UefiCpuPkg/Library/CpuTimerLib/DxeCpuTimerLib.c

   1 /** @file
   2   CPUID Leaf 0x15 for Core Crystal Clock frequency instance of Timer Library.
   3
   4   Copyright (c) 2019 Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <PiDxe.h>
  10 #include <Library/TimerLib.h>
  11 #include <Library/BaseLib.h>
  12 #include <Library/HobLib.h>
  13
  14 extern GUID mCpuCrystalFrequencyHobGuid;
  15
  16 /**
  17   CPUID Leaf 0x15 for Core Crystal Clock Frequency.
  18
  19   The TSC counting frequency is determined by using CPUID leaf 0x15. Frequency in MHz = Core XTAL frequency * EBX/EAX.
  20   In newer flavors of the CPU, core xtal frequency is returned in ECX or 0 if not supported.
  21   @return The number of TSC counts per second.
  22
  23 **/
  24 UINT64
  25 CpuidCoreClockCalculateTscFrequency (
  26   VOID
  27   );
  28
  29 //
  30 // Cached CPU Crystal counter frequency
  31 //
  32 UINT64  mCpuCrystalCounterFrequency = 0;
  33
  34
  35 /**
  36   Internal function to retrieves the 64-bit frequency in Hz.
  37
  38   Internal function to retrieves the 64-bit frequency in Hz.
  39
  40   @return The frequency in Hz.
  41
  42 **/
  43 UINT64
  44 InternalGetPerformanceCounterFrequency (
  45   VOID
  46   )
  47 {
  48   return mCpuCrystalCounterFrequency;
  49 }
  50
  51 /**
  52   The constructor function is to initialize CpuCrystalCounterFrequency.
  53
  54   @param  ImageHandle   The firmware allocated handle for the EFI image.
  55   @param  SystemTable   A pointer to the EFI System Table.
  56
  57   @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.
  58
  59 **/
  60 EFI_STATUS
  61 EFIAPI
  62 DxeCpuTimerLibConstructor (
  63   IN EFI_HANDLE        ImageHandle,
  64   IN EFI_SYSTEM_TABLE  *SystemTable
  65   )
  66 {
  67   EFI_HOB_GUID_TYPE   *GuidHob;
  68
  69   //
  70   // Initialize CpuCrystalCounterFrequency
  71   //
  72   GuidHob = GetFirstGuidHob (&mCpuCrystalFrequencyHobGuid);
  73   if (GuidHob != NULL) {
  74     mCpuCrystalCounterFrequency = *(UINT64*)GET_GUID_HOB_DATA (GuidHob);
  75   } else {
  76     mCpuCrystalCounterFrequency = CpuidCoreClockCalculateTscFrequency ();
  77   }
  78
  79   if (mCpuCrystalCounterFrequency == 0) {
  80     return EFI_UNSUPPORTED;
  81   }
  82
  83   return EFI_SUCCESS;
  84 }
  85