034307a7ec
Signed-off-by: lzeng14 Reviewed-by: lgao4 git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12604 6f19259b-4bc3-4df7-8a09-765794883524
56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
/** @file
|
|
Internal header file for TscTimerLib instances.
|
|
|
|
Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>
|
|
This program and the accompanying materials
|
|
are licensed and made available under the terms and conditions of the BSD License
|
|
which accompanies this distribution. The full text of the license may be found at
|
|
http://opensource.org/licenses/bsd-license.php
|
|
|
|
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
|
|
|
|
**/
|
|
|
|
#ifndef _TSC_TIMER_LIB_INTERNAL_H_
|
|
#define _TSC_TIMER_LIB_INTERNAL_H_
|
|
|
|
#include <Ich/GenericIch.h>
|
|
|
|
#include <Library/TimerLib.h>
|
|
#include <Library/BaseLib.h>
|
|
#include <Library/IoLib.h>
|
|
#include <Library/PciLib.h>
|
|
#include <Library/PcdLib.h>
|
|
|
|
/** Get TSC frequency.
|
|
|
|
@return The number of TSC counts per second.
|
|
|
|
**/
|
|
UINT64
|
|
InternalGetTscFrequency (
|
|
VOID
|
|
);
|
|
|
|
/** Calculate TSC frequency.
|
|
|
|
The TSC counting frequency is determined by comparing how far it counts
|
|
during a 1ms period as determined by the ACPI timer. The ACPI timer is
|
|
used because it counts at a known frequency.
|
|
If ACPI I/O space not enabled, this function will enable it. Then the
|
|
TSC is sampled, followed by waiting for 3579 clocks of the ACPI timer, or 1ms.
|
|
The TSC is then sampled again. The difference multiplied by 1000 is the TSC
|
|
frequency. There will be a small error because of the overhead of reading
|
|
the ACPI timer. An attempt is made to determine and compensate for this error.
|
|
|
|
@return The number of TSC counts per second.
|
|
|
|
**/
|
|
UINT64
|
|
InternalCalculateTscFrequency (
|
|
VOID
|
|
);
|
|
|
|
#endif
|