176 lines
4.8 KiB
C
176 lines
4.8 KiB
C
// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
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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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* Copyright (C) 2000 - 2022, Intel Corp.
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*
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*****************************************************************************/
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#define EXPORT_ACPI_INTERFACES
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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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#if (!ACPI_REDUCED_HARDWARE) /* Entire module */
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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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u64 timer_value;
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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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/* ACPI 5.0A: PM Timer is optional */
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if (!acpi_gbl_FADT.xpm_timer_block.address) {
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return_ACPI_STATUS(AE_SUPPORT);
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}
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status = acpi_hw_read(&timer_value, &acpi_gbl_FADT.xpm_timer_block);
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if (ACPI_SUCCESS(status)) {
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/* ACPI PM Timer is defined to be 32 bits (PM_TMR_LEN) */
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*ticks = (u32)timer_value;
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}
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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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u64 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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/* ACPI 5.0A: PM Timer is optional */
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if (!acpi_gbl_FADT.xpm_timer_block.address) {
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return_ACPI_STATUS(AE_SUPPORT);
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}
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if (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 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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delta_ticks = end_ticks;
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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 |= (u64)1 << 24;
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} else {
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/* 32-bit Timer */
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delta_ticks |= (u64)1 << 32;
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}
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}
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delta_ticks -= start_ticks;
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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 (microseconds) =
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* (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
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*/
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status = acpi_ut_short_divide(delta_ticks * ACPI_USEC_PER_SEC,
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ACPI_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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#endif /* !ACPI_REDUCED_HARDWARE */
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