/*
   * MixCom Watchdog: A Simple Hardware Watchdog Device
   * Based on Softdog driver by Alan Cox and PC Watchdog driver by Ken Hollis
   *
   * Author: Gergely Madarasz <gorgo@itc.hu>
   *
   * Copyright (c) 1999 ITConsult-Pro Co. <info@itc.hu>
   *
   * 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.
   *
   * Version 0.1 (99/04/15):
   *		- first version
   *
   * Version 0.2 (99/06/16):
   *		- added kernel timer watchdog ping after close
   *		  since the hardware does not support watchdog shutdown
   *
   * Version 0.3 (99/06/21):
   *		- added WDIOC_GETSTATUS and WDIOC_GETSUPPORT ioctl calls
   *
   * Version 0.3.1 (99/06/22):
   *		- allow module removal while internal timer is active,
   *		  print warning about probable reset
   *
   * Version 0.4 (99/11/15):
   *		- support for one more type board
   *
   * Version 0.5 (2001/12/14) Matt Domsch <Matt_Domsch@dell.com>

   *		- added nowayout module option to override
   *		  CONFIG_WATCHDOG_NOWAYOUT

   *
   * Version 0.6 (2002/04/12): Rob Radez <rob@osinvestor.com>
   *		- make mixcomwd_opened unsigned,
   *		  removed lock_kernel/unlock_kernel from mixcomwd_release,
   *		  modified ioctl a bit to conform to API

   *
   */

  #define VERSION "0.6"

  #define WATCHDOG_NAME "mixcomwd"
  #define PFX WATCHDOG_NAME ": "

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

  #include <linux/types.h>
  #include <linux/miscdevice.h>
  #include <linux/ioport.h>
  #include <linux/watchdog.h>
  #include <linux/fs.h>
  #include <linux/reboot.h>
  #include <linux/init.h>

  #include <linux/jiffies.h>
  #include <linux/timer.h>

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

  /*
   * We have two types of cards that can be probed:
   * 1) The Mixcom cards: these cards can be found at addresses
   *    0x180, 0x280, 0x380 with an additional offset of 0xc10.
   *    (Or 0xd90, 0xe90, 0xf90).
   * 2) The FlashCOM cards: these cards can be set up at
   *    0x300 -> 0x378, in 0x8 jumps with an offset of 0x04.
   *    (Or 0x304 -> 0x37c in 0x8 jumps).
   *    Each card has it's own ID.
   */

  #define MIXCOM_ID 0x11

  #define FLASHCOM_ID 0x18

  static struct {
  	int ioport;
  	int id;
  } mixcomwd_io_info[] __devinitdata = {
  	/* The Mixcom cards */
  	{0x0d90, MIXCOM_ID},
  	{0x0e90, MIXCOM_ID},
  	{0x0f90, MIXCOM_ID},
  	/* The FlashCOM cards */
  	{0x0304, FLASHCOM_ID},
  	{0x030c, FLASHCOM_ID},
  	{0x0314, FLASHCOM_ID},
  	{0x031c, FLASHCOM_ID},
  	{0x0324, FLASHCOM_ID},
  	{0x032c, FLASHCOM_ID},
  	{0x0334, FLASHCOM_ID},
  	{0x033c, FLASHCOM_ID},
  	{0x0344, FLASHCOM_ID},
  	{0x034c, FLASHCOM_ID},
  	{0x0354, FLASHCOM_ID},
  	{0x035c, FLASHCOM_ID},
  	{0x0364, FLASHCOM_ID},
  	{0x036c, FLASHCOM_ID},
  	{0x0374, FLASHCOM_ID},
  	{0x037c, FLASHCOM_ID},
  	/* The end of the list */
  	{0x0000, 0},
  };

  static void mixcomwd_timerfun(unsigned long d);

  static unsigned long mixcomwd_opened; /* long req'd for setbit --RR */
  
  static int watchdog_port;
  static int mixcomwd_timer_alive;

  static DEFINE_TIMER(mixcomwd_timer, mixcomwd_timerfun, 0, 0);

  static char expect_close;

  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 void mixcomwd_ping(void)
  {

  	outb_p(55, watchdog_port);

  	return;
  }
  
  static void mixcomwd_timerfun(unsigned long d)
  {
  	mixcomwd_ping();

  	mod_timer(&mixcomwd_timer, jiffies + 5 * HZ);

  }
  
  /*
   *	Allow only one person to hold it open
   */
  
  static int mixcomwd_open(struct inode *inode, struct file *file)
  {

  	if (test_and_set_bit(0, &mixcomwd_opened))

  		return -EBUSY;

  	mixcomwd_ping();

  	if (nowayout)

