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/******************************************************************************
*
* Name: hwtimer.c - ACPI Power Management Timer Interface
*
*****************************************************************************/
/*
* Copyright (C) 2000 - 2011, 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 <linux/export.h>
#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;
u64 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, "ient, NULL);
*time_elapsed = (u32) quotient;
return_ACPI_STATUS(status);
}
ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
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