[PATCH] UefiCpuPkg/CpuDxe: Fix hard code actual TimerPeriod value

[Jeff Fan <jeff.fan@intel.com>]

Current CpuGetTimerValue() implementation return hard code TimerPeriod value. We
could calculate the actual TimerPeriod value over period of time (100us) at the
first time invoking CpuGetTimerValue() and save the TimerPeriod value into one
global variable to avoid delay at the next CpuGetTimerValue() invoking.

https://bugzilla.tianocore.org/show_bug.cgi?id=382

Cc: Feng Tian <feng.tian@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
---
 UefiCpuPkg/CpuDxe/CpuDxe.c   | 26 +++++++++++++++++++++++---
 UefiCpuPkg/CpuDxe/CpuDxe.h   |  3 ++-
 UefiCpuPkg/CpuDxe/CpuDxe.inf |  3 ++-
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.c b/UefiCpuPkg/CpuDxe/CpuDxe.c
index f6d0a67..9fb6d76 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.c
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.c
@@ -1,7 +1,7 @@
 /** @file
   CPU DXE Module to produce CPU ARCH Protocol.
 
-  Copyright (c) 2008 - 2016, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2008 - 2017, 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
@@ -23,6 +23,7 @@ EFI_HANDLE                mCpuHandle = NULL;
 BOOLEAN                   mIsFlushingGCD;
 UINT64                    mValidMtrrAddressMask = MTRR_LIB_CACHE_VALID_ADDRESS;
 UINT64                    mValidMtrrBitsMask    = MTRR_LIB_MSR_VALID_MASK;
+UINT64                    mTimerPeriod = 0;
 
 FIXED_MTRR    mFixedMtrrTable[] = {
   {
@@ -293,6 +294,9 @@ CpuGetTimerValue (
   OUT UINT64                    *TimerPeriod OPTIONAL
   )
 {
+  UINT64          BeginValue;
+  UINT64          EndValue;
+
   if (TimerValue == NULL) {
     return EFI_INVALID_PARAMETER;
   }
@@ -304,10 +308,26 @@ CpuGetTimerValue (
   *TimerValue = AsmReadTsc ();
 
   if (TimerPeriod != NULL) {
+    if (mTimerPeriod == 0) {
+      //
+      // Read time stamp counter before and after delay of 100 microseconds
       //
-      // BugBug: Hard coded. Don't know how to do this generically
+      BeginValue = AsmReadTsc ();
+      MicroSecondDelay (100);
+      EndValue   = AsmReadTsc ();
       //
-      *TimerPeriod = 1000000000;
+      // Calculate the actual frequency
+      //
+      mTimerPeriod = DivU64x64Remainder (
+                       MultU64x32 (
+                         1000 * 1000 * 1000,
+                         100
+                         ),
+                       EndValue - BeginValue,
+                       NULL
+                       );
+    }
+    *TimerPeriod = mTimerPeriod;
   }
 
   return EFI_SUCCESS;
diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.h b/UefiCpuPkg/CpuDxe/CpuDxe.h
index 6dd0ad3..27ad45b 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.h
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.h
@@ -1,7 +1,7 @@
 /** @file
   CPU DXE Module to produce CPU ARCH Protocol and CPU MP Protocol.
 
-  Copyright (c) 2008 - 2016, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2008 - 2017, 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
@@ -39,6 +39,7 @@
 #include <Library/HobLib.h>
 #include <Library/ReportStatusCodeLib.h>
 #include <Library/MpInitLib.h>
+#include <Library/TimerLib.h>
 
 #include <Guid/IdleLoopEvent.h>
 #include <Guid/VectorHandoffTable.h>
diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.inf b/UefiCpuPkg/CpuDxe/CpuDxe.inf
index bf389bb..3cedce1 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.inf
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.inf
@@ -1,7 +1,7 @@
 ## @file
 #  CPU driver installs CPU Architecture Protocol and CPU MP protocol.
 #
-#  Copyright (c) 2008 - 2016, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2008 - 2017, 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
@@ -44,6 +44,7 @@
   HobLib
   ReportStatusCodeLib
   MpInitLib
+  TimerLib
 
 [Sources]
   CpuDxe.c
-- 
2.9.3.windows.2