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   This program and the accompanying materials are licensed and made
   7   available under the terms and conditions of the BSD License which
   8   accompanies this distribution.   The full text of the license may
   9   be found at http://opensource.org/licenses/bsd-license.php
  10
  11   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 **/
  14
  15 #include <Library/DebugLib.h>
  16 #include <Library/IoLib.h>
  17 #include <Library/PcdLib.h>
  18 #include <Library/PciLib.h>
  19 #include <OvmfPlatforms.h>
  20
  21 //
  22 // Power Management PCI Configuration Register fields
  23 //
  24 #define PMBA_RTE  BIT0
  25
  26 //
  27 // Offset in the Power Management Base Address to the ACPI Timer
  28 //
  29 #define ACPI_TIMER_OFFSET  0x8
  30
  31 //
  32 // Cached ACPI Timer IO Address
  33 //
  34 STATIC UINT32 mAcpiTimerIoAddr;
  35
  36 /**
  37   The constructor function caches the ACPI tick counter address
  38
  39   At the time this constructor runs (DXE_CORE or later), ACPI IO space
  40   has already been enabled by either PlatformPei or by the "Base"
  41   instance of this library.
  42   In order to avoid querying the underlying platform type during each
  43   tick counter read operation, we cache the counter address during
  44   initialization of this instance of the Timer Library.
  45
  46   @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.
  47
  48 **/
  49 RETURN_STATUS
  50 EFIAPI
  51 AcpiTimerLibConstructor (
  52   VOID
  53   )
  54 {
  55   UINT16 HostBridgeDevId;
  56   UINTN Pmba;
  57
  58   //
  59   // Query Host Bridge DID to determine platform type
  60   //
  61   HostBridgeDevId = PcdGet16 (PcdOvmfHostBridgePciDevId);
  62   switch (HostBridgeDevId) {
  63     case INTEL_82441_DEVICE_ID:
  64       Pmba = POWER_MGMT_REGISTER_PIIX4 (0x40);
  65       break;
  66     case INTEL_Q35_MCH_DEVICE_ID:
  67       Pmba = POWER_MGMT_REGISTER_Q35 (ICH9_PMBASE);
  68       break;
  69     default:
  70       DEBUG ((EFI_D_ERROR, "%a: Unknown Host Bridge Device ID: 0x%04x\n",
  71         __FUNCTION__, HostBridgeDevId));
  72       ASSERT (FALSE);
  73       return RETURN_UNSUPPORTED;
  74   }
  75
  76   mAcpiTimerIoAddr = (PciRead32 (Pmba) & ~PMBA_RTE) + ACPI_TIMER_OFFSET;
  77
  78   return RETURN_SUCCESS;
  79 }
  80
  81 /**
  82   Internal function to read the current tick counter of ACPI.
  83
  84   Read the current ACPI tick counter using the counter address cached
  85   by this instance's constructor.
  86
  87   @return The tick counter read.
  88
  89 **/
  90 UINT32
  91 InternalAcpiGetTimerTick (
  92   VOID
  93   )
  94 {
  95   //
  96   //   Return the current ACPI timer value.
  97   //
  98   return IoRead32 (mAcpiTimerIoAddr);
  99 }