mirror of https://github.com/acidanthera/audk.git
86 lines
2.0 KiB
C
86 lines
2.0 KiB
C
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/** @file
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CPUID Leaf 0x15 for Core Crystal Clock frequency instance of Timer Library.
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Copyright (c) 2019 Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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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 mCpuCrystalFrequencyHobGuid;
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/**
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CPUID Leaf 0x15 for Core Crystal Clock Frequency.
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The TSC counting frequency is determined by using CPUID leaf 0x15. Frequency in MHz = Core XTAL frequency * EBX/EAX.
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In newer flavors of the CPU, core xtal frequency is returned in ECX or 0 if not supported.
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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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CpuidCoreClockCalculateTscFrequency (
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VOID
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);
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//
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// Cached CPU Crystal counter frequency
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//
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UINT64 mCpuCrystalCounterFrequency = 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 mCpuCrystalCounterFrequency;
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}
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/**
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The constructor function is to initialize CpuCrystalCounterFrequency.
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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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DxeCpuTimerLibConstructor (
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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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// Initialize CpuCrystalCounterFrequency
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//
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GuidHob = GetFirstGuidHob (&mCpuCrystalFrequencyHobGuid);
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if (GuidHob != NULL) {
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mCpuCrystalCounterFrequency = *(UINT64*)GET_GUID_HOB_DATA (GuidHob);
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} else {
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mCpuCrystalCounterFrequency = CpuidCoreClockCalculateTscFrequency ();
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}
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if (mCpuCrystalCounterFrequency == 0) {
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return EFI_UNSUPPORTED;
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}
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return EFI_SUCCESS;
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}
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