/*

   *	Industrial Computer Source WDT501 driver

   *

   *	(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>
   *
   *	Release 0.10.
   *
   *	Fixes
   *		Dave Gregorich	:	Modularisation and minor bugs
   *		Alan Cox	:	Added the watchdog ioctl() stuff
   *		Alan Cox	:	Fixed the reboot problem (as noted by
   *					Matt Crocker).
   *		Alan Cox	:	Added wdt= boot option
   *		Alan Cox	:	Cleaned up copy/user stuff

   *		Tim Hockin	:	Added insmod parameters, comment
   *					cleanup, parameterized timeout
   *		Tigran Aivazian	:	Restructured wdt_init() to handle
   *					failures

   *		Joel Becker	:	Added WDIOC_GET/SETTIMEOUT
   *		Matt Domsch	:	Added nowayout module option
   */

  #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>
  #include "wd501p.h"
  
  static unsigned long wdt_is_open;
  static char expect_close;
  
  /*
   *	Module parameters
   */
  
  #define WD_TIMO 60			/* Default heartbeat = 60 seconds */
  
  static int heartbeat = WD_TIMO;
  static int wd_heartbeat;
  module_param(heartbeat, int, 0);

  MODULE_PARM_DESC(heartbeat,
  	"Watchdog heartbeat in seconds. (0 < heartbeat < 65536, default="
  				__MODULE_STRING(WD_TIMO) ")");

  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) ")");

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

  static int io = 0x240;
  static int irq = 11;

  static DEFINE_SPINLOCK(wdt_lock);

  module_param(io, int, 0);
  MODULE_PARM_DESC(io, "WDT io port (default=0x240)");
  module_param(irq, int, 0);
  MODULE_PARM_DESC(irq, "WDT irq (default=11)");

  /* Support for the Fan Tachometer on the WDT501-P */
  static int tachometer;

  module_param(tachometer, int, 0);

  MODULE_PARM_DESC(tachometer,
  		"WDT501-P Fan Tachometer support (0=disable, default=0)");

  
  static int type = 500;
  module_param(type, int, 0);
  MODULE_PARM_DESC(type,

  		"WDT501-P Card type (500 or 501, default=500)");

  
  /*
   *	Programming support
   */
  
  static void wdt_ctr_mode(int ctr, int mode)
  {

  	ctr <<= 6;
  	ctr |= 0x30;
  	ctr |= (mode << 1);

  	outb_p(ctr, WDT_CR);
  }
  
  static void wdt_ctr_load(int ctr, int val)
  {
  	outb_p(val&0xFF, WDT_COUNT0+ctr);
  	outb_p(val>>8, WDT_COUNT0+ctr);
  }
  
  /**
   *	wdt_start:
   *
   *	Start the watchdog driver.
   */
  
  static int wdt_start(void)
  {

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

  	inb_p(WDT_DC);			/* Disable watchdog */

  	wdt_ctr_mode(0, 3);		/* Program CTR0 for Mode 3:
  						Square Wave Generator */
  	wdt_ctr_mode(1, 2);		/* Program CTR1 for Mode 2:
  						Rate Generator */
  	wdt_ctr_mode(2, 0);		/* Program CTR2 for Mode 0:
  						Pulse on Terminal Count */

  	wdt_ctr_load(0, 8948);		/* Count at 100Hz */

  	wdt_ctr_load(1, wd_heartbeat);	/* Heartbeat */
  	wdt_ctr_load(2, 65535);		/* Length of reset pulse */

  	outb_p(0, WDT_DC);		/* Enable watchdog */

  	spin_unlock_irqrestore(&wdt_lock, flags);

  	return 0;
  }
  
  /**
   *	wdt_stop:
   *
   *	Stop the watchdog driver.
   */

  static int wdt_stop(void)

  {

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

  	/* Turn the card off */
  	inb_p(WDT_DC);			/* Disable watchdog */

  	wdt_ctr_load(2, 0);		/* 0 length reset pulses now */

  	spin_unlock_irqrestore(&wdt_lock, flags);

  	return 0;
  }
  
  /**
   *	wdt_ping:
   *

   *	Reload counter one with the watchdog heartbeat. We don't bother
   *	reloading the cascade counter.

