fd501a7984
In V2: 1) Update PeiAcpiTimerLib base name to PeiAcpiTimerLib 2) Update PeiAcpiTimerLib to add the missing constructor to enable ACPI IO space 3) Update DxeAcpiTimerLib to cache frequency in constructor. PeiAcpiTimerLib caches PerformanceCounterFrequency in HOB, then Pei and Dxe AcpiTimerLib can share the same PerformanceCounterFrequency. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Liming Gao <liming.gao@intel.com> Cc: Star Zeng <star.zeng@intel.com> Reviewed-by: Star Zeng <star.zeng@intel.com>
113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/** @file
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ACPI Timer implements one instance of Timer Library.
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Copyright (c) 2013 - 2016, 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/TimerLib.h>
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#include <Library/BaseLib.h>
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#include <Library/HobLib.h>
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extern GUID mFrequencyHobGuid;
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/**
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The constructor function enables ACPI IO space.
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If ACPI I/O space not enabled, this function will enable it.
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It will always return RETURN_SUCCESS.
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@retval EFI_SUCCESS The constructor always returns RETURN_SUCCESS.
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**/
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RETURN_STATUS
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EFIAPI
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AcpiTimerLibConstructor (
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VOID
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);
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/**
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Calculate TSC frequency.
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The TSC counting frequency is determined by comparing how far it counts
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during a 101.4 us period as determined by the ACPI timer.
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The ACPI timer is used because it counts at a known frequency.
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The TSC is sampled, followed by waiting 363 counts of the ACPI timer,
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or 101.4 us. The TSC is then sampled again. The difference multiplied by
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9861 is the TSC frequency. There will be a small error because of the
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overhead of reading the ACPI timer. An attempt is made to determine and
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compensate for this error.
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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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InternalCalculateTscFrequency (
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VOID
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);
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//
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// Cached performance counter frequency
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//
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UINT64 mPerformanceCounterFrequency = 0;
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/**
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Internal function to retrieves the 64-bit frequency in Hz.
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Internal function to retrieves the 64-bit frequency in Hz.
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@return The frequency in Hz.
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**/
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UINT64
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InternalGetPerformanceCounterFrequency (
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VOID
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)
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{
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return mPerformanceCounterFrequency;
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}
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/**
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The constructor function enables ACPI IO space, and caches PerformanceCounterFrequency.
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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 RETURN_SUCCESS.
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**/
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EFI_STATUS
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EFIAPI
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DxeAcpiTimerLibConstructor (
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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_HOB_GUID_TYPE *GuidHob;
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//
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// Enable ACPI IO space.
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//
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AcpiTimerLibConstructor ();
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//
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// Initialize PerformanceCounterFrequency
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//
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GuidHob = GetFirstGuidHob (&mFrequencyHobGuid);
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if (GuidHob != NULL) {
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mPerformanceCounterFrequency = *(UINT64*)GET_GUID_HOB_DATA (GuidHob);
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} else {
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mPerformanceCounterFrequency = InternalCalculateTscFrequency ();
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}
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return EFI_SUCCESS;
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}
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