OvmfPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c

   1 /** @file
   2   Provide constructor and GetTick for Base 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/PciLib.h>
  18 #include <OvmfPlatforms.h>
  19
  20 //
  21 // Power Management PCI Configuration Register fields
  22 //
  23 #define PMBA_RTE  BIT0
  24
  25 //
  26 // Offset in the Power Management Base Address to the ACPI Timer
  27 //
  28 #define ACPI_TIMER_OFFSET  0x8
  29
  30 //
  31 // Cached ACPI Timer IO Address
  32 //
  33 STATIC UINT32 mAcpiTimerIoAddr;
  34
  35 /**
  36   The constructor function caches the ACPI tick counter address
  37
  38   At the time this constructor runs (DXE_CORE or later), ACPI IO space
  39   has already been enabled by either PlatformPei or by the "Base"
  40   instance of this library.
  41   In order to avoid querying the underlying platform type during each
  42   tick counter read operation, we cache the counter address during
  43   initialization of this instance of the Timer Library.
  44
  45   @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.
  46
  47 **/
  48 RETURN_STATUS
  49 EFIAPI
  50 AcpiTimerLibConstructor (
  51   VOID
  52   )
  53 {
  54   UINT16 HostBridgeDevId;
  55   UINTN Pmba;
  56
  57   //
  58   // Query Host Bridge DID to determine platform type
  59   //
  60   HostBridgeDevId = PciRead16 (OVMF_HOSTBRIDGE_DID);
  61   switch (HostBridgeDevId) {
  62     case INTEL_82441_DEVICE_ID:
  63       Pmba = POWER_MGMT_REGISTER_PIIX4 (0x40);
  64       break;
  65     case INTEL_Q35_MCH_DEVICE_ID:
  66       Pmba = POWER_MGMT_REGISTER_Q35 (0x40);
  67       break;
  68     default:
  69       DEBUG ((EFI_D_ERROR, "%a: Unknown Host Bridge Device ID: 0x%04x\n",
  70         __FUNCTION__, HostBridgeDevId));
  71       ASSERT (FALSE);
  72       return RETURN_UNSUPPORTED;
  73   }
  74
  75   mAcpiTimerIoAddr = (PciRead32 (Pmba) & ~PMBA_RTE) + ACPI_TIMER_OFFSET;
  76
  77   return RETURN_SUCCESS;
  78 }
  79
  80 /**
  81   Internal function to read the current tick counter of ACPI.
  82
  83   Read the current ACPI tick counter using the counter address cached
  84   by this instance's constructor.
  85
  86   @return The tick counter read.
  87
  88 **/
  89 UINT32
  90 InternalAcpiGetTimerTick (
  91   VOID
  92   )
  93 {
  94   //
  95   //   Return the current ACPI timer value.
  96   //
  97   return IoRead32 (mAcpiTimerIoAddr);
  98 }