audk/OvmfPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c

/** @file
  Provide constructor and GetTick for Base instance of ACPI Timer Library

  Copyright (C) 2014, Gabriel L. Somlo <somlo@cmu.edu>

  This program and the accompanying materials are licensed and made
  available under the terms and conditions of the BSD License which
  accompanies this distribution.   The full text of the license may
  be found at http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/

#include <Library/DebugLib.h>
#include <Library/IoLib.h>
#include <Library/PciLib.h>
#include <Library/PcdLib.h>
#include <OvmfPlatforms.h>

//
// Power Management PCI Configuration Register fields
//
#define PMBA_RTE  BIT0
#define PMIOSE    BIT0

//
// Offset in the Power Management Base Address to the ACPI Timer
//
#define ACPI_TIMER_OFFSET  0x8

//
// Cached ACPI Timer IO Address
//
STATIC UINT32 mAcpiTimerIoAddr;

/**
  The constructor function caches the ACPI tick counter address, and,
  if necessary, enables ACPI IO space.

  @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.

**/
RETURN_STATUS
EFIAPI
AcpiTimerLibConstructor (
  VOID
  )
{
  UINT16 HostBridgeDevId;
  UINTN Pmba;
  UINTN PmRegMisc;

  //
  // Query Host Bridge DID to determine platform type
  //
  HostBridgeDevId = PciRead16 (OVMF_HOSTBRIDGE_DID);
  switch (HostBridgeDevId) {
    case INTEL_82441_DEVICE_ID:
      Pmba      = POWER_MGMT_REGISTER_PIIX4 (0x40);
      PmRegMisc = POWER_MGMT_REGISTER_PIIX4 (0x80);
      break;
    case INTEL_Q35_MCH_DEVICE_ID:
      Pmba      = POWER_MGMT_REGISTER_Q35 (0x40);
      PmRegMisc = POWER_MGMT_REGISTER_Q35 (0x80);
      break;
    default:
      DEBUG ((EFI_D_ERROR, "%a: Unknown Host Bridge Device ID: 0x%04x\n",
        __FUNCTION__, HostBridgeDevId));
      ASSERT (FALSE);
      return RETURN_UNSUPPORTED;
  }

  mAcpiTimerIoAddr = (PciRead32 (Pmba) & ~PMBA_RTE) + ACPI_TIMER_OFFSET;

  //
  // Check to see if the Power Management Base Address is already enabled
  //
  if ((PciRead8 (PmRegMisc) & PMIOSE) == 0) {
    //
    // If the Power Management Base Address is not programmed,
    // then program the Power Management Base Address from a PCD.
    //
    PciAndThenOr32 (Pmba, (UINT32) ~0xFFC0, PcdGet16 (PcdAcpiPmBaseAddress));

    //
    // Enable PMBA I/O port decodes in PMREGMISC
    //
    PciOr8 (PmRegMisc, PMIOSE);
  }

  return RETURN_SUCCESS;
}

/**
  Internal function to read the current tick counter of ACPI.

  Read the current ACPI tick counter using the counter address cached
  by this instance's constructor.

  @return The tick counter read.

**/
UINT32
InternalAcpiGetTimerTick (
  VOID
  )
{
  //
  //   Return the current ACPI timer value.
  //
  return IoRead32 (mAcpiTimerIoAddr);
}