */
  
  static int wdt977_get_status(int *status)
  {
  	int new_status;

  	unsigned long flags;

  	spin_lock_irqsave(&spinlock, flags);

  
  	/* unlock the SuperIO chip */

  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);
  	outb_p(UNLOCK_DATA, IO_INDEX_PORT);

  
  	/* select device Aux2 (device=8) and read watchdog reg F4 */

  	outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
  	outb_p(0x08, IO_DATA_PORT);
  	outb_p(0xF4, IO_INDEX_PORT);
  	new_status = inb_p(IO_DATA_PORT);

  
  	/* lock the SuperIO chip */

  	outb_p(LOCK_DATA, IO_INDEX_PORT);

  	spin_unlock_irqrestore(&spinlock, flags);

  	*status = 0;

  	if (new_status & 1)
  		*status |= WDIOF_CARDRESET;
  
  	return 0;
  }
  
  
  /*
   *	/dev/watchdog handling
   */
  
  static int wdt977_open(struct inode *inode, struct file *file)
  {
  	/* If the watchdog is alive we don't need to start it again */

  	if (test_and_set_bit(0, &timer_alive))

  		return -EBUSY;
  
  	if (nowayout)
  		__module_get(THIS_MODULE);
  
  	wdt977_start();
  	return nonseekable_open(inode, file);
  }
  
  static int wdt977_release(struct inode *inode, struct file *file)
  {
  	/*
  	 *	Shut off the timer.

  	 *	Lock it in if it's a module and we set nowayout

  	 */

  	if (expect_close == 42) {

  		wdt977_stop();

  		clear_bit(0, &timer_alive);

  	} else {

  		wdt977_keepalive();

  		printk(KERN_CRIT PFX
  			"Unexpected close, not stopping watchdog!
  ");

  	}
  	expect_close = 0;
  	return 0;
  }
  
  
  /*
   *      wdt977_write:
   *      @file: file handle to the watchdog
   *      @buf: buffer to write (unused as data does not matter here
   *      @count: count of bytes
   *      @ppos: pointer to the position to write. No seeks allowed
   *
   *      A write to a watchdog device is defined as a keepalive signal. Any
   *      write of data will do, as we we don't define content meaning.
   */
  
  static ssize_t wdt977_write(struct file *file, const char __user *buf,
  			    size_t count, loff_t *ppos)
  {

  	if (count) {
  		if (!nowayout) {

  			size_t i;
  
  			/* In case it was set long ago */
  			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;
  			}
  		}

  		/* someone wrote to us, we should restart timer */

  		wdt977_keepalive();
  	}
  	return count;
  }

  static const struct watchdog_info ident = {
  	.options =		WDIOF_SETTIMEOUT |
  				WDIOF_MAGICCLOSE |
  				WDIOF_KEEPALIVEPING,
  	.firmware_version =	1,
  	.identity =		WATCHDOG_NAME,
  };

  /*
   *      wdt977_ioctl:
   *      @inode: inode of the device
   *      @file: file handle to the device
   *      @cmd: watchdog command
   *      @arg: argument pointer
   *
   *      The watchdog API defines a common set of functions for all watchdogs
   *      according to their available features.
   */

  static long wdt977_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)

  {
  	int status;
  	int new_options, retval = -EINVAL;
  	int new_timeout;
  	union {
  		struct watchdog_info __user *ident;
  		int __user *i;
  	} uarg;
  
  	uarg.i = (int __user *)arg;

  	switch (cmd) {

  	case WDIOC_GETSUPPORT:
  		return copy_to_user(uarg.ident, &ident,
  			sizeof(ident)) ? -EFAULT : 0;
  
  	case WDIOC_GETSTATUS:
  		wdt977_get_status(&status);
  		return put_user(status, uarg.i);
  
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, uarg.i);

  	case WDIOC_SETOPTIONS:

  		if (get_user(new_options, uarg.i))

  			return -EFAULT;
  
  		if (new_options & WDIOS_DISABLECARD) {
  			wdt977_stop();
  			retval = 0;
  		}
  
  		if (new_options & WDIOS_ENABLECARD) {
  			wdt977_start();
  			retval = 0;
  		}
  
  		return retval;

  	case WDIOC_KEEPALIVE:
  		wdt977_keepalive();
  		return 0;

  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_timeout, uarg.i))
  			return -EFAULT;
  
  		if (wdt977_set_timeout(new_timeout))

  			return -EINVAL;

  
  		wdt977_keepalive();
  		/* Fall */
  
  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout, uarg.i);

  	default:
  		return -ENOTTY;

  	}
  }
  
  static int wdt977_notify_sys(struct notifier_block *this, unsigned long code,
  	void *unused)
  {

  	if (code == SYS_DOWN || code == SYS_HALT)

  		wdt977_stop();
  	return NOTIFY_DONE;
  }

  static const struct file_operations wdt977_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= wdt977_write,

  	.unlocked_ioctl	= wdt977_ioctl,

  	.open		= wdt977_open,
  	.release	= wdt977_release,
  };

  static struct miscdevice wdt977_miscdev = {

  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &wdt977_fops,
  };
  
  static struct notifier_block wdt977_notifier = {
  	.notifier_call = wdt977_notify_sys,
  };

  static int __init wd977_init(void)

  {

  	int rc;

  	printk(KERN_INFO PFX DRIVER_VERSION);

  	/* Check that the timeout value is within its range;
  	   if not reset to the default */
  	if (wdt977_set_timeout(timeout)) {

  		wdt977_set_timeout(DEFAULT_TIMEOUT);

  		printk(KERN_INFO PFX
  		      "timeout value must be 60 < timeout < 15300, using %d
  ",
  							DEFAULT_TIMEOUT);

  	}

  	/* on Netwinder the IOports are already reserved by
  	 * arch/arm/mach-footbridge/netwinder-hw.c
  	 */

  	if (!machine_is_netwinder()) {
  		if (!request_region(IO_INDEX_PORT, 2, WATCHDOG_NAME)) {
  			printk(KERN_ERR PFX
  				"I/O address 0x%04x already in use
  ",
  								IO_INDEX_PORT);

  			rc = -EIO;
  			goto err_out;
  		}

  	}

  	rc = register_reboot_notifier(&wdt977_notifier);

  	if (rc) {
  		printk(KERN_ERR PFX
  			"cannot register reboot notifier (err=%d)
  ", rc);

  		goto err_out_region;
  	}

  	rc = misc_register(&wdt977_miscdev);

  	if (rc) {
  		printk(KERN_ERR PFX
  			"cannot register miscdev on minor=%d (err=%d)
  ",
  						wdt977_miscdev.minor, rc);

  		goto err_out_reboot;

  	}

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

  
  	return 0;

  err_out_reboot:
  	unregister_reboot_notifier(&wdt977_notifier);

  err_out_region:
  	if (!machine_is_netwinder())

  		release_region(IO_INDEX_PORT, 2);

  err_out:
  	return rc;

  }

  static void __exit wd977_exit(void)

  {

  	wdt977_stop();

  	misc_deregister(&wdt977_miscdev);
  	unregister_reboot_notifier(&wdt977_notifier);

  	release_region(IO_INDEX_PORT, 2);

  }

  module_init(wd977_init);
  module_exit(wd977_exit);

  MODULE_AUTHOR("Woody Suwalski <woodys@xandros.com>");

  MODULE_DESCRIPTION("W83977AF Watchdog driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);