MdeModulePkg/Bus/Pci/PciBusDxe/PciPowerManagement.c

   1 /** @file
   2   Power management support fucntions implementation for PCI Bus module.
   3
   4 Copyright (c) 2006 - 2009, Intel Corporation
   5 All rights reserved. This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include "PciBus.h"
  16
  17 /**
  18   This function is intended to turn off PWE assertion and
  19   put the device to D0 state if the device supports
  20   PCI Power Management.
  21
  22   @param PciIoDevice      PCI device instance.
  23
  24   @retval EFI_UNSUPPORTED PCI Device does not support power management.
  25   @retval EFI_SUCCESS     Turned off PWE successfully.
  26
  27 **/
  28 EFI_STATUS
  29 ResetPowerManagementFeature (
  30   IN PCI_IO_DEVICE *PciIoDevice
  31   )
  32 {
  33   EFI_STATUS  Status;
  34   UINT8       PowerManagementRegBlock;
  35   UINT16      PowerManagementCSR;
  36
  37   PowerManagementRegBlock = 0;
  38
  39   Status = LocateCapabilityRegBlock (
  40             PciIoDevice,
  41             EFI_PCI_CAPABILITY_ID_PMI,
  42             &PowerManagementRegBlock,
  43             NULL
  44             );
  45
  46   if (EFI_ERROR (Status)) {
  47     return EFI_UNSUPPORTED;
  48   }
  49
  50   //
  51   // Turn off the PWE assertion and put the device into D0 State
  52   //
  53   PowerManagementCSR = 0x8000;
  54
  55   //
  56   // Write PMCSR
  57   //
  58   PciIoDevice->PciIo.Pci.Write (
  59                            &PciIoDevice->PciIo,
  60                            EfiPciIoWidthUint16,
  61                            PowerManagementRegBlock + 4,
  62                            1,
  63                            &PowerManagementCSR
  64                            );
  65
  66   return EFI_SUCCESS;
  67 }
  68