189 lines
6.1 KiB
C
189 lines
6.1 KiB
C
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/******************************************************************************
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*
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* Name: hwtimer.c - ACPI Power Management Timer Interface
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*
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*****************************************************************************/
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/*
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* Copyright (C) 2000 - 2010, Intel Corp.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification.
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* 2. Redistributions in binary form must reproduce at minimum a disclaimer
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* substantially similar to the "NO WARRANTY" disclaimer below
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* ("Disclaimer") and any redistribution must be conditioned upon
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* including a substantially similar Disclaimer requirement for further
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* binary redistribution.
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* 3. Neither the names of the above-listed copyright holders nor the names
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* of any contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* NO WARRANTY
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGES.
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*/
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#include <acpi/acpi.h>
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#include "accommon.h"
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#define _COMPONENT ACPI_HARDWARE
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ACPI_MODULE_NAME("hwtimer")
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/******************************************************************************
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*
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* FUNCTION: acpi_get_timer_resolution
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*
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* PARAMETERS: Resolution - Where the resolution is returned
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*
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* RETURN: Status and timer resolution
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*
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* DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
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*
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******************************************************************************/
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acpi_status acpi_get_timer_resolution(u32 * resolution)
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{
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ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
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if (!resolution) {
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return_ACPI_STATUS(AE_BAD_PARAMETER);
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}
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if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
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*resolution = 24;
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} else {
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*resolution = 32;
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}
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return_ACPI_STATUS(AE_OK);
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}
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ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
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/******************************************************************************
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*
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* FUNCTION: acpi_get_timer
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*
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* PARAMETERS: Ticks - Where the timer value is returned
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*
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* RETURN: Status and current timer value (ticks)
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*
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* DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
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*
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******************************************************************************/
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acpi_status acpi_get_timer(u32 * ticks)
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{
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acpi_status status;
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ACPI_FUNCTION_TRACE(acpi_get_timer);
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if (!ticks) {
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return_ACPI_STATUS(AE_BAD_PARAMETER);
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}
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status =
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acpi_hw_read(ticks, &acpi_gbl_FADT.xpm_timer_block);
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return_ACPI_STATUS(status);
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}
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ACPI_EXPORT_SYMBOL(acpi_get_timer)
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/******************************************************************************
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*
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* FUNCTION: acpi_get_timer_duration
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*
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* PARAMETERS: start_ticks - Starting timestamp
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* end_ticks - End timestamp
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* time_elapsed - Where the elapsed time is returned
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*
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* RETURN: Status and time_elapsed
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*
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* DESCRIPTION: Computes the time elapsed (in microseconds) between two
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* PM Timer time stamps, taking into account the possibility of
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* rollovers, the timer resolution, and timer frequency.
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*
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* The PM Timer's clock ticks at roughly 3.6 times per
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* _microsecond_, and its clock continues through Cx state
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* transitions (unlike many CPU timestamp counters) -- making it
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* a versatile and accurate timer.
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*
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* Note that this function accommodates only a single timer
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* rollover. Thus for 24-bit timers, this function should only
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* be used for calculating durations less than ~4.6 seconds
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* (~20 minutes for 32-bit timers) -- calculations below:
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*
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* 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
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* 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
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*
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******************************************************************************/
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acpi_status
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acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 * time_elapsed)
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{
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acpi_status status;
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u32 delta_ticks;
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u64 quotient;
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ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
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if (!time_elapsed) {
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return_ACPI_STATUS(AE_BAD_PARAMETER);
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}
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/*
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* Compute Tick Delta:
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* Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
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*/
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if (start_ticks < end_ticks) {
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delta_ticks = end_ticks - start_ticks;
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} else if (start_ticks > end_ticks) {
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if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
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/* 24-bit Timer */
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delta_ticks =
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(((0x00FFFFFF - start_ticks) +
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end_ticks) & 0x00FFFFFF);
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} else {
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/* 32-bit Timer */
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delta_ticks = (0xFFFFFFFF - start_ticks) + end_ticks;
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}
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} else { /* start_ticks == end_ticks */
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*time_elapsed = 0;
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return_ACPI_STATUS(AE_OK);
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}
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/*
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* Compute Duration (Requires a 64-bit multiply and divide):
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*
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* time_elapsed = (delta_ticks * 1000000) / PM_TIMER_FREQUENCY;
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*/
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status = acpi_ut_short_divide(((u64) delta_ticks) * 1000000,
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PM_TIMER_FREQUENCY, "ient, NULL);
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*time_elapsed = (u32) quotient;
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return_ACPI_STATUS(status);
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}
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ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
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