Revision: 16691
http://sourceforge.net/p/edk2/code/16691
Author: lersek
Date: 2015-02-02 12:01:48 +0000 (Mon, 02 Feb 2015)
Log Message:
-----------
ArmPkg: ArmArchTimerLib: conditionally rebase to actual timer frequency
Allow a platform to set PcdArmArchTimerFreqInHz to zero, and consider it a
request to use the actual timer frequency.
No global variable is introduced, so that the library can be used in PEIMs
that execute from flash.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <[email protected]>
Reviewed-by: Olivier Martin <[email protected]>
Modified Paths:
--------------
trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
Modified: trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
===================================================================
--- trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c 2015-02-02
12:01:38 UTC (rev 16690)
+++ trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c 2015-02-02
12:01:48 UTC (rev 16691)
@@ -37,28 +37,29 @@
UINTN TimerFreq;
//
- // Check if Architectural Timer frequency is valid (should not be 0).
+ // Check if Architectural Timer frequency is pre-determined by the platform
+ // (ie. nonzero).
//
- ASSERT (PcdGet32 (PcdArmArchTimerFreqInHz));
+ if (PcdGet32 (PcdArmArchTimerFreqInHz) != 0) {
+ //
+ // Check if ticks/uS is not 0. The Architectural timer runs at constant
+ // frequency, irrespective of CPU frequency. According to General Timer
+ // Ref manual, lower bound of the frequency is in the range of 1-10MHz.
+ //
+ ASSERT (TICKS_PER_MICRO_SEC);
- //
- // Check if ticks/uS is not 0. The Architectural timer runs at constant
- // frequency, irrespective of CPU frequency. According to General Timer
- // Ref manual, lower bound of the frequency is in the range of 1-10MHz.
- //
- ASSERT (TICKS_PER_MICRO_SEC);
-
#ifdef MDE_CPU_ARM
- //
- // Only set the frequency for ARMv7. We expect the secure firmware to
- // have already done it.
- // If the security extension is not implemented, set Timer Frequency
- // here.
- //
- if ((ArmReadIdPfr1 () & ARM_PFR1_SEC) == 0x0) {
- ArmGenericTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
+ //
+ // Only set the frequency for ARMv7. We expect the secure firmware to
+ // have already done it.
+ // If the security extension is not implemented, set Timer Frequency
+ // here.
+ //
+ if ((ArmReadIdPfr1 () & ARM_PFR1_SEC) == 0x0) {
+ ArmGenericTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
+ }
+#endif
}
-#endif
//
// Architectural Timer Frequency must be set in the Secure privileged
@@ -92,14 +93,31 @@
{
UINT64 TimerTicks64;
UINT64 SystemCounterVal;
+ UINT64 (EFIAPI
+ *MultU64xN) (
+ IN UINT64 Multiplicand,
+ IN UINTN Multiplier
+ );
+ UINTN TimerFreq;
+#ifdef MDE_CPU_ARM
+ MultU64xN = MultU64x32;
+#else
+ MultU64xN = MultU64x64;
+#endif
+
+ TimerFreq = PcdGet32 (PcdArmArchTimerFreqInHz);
+ if (TimerFreq == 0) {
+ TimerFreq = ArmGenericTimerGetTimerFreq ();
+ }
+
// Calculate counter ticks that can represent requested delay:
// = MicroSeconds x TICKS_PER_MICRO_SEC
// = MicroSeconds x Frequency.10^-6
TimerTicks64 = DivU64x32 (
- MultU64x32 (
+ MultU64xN (
MicroSeconds,
- PcdGet32 (PcdArmArchTimerFreqInHz)
+ TimerFreq
),
1000000U
);
------------------------------------------------------------------------------
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