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/** @file
CPUID Leaf 0x15 for Core Crystal Clock frequency instance of Timer Library.
Copyright (c) 2019 Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <PiDxe.h>
#include <Library/TimerLib.h>
#include <Library/BaseLib.h>
#include <Library/HobLib.h>
extern GUID mCpuCrystalFrequencyHobGuid;
/**
CPUID Leaf 0x15 for Core Crystal Clock Frequency.
The TSC counting frequency is determined by using CPUID leaf 0x15. Frequency in MHz = Core XTAL frequency * EBX/EAX.
In newer flavors of the CPU, core xtal frequency is returned in ECX or 0 if not supported.
@return The number of TSC counts per second.
**/
UINT64
CpuidCoreClockCalculateTscFrequency (
VOID
);
//
// Cached CPU Crystal counter frequency
//
UINT64 mCpuCrystalCounterFrequency = 0;
/**
Internal function to retrieves the 64-bit frequency in Hz.
Internal function to retrieves the 64-bit frequency in Hz.
@return The frequency in Hz.
**/
UINT64
InternalGetPerformanceCounterFrequency (
VOID
)
{
return mCpuCrystalCounterFrequency;
}
/**
The constructor function is to initialize CpuCrystalCounterFrequency.
@param ImageHandle The firmware allocated handle for the EFI image.
@param SystemTable A pointer to the EFI System Table.
@retval EFI_SUCCESS The constructor always returns RETURN_SUCCESS.
**/
EFI_STATUS
EFIAPI
DxeCpuTimerLibConstructor (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_HOB_GUID_TYPE *GuidHob;
//
// Initialize CpuCrystalCounterFrequency
//
GuidHob = GetFirstGuidHob (&mCpuCrystalFrequencyHobGuid);
if (GuidHob != NULL) {
mCpuCrystalCounterFrequency = *(UINT64*)GET_GUID_HOB_DATA (GuidHob);
} else {
mCpuCrystalCounterFrequency = CpuidCoreClockCalculateTscFrequency ();
}
if (mCpuCrystalCounterFrequency == 0) {
return EFI_UNSUPPORTED;
}
return EFI_SUCCESS;
}
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