DxeStandaloneMmAcpiTimerLib.c

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#include <PiDxe.h>
#include <Library/TimerLib.h>
#include <Library/BaseLib.h>
#include <Library/HobLib.h>
 
//
// Cached performance counter frequency
//
static UINT64  mAcpiTimerLibTscFrequency = 0;
 
extern GUID  mFrequencyHobGuid;
 
RETURN_STATUS
EFIAPI
AcpiTimerLibConstructor (
  VOID
  );
 
UINT64
InternalCalculateTscFrequency (
  VOID
  );
 
UINT64
InternalGetPerformanceCounterFrequency (
  VOID
  )
{
  return mAcpiTimerLibTscFrequency;
}
 
EFI_STATUS
CommonAcpiTimerLibConstructor (
  VOID
  )
{
  EFI_HOB_GUID_TYPE  *GuidHob;
 
  //
  // Enable ACPI IO space.
  //
  AcpiTimerLibConstructor ();
 
  //
  // Initialize PerformanceCounterFrequency
  //
  GuidHob = GetFirstGuidHob (&mFrequencyHobGuid);
  if (GuidHob != NULL) {
    mAcpiTimerLibTscFrequency = *(UINT64 *)GET_GUID_HOB_DATA (GuidHob);
  } else {
    mAcpiTimerLibTscFrequency = InternalCalculateTscFrequency ();
  }
 
  return EFI_SUCCESS;
}