/*

   *	Eurotech CPU-1220/1410/1420 on board WDT driver

   *
   *	(c) Copyright 2001 Ascensit <support@ascensit.com>
   *	(c) Copyright 2001 Rodolfo Giometti <giometti@ascensit.com>
   *	(c) Copyright 2002 Rob Radez <rob@osinvestor.com>
   *
   *	Based on wdt.c.
   *	Original copyright messages:
   *

   *	(c) Copyright 1996-1997 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>*

   */
  
  /* Changelog:
   *

   * 2001 - Rodolfo Giometti
   *	Initial release
   *

   * 2002/04/25 - Rob Radez
   *	clean up #includes
   *	clean up locking
   *	make __setup param unique
   *	proper options in watchdog_info
   *	add WDIOC_GETSTATUS and WDIOC_SETOPTIONS ioctls
   *	add expect_close support
   *

   * 2002.05.30 - Joel Becker <joel.becker@oracle.com>

   *	Added Matt Domsch's nowayout module option.

   */

  /*
   *	The eurotech CPU-1220/1410/1420's watchdog is a part
   *	of the on-board SUPER I/O device SMSC FDC 37B782.
   */

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

  #include <asm/system.h>
  
  static unsigned long eurwdt_is_open;
  static int eurwdt_timeout;
  static char eur_expect_close;

  static spinlock_t eurwdt_lock;

  
  /*
   * You must set these - there is no sane way to probe for this board.

   */
  
  static int io = 0x3f0;
  static int irq = 10;
  static char *ev = "int";
  
  #define WDT_TIMEOUT		60                /* 1 minute */

  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) ")");

  
  /*
   * Some symbolic names
   */
  
  #define WDT_CTRL_REG		0x30
  #define WDT_OUTPIN_CFG		0xe2
  #define WDT_EVENT_INT		0x00
  #define WDT_EVENT_REBOOT	0x08
  #define WDT_UNIT_SEL		0xf1
  #define WDT_UNIT_SECS		0x80
  #define WDT_TIMEOUT_VAL		0xf2
  #define WDT_TIMER_CFG		0xf3
  
  
  module_param(io, int, 0);
  MODULE_PARM_DESC(io, "Eurotech WDT io port (default=0x3f0)");
  module_param(irq, int, 0);
  MODULE_PARM_DESC(irq, "Eurotech WDT irq (default=10)");
  module_param(ev, charp, 0);
  MODULE_PARM_DESC(ev, "Eurotech WDT event type (default is `int')");
  
  
  /*
   * Programming support
   */
  
  static inline void eurwdt_write_reg(u8 index, u8 data)
  {
  	outb(index, io);
  	outb(data, io+1);
  }
  
  static inline void eurwdt_lock_chip(void)
  {
  	outb(0xaa, io);
  }
  
  static inline void eurwdt_unlock_chip(void)
  {
  	outb(0x55, io);
  	eurwdt_write_reg(0x07, 0x08);	/* set the logical device */
  }
  
  static inline void eurwdt_set_timeout(int timeout)
  {
  	eurwdt_write_reg(WDT_TIMEOUT_VAL, (u8) timeout);
  }
  
  static inline void eurwdt_disable_timer(void)
  {
  	eurwdt_set_timeout(0);
  }
  
  static void eurwdt_activate_timer(void)
  {
  	eurwdt_disable_timer();
  	eurwdt_write_reg(WDT_CTRL_REG, 0x01);	/* activate the WDT */

  	eurwdt_write_reg(WDT_OUTPIN_CFG,
  		!strcmp("int", ev) ? WDT_EVENT_INT : WDT_EVENT_REBOOT);

  
  	/* Setting interrupt line */
  	if (irq == 2 || irq > 15 || irq < 0) {
  		printk(KERN_ERR ": invalid irq number
  ");
  		irq = 0;	/* if invalid we disable interrupt */
  	}
  	if (irq == 0)
  		printk(KERN_INFO ": interrupt disabled
  ");

  	eurwdt_write_reg(WDT_TIMER_CFG, irq << 4);

  
  	eurwdt_write_reg(WDT_UNIT_SEL, WDT_UNIT_SECS);	/* we use seconds */
  	eurwdt_set_timeout(0);	/* the default timeout */
  }
  
  
  /*
   * Kernel methods.
   */

  static irqreturn_t eurwdt_interrupt(int irq, void *dev_id)

