diff options
| -rw-r--r-- | ArmPkg/Drivers/TimerDxe/TimerDxe.c | 58 |
1 files changed, 50 insertions, 8 deletions
diff --git a/ArmPkg/Drivers/TimerDxe/TimerDxe.c b/ArmPkg/Drivers/TimerDxe/TimerDxe.c index 279b50f290..329b085ec4 100644 --- a/ArmPkg/Drivers/TimerDxe/TimerDxe.c +++ b/ArmPkg/Drivers/TimerDxe/TimerDxe.c @@ -35,6 +35,10 @@ 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;
@@ -135,26 +139,44 @@ TimerDriverSetTimerPeriod ( IN UINT64 TimerPeriod
)
{
+ UINT64 CounterValue;
UINT64 TimerTicks;
+ EFI_TPL OriginalTPL;
// Always disable the timer
ArmArchTimerDisableTimer ();
if (TimerPeriod != 0) {
- // TimerTicks = TimerPeriod in 1ms unit x Frequency.10^-3
- // = TimerPeriod.10^-4 x Frequency.10^-3
- // = (TimerPeriod x Frequency) x 10^-7
+ // 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, FixedPcdGet32 (PcdArmArchTimerFreqInHz));
TimerTicks = DivU64x32 (TimerTicks, 10000000U);
- ArmArchTimerSetTimerVal ((UINTN)TimerTicks);
+ // 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 physical timer
+ CounterValue = ArmReadCntPct ();
+ // Set the interrupt in Current Time + mTimerTick
+ ArmWriteCntpCval (CounterValue + mTimerTicks);
// Enable the timer
ArmArchTimerEnableTimer ();
+ } else {
+ // Save the new timer period
+ mTimerPeriod = TimerPeriod;
+ // Reset the elapsed period
+ mElapsedPeriod = 1;
}
- // Save the new timer period
- mTimerPeriod = TimerPeriod;
return EFI_SUCCESS;
}
@@ -274,6 +296,8 @@ TimerInterruptHandler ( )
{
EFI_TPL OriginalTPL;
+ UINT64 CurrentValue;
+ UINT64 CompareValue;
//
// DXE core uses this callback for the EFI timer tick. The DXE core uses locks
@@ -289,11 +313,29 @@ TimerInterruptHandler ( gInterrupt->EndOfInterrupt (gInterrupt, Source);
if (mTimerNotifyFunction) {
- mTimerNotifyFunction (mTimerPeriod);
+ mTimerNotifyFunction (mTimerPeriod * mElapsedPeriod);
}
+ //
// Reload the Timer
- TimerDriverSetTimerPeriod (&gTimer, mTimerPeriod);
+ //
+
+ // Get current counter value
+ CurrentValue = ArmReadCntPct ();
+ // Get the counter value to compare with
+ CompareValue = ArmReadCntpCval ();
+
+ // 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
+ ArmWriteCntpCval (CompareValue);
}
// Enable timer interrupts
|