DebugTimer.c

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#include "DebugAgent.h"
 
UINT32
InitializeDebugTimer (
  OUT UINT32   *TimerFrequency,
  IN  BOOLEAN  DumpFlag
  )
{
  UINTN   ApicTimerDivisor;
  UINT32  InitialCount;
  UINT32  ApicTimerFrequency;
 
  InitializeLocalApicSoftwareEnable (TRUE);
  GetApicTimerState (&ApicTimerDivisor, NULL, NULL);
  ApicTimerFrequency = PcdGet32 (PcdFSBClock) / (UINT32)ApicTimerDivisor;
  //
  // Cpu Local Apic timer interrupt frequency, it is set to 0.1s
  //
  InitialCount = (UINT32)DivU64x32 (
                           MultU64x64 (
                             ApicTimerFrequency,
                             DEBUG_TIMER_INTERVAL
                             ),
                           1000000u
                           );
 
  InitializeApicTimer (ApicTimerDivisor, InitialCount, TRUE, DEBUG_TIMER_VECTOR);
  //
  // Disable Debug Timer interrupt to avoid it is delivered before Debug Port
  // is initialized
  //
  DisableApicTimerInterrupt ();
 
  if (DumpFlag) {
    DEBUG ((DEBUG_INFO, "Debug Timer: FSB Clock    = %d\n", PcdGet32 (PcdFSBClock)));
    DEBUG ((DEBUG_INFO, "Debug Timer: Divisor      = %d\n", ApicTimerDivisor));
    DEBUG ((DEBUG_INFO, "Debug Timer: Frequency    = %d\n", ApicTimerFrequency));
    DEBUG ((DEBUG_INFO, "Debug Timer: InitialCount = %d\n", InitialCount));
  }
 
  if (TimerFrequency != NULL) {
    *TimerFrequency = ApicTimerFrequency;
  }
 
  return InitialCount;
}
 
BOOLEAN
EFIAPI
SaveAndSetDebugTimerInterrupt (
  IN BOOLEAN  EnableStatus
  )
{
  BOOLEAN  OldDebugTimerInterruptState;
 
  OldDebugTimerInterruptState = GetApicTimerInterruptState ();
 
  if (OldDebugTimerInterruptState != EnableStatus) {
    if (EnableStatus) {
      EnableApicTimerInterrupt ();
    } else {
      DisableApicTimerInterrupt ();
    }
 
    //
    // Validate the Debug Timer interrupt state
    // This will make additional delay after Local Apic Timer interrupt state is changed.
    // Thus, CPU could handle the potential pending interrupt of Local Apic timer.
    //
    while (GetApicTimerInterruptState () != EnableStatus) {
      CpuPause ();
    }
  }
 
  return OldDebugTimerInterruptState;
}
 
BOOLEAN
IsDebugTimerTimeout (
  IN UINT32  TimerCycle,
  IN UINT32  Timer,
  IN UINT32  TimeoutTicker
  )
{
  UINT64  CurrentTimer;
  UINT64  Delta;
 
  CurrentTimer = GetApicTimerCurrentCount ();
 
  //
  // This timer counter counts down.  Check for roll over condition.
  // If CurrentTimer is equal to Timer, it does not mean that roll over
  // happened.
  //
  if (CurrentTimer <= Timer) {
    Delta = Timer - CurrentTimer;
  } else {
    //
    // Handle one roll-over.
    //
    Delta = TimerCycle - (CurrentTimer - Timer) + 1;
  }
 
  return (BOOLEAN)(Delta >= TimeoutTicker);
}