/******************************************************************************
   *
   * Name: hwtimer.c - ACPI Power Management Timer Interface
   *
   *****************************************************************************/
  
  /*

   * Copyright (C) 2000 - 2008, Intel Corp.

   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions, and the following disclaimer,
   *    without modification.
   * 2. Redistributions in binary form must reproduce at minimum a disclaimer
   *    substantially similar to the "NO WARRANTY" disclaimer below
   *    ("Disclaimer") and any redistribution must be conditioned upon
   *    including a substantially similar Disclaimer requirement for further
   *    binary redistribution.
   * 3. Neither the names of the above-listed copyright holders nor the names
   *    of any contributors may be used to endorse or promote products derived
   *    from this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * NO WARRANTY
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGES.
   */

  #include <acpi/acpi.h>

  #include "accommon.h"

  
  #define _COMPONENT          ACPI_HARDWARE

  ACPI_MODULE_NAME("hwtimer")

  
  /******************************************************************************
   *
   * FUNCTION:    acpi_get_timer_resolution
   *
   * PARAMETERS:  Resolution          - Where the resolution is returned
   *
   * RETURN:      Status and timer resolution
   *
   * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
   *
   ******************************************************************************/

  acpi_status acpi_get_timer_resolution(u32 * resolution)

  {

  	ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);

  
  	if (!resolution) {

  		return_ACPI_STATUS(AE_BAD_PARAMETER);

  	}

  	if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {

  		*resolution = 24;

  	} else {

  		*resolution = 32;
  	}

  	return_ACPI_STATUS(AE_OK);

  }

  ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)

  /******************************************************************************
   *
   * FUNCTION:    acpi_get_timer
   *
   * PARAMETERS:  Ticks               - Where the timer value is returned
   *

   * RETURN:      Status and current timer value (ticks)

   *
   * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
   *
   ******************************************************************************/

  acpi_status acpi_get_timer(u32 * ticks)

  {

  	acpi_status status;

  	ACPI_FUNCTION_TRACE(acpi_get_timer);

  
  	if (!ticks) {

  		return_ACPI_STATUS(AE_BAD_PARAMETER);

  	}

  	status =

  	    acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block);

  	return_ACPI_STATUS(status);

  }

  ACPI_EXPORT_SYMBOL(acpi_get_timer)

  
  /******************************************************************************
   *
   * FUNCTION:    acpi_get_timer_duration
   *
   * PARAMETERS:  start_ticks         - Starting timestamp
   *              end_ticks           - End timestamp
   *              time_elapsed        - Where the elapsed time is returned
   *
   * RETURN:      Status and time_elapsed
   *
   * DESCRIPTION: Computes the time elapsed (in microseconds) between two
   *              PM Timer time stamps, taking into account the possibility of
   *              rollovers, the timer resolution, and timer frequency.
   *
   *              The PM Timer's clock ticks at roughly 3.6 times per
   *              _microsecond_, and its clock continues through Cx state
   *              transitions (unlike many CPU timestamp counters) -- making it
   *              a versatile and accurate timer.
   *
   *              Note that this function accommodates only a single timer
   *              rollover.  Thus for 24-bit timers, this function should only
   *              be used for calculating durations less than ~4.6 seconds
   *              (~20 minutes for 32-bit timers) -- calculations below:
   *
   *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
   *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
   *
   ******************************************************************************/

  acpi_status

  acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed)

  {

  	acpi_status status;
  	u32 delta_ticks;
  	acpi_integer quotient;

  	ACPI_FUNCTION_TRACE(acpi_get_timer_duration);

  
  	if (!time_elapsed) {

  		return_ACPI_STATUS(AE_BAD_PARAMETER);

  	}
  
  	/*
  	 * Compute Tick Delta:
  	 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
  	 */
  	if (start_ticks < end_ticks) {
  		delta_ticks = end_ticks - start_ticks;

  	} else if (start_ticks > end_ticks) {

  		if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {

  			/* 24-bit Timer */

  			delta_ticks =
  			    (((0x00FFFFFF - start_ticks) +
  			      end_ticks) & 0x00FFFFFF);
  		} else {

  			/* 32-bit Timer */
  
  			delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
  		}

  	} else {		/* start_ticks == end_ticks */

  		*time_elapsed = 0;

  		return_ACPI_STATUS(AE_OK);

  	}
  
  	/*
  	 * Compute Duration (Requires a 64-bit multiply and divide):
  	 *
  	 * time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
  	 */

  	status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000,
  				      PM_TIMER_FREQUENCY, &quotient, NULL);

  
  	*time_elapsed = (u32) quotient;

  	return_ACPI_STATUS(status);

  }

  ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)