Revision: 14603
http://sourceforge.net/p/edk2/code/14603
Author: vanjeff
Date: 2013-08-27 07:29:14 +0000 (Tue, 27 Aug 2013)
Log Message:
-----------
Removed the assumption on APIC timer initial Count is all 1s and updated it to
handle the long delay that timer initial count.
Signed-off-by: Jeff Fan <[email protected]>
Reviewed-by: Liming Gao <[email protected]>
Modified Paths:
--------------
trunk/edk2/MdePkg/Library/SecPeiDxeTimerLibCpu/X86TimerLib.c
Modified: trunk/edk2/MdePkg/Library/SecPeiDxeTimerLibCpu/X86TimerLib.c
===================================================================
--- trunk/edk2/MdePkg/Library/SecPeiDxeTimerLibCpu/X86TimerLib.c
2013-08-26 02:47:41 UTC (rev 14602)
+++ trunk/edk2/MdePkg/Library/SecPeiDxeTimerLibCpu/X86TimerLib.c
2013-08-27 07:29:14 UTC (rev 14603)
@@ -1,7 +1,7 @@
/** @file
Timer Library functions built upon local APIC on IA32/x64.
- Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
+ Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD
License
which accompanies this distribution. The full text of the license may be
found at
@@ -88,6 +88,22 @@
}
/**
+ Internal function to read the initial timer count of local APIC.
+
+ @param ApicBase The base address of memory mapped registers of local APIC.
+
+ @return The initial timer count read.
+
+**/
+UINT32
+InternalX86GetInitTimerCount (
+ IN UINTN ApicBase
+ )
+{
+ return MmioRead32 (ApicBase + APIC_TMICT);
+}
+
+/**
Stalls the CPU for at least the given number of ticks.
Stalls the CPU for at least the given number of ticks. It's invoked by
@@ -105,22 +121,49 @@
)
{
INT32 Ticks;
- UINT32 PowerOfTwoCounter;
+ UINT32 Times;
+ UINT32 InitCount;
+ UINT32 StartTick;
//
- // The target timer count is calculated here
+ // In case Delay is too larger, separate it into several small delay slot.
+ // Devided Delay by half value of Init Count is to avoid Delay close to
+ // the Init Count, timeout maybe missing if the time consuming between 2
+ // GetApicTimerCurrentCount() invoking is larger than the time gap between
+ // Delay and the Init Count.
//
- Ticks = InternalX86GetTimerTick (ApicBase) - Delay;
+ InitCount = InternalX86GetInitTimerCount (ApicBase);
+ Times = Delay / (InitCount / 2);
+ Delay = Delay % (InitCount / 2);
//
- // Wait until time out
- // Delay > 2^31 could not be handled by this function
- // Timer wrap-arounds are handled correctly by this function
+ // Get Start Tick and do delay
//
- PowerOfTwoCounter = GetPowerOfTwo32 (MmioRead32 (ApicBase + APIC_TMICT));
- while (((UINT32)(InternalX86GetTimerTick (ApicBase) - Ticks) &
PowerOfTwoCounter) == 0) {
- CpuPause ();
- }
+ StartTick = InternalX86GetTimerTick (ApicBase);
+ do {
+ //
+ // Wait until time out by Delay value
+ //
+ do {
+ CpuPause ();
+ //
+ // Get Ticks from Start to Current.
+ //
+ Ticks = StartTick - InternalX86GetTimerTick (ApicBase);
+ //
+ // Ticks < 0 means Timer wrap-arounds happens.
+ //
+ if (Ticks < 0) {
+ Ticks += InitCount;
+ }
+ } while ((UINT32)Ticks < Delay);
+
+ //
+ // Update StartTick and Delay for next delay slot
+ //
+ StartTick -= (StartTick > Delay) ? Delay : (Delay - InitCount);
+ Delay = InitCount / 2;
+ } while (Times-- > 0);
}
/**
@@ -242,11 +285,7 @@
ApicBase = InternalX86GetApicBase ();
if (StartValue != NULL) {
- *StartValue = MmioRead32 (ApicBase + APIC_TMICT);
- //
- // make sure StartValue is all 1s from High Bit
- //
- ASSERT ((*StartValue & (*StartValue + 1)) == 0);
+ *StartValue = (UINT64)InternalX86GetInitTimerCount (ApicBase);
}
if (EndValue != NULL) {
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