/******************************************************************************
*
* Name: hwtimer.c - ACPI Power Management Timer Interface
*
*****************************************************************************/
/*
* Copyright (C) 2000 - 2005, R. Byron Moore
* 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/module.h>
#include <acpi/acpi.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 (0 == acpi_gbl_FADT->tmr_val_ext) {
*resolution = 24;
}
else {
*resolution = 32;
}
return_ACPI_STATUS (AE_OK);
}
/******************************************************************************
*
* FUNCTION: acpi_get_timer
*
* PARAMETERS: Ticks - Where the timer value is returned
*
* RETURN: Status and current 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_low_level_read (32, ticks, &acpi_gbl_FADT->xpm_tmr_blk);
return_ACPI_STATUS (status);
}
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 (0 == acpi_gbl_FADT->tmr_val_ext) {
/* 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);
}
EXPORT_SYMBOL(acpi_get_timer_duration);