   */

  static void wdt_ping(void)

  {

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

  	/* Write a watchdog value */
  	inb_p(WDT_DC);			/* Disable watchdog */

  	wdt_ctr_mode(1, 2);		/* Re-Program CTR1 for Mode 2:
  							Rate Generator */
  	wdt_ctr_load(1, wd_heartbeat);	/* Heartbeat */

  	outb_p(0, WDT_DC);		/* Enable watchdog */

  	spin_unlock_irqrestore(&wdt_lock, flags);

  }
  
  /**
   *	wdt_set_heartbeat:
   *	@t:		the new heartbeat value that needs to be set.
   *

   *	Set a new heartbeat value for the watchdog device. If the heartbeat
   *	value is incorrect we keep the old value and return -EINVAL. If
   *	successful we return 0.

   */

  static int wdt_set_heartbeat(int t)
  {

  	if (t < 1 || t > 65535)

  		return -EINVAL;
  
  	heartbeat = t;
  	wd_heartbeat = t * 100;
  	return 0;
  }
  
  /**
   *	wdt_get_status:

   *
   *	Extract the status information from a WDT watchdog device. There are
   *	several board variants so we have to know which bits are valid. Some
   *	bits default to one and some to zero in order to be maximally painful.
   *
   *	we then map the bits onto the status ioctl flags.
   */

  static int wdt_get_status(void)

  {

  	unsigned char new_status;

  	int status = 0;

  	unsigned long flags;
  
  	spin_lock_irqsave(&wdt_lock, flags);
  	new_status = inb_p(WDT_SR);
  	spin_unlock_irqrestore(&wdt_lock, flags);

  	if (new_status & WDC_SR_ISOI0)

  		status |= WDIOF_EXTERN1;

  	if (new_status & WDC_SR_ISII1)

  		status |= WDIOF_EXTERN2;
  	if (type == 501) {
  		if (!(new_status & WDC_SR_TGOOD))
  			status |= WDIOF_OVERHEAT;
  		if (!(new_status & WDC_SR_PSUOVER))
  			status |= WDIOF_POWEROVER;
  		if (!(new_status & WDC_SR_PSUUNDR))
  			status |= WDIOF_POWERUNDER;
  		if (tachometer) {
  			if (!(new_status & WDC_SR_FANGOOD))
  				status |= WDIOF_FANFAULT;
  		}

  	}

  	return status;

  }

  /**
   *	wdt_get_temperature:
   *
   *	Reports the temperature in degrees Fahrenheit. The API is in
   *	farenheit. It was designed by an imperial measurement luddite.
   */

  static int wdt_get_temperature(void)

  {

  	unsigned short c;
  	unsigned long flags;

  	spin_lock_irqsave(&wdt_lock, flags);
  	c = inb_p(WDT_RT);
  	spin_unlock_irqrestore(&wdt_lock, flags);

  	return (c * 11 / 15) + 7;
  }
  
  static void wdt_decode_501(int status)
  {
  	if (!(status & WDC_SR_TGOOD))
  		printk(KERN_CRIT "Overheat alarm.(%d)
  ", inb_p(WDT_RT));
  	if (!(status & WDC_SR_PSUOVER))
  		printk(KERN_CRIT "PSU over voltage.
  ");
  	if (!(status & WDC_SR_PSUUNDR))
  		printk(KERN_CRIT "PSU under voltage.
  ");

  }

  
  /**
   *	wdt_interrupt:
   *	@irq:		Interrupt number
   *	@dev_id:	Unused as we don't allow multiple devices.

   *
   *	Handle an interrupt from the board. These are raised when the status
   *	map changes in what the board considers an interesting way. That means
   *	a failure condition occurring.
   */

  static irqreturn_t wdt_interrupt(int irq, void *dev_id)

  {
  	/*
  	 *	Read the status register see what is up and
  	 *	then printk it.
  	 */

  	unsigned char status;
  
  	spin_lock(&wdt_lock);
  	status = inb_p(WDT_SR);

  
  	printk(KERN_CRIT "WDT status %d
  ", status);

  	if (type == 501) {
  		wdt_decode_501(status);
  		if (tachometer) {
  			if (!(status & WDC_SR_FANGOOD))
  				printk(KERN_CRIT "Possible fan fault.
  ");
  		}

  	}

  	if (!(status & WDC_SR_WCCR)) {

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

  		emergency_restart();

  #endif
  #else
  		printk(KERN_CRIT "Reset in 5ms.
  ");
  #endif

  	}

  	spin_unlock(&wdt_lock);

  	return IRQ_HANDLED;
  }
  
  
  /**
   *	wdt_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 wdt_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;
  			}
  		}
  		wdt_ping();
  	}
  	return count;
  }
  
  /**
   *	wdt_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. We only actually usefully support
   *	querying capabilities and current status.
   */

  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_heartbeat;
  	int status;

  	struct watchdog_info ident = {

  		.options =		WDIOF_SETTIMEOUT|
  					WDIOF_MAGICCLOSE|
  					WDIOF_KEEPALIVEPING,
  		.firmware_version =	1,
  		.identity =		"WDT500/501",
  	};
  
  	/* Add options according to the card we have */
  	ident.options |= (WDIOF_EXTERN1|WDIOF_EXTERN2);

  	if (type == 501) {
  		ident.options |= (WDIOF_OVERHEAT|WDIOF_POWERUNDER|
  							WDIOF_POWEROVER);
  		if (tachometer)
  			ident.options |= WDIOF_FANFAULT;
  	}

  	switch (cmd) {

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

  		status = wdt_get_status();

  		return put_user(status, p);
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);
  	case WDIOC_KEEPALIVE:
  		wdt_ping();
  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_heartbeat, p))
  			return -EFAULT;
  		if (wdt_set_heartbeat(new_heartbeat))
  			return -EINVAL;
  		wdt_ping();
  		/* Fall */
  	case WDIOC_GETTIMEOUT:
  		return put_user(heartbeat, p);

  	default:
  		return -ENOTTY;

  	}
  }
  
  /**
   *	wdt_open:
   *	@inode: inode of device
   *	@file: file handle to device
   *
   *	The watchdog device has been opened. The watchdog device is single
   *	open and on opening we load the counters. Counter zero is a 100Hz
   *	cascade, into counter 1 which downcounts to reboot. When the counter
   *	triggers counter 2 downcounts the length of the reset pulse which
   *	set set to be as long as possible.
   */
  
  static int wdt_open(struct inode *inode, struct file *file)
  {

  	if (test_and_set_bit(0, &wdt_is_open))

  		return -EBUSY;
  	/*
  	 *	Activate
  	 */
  	wdt_start();
  	return nonseekable_open(inode, file);
  }
  
  /**
   *	wdt_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 wdt_release(struct inode *inode, struct file *file)
  {
  	if (expect_close == 42) {
  		wdt_stop();
  		clear_bit(0, &wdt_is_open);
  	} else {

  		printk(KERN_CRIT
  		 "wdt: WDT device closed unexpectedly.  WDT will not stop!
  ");

  		wdt_ping();
  	}
  	expect_close = 0;
  	return 0;
  }

  /**
   *	wdt_temp_read:
   *	@file: file handle to the watchdog board
   *	@buf: buffer to write 1 byte into
   *	@count: length of buffer
   *	@ptr: offset (no seek allowed)
   *
   *	Temp_read reports the temperature in degrees Fahrenheit. The API is in
   *	farenheit. It was designed by an imperial measurement luddite.
   */

  static ssize_t wdt_temp_read(struct file *file, char __user *buf,
  						size_t count, loff_t *ptr)

  {

  	int temperature = wdt_get_temperature();

  	if (copy_to_user(buf, &temperature, 1))

  		return -EFAULT;
  
  	return 1;
  }
  
  /**
   *	wdt_temp_open:
   *	@inode: inode of device
   *	@file: file handle to device
   *
   *	The temperature device has been opened.
   */
  
  static int wdt_temp_open(struct inode *inode, struct file *file)
  {
  	return nonseekable_open(inode, file);
  }
  
  /**
   *	wdt_temp_release:
   *	@inode: inode to board
   *	@file: file handle to board
   *
   *	The temperature device has been closed.
   */
  
  static int wdt_temp_release(struct inode *inode, struct file *file)
  {
  	return 0;
  }

  
  /**
   *	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 wdt_notify_sys(struct notifier_block *this, unsigned long code,
  	void *unused)
  {

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

  		wdt_stop();

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

  static const struct file_operations wdt_temp_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.read		= wdt_temp_read,
  	.open		= wdt_temp_open,
  	.release	= wdt_temp_release,
  };
  
  static struct miscdevice temp_miscdev = {
  	.minor	= TEMP_MINOR,
  	.name	= "temperature",
  	.fops	= &wdt_temp_fops,
  };

  
  /*
   *	The WDT card 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,
  };
  
  /**
   *	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 wdt_exit(void)
  {
  	misc_deregister(&wdt_miscdev);

  	if (type == 501)
  		misc_deregister(&temp_miscdev);

  	unregister_reboot_notifier(&wdt_notifier);
  	free_irq(irq, NULL);

  	release_region(io, 8);

  }
  
  /**

   *	wdt_init:

   *
   *	Set up the WDT watchdog board. All we have to do is grab the
   *	resources we require and bitch if anyone beat us to them.
   *	The open() function will actually kick the board off.
   */
  
  static int __init wdt_init(void)
  {
  	int ret;

  	if (type != 500 && type != 501) {
  		printk(KERN_ERR "wdt: unknown card type '%d'.
  ", type);
  		return -ENODEV;
  	}

  	/* Check that the heartbeat value is within it's range;
  	   if not reset to the default */

  	if (wdt_set_heartbeat(heartbeat)) {
  		wdt_set_heartbeat(WD_TIMO);

  		printk(KERN_INFO "wdt: heartbeat value must be "
  			"0 < heartbeat < 65536, using %d
  ", WD_TIMO);

  	}
  
  	if (!request_region(io, 8, "wdt501p")) {

  		printk(KERN_ERR
  			"wdt: I/O address 0x%04x already in use
  ", io);

  		ret = -EBUSY;
  		goto out;
  	}

  	ret = request_irq(irq, wdt_interrupt, 0, "wdt501p", NULL);

  	if (ret) {

  		printk(KERN_ERR "wdt: IRQ %d is not free.
  ", irq);
  		goto outreg;
  	}
  
  	ret = register_reboot_notifier(&wdt_notifier);

  	if (ret) {
  		printk(KERN_ERR
  		      "wdt: cannot register reboot notifier (err=%d)
  ", ret);

  		goto outirq;
  	}

  	if (type == 501) {
  		ret = misc_register(&temp_miscdev);
  		if (ret) {
  			printk(KERN_ERR "wdt: cannot register miscdev "
  				"on minor=%d (err=%d)
  ", TEMP_MINOR, ret);
  			goto outrbt;
  		}

  	}

  
  	ret = misc_register(&wdt_miscdev);
  	if (ret) {

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

  		goto outmisc;
  	}

  	printk(KERN_INFO "WDT500/501-P driver 0.10 "
  		"at 0x%04x (Interrupt %d). heartbeat=%d sec (nowayout=%d)
  ",

  		io, irq, heartbeat, nowayout);

  	if (type == 501)
  		printk(KERN_INFO "wdt: Fan Tachometer is %s
  ",

  				(tachometer ? "Enabled" : "Disabled"));

  	return 0;

  
  outmisc:

  	if (type == 501)
  		misc_deregister(&temp_miscdev);

  outrbt:

  	unregister_reboot_notifier(&wdt_notifier);
  outirq:
  	free_irq(irq, NULL);
  outreg:

  	release_region(io, 8);

  out:
  	return ret;

  }
  
  module_init(wdt_init);
  module_exit(wdt_exit);
  
  MODULE_AUTHOR("Alan Cox");
  MODULE_DESCRIPTION("Driver for ISA ICS watchdog cards (WDT500/501)");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  MODULE_ALIAS_MISCDEV(TEMP_MINOR);
  MODULE_LICENSE("GPL");