da27b950d5
Signed-off-by: lzeng14 Reviewed-by: vanjeff git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12608 6f19259b-4bc3-4df7-8a09-765794883524
46 lines
1.9 KiB
C
46 lines
1.9 KiB
C
/** @file
|
|
A Base Timer Library implementation which uses the Time Stamp Counter in the processor.
|
|
|
|
For Pentium 4 processors, Intel Xeon processors (family [0FH], models [03H and higher]);
|
|
for Intel Core Solo and Intel Core Duo processors (family [06H], model [0EH]);
|
|
for the Intel Xeon processor 5100 series and Intel Core 2 Duo processors (family [06H], model [0FH]);
|
|
for Intel Core 2 and Intel Xeon processors (family [06H], display_model [17H]);
|
|
for Intel Atom processors (family [06H], display_model [1CH]):
|
|
the time-stamp counter increments at a constant rate.
|
|
That rate may be set by the maximum core-clock to bus-clock ratio of the processor or may be set by
|
|
the maximum resolved frequency at which the processor is booted. The maximum resolved frequency may
|
|
differ from the maximum qualified frequency of the processor.
|
|
|
|
The specific processor configuration determines the behavior. Constant TSC behavior ensures that the
|
|
duration of each clock tick is uniform and supports the use of the TSC as a wall clock timer even if
|
|
the processor core changes frequency. This is the architectural behavior moving forward.
|
|
|
|
A Processor's support for invariant TSC is indicated by CPUID.0x80000007.EDX[8].
|
|
|
|
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.
|
|
|
|
**/
|
|
|
|
#include "TscTimerLibInternal.h"
|
|
|
|
/** Get TSC frequency.
|
|
|
|
@return The number of TSC counts per second.
|
|
|
|
**/
|
|
UINT64
|
|
InternalGetTscFrequency (
|
|
VOID
|
|
)
|
|
{
|
|
return InternalCalculateTscFrequency ();
|
|
}
|
|
|