/*
 * Copyright (c) 2021, Konstantin Aladyshev <aladyshev22@gmail.com>
 *
 * SPDX-License-Identifier: MIT
 */

#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>

#include <Protocol/PciRootBridgeIo.h>
#include <Library/MemoryAllocationLib.h>
#include <IndustryStandard/Pci.h>


UINT64 PciConfigurationAddress(UINT8 Bus,
                               UINT8 Device,
                               UINT8 Function,
                               UINT32 Register)
{
  UINT64 Address = (((UINT64)Bus) << 24) + (((UINT64)Device) << 16) + (((UINT64)Function) << 8);
  if (Register & 0xFFFFFF00) {
    Address += (((UINT64)Register) << 32);
  } else {
    Address += (((UINT64)Register) << 0);
  }
  return Address;
}


EFI_STATUS PrintRootBridge(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL* PciRootBridgeIo)
{
  EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR* AddressDescriptor;
  EFI_STATUS Status = PciRootBridgeIo->Configuration(
                                         PciRootBridgeIo,
                                         (VOID**)&AddressDescriptor
                                       );
  if (EFI_ERROR(Status)) {
    Print(L"\tError! Can't get EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR: %r\n", Status);
    return Status;
  }
  while (AddressDescriptor->Desc != ACPI_END_TAG_DESCRIPTOR) {
    if (AddressDescriptor->ResType == ACPI_ADDRESS_SPACE_TYPE_BUS) {
      for (UINT8 Bus = AddressDescriptor->AddrRangeMin; Bus <= AddressDescriptor->AddrRangeMax; Bus++) {
        for (UINT8 Device = 0; Device <= PCI_MAX_DEVICE; Device++) {
          for (UINT8 Func = 0; Func <= PCI_MAX_FUNC; Func++) {
            UINT64 Address = PciConfigurationAddress(Bus, Device, Func, 0);
            PCI_DEVICE_INDEPENDENT_REGION PCIConfHdr;
            Status = PciRootBridgeIo->Pci.Read(
              PciRootBridgeIo,
              EfiPciWidthUint8,
              Address,
              sizeof(PCI_DEVICE_INDEPENDENT_REGION),
              &PCIConfHdr
            );
            if (!EFI_ERROR(Status)) {
              if (PCIConfHdr.VendorId != 0xffff) {
                Print(L"\tBus: %02x, Dev: %02x, Func: %02x - Vendor:%04x, Device:%04x\n",
                                                                        Bus,
                                                                        Device,
                                                                        Func,
                                                                        PCIConfHdr.VendorId, 
                                                                        PCIConfHdr.DeviceId);
              }
            } else {
              Print(L"\tError in PCI read: %r\n", Status);
            }
          }
        }
      }
    }
    AddressDescriptor++;
  }
  return Status;
}

EFI_STATUS
EFIAPI
UefiMain (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_STATUS             Status;
  UINTN                  HandleCount;
  EFI_HANDLE             *HandleBuffer;
  Status = gBS->LocateHandleBuffer(
                  ByProtocol,
                  &gEfiPciRootBridgeIoProtocolGuid,
                  NULL,
                  &HandleCount,
                  &HandleBuffer
                );
  if (EFI_ERROR (Status)) {
    Print(L"Can't locate EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL: %r\n", Status);
    return Status;
  }

  Print(L"Number of PCI root bridges in the system: %d\n", HandleCount);
  EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL* PciRootBridgeIo;
  for (UINTN Index = 0; Index < HandleCount; Index++) {
    Status = gBS->OpenProtocol (
                    HandleBuffer[Index],
                    &gEfiPciRootBridgeIoProtocolGuid,
                    (VOID **)&PciRootBridgeIo,
                    ImageHandle,
                    NULL,
                    EFI_OPEN_PROTOCOL_GET_PROTOCOL
                  );
    if (EFI_ERROR(Status)) {
      Print(L"Can't open protocol: %r\n", Status);
      return Status;
    }
    Print(L"\nPCI Root Bridge %d\n", Index);
    Status = PrintRootBridge(PciRootBridgeIo);
    if (EFI_ERROR(Status)) {
      Print(L"Error in PCI Root Bridge printing\n");
    }
  }
  FreePool(HandleBuffer);

  return EFI_SUCCESS;
}