/*
   * drivers/char/watchdog/iop_wdt.c
   *
   * WDT driver for Intel I/O Processors
   * Copyright (C) 2005, Intel Corporation.
   *
   * Based on ixp4xx driver, Copyright 2004 (c) MontaVista, Software, Inc.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
   * Place - Suite 330, Boston, MA 02111-1307 USA.
   *
   *	Curt E Bruns <curt.e.bruns@intel.com>
   *	Peter Milne <peter.milne@d-tacq.com>
   *	Dan Williams <dan.j.williams@intel.com>
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/init.h>
  #include <linux/device.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/uaccess.h>
  #include <mach/hardware.h>
  
  static bool nowayout = WATCHDOG_NOWAYOUT;
  static unsigned long wdt_status;
  static unsigned long boot_status;
  static DEFINE_SPINLOCK(wdt_lock);
  
  #define WDT_IN_USE		0
  #define WDT_OK_TO_CLOSE		1
  #define WDT_ENABLED		2
  
  static unsigned long iop_watchdog_timeout(void)
  {
  	return (0xffffffffUL / get_iop_tick_rate());
  }
  
  /**
   * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
   * or iop3xx by whether it has a disable command
   */
  static int wdt_supports_disable(void)
  {
  	int can_disable;
  
  	if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
  		can_disable = 1;
  	else
  		can_disable = 0;
  
  	return can_disable;
  }
  
  static void wdt_enable(void)
  {
  	/* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
  	 * Takes approx. 10.7s to timeout
  	 */
  	spin_lock(&wdt_lock);
  	write_wdtcr(IOP_WDTCR_EN_ARM);
  	write_wdtcr(IOP_WDTCR_EN);
  	spin_unlock(&wdt_lock);
  }
  
  /* returns 0 if the timer was successfully disabled */
  static int wdt_disable(void)
  {
  	/* Stop Counting */
  	if (wdt_supports_disable()) {
  		spin_lock(&wdt_lock);
  		write_wdtcr(IOP_WDTCR_DIS_ARM);
  		write_wdtcr(IOP_WDTCR_DIS);
  		clear_bit(WDT_ENABLED, &wdt_status);
  		spin_unlock(&wdt_lock);
  		pr_info("Disabled
  ");
  		return 0;
  	} else
  		return 1;
  }
  
  static int iop_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();
  	set_bit(WDT_ENABLED, &wdt_status);
  	return nonseekable_open(inode, file);
  }
  
  static ssize_t iop_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_enable();
  	}
  	return len;
  }
  
  static const struct watchdog_info ident = {
  	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
  	.identity = "iop watchdog",
  };
  
  static long iop_wdt_ioctl(struct file *file,
  				unsigned int cmd, unsigned long arg)
  {
  	int options;
  	int ret = -ENOTTY;
  	int __user *argp = (int __user *)arg;
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		if (copy_to_user(argp, &ident, sizeof(ident)))
  			ret = -EFAULT;
  		else
  			ret = 0;
  		break;
  
  	case WDIOC_GETSTATUS:
  		ret = put_user(0, argp);
  		break;
  
  	case WDIOC_GETBOOTSTATUS:
  		ret = put_user(boot_status, argp);
  		break;
  
  	case WDIOC_SETOPTIONS:
  		if (get_user(options, (int *)arg))
  			return -EFAULT;
  
  		if (options & WDIOS_DISABLECARD) {
  			if (!nowayout) {
  				if (wdt_disable() == 0) {
  					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  					ret = 0;
  				} else
  					ret = -ENXIO;
  			} else
  				ret = 0;
  		}
  		if (options & WDIOS_ENABLECARD) {
  			wdt_enable();
  			ret = 0;
  		}
  		break;
  
  	case WDIOC_KEEPALIVE:
  		wdt_enable();
  		ret = 0;
  		break;
  
  	case WDIOC_GETTIMEOUT:
  		ret = put_user(iop_watchdog_timeout(), argp);
  		break;
  	}
  	return ret;
  }
  
  static int iop_wdt_release(struct inode *inode, struct file *file)
  {
  	int state = 1;
  	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
  		if (test_bit(WDT_ENABLED, &wdt_status))
  			state = wdt_disable();
  
  	/* if the timer is not disabled reload and notify that we are still
  	 * going down
  	 */
  	if (state != 0) {
  		wdt_enable();
  		pr_crit("Device closed unexpectedly - reset in %lu seconds
  ",
  			iop_watchdog_timeout());
  	}
  
  	clear_bit(WDT_IN_USE, &wdt_status);
  	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  
  	return 0;
  }
  
  static const struct file_operations iop_wdt_fops = {
  	.owner = THIS_MODULE,
  	.llseek = no_llseek,
  	.write = iop_wdt_write,
  	.unlocked_ioctl = iop_wdt_ioctl,
  	.open = iop_wdt_open,
  	.release = iop_wdt_release,
  };
  
  static struct miscdevice iop_wdt_miscdev = {
  	.minor = WATCHDOG_MINOR,
  	.name = "watchdog",
  	.fops = &iop_wdt_fops,
  };
  
  static int __init iop_wdt_init(void)
  {
  	int ret;
  
  	/* check if the reset was caused by the watchdog timer */
  	boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
  
  	/* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
  	 * NOTE: An IB Reset will Reset both cores in the IOP342
  	 */
  	write_wdtsr(IOP13XX_WDTCR_IB_RESET);
  
  	/* Register after we have the device set up so we cannot race
  	   with an open */
  	ret = misc_register(&iop_wdt_miscdev);
  	if (ret == 0)
  		pr_info("timeout %lu sec
  ", iop_watchdog_timeout());
  
  	return ret;
  }
  
  static void __exit iop_wdt_exit(void)
  {
  	misc_deregister(&iop_wdt_miscdev);
  }
  
  module_init(iop_wdt_init);
  module_exit(iop_wdt_exit);
  
  module_param(nowayout, bool, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  
  MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
  MODULE_DESCRIPTION("iop watchdog timer driver");
  MODULE_LICENSE("GPL");