/*

   * drivers/char/watchdog/ixp2000_wdt.c

   *
   * Watchdog driver for Intel IXP2000 network processors
   *
   * Adapted from the IXP4xx watchdog driver by Lennert Buytenhek.
   * The original version carries these notices:
   *
   * Author: Deepak Saxena <dsaxena@plexity.net>
   *
   * Copyright 2004 (c) MontaVista, Software, Inc.
   * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
   *
   * This file is licensed under  the terms of the GNU General Public
   * License version 2. This program is licensed "as is" without any
   * warranty of any kind, whether express or implied.
   */

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

  #include <linux/timer.h>

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

  #include <linux/uaccess.h>

  #include <mach/hardware.h>

  static int nowayout = WATCHDOG_NOWAYOUT;

  static unsigned int heartbeat = 60;	/* (secs) Default is 1 minute */
  static unsigned long wdt_status;

  static DEFINE_SPINLOCK(wdt_lock);

  
  #define	WDT_IN_USE		0
  #define	WDT_OK_TO_CLOSE		1
  
  static unsigned long wdt_tick_rate;

  static void wdt_enable(void)

  {

  	spin_lock(&wdt_lock);

  	ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
  	ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
  	ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  	ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);

  	spin_unlock(&wdt_lock);

  }

  static void wdt_disable(void)

  {

  	spin_lock(&wdt_lock);

  	ixp2000_reg_write(IXP2000_T4_CTL, 0);

  	spin_unlock(&wdt_lock);

  }

  static void wdt_keepalive(void)

  {

  	spin_lock(&wdt_lock);

  	ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);

  	spin_unlock(&wdt_lock);

  }

  static int ixp2000_wdt_open(struct inode *inode, struct file *file)

  {
  	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  		return -EBUSY;
  
  	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  
  	wdt_enable();
  
  	return nonseekable_open(inode, file);
  }

  static ssize_t ixp2000_wdt_write(struct file *file, const char *data,
  						size_t len, loff_t *ppos)

  {
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  
  			for (i = 0; i != len; i++) {
  				char c;
  
  				if (get_user(c, data + i))
  					return -EFAULT;
  				if (c == 'V')
  					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  			}
  		}
  		wdt_keepalive();
  	}
  
  	return len;
  }

  static const struct watchdog_info ident = {

  	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
  				WDIOF_KEEPALIVEPING,
  	.identity	= "IXP2000 Watchdog",
  };

  static long ixp2000_wdt_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)

  {

  	int ret = -ENOTTY;

  	int time;
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		ret = copy_to_user((struct watchdog_info *)arg, &ident,
  				   sizeof(ident)) ? -EFAULT : 0;
  		break;
  
  	case WDIOC_GETSTATUS:
  		ret = put_user(0, (int *)arg);
  		break;
  
  	case WDIOC_GETBOOTSTATUS:
  		ret = put_user(0, (int *)arg);
  		break;

  	case WDIOC_KEEPALIVE:
  		wdt_enable();
  		ret = 0;
  		break;

  	case WDIOC_SETTIMEOUT:
  		ret = get_user(time, (int *)arg);
  		if (ret)
  			break;
  
  		if (time <= 0 || time > 60) {
  			ret = -EINVAL;
  			break;
  		}
  
  		heartbeat = time;
  		wdt_keepalive();
  		/* Fall through */
  
  	case WDIOC_GETTIMEOUT:
  		ret = put_user(heartbeat, (int *)arg);
  		break;

  	}
  
  	return ret;
  }

  static int ixp2000_wdt_release(struct inode *inode, struct file *file)

  {

  	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))

  		wdt_disable();

  	else

  		printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "

  					"timer will not stop
  ");

  	clear_bit(WDT_IN_USE, &wdt_status);
  	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  
  	return 0;
  }

  static const struct file_operations ixp2000_wdt_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= ixp2000_wdt_write,

  	.unlocked_ioctl	= ixp2000_wdt_ioctl,

  	.open		= ixp2000_wdt_open,
  	.release	= ixp2000_wdt_release,
  };

  static struct miscdevice ixp2000_wdt_miscdev = {

  	.minor		= WATCHDOG_MINOR,

  	.name		= "watchdog",

  	.fops		= &ixp2000_wdt_fops,
  };
  
  static int __init ixp2000_wdt_init(void)
  {

  	if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
  		printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.
  ");
  		return -EIO;
  	}

  	wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;

  	return misc_register(&ixp2000_wdt_miscdev);
  }
  
  static void __exit ixp2000_wdt_exit(void)
  {
  	misc_deregister(&ixp2000_wdt_miscdev);
  }
  
  module_init(ixp2000_wdt_init);
  module_exit(ixp2000_wdt_exit);

  MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");

  MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
  
  module_param(heartbeat, int, 0);
  MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
  
  module_param(nowayout, int, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);