  {
  	printk(KERN_CRIT "timeout WDT timeout
  ");
  
  #ifdef ONLY_TESTING
  	printk(KERN_CRIT "Would Reboot.
  ");
  #else
  	printk(KERN_CRIT "Initiating system reboot.
  ");

  	emergency_restart();

  #endif
  	return IRQ_HANDLED;
  }
  
  
  /**
   * eurwdt_ping:
   *
   * Reload counter one with the watchdog timeout.
   */
  
  static void eurwdt_ping(void)
  {
  	/* Write the watchdog default value */
  	eurwdt_set_timeout(eurwdt_timeout);
  }
  
  /**
   * eurwdt_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 eurwdt_write(struct file *file, const char __user *buf,
  size_t count, loff_t *ppos)
  {

  	if (count) {

  		if (!nowayout) {
  			size_t i;
  
  			eur_expect_close = 0;
  
  			for (i = 0; i != count; i++) {
  				char c;

  				if (get_user(c, buf + i))

  					return -EFAULT;
  				if (c == 'V')
  					eur_expect_close = 42;
  			}
  		}

  		spin_lock(&eurwdt_lock);

  		eurwdt_ping();	/* the default timeout */

  		spin_unlock(&eurwdt_lock);

  	}

  	return count;
  }
  
  /**
   * eurwdt_ioctl:

   * @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 eurwdt_ioctl(struct file *file,
  					unsigned int cmd, unsigned long arg)

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

  	static const struct watchdog_info ident = {

  		.options	  = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
  							| WDIOF_MAGICCLOSE,

  		.firmware_version = 1,
  		.identity	  = "WDT Eurotech CPU-1220/1410",
  	};
  
  	int time;
  	int options, retval = -EINVAL;

  	switch (cmd) {

  	case WDIOC_GETSUPPORT:
  		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
  
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);

  	case WDIOC_SETOPTIONS:
  		if (get_user(options, p))
  			return -EFAULT;
  		spin_lock(&eurwdt_lock);
  		if (options & WDIOS_DISABLECARD) {
  			eurwdt_disable_timer();
  			retval = 0;
  		}
  		if (options & WDIOS_ENABLECARD) {
  			eurwdt_activate_timer();
  			eurwdt_ping();
  			retval = 0;
  		}
  		spin_unlock(&eurwdt_lock);
  		return retval;

  	case WDIOC_KEEPALIVE:

  		spin_lock(&eurwdt_lock);

  		eurwdt_ping();

  		spin_unlock(&eurwdt_lock);

  		return 0;
  
  	case WDIOC_SETTIMEOUT:
  		if (copy_from_user(&time, p, sizeof(int)))
  			return -EFAULT;
  
  		/* Sanity check */
  		if (time < 0 || time > 255)
  			return -EINVAL;

  		spin_lock(&eurwdt_lock);

  		eurwdt_timeout = time;
  		eurwdt_set_timeout(time);

  		spin_unlock(&eurwdt_lock);

  		/* Fall */
  
  	case WDIOC_GETTIMEOUT:
  		return put_user(eurwdt_timeout, p);

  	default:
  		return -ENOTTY;

  	}
  }
  
  /**
   * eurwdt_open:
   * @inode: inode of device
   * @file: file handle to device
   *
   * The misc device has been opened. The watchdog device is single
   * open and on opening we load the counter.
   */
  
  static int eurwdt_open(struct inode *inode, struct file *file)
  {
  	if (test_and_set_bit(0, &eurwdt_is_open))
  		return -EBUSY;
  	eurwdt_timeout = WDT_TIMEOUT;	/* initial timeout */
  	/* Activate the WDT */
  	eurwdt_activate_timer();
  	return nonseekable_open(inode, file);
  }
  
  /**
   * eurwdt_release:
   * @inode: inode to board
   * @file: file handle to board
   *
   * The watchdog has a configurable API. There is a religious dispute
   * between people who want their watchdog to be able to shut down and
   * those who want to be sure if the watchdog manager dies the machine
   * reboots. In the former case we disable the counters, in the latter
   * case you have to open it again very soon.
   */
  
  static int eurwdt_release(struct inode *inode, struct file *file)
  {

  	if (eur_expect_close == 42)

  		eurwdt_disable_timer();

  	else {
  		printk(KERN_CRIT
  			"eurwdt: Unexpected close, not stopping watchdog!
  ");

  		eurwdt_ping();
  	}
  	clear_bit(0, &eurwdt_is_open);
  	eur_expect_close = 0;
  	return 0;
  }
  
