/** @file
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Power management support functions implementation for PCI Bus module.
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Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include "PciBus.h"
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/**
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This function is intended to turn off PWE assertion and
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put the device to D0 state if the device supports
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PCI Power Management.
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@param PciIoDevice PCI device instance.
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@retval EFI_UNSUPPORTED PCI Device does not support power management.
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@retval EFI_SUCCESS Turned off PWE successfully.
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**/
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EFI_STATUS
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ResetPowerManagementFeature (
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IN PCI_IO_DEVICE *PciIoDevice
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)
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{
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EFI_STATUS Status;
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UINT8 PowerManagementRegBlock;
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UINT16 PowerManagementCSR;
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PowerManagementRegBlock = 0;
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Status = LocateCapabilityRegBlock (
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PciIoDevice,
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EFI_PCI_CAPABILITY_ID_PMI,
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&PowerManagementRegBlock,
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NULL
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);
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if (EFI_ERROR (Status)) {
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return EFI_UNSUPPORTED;
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}
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//
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// Turn off the PWE assertion and put the device into D0 State
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//
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//
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// Read PMCSR
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//
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Status = PciIoDevice->PciIo.Pci.Read (
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&PciIoDevice->PciIo,
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EfiPciIoWidthUint16,
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PowerManagementRegBlock + 4,
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1,
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&PowerManagementCSR
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);
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if (!EFI_ERROR (Status)) {
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//
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// Clear PME_Status bit
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//
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PowerManagementCSR |= BIT15;
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//
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// Clear PME_En bit. PowerState = D0.
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//
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PowerManagementCSR &= ~(BIT8 | BIT1 | BIT0);
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//
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// Write PMCSR
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//
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Status = PciIoDevice->PciIo.Pci.Write (
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&PciIoDevice->PciIo,
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EfiPciIoWidthUint16,
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PowerManagementRegBlock + 4,
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1,
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&PowerManagementCSR
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);
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}
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return Status;
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}
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