MdeModulePkg/Universal/TimestampDxe/TimestampDxe.c

   1 /** @file
   2   Implementation of Timestamp Protocol using UEFI APIs.
   3
   4 Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <Uefi.h>
  10 #include <Library/DebugLib.h>
  11 #include <Library/UefiDriverEntryPoint.h>
  12 #include <Library/UefiBootServicesTableLib.h>
  13 #include <Library/TimerLib.h>
  14 #include <Library/BaseMemoryLib.h>
  15 #include <Protocol/Timestamp.h>
  16
  17 //
  18 // The StartValue in TimerLib
  19 //
  20 UINT64 mTimerLibStartValue = 0;
  21
  22 //
  23 // The EndValue in TimerLib
  24 //
  25 UINT64 mTimerLibEndValue = 0;
  26
  27 //
  28 // The properties of timestamp
  29 //
  30 EFI_TIMESTAMP_PROPERTIES mTimestampProperties = {
  31   0,
  32   0
  33 };
  34
  35 /**
  36   Retrieves the current value of a 64-bit free running timestamp counter.
  37
  38   The counter shall count up in proportion to the amount of time that has passed. The counter value
  39   will always roll over to zero. The properties of the counter can be retrieved from GetProperties().
  40   The caller should be prepared for the function to return the same value twice across successive calls.
  41   The counter value will not go backwards other than when wrapping, as defined by EndValue in GetProperties().
  42   The frequency of the returned timestamp counter value must remain constant. Power management operations that
  43   affect clocking must not change the returned counter frequency. The quantization of counter value updates may
  44   vary as long as the value reflecting time passed remains consistent.
  45
  46   @retval The current value of the free running timestamp counter.
  47
  48 **/
  49 UINT64
  50 EFIAPI
  51 TimestampDriverGetTimestamp (
  52   VOID
  53   )
  54 {
  55   //
  56   // The timestamp of Timestamp Protocol
  57   //
  58   UINT64  TimestampValue;
  59   TimestampValue = 0;
  60
  61   //
  62   // Get the timestamp
  63   //
  64   if (mTimerLibStartValue > mTimerLibEndValue) {
  65     TimestampValue = mTimerLibStartValue - GetPerformanceCounter();
  66   } else {
  67     TimestampValue = GetPerformanceCounter() - mTimerLibStartValue;
  68   }
  69
  70   return TimestampValue;
  71 }
  72
  73 /**
  74   Obtains timestamp counter properties including frequency and value limits.
  75
  76   @param[out]  Properties              The properties of the timestamp counter.
  77
  78   @retval      EFI_SUCCESS             The properties were successfully retrieved.
  79   @retval      EFI_DEVICE_ERROR        An error occurred trying to retrieve the properties of the timestamp
  80                                        counter subsystem. Properties is not pedated.
  81   @retval      EFI_INVALID_PARAMETER   Properties is NULL.
  82
  83 **/
  84 EFI_STATUS
  85 EFIAPI
  86 TimestampDriverGetProperties(
  87   OUT   EFI_TIMESTAMP_PROPERTIES       *Properties
  88   )
  89 {
  90   if (Properties == NULL) {
  91     return EFI_INVALID_PARAMETER;
  92   }
  93
  94   //
  95   // Get timestamp properties
  96   //
  97   CopyMem((VOID *) Properties, (VOID *) &mTimestampProperties, sizeof (mTimestampProperties));
  98
  99   return EFI_SUCCESS;
 100 }
 101
 102 //
 103 // The Timestamp Protocol instance produced by this driver
 104 //
 105 EFI_TIMESTAMP_PROTOCOL  mTimestamp = {
 106   TimestampDriverGetTimestamp,
 107   TimestampDriverGetProperties
 108 };
 109
 110 /**
 111   Entry point of the Timestamp Protocol driver.
 112
 113   @param  ImageHandle   The image handle of this driver.
 114   @param  SystemTable   The pointer of EFI_SYSTEM_TABLE.
 115
 116   @retval EFI_SUCCESS   Watchdog Timer Architectural Protocol successfully installed.
 117
 118 **/
 119 EFI_STATUS
 120 EFIAPI
 121 TimestampDriverInitialize (
 122   IN EFI_HANDLE        ImageHandle,
 123   IN EFI_SYSTEM_TABLE  *SystemTable
 124   )
 125 {
 126   EFI_STATUS  Status;
 127
 128   EFI_HANDLE  TimestampHandle;
 129   TimestampHandle = NULL;
 130
 131   //
 132   // Get the start value, end value and frequency in Timerlib
 133   //
 134   mTimestampProperties.Frequency = GetPerformanceCounterProperties(&mTimerLibStartValue, &mTimerLibEndValue);
 135
 136   //
 137   // Set the EndValue
 138   //
 139   if (mTimerLibEndValue > mTimerLibStartValue) {
 140     mTimestampProperties.EndValue = mTimerLibEndValue - mTimerLibStartValue;
 141   } else {
 142     mTimestampProperties.EndValue = mTimerLibStartValue - mTimerLibEndValue;
 143   }
 144
 145   DEBUG ((EFI_D_INFO, "TimerFrequency:0x%lx, TimerLibStartTime:0x%lx, TimerLibEndtime:0x%lx\n", mTimestampProperties.Frequency, mTimerLibStartValue, mTimerLibEndValue));
 146
 147   //
 148   // Install the Timestamp Protocol onto a new handle
 149   //
 150   Status = gBS->InstallMultipleProtocolInterfaces (
 151                   &TimestampHandle,
 152                   &gEfiTimestampProtocolGuid,
 153                   &mTimestamp,
 154                   NULL
 155                   );
 156
 157   ASSERT_EFI_ERROR (Status);
 158
 159   return EFI_SUCCESS;
 160 }