d0f65b21c5
Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Eric Dong <eric.dong@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15597 6f19259b-4bc3-4df7-8a09-765794883524
103 lines
3.6 KiB
C
103 lines
3.6 KiB
C
/** @file
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A Dxe Timer Library implementation which uses the Time Stamp Counter in the processor.
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For Pentium 4 processors, Intel Xeon processors (family [0FH], models [03H and higher]);
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for Intel Core Solo and Intel Core Duo processors (family [06H], model [0EH]);
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for the Intel Xeon processor 5100 series and Intel Core 2 Duo processors (family [06H], model [0FH]);
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for Intel Core 2 and Intel Xeon processors (family [06H], display_model [17H]);
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for Intel Atom processors (family [06H], display_model [1CH]):
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the time-stamp counter increments at a constant rate.
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That rate may be set by the maximum core-clock to bus-clock ratio of the processor or may be set by
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the maximum resolved frequency at which the processor is booted. The maximum resolved frequency may
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differ from the maximum qualified frequency of the processor.
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The specific processor configuration determines the behavior. Constant TSC behavior ensures that the
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duration of each clock tick is uniform and supports the use of the TSC as a wall clock timer even if
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the processor core changes frequency. This is the architectural behavior moving forward.
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A Processor's support for invariant TSC is indicated by CPUID.0x80000007.EDX[8].
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Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include <PiDxe.h>
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#include <Library/UefiBootServicesTableLib.h>
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#include <Library/UefiLib.h>
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#include <Library/DebugLib.h>
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#include <Guid/TscFrequency.h>
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#include "TscTimerLibInternal.h"
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UINT64 mTscFrequency;
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/** The constructor function determines the actual TSC frequency.
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First, Get TSC frequency from system configuration table with TSC frequency GUID,
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if the table is not found, install it.
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This function will always return EFI_SUCCESS.
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@param ImageHandle The firmware allocated handle for the EFI image.
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@param SystemTable A pointer to the EFI System Table.
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@retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.
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**/
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EFI_STATUS
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EFIAPI
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DxeTscTimerLibConstructor (
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IN EFI_HANDLE ImageHandle,
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IN EFI_SYSTEM_TABLE *SystemTable
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)
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{
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EFI_STATUS Status;
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UINT64 *TscFrequency;
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TscFrequency = NULL;
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//
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// Get TSC frequency from system configuration table with TSC frequency GUID.
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//
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Status = EfiGetSystemConfigurationTable (&gEfiTscFrequencyGuid, (VOID **) &TscFrequency);
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if (Status == EFI_SUCCESS) {
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ASSERT (TscFrequency != NULL);
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mTscFrequency = *TscFrequency;
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return EFI_SUCCESS;
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}
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//
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// TSC frequency GUID system configuration table is not found, install it.
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//
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Status = gBS->AllocatePool (EfiBootServicesData, sizeof (UINT64), (VOID **) &TscFrequency);
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ASSERT_EFI_ERROR (Status);
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*TscFrequency = InternalCalculateTscFrequency ();
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//
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// TscFrequency now points to the number of TSC counts per second, install system configuration table for it.
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//
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gBS->InstallConfigurationTable (&gEfiTscFrequencyGuid, TscFrequency);
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mTscFrequency = *TscFrequency;
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return EFI_SUCCESS;
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}
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/** Get TSC frequency.
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@return The number of TSC counts per second.
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**/
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UINT64
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InternalGetTscFrequency (
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VOID
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)
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{
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return mTscFrequency;
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}
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