CloverBootloader/NetworkPkg/SnpDxe/Snp.c

/** @file
  Implementation of driver entry point and driver binding protocol.

Copyright (c) 2004 - 2019, Intel Corporation. All rights reserved.<BR>
Copyright (c) Microsoft Corporation.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "Snp.h"

/**
  One notified function to stop UNDI device when gBS->ExitBootServices() called.

  @param  Event                   Pointer to this event
  @param  Context                 Event handler private data

**/
VOID
EFIAPI
SnpNotifyExitBootServices (
  EFI_EVENT  Event,
  VOID       *Context
  )
{
  SNP_DRIVER  *Snp;

  Snp = (SNP_DRIVER *)Context;

  //
  // Shutdown and stop UNDI driver
  //
  PxeShutdown (Snp);
  PxeStop (Snp);
}

/**
  Send command to UNDI. It does nothing currently.

  @param Cdb   command to be sent to UNDI.

  @retval EFI_INVALID_PARAMETER  The command is 0.
  @retval EFI_UNSUPPORTED        Default return status because it's not
                                 supported currently.

**/
EFI_STATUS
EFIAPI
IssueHwUndiCommand (
  UINT64  Cdb
  )
{
  DEBUG ((DEBUG_ERROR, "\nIssueHwUndiCommand() - This should not be called!"));

  if (Cdb == 0) {
    return EFI_INVALID_PARAMETER;
  }

  //
  //  %%TBD - For now, nothing is done.
  //
  return EFI_UNSUPPORTED;
}

/**
  Compute 8-bit checksum of a buffer.

  @param  Buffer               Pointer to buffer.
  @param  Length               Length of buffer in bytes.

  @return 8-bit checksum of all bytes in buffer, or zero if ptr is NULL or len
          is zero.

**/
UINT8
Calc8BitCksum (
  VOID   *Buffer,
  UINTN  Length
  )
{
  UINT8  *Ptr;
  UINT8  Cksum;

  Ptr   = Buffer;
  Cksum = 0;

  if ((Ptr == NULL) || (Length == 0)) {
    return 0;
  }

  while (Length-- != 0) {
    Cksum = (UINT8)(Cksum + *Ptr++);
  }

  return Cksum;
}

/**
  Test to see if this driver supports ControllerHandle. This service
  is called by the EFI boot service ConnectController(). In
  order to make drivers as small as possible, there are a few calling
  restrictions for this service. ConnectController() must
  follow these calling restrictions. If any other agent wishes to call
  Supported() it must also follow these calling restrictions.

  @param  This                Protocol instance pointer.
  @param  ControllerHandle    Handle of device to test.
  @param  RemainingDevicePath Optional parameter use to pick a specific child
                              device to start.

  @retval EFI_SUCCESS         This driver supports this device.
  @retval EFI_ALREADY_STARTED This driver is already running on this device.
  @retval other               This driver does not support this device.

**/
EFI_STATUS
EFIAPI
SimpleNetworkDriverSupported (
  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
  IN EFI_HANDLE                   Controller,
  IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath
  )
{
  EFI_STATUS                                 Status;
  EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL  *NiiProtocol;
  PXE_UNDI                                   *Pxe;

  Status = gBS->OpenProtocol (
                  Controller,
                  &gEfiDevicePathProtocolGuid,
                  NULL,
                  This->DriverBindingHandle,
                  Controller,
                  EFI_OPEN_PROTOCOL_TEST_PROTOCOL
                  );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  Status = gBS->OpenProtocol (
                  Controller,
                  &gEfiNetworkInterfaceIdentifierProtocolGuid_31,
                  (VOID **)&NiiProtocol,
                  This->DriverBindingHandle,
                  Controller,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );

  if (EFI_ERROR (Status)) {
    if (Status == EFI_ALREADY_STARTED) {
      DEBUG ((DEBUG_INFO, "Support(): Already Started. on handle %p\n", Controller));
    }

    return Status;
  }

  DEBUG ((DEBUG_INFO, "Support(): UNDI3.1 found on handle %p\n", Controller));

  //
  // check the version, we don't want to connect to the undi16
  //
  if (NiiProtocol->Type != EfiNetworkInterfaceUndi) {
    Status = EFI_UNSUPPORTED;
    goto Done;
  }

  //
  // Check to see if !PXE structure is valid. Paragraph alignment of !PXE structure is required.
  //
  if ((NiiProtocol->Id & 0x0F) != 0) {
    DEBUG ((DEBUG_NET, "\n!PXE structure is not paragraph aligned.\n"));
    Status = EFI_UNSUPPORTED;
    goto Done;
  }

  Pxe = (PXE_UNDI *)(UINTN)(NiiProtocol->Id);

  //
  //  Verify !PXE revisions.
  //
  if (Pxe->hw.Signature != PXE_ROMID_SIGNATURE) {
    DEBUG ((DEBUG_NET, "\n!PXE signature is not valid.\n"));
    Status = EFI_UNSUPPORTED;
    goto Done;
  }

  if (Pxe->hw.Rev < PXE_ROMID_REV) {
    DEBUG ((DEBUG_NET, "\n!PXE.Rev is not supported.\n"));
    Status = EFI_UNSUPPORTED;
    goto Done;
  }

  if (Pxe->hw.MajorVer < PXE_ROMID_MAJORVER) {
    DEBUG ((DEBUG_NET, "\n!PXE.MajorVer is not supported.\n"));
    Status = EFI_UNSUPPORTED;
    goto Done;
  } else if ((Pxe->hw.MajorVer == PXE_ROMID_MAJORVER) && (Pxe->hw.MinorVer < PXE_ROMID_MINORVER)) {
    DEBUG ((DEBUG_NET, "\n!PXE.MinorVer is not supported."));
    Status = EFI_UNSUPPORTED;
    goto Done;
  }

  //
  // Do S/W UNDI specific checks.
  //
  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_HW_UNDI) == 0) {
    if (Pxe->sw.EntryPoint < Pxe->sw.Len) {
      DEBUG ((DEBUG_NET, "\n!PXE S/W entry point is not valid."));
      Status = EFI_UNSUPPORTED;
      goto Done;
    }

    if (Pxe->sw.BusCnt == 0) {
      DEBUG ((DEBUG_NET, "\n!PXE.BusCnt is zero."));
      Status = EFI_UNSUPPORTED;
      goto Done;
    }
  }

  Status = EFI_SUCCESS;
  DEBUG ((DEBUG_INFO, "Support(): supported on %p\n", Controller));

Done:
  gBS->CloseProtocol (
         Controller,
         &gEfiNetworkInterfaceIdentifierProtocolGuid_31,
         This->DriverBindingHandle,
         Controller
         );

  return Status;
}

/**
  Start this driver on ControllerHandle. This service is called by the
  EFI boot service ConnectController(). In order to make
  drivers as small as possible, there are a few calling restrictions for
  this service. ConnectController() must follow these
  calling restrictions. If any other agent wishes to call Start() it
  must also follow these calling restrictions.

  @param  This                 Protocol instance pointer.
  @param  ControllerHandle     Handle of device to bind driver to.