UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c

   1 /** @file
   2 SMM Timer feature support
   3
   4 Copyright (c) 2009 - 2015, Intel Corporation. All rights reserved.<BR>
   5 This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include "PiSmmCpuDxeSmm.h"
  16
  17 UINT64   mTimeoutTicker = 0;
  18 //
  19 //  Number of counts in a roll-over cycle of the performance counter.
  20 //
  21 UINT64   mCycle = 0;
  22 //
  23 // Flag to indicate the performance counter is count-up or count-down.
  24 //
  25 BOOLEAN  mCountDown;
  26
  27 /**
  28   Initialize Timer for SMM AP Sync.
  29
  30 **/
  31 VOID
  32 InitializeSmmTimer (
  33   VOID
  34   )
  35 {
  36   UINT64  TimerFrequency;
  37   UINT64  Start;
  38   UINT64  End;
  39
  40   TimerFrequency = GetPerformanceCounterProperties (&Start, &End);
  41   mTimeoutTicker = DivU64x32 (
  42                      MultU64x64(TimerFrequency, PcdGet64 (PcdCpuSmmApSyncTimeout)),
  43                      1000 * 1000
  44                      );
  45   if (End < Start) {
  46     mCountDown = TRUE;
  47     mCycle = Start - End;
  48   } else {
  49     mCountDown = FALSE;
  50     mCycle = End - Start;
  51   }
  52 }
  53
  54 /**
  55   Start Timer for SMM AP Sync.
  56
  57 **/
  58 UINT64
  59 EFIAPI
  60 StartSyncTimer (
  61   VOID
  62   )
  63 {
  64   return GetPerformanceCounter ();
  65 }
  66
  67
  68 /**
  69   Check if the SMM AP Sync timer is timeout.
  70
  71   @param Timer  The start timer from the begin.
  72
  73 **/
  74 BOOLEAN
  75 EFIAPI
  76 IsSyncTimerTimeout (
  77   IN      UINT64                    Timer
  78   )
  79 {
  80   UINT64  CurrentTimer;
  81   UINT64  Delta;
  82
  83   CurrentTimer = GetPerformanceCounter ();
  84   //
  85   // We need to consider the case that CurrentTimer is equal to Timer
  86   // when some timer runs too slow and CPU runs fast. We think roll over
  87   // condition does not happen on this case.
  88   //
  89   if (mCountDown) {
  90     //
  91     // The performance counter counts down.  Check for roll over condition.
  92     //
  93     if (CurrentTimer <= Timer) {
  94       Delta = Timer - CurrentTimer;
  95     } else {
  96       //
  97       // Handle one roll-over.
  98       //
  99       Delta = mCycle - (CurrentTimer - Timer) + 1;
 100     }
 101   } else {
 102     //
 103     // The performance counter counts up.  Check for roll over condition.
 104     //
 105     if (CurrentTimer >= Timer) {
 106       Delta = CurrentTimer - Timer;
 107     } else {
 108       //
 109       // Handle one roll-over.
 110       //
 111       Delta = mCycle - (Timer - CurrentTimer) + 1;
 112     }
 113   }
 114
 115   return (BOOLEAN) (Delta >= mTimeoutTicker);
 116 }