  /**
   * eurwdt_notify_sys:
   * @this: our notifier block
   * @code: the event being reported
   * @unused: unused
   *
   * Our notifier is called on system shutdowns. We want to turn the card
   * off at reboot otherwise the machine will reboot again during memory
   * test or worse yet during the following fsck. This would suck, in fact
   * trust me - if it happens it does suck.
   */
  
  static int eurwdt_notify_sys(struct notifier_block *this, unsigned long code,
  	void *unused)
  {

  	if (code == SYS_DOWN || code == SYS_HALT)
  		eurwdt_disable_timer();	/* Turn the card off */

  
  	return NOTIFY_DONE;
  }
  
  /*
   * Kernel Interfaces
   */

  static const struct file_operations eurwdt_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= eurwdt_write,
  	.unlocked_ioctl	= eurwdt_ioctl,
  	.open		= eurwdt_open,

  	.release	= eurwdt_release,
  };
  
  static struct miscdevice eurwdt_miscdev = {
  	.minor	= WATCHDOG_MINOR,
  	.name	= "watchdog",
  	.fops	= &eurwdt_fops,
  };
  
  /*
   * The WDT card needs to learn about soft shutdowns in order to
   * turn the timebomb registers off.
   */
  
  static struct notifier_block eurwdt_notifier = {
  	.notifier_call = eurwdt_notify_sys,
  };
  
  /**
   * cleanup_module:
   *
   * Unload the watchdog. You cannot do this with any file handles open.
   * If your watchdog is set to continue ticking on close and you unload
   * it, well it keeps ticking. We won't get the interrupt but the board
   * will not touch PC memory so all is fine. You just have to load a new
   * module in 60 seconds or reboot.
   */
  
  static void __exit eurwdt_exit(void)
  {
  	eurwdt_lock_chip();
  
  	misc_deregister(&eurwdt_miscdev);
  
  	unregister_reboot_notifier(&eurwdt_notifier);
  	release_region(io, 2);
  	free_irq(irq, NULL);
  }
  
  /**
   * eurwdt_init:
   *
   * Set up the WDT watchdog board. After grabbing the resources
   * we require we need also to unlock the device.
   * The open() function will actually kick the board off.
   */
  
  static int __init eurwdt_init(void)
  {
  	int ret;

  	ret = request_irq(irq, eurwdt_interrupt, IRQF_DISABLED, "eurwdt", NULL);

  	if (ret) {

  		printk(KERN_ERR "eurwdt: IRQ %d is not free.
  ", irq);

  		goto out;

  	}
  
  	if (!request_region(io, 2, "eurwdt")) {
  		printk(KERN_ERR "eurwdt: IO %X is not free.
  ", io);
  		ret = -EBUSY;
  		goto outirq;
  	}
  
  	ret = register_reboot_notifier(&eurwdt_notifier);
  	if (ret) {

  		printk(KERN_ERR
  		    "eurwdt: can't register reboot notifier (err=%d)
  ", ret);

  		goto outreg;
  	}

  	spin_lock_init(&eurwdt_lock);

  	ret = misc_register(&eurwdt_miscdev);
  	if (ret) {
  		printk(KERN_ERR "eurwdt: can't misc_register on minor=%d
  ",
  		WATCHDOG_MINOR);
  		goto outreboot;
  	}

  	eurwdt_unlock_chip();
  
  	ret = 0;
  	printk(KERN_INFO "Eurotech WDT driver 0.01 at %X (Interrupt %d)"
  		" - timeout event: %s
  ",
  		io, irq, (!strcmp("int", ev) ? "int" : "reboot"));
  
  out:
  	return ret;

  outreboot:
  	unregister_reboot_notifier(&eurwdt_notifier);

  outreg:
  	release_region(io, 2);
  
  outirq:
  	free_irq(irq, NULL);

  	goto out;
  }
  
  module_init(eurwdt_init);
  module_exit(eurwdt_exit);
  
  MODULE_AUTHOR("Rodolfo Giometti");
  MODULE_DESCRIPTION("Driver for Eurotech CPU-1220/1410 on board watchdog");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);