/** @file

Copyright (c) 2018, 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 that 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 "PiDxe.h"
#include <Base.h>
#include <Guid/SocketIioVariable.h>
#include <Library/IoLib.h>
#include <Library/DebugLib.h>
#include <Library/UefiRuntimeServicesTableLib.h>
#include "IndustryStandard/Pci.h"
#include "PciSupportLib.h"

PCIE_STACK  mPcieStack;


/**

  This routine is used to check whether the pci device is present

  @retval None

**/
BOOLEAN
IsPciDevicePresent (
  IN EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL  *PciRootBridgeIo,
  PCI_TYPE00                          *Pci,
  UINT8                               Bus,
  UINT8                               Device,
  UINT8                               Func
  )
// TODO:    PciRootBridgeIo - add argument and description to function comment
// TODO:    Pci - add argument and description to function comment
// TODO:    Bus - add argument and description to function comment
// TODO:    Device - add argument and description to function comment
// TODO:    Func - add argument and description to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
// TODO:    EFI_NOT_FOUND - add return value to function comment
{
  UINT64      Address;
  UINT32      Dummy;
  EFI_STATUS  Status;
  
  Dummy=0xFFFFFFFF;
  //
  // Create PCI address map in terms of Bus, Device and Func
  //
  Address = EFI_PCI_ADDRESS (Bus, Device, Func, 0);

  //
  // Read the Vendor Id register
  //
  Status = PciRootBridgeIo->Pci.Read (
                                  PciRootBridgeIo,
                                  EfiPciWidthUint32,
                                  Address,
                                  1,
                                  Pci
                                  );
  if ((Pci->Hdr).VendorId == 0xffff) {
    /// PCIe card could have been assigned a temporary bus number. 
    /// An write cycle can be used to try to rewrite the Bus number in the card
    /// Try to write the Vendor Id register, and recheck if the card is present. 
    Status = PciRootBridgeIo->Pci.Write(
                                    PciRootBridgeIo, 
                                    EfiPciWidthUint32, 
                                    Address, 
                                    1,							  
                                    &Dummy
                                    ); 
									
    // Retry the previous read after the PCI cycle has been tried. 
    Status = PciRootBridgeIo->Pci.Read (
                                    PciRootBridgeIo,
                                    EfiPciWidthUint32,
                                    Address,
                                    1,
                                    Pci
                                    );
  }

  if (!EFI_ERROR (Status) && (Pci->Hdr).VendorId != 0xffff) {

    //
    // Read the entire config header for the device
    //

    Status = PciRootBridgeIo->Pci.Read (
                                    PciRootBridgeIo,
                                    EfiPciWidthUint32,
                                    Address,
                                    sizeof (PCI_TYPE00) / sizeof (UINT32),
                                    Pci
                                    );

    return TRUE;
  }

  return FALSE;
}