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
  60   TimestampValue = 0;
  61
  62   //
  63   // Get the timestamp
  64   //
  65   if (mTimerLibStartValue > mTimerLibEndValue) {
  66     TimestampValue = mTimerLibStartValue - GetPerformanceCounter ();
  67   } else {
  68     TimestampValue = GetPerformanceCounter () - mTimerLibStartValue;
  69   }
  70
  71   return TimestampValue;
  72 }
  73
  74 /**
  75   Obtains timestamp counter properties including frequency and value limits.
  76
  77   @param[out]  Properties              The properties of the timestamp counter.
  78
  79   @retval      EFI_SUCCESS             The properties were successfully retrieved.
  80   @retval      EFI_DEVICE_ERROR        An error occurred trying to retrieve the properties of the timestamp
  81                                        counter subsystem. Properties is not pedated.
  82   @retval      EFI_INVALID_PARAMETER   Properties is NULL.
  83
  84 **/
  85 EFI_STATUS
  86 EFIAPI
  87 TimestampDriverGetProperties (
  88   OUT   EFI_TIMESTAMP_PROPERTIES  *Properties
  89   )
  90 {
  91   if (Properties == NULL) {
  92     return EFI_INVALID_PARAMETER;
  93   }
  94
  95   //
  96   // Get timestamp properties
  97   //
  98   CopyMem ((VOID *)Properties, (VOID *)&mTimestampProperties, sizeof (mTimestampProperties));
  99
 100   return EFI_SUCCESS;
 101 }
 102
 103 //
 104 // The Timestamp Protocol instance produced by this driver
 105 //
 106 EFI_TIMESTAMP_PROTOCOL  mTimestamp = {
 107   TimestampDriverGetTimestamp,
 108   TimestampDriverGetProperties
 109 };
 110
 111 /**
 112   Entry point of the Timestamp Protocol driver.
 113
 114   @param  ImageHandle   The image handle of this driver.
 115   @param  SystemTable   The pointer of EFI_SYSTEM_TABLE.
 116
 117   @retval EFI_SUCCESS   Watchdog Timer Architectural Protocol successfully installed.
 118
 119 **/
 120 EFI_STATUS
 121 EFIAPI
 122 TimestampDriverInitialize (
 123   IN EFI_HANDLE        ImageHandle,
 124   IN EFI_SYSTEM_TABLE  *SystemTable
 125   )
 126 {
 127   EFI_STATUS  Status;
 128
 129   EFI_HANDLE  TimestampHandle;
 130
 131   TimestampHandle = NULL;
 132
 133   //
 134   // Get the start value, end value and frequency in Timerlib
 135   //
 136   mTimestampProperties.Frequency = GetPerformanceCounterProperties (&mTimerLibStartValue, &mTimerLibEndValue);
 137
 138   //
 139   // Set the EndValue
 140   //
 141   if (mTimerLibEndValue > mTimerLibStartValue) {
 142     mTimestampProperties.EndValue = mTimerLibEndValue - mTimerLibStartValue;
 143   } else {
 144     mTimestampProperties.EndValue = mTimerLibStartValue - mTimerLibEndValue;
 145   }
 146
 147   DEBUG ((DEBUG_INFO, "TimerFrequency:0x%lx, TimerLibStartTime:0x%lx, TimerLibEndtime:0x%lx\n", mTimestampProperties.Frequency, mTimerLibStartValue, mTimerLibEndValue));
 148
 149   //
 150   // Install the Timestamp Protocol onto a new handle
 151   //
 152   Status = gBS->InstallMultipleProtocolInterfaces (
 153                   &TimestampHandle,
 154                   &gEfiTimestampProtocolGuid,
 155                   &mTimestamp,
 156                   NULL
 157                   );
 158
 159   ASSERT_EFI_ERROR (Status);
 160
 161   return EFI_SUCCESS;
 162 }