OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.c

   1 /** @file
   2   Provide constructor and GetTick for Dxe instance of ACPI Timer Library
   3
   4   Copyright (C) 2014, Gabriel L. Somlo <somlo@cmu.edu>
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7 **/
   8
   9 #include <Uefi/UefiBaseType.h>
  10 #include <Uefi/UefiMultiPhase.h>
  11 #include <Pi/PiBootMode.h>
  12 #include <Pi/PiHob.h>
  13 #include <Library/HobLib.h>
  14 #include <Library/DebugLib.h>
  15 #include <Library/IoLib.h>
  16 #include <Library/PcdLib.h>
  17 #include <Library/PciLib.h>
  18 #include <Library/PlatformInitLib.h>
  19 #include <OvmfPlatforms.h>
  20
  21 //
  22 // Cached ACPI Timer IO Address
  23 //
  24 STATIC UINT32  mAcpiTimerIoAddr;
  25
  26 /**
  27   The constructor function caches the ACPI tick counter address
  28
  29   At the time this constructor runs (DXE_CORE or later), ACPI IO space
  30   has already been enabled by either PlatformPei or by the "Base"
  31   instance of this library.
  32   In order to avoid querying the underlying platform type during each
  33   tick counter read operation, we cache the counter address during
  34   initialization of this instance of the Timer Library.
  35
  36   @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.
  37
  38 **/
  39 RETURN_STATUS
  40 EFIAPI
  41 AcpiTimerLibConstructor (
  42   VOID
  43   )
  44 {
  45   UINT16                 HostBridgeDevId;
  46   UINTN                  Pmba;
  47   EFI_HOB_GUID_TYPE      *GuidHob;
  48   EFI_HOB_PLATFORM_INFO  *PlatformInfoHob = NULL;
  49
  50   //
  51   // Query Host Bridge DID to determine platform type
  52   // Tdx guest stores the HostBridgePciDevId in a GuidHob.
  53   // So we first check if this HOB exists
  54   //
  55   GuidHob = GetFirstGuidHob (&gUefiOvmfPkgPlatformInfoGuid);
  56   if (GuidHob != NULL) {
  57     PlatformInfoHob = (EFI_HOB_PLATFORM_INFO *)GET_GUID_HOB_DATA (GuidHob);
  58     HostBridgeDevId = PlatformInfoHob->HostBridgeDevId;
  59   } else {
  60     DEBUG ((DEBUG_ERROR, "PlatformInfoHob is not found.\n"));
  61     ASSERT (FALSE);
  62     return RETURN_UNSUPPORTED;
  63   }
  64
  65   switch (HostBridgeDevId) {
  66     case INTEL_82441_DEVICE_ID:
  67       Pmba = POWER_MGMT_REGISTER_PIIX4 (PIIX4_PMBA);
  68       break;
  69     case INTEL_Q35_MCH_DEVICE_ID:
  70       Pmba = POWER_MGMT_REGISTER_Q35 (ICH9_PMBASE);
  71       break;
  72     case CLOUDHV_DEVICE_ID:
  73       mAcpiTimerIoAddr = CLOUDHV_ACPI_TIMER_IO_ADDRESS;
  74       return RETURN_SUCCESS;
  75     default:
  76       DEBUG ((
  77         DEBUG_ERROR,
  78         "%a: Unknown Host Bridge Device ID: 0x%04x\n",
  79         __FUNCTION__,
  80         HostBridgeDevId
  81         ));
  82       ASSERT (FALSE);
  83       return RETURN_UNSUPPORTED;
  84   }
  85
  86   mAcpiTimerIoAddr = (PciRead32 (Pmba) & ~PMBA_RTE) + ACPI_TIMER_OFFSET;
  87
  88   return RETURN_SUCCESS;
  89 }
  90
  91 /**
  92   Internal function to read the current tick counter of ACPI.
  93
  94   Read the current ACPI tick counter using the counter address cached
  95   by this instance's constructor.
  96
  97   @return The tick counter read.
  98
  99 **/
 100 UINT32
 101 InternalAcpiGetTimerTick (
 102   VOID
 103   )
 104 {
 105   //
 106   //   Return the current ACPI timer value.
 107   //
 108   return IoRead32 (mAcpiTimerIoAddr);
 109 }