  		/*
  		 * fops_get() code via open() has already done
  		 * a try_module_get() so it is safe to do the
  		 * __module_get().
  		 */
  		__module_get(THIS_MODULE);

  	else {
  		if (mixcomwd_timer_alive) {

  			del_timer(&mixcomwd_timer);

  			mixcomwd_timer_alive = 0;

  		}
  	}
  	return nonseekable_open(inode, file);
  }
  
  static int mixcomwd_release(struct inode *inode, struct file *file)
  {
  	if (expect_close == 42) {

  		if (mixcomwd_timer_alive) {
  			printk(KERN_ERR PFX
  				"release called while internal timer alive");

  			return -EBUSY;
  		}

  		mixcomwd_timer_alive = 1;

  		mod_timer(&mixcomwd_timer, jiffies + 5 * HZ);

  	} else
  		printk(KERN_CRIT PFX
  		    "WDT device closed unexpectedly.  WDT will not stop!
  ");

  	clear_bit(0, &mixcomwd_opened);
  	expect_close = 0;

  	return 0;
  }

  static ssize_t mixcomwd_write(struct file *file, const char __user *data,
  						size_t len, loff_t *ppos)

  {

  	if (len) {

  		if (!nowayout) {
  			size_t i;
  
  			/* In case it was set long ago */
  			expect_close = 0;
  
  			for (i = 0; i != len; i++) {
  				char c;
  				if (get_user(c, data + i))
  					return -EFAULT;
  				if (c == 'V')
  					expect_close = 42;
  			}
  		}
  		mixcomwd_ping();
  	}
  	return len;
  }

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

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

  	static const struct watchdog_info ident = {

  		.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  		.firmware_version = 1,
  		.identity = "MixCOM watchdog",
  	};

  	switch (cmd) {

  	case WDIOC_GETSUPPORT:
  		if (copy_to_user(argp, &ident, sizeof(ident)))
  			return -EFAULT;
  		break;

  	case WDIOC_GETSTATUS:
  		status = mixcomwd_opened;
  		if (!nowayout)
  			status |= mixcomwd_timer_alive;
  		return put_user(status, p);
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);

  	case WDIOC_KEEPALIVE:
  		mixcomwd_ping();
  		break;
  	default:
  		return -ENOTTY;

  	}
  	return 0;
  }

  static const struct file_operations mixcomwd_fops = {

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

  	.unlocked_ioctl	= mixcomwd_ioctl,

  	.open		= mixcomwd_open,
  	.release	= mixcomwd_release,
  };

  static struct miscdevice mixcomwd_miscdev = {

  	.minor	= WATCHDOG_MINOR,
  	.name	= "watchdog",
  	.fops	= &mixcomwd_fops,
  };

  static int __init checkcard(int port, int card_id)

  {
  	int id;

  	if (!request_region(port, 1, "MixCOM watchdog"))

  		return 0;

  	id = inb_p(port);
  	if (card_id == MIXCOM_ID)

  		id &= 0x3f;

  	if (id != card_id) {

  		release_region(port, 1);
  		return 0;
  	}

  	return 1;
  }

  
  static int __init mixcomwd_init(void)
  {

  	int i, ret, found = 0;

  	for (i = 0; !found && mixcomwd_io_info[i].ioport != 0; i++) {
  		if (checkcard(mixcomwd_io_info[i].ioport,
  			      mixcomwd_io_info[i].id)) {

  			found = 1;

  			watchdog_port = mixcomwd_io_info[i].ioport;

  		}
  	}
  
  	if (!found) {

  		printk(KERN_ERR PFX
  			"No card detected, or port not available.
  ");

  		return -ENODEV;
  	}
  
  	ret = misc_register(&mixcomwd_miscdev);

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

  		goto error_misc_register_watchdog;

  	}

  	printk(KERN_INFO
  		"MixCOM watchdog driver v%s, watchdog port at 0x%3x
  ",
  					VERSION, watchdog_port);

  
  	return 0;

  
  error_misc_register_watchdog:
  	release_region(watchdog_port, 1);
  	watchdog_port = 0x0000;
  	return ret;

  }
  
  static void __exit mixcomwd_exit(void)
  {
  	if (!nowayout) {

  		if (mixcomwd_timer_alive) {

  			printk(KERN_WARNING PFX "I quit now, hardware will"

  			       " probably reboot!
  ");

  			del_timer_sync(&mixcomwd_timer);

  			mixcomwd_timer_alive = 0;

  		}
  	}

  	misc_deregister(&mixcomwd_miscdev);

  	release_region(watchdog_port, 1);

  }
  
  module_init(mixcomwd_init);
  module_exit(mixcomwd_exit);
  
  MODULE_AUTHOR("Gergely Madarasz <gorgo@itc.hu>");
  MODULE_DESCRIPTION("MixCom Watchdog driver");

  MODULE_VERSION(VERSION);

  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);