/******************************************************************************
*
* Name: hwtimer.c - ACPI Power Management Timer Interface
*
*****************************************************************************/
/*
* Copyright (C) 2000 - 2016, 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.
*/
#define EXPORT_ACPI_INTERFACES
#include "acpi.h"
#include "accommon.h"
ACPI_MODULE_NAME ("hwtimer")
#if (!ACPI_REDUCED_HARDWARE) /* Entire module */
/******************************************************************************
*
* FUNCTION: AcpiGetTimerResolution
*
* PARAMETERS: Resolution - Where the resolution is returned
*
* RETURN: Status and timer resolution
*
* DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
*
******************************************************************************/
{
if (!Resolution)
{
}
{
*Resolution = 24;
}
else
{
*Resolution = 32;
}
}
/******************************************************************************
*
* FUNCTION: AcpiGetTimer
*
* 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).
*
******************************************************************************/
{
if (!Ticks)
{
}
/* ACPI 5.0A: PM Timer is optional */
{
}
}
/******************************************************************************
*
* FUNCTION: AcpiGetTimerDuration
*
* PARAMETERS: StartTicks - Starting timestamp
* EndTicks - End timestamp
* TimeElapsed - Where the elapsed time is returned
*
* RETURN: Status and TimeElapsed
*
* 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:
*
*
******************************************************************************/
{
if (!TimeElapsed)
{
}
/* ACPI 5.0A: PM Timer is optional */
{
}
/*
* Compute Tick Delta:
* Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
*/
if (StartTicks < EndTicks)
{
}
else if (StartTicks > EndTicks)
{
{
/* 24-bit Timer */
}
else
{
/* 32-bit Timer */
}
}
else /* StartTicks == EndTicks */
{
*TimeElapsed = 0;
}
/*
* Compute Duration (Requires a 64-bit multiply and divide):
*
* TimeElapsed (microseconds) =
* (DeltaTicks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
*/
}
#endif /* !ACPI_REDUCED_HARDWARE */