audk/MdeModulePkg/Bus/Pci/PciBusDxe/PciPowerManagement.c

/** @file
  Power management support fucntions implementation for PCI Bus module.

Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
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 "PciBus.h"

/**
  This function is intended to turn off PWE assertion and
  put the device to D0 state if the device supports
  PCI Power Management.

  @param PciIoDevice      PCI device instance.

  @retval EFI_UNSUPPORTED PCI Device does not support power management.
  @retval EFI_SUCCESS     Turned off PWE successfully.

**/
EFI_STATUS
ResetPowerManagementFeature (
  IN PCI_IO_DEVICE *PciIoDevice
  )
{
  EFI_STATUS  Status;
  UINT8       PowerManagementRegBlock;
  UINT16      PowerManagementCSR;

  PowerManagementRegBlock = 0;

  Status = LocateCapabilityRegBlock (
            PciIoDevice,
            EFI_PCI_CAPABILITY_ID_PMI,
            &PowerManagementRegBlock,
            NULL
            );

  if (EFI_ERROR (Status)) {
    return EFI_UNSUPPORTED;
  }

  //
  // Turn off the PWE assertion and put the device into D0 State
  //

  //
  // Read PMCSR
  //
  Status = PciIoDevice->PciIo.Pci.Read (
                                    &PciIoDevice->PciIo,
                                    EfiPciIoWidthUint16,
                                    PowerManagementRegBlock + 4,
                                    1,
                                    &PowerManagementCSR
                                    );

  if (!EFI_ERROR (Status)) {
    //
    // Clear PME_Status bit
    //
    PowerManagementCSR |= BIT15;
    //
    // Clear PME_En bit. PowerState = D0.
    //
    PowerManagementCSR &= ~(BIT8 | BIT1 | BIT0);

    //
    // Write PMCSR
    //
    Status = PciIoDevice->PciIo.Pci.Write (
                                      &PciIoDevice->PciIo,
                                      EfiPciIoWidthUint16,
                                      PowerManagementRegBlock + 4,
                                      1,
                                      &PowerManagementCSR
                                      );
  }
  return Status;
}