TimerDxe.c

Go to the documentation of this file.

 
#include <PiDxe.h>
 
#include <Library/ArmLib.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>
#include <Library/PcdLib.h>
#include <Library/IoLib.h>
#include <Library/ArmGenericTimerCounterLib.h>
 
#include <Protocol/Timer.h>
#include <Protocol/HardwareInterrupt.h>
 
// The notification function to call on every timer interrupt.
EFI_TIMER_NOTIFY  mTimerNotifyFunction     = (EFI_TIMER_NOTIFY)NULL;
EFI_EVENT         EfiExitBootServicesEvent = (EFI_EVENT)NULL;
 
// The current period of the timer interrupt
UINT64  mTimerPeriod = 0;
// The latest Timer Tick calculated for mTimerPeriod
UINT64  mTimerTicks = 0;
// Number of elapsed period since the last Timer interrupt
UINT64  mElapsedPeriod = 1;
 
// Cached copy of the Hardware Interrupt protocol instance
EFI_HARDWARE_INTERRUPT_PROTOCOL  *gInterrupt = NULL;
 
EFI_STATUS
EFIAPI
TimerDriverRegisterHandler (
  IN EFI_TIMER_ARCH_PROTOCOL  *This,
  IN EFI_TIMER_NOTIFY         NotifyFunction
  )
{
  if ((NotifyFunction == NULL) && (mTimerNotifyFunction == NULL)) {
    return EFI_INVALID_PARAMETER;
  }
 
  if ((NotifyFunction != NULL) && (mTimerNotifyFunction != NULL)) {
    return EFI_ALREADY_STARTED;
  }
 
  mTimerNotifyFunction = NotifyFunction;
 
  return EFI_SUCCESS;
}
 
VOID
EFIAPI
ExitBootServicesEvent (
  IN EFI_EVENT  Event,
  IN VOID       *Context
  )
{
  ArmGenericTimerDisableTimer ();
}
 
EFI_STATUS
EFIAPI
TimerDriverSetTimerPeriod (
  IN EFI_TIMER_ARCH_PROTOCOL  *This,
  IN UINT64                   TimerPeriod
  )
{
  UINT64   CounterValue;
  UINT64   TimerTicks;
  EFI_TPL  OriginalTPL;
 
  // Always disable the timer
  ArmGenericTimerDisableTimer ();
 
  if (TimerPeriod != 0) {
    // mTimerTicks = TimerPeriod in 1ms unit x Frequency.10^-3
    //             = TimerPeriod.10^-4 x Frequency.10^-3
    //             = (TimerPeriod x Frequency) x 10^-7
    TimerTicks = MultU64x32 (TimerPeriod, ArmGenericTimerGetTimerFreq ());
    TimerTicks = DivU64x32 (TimerTicks, 10000000U);
 
    // Raise TPL to update the mTimerTicks and mTimerPeriod to ensure these values
    // are coherent in the interrupt handler
    OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 
    mTimerTicks    = TimerTicks;
    mTimerPeriod   = TimerPeriod;
    mElapsedPeriod = 1;
 
    gBS->RestoreTPL (OriginalTPL);
 
    // Get value of the current timer
    CounterValue = ArmGenericTimerGetSystemCount ();
    // Set the interrupt in Current Time + mTimerTick
    ArmGenericTimerSetCompareVal (CounterValue + mTimerTicks);
 
    // Enable the timer
    ArmGenericTimerEnableTimer ();
  } else {
    // Save the new timer period
    mTimerPeriod = TimerPeriod;
    // Reset the elapsed period
    mElapsedPeriod = 1;
  }
 
  return EFI_SUCCESS;
}
 
EFI_STATUS
EFIAPI
TimerDriverGetTimerPeriod (
  IN EFI_TIMER_ARCH_PROTOCOL  *This,
  OUT UINT64                  *TimerPeriod
  )
{
  if (TimerPeriod == NULL) {
    return EFI_INVALID_PARAMETER;
  }
 
  *TimerPeriod = mTimerPeriod;
  return EFI_SUCCESS;
}
 
EFI_STATUS
EFIAPI
TimerDriverGenerateSoftInterrupt (
  IN EFI_TIMER_ARCH_PROTOCOL  *This
  )
{
  return EFI_UNSUPPORTED;
}
 
EFI_TIMER_ARCH_PROTOCOL  gTimer = {
  TimerDriverRegisterHandler,
  TimerDriverSetTimerPeriod,
  TimerDriverGetTimerPeriod,
  TimerDriverGenerateSoftInterrupt
};
 
VOID
EFIAPI
TimerInterruptHandler (
  IN  HARDWARE_INTERRUPT_SOURCE  Source,
  IN  EFI_SYSTEM_CONTEXT         SystemContext
  )
{
  EFI_TPL  OriginalTPL;
  UINT64   CurrentValue;
  UINT64   CompareValue;
 
  //
  // DXE core uses this callback for the EFI timer tick. The DXE core uses locks
  // that raise to TPL_HIGH and then restore back to current level. Thus we need
  // to make sure TPL level is set to TPL_HIGH while we are handling the timer tick.
  //
  OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 
  // Signal end of interrupt early to help avoid losing subsequent ticks
  // from long duration handlers
  gInterrupt->EndOfInterrupt (gInterrupt, Source);
 
  // Check if the timer interrupt is active
  if ((ArmGenericTimerGetTimerCtrlReg ()) & ARM_ARCH_TIMER_ISTATUS) {
    if (mTimerNotifyFunction != 0) {
      mTimerNotifyFunction (mTimerPeriod * mElapsedPeriod);
    }
 
    //
    // Reload the Timer
    //
 
    // Get current counter value
    CurrentValue = ArmGenericTimerGetSystemCount ();
    // Get the counter value to compare with
    CompareValue = ArmGenericTimerGetCompareVal ();
 
    // This loop is needed in case we missed interrupts (eg: case when the interrupt handling
    // has taken longer than mTickPeriod).
    // Note: Physical Counter is counting up
    mElapsedPeriod = 0;
    do {
      CompareValue += mTimerTicks;
      mElapsedPeriod++;
    } while (CompareValue < CurrentValue);
 
    // Set next compare value
    ArmGenericTimerSetCompareVal (CompareValue);
    ArmGenericTimerReenableTimer ();
    ArmInstructionSynchronizationBarrier ();
  }
 
  gBS->RestoreTPL (OriginalTPL);
}
 
EFI_STATUS
EFIAPI
TimerInitialize (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_HANDLE  Handle;
  EFI_STATUS  Status;
  UINTN       TimerCtrlReg;
  UINT32      TimerHypIntrNum;
 
  if (ArmIsArchTimerImplemented () == 0) {
    DEBUG ((DEBUG_ERROR, "ARM Architectural Timer is not available in the CPU, hence can't use this Driver \n"));
    ASSERT (0);
  }
 
  // Find the interrupt controller protocol.  ASSERT if not found.
  Status = gBS->LocateProtocol (&gHardwareInterruptProtocolGuid, NULL, (VOID **)&gInterrupt);
  ASSERT_EFI_ERROR (Status);
 
  // Disable the timer
  TimerCtrlReg  = ArmGenericTimerGetTimerCtrlReg ();
  TimerCtrlReg |= ARM_ARCH_TIMER_IMASK;
  TimerCtrlReg &= ~ARM_ARCH_TIMER_ENABLE;
  ArmGenericTimerSetTimerCtrlReg (TimerCtrlReg);
  Status = TimerDriverSetTimerPeriod (&gTimer, 0);
  ASSERT_EFI_ERROR (Status);
 
  // Install secure and Non-secure interrupt handlers
  // Note: Because it is not possible to determine the security state of the
  // CPU dynamically, we just install interrupt handler for both sec and non-sec
  // timer PPI
  Status = gInterrupt->RegisterInterruptSource (gInterrupt, PcdGet32 (PcdArmArchTimerVirtIntrNum), TimerInterruptHandler);
  ASSERT_EFI_ERROR (Status);
 
  //
  // The hypervisor timer interrupt may be omitted by implementations that
  // execute under virtualization.
  //
  TimerHypIntrNum = PcdGet32 (PcdArmArchTimerHypIntrNum);
  if (TimerHypIntrNum != 0) {
    Status = gInterrupt->RegisterInterruptSource (gInterrupt, TimerHypIntrNum, TimerInterruptHandler);
    ASSERT_EFI_ERROR (Status);
  }
 
  Status = gInterrupt->RegisterInterruptSource (gInterrupt, PcdGet32 (PcdArmArchTimerSecIntrNum), TimerInterruptHandler);
  ASSERT_EFI_ERROR (Status);
 
  Status = gInterrupt->RegisterInterruptSource (gInterrupt, PcdGet32 (PcdArmArchTimerIntrNum), TimerInterruptHandler);
  ASSERT_EFI_ERROR (Status);
 
  // Set up default timer
  Status = TimerDriverSetTimerPeriod (&gTimer, FixedPcdGet32 (PcdTimerPeriod)); // TIMER_DEFAULT_PERIOD
  ASSERT_EFI_ERROR (Status);
 
  Handle = NULL;
  // Install the Timer Architectural Protocol onto a new handle
  Status = gBS->InstallMultipleProtocolInterfaces (
                  &Handle,
                  &gEfiTimerArchProtocolGuid,
                  &gTimer,
                  NULL
                  );
  ASSERT_EFI_ERROR (Status);
 
  // Everything is ready, unmask and enable timer interrupts
  TimerCtrlReg = ARM_ARCH_TIMER_ENABLE;
  ArmGenericTimerSetTimerCtrlReg (TimerCtrlReg);
 
  // Register for an ExitBootServicesEvent
  Status = gBS->CreateEvent (EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_NOTIFY, ExitBootServicesEvent, NULL, &EfiExitBootServicesEvent);
  ASSERT_EFI_ERROR (Status);
 
  return Status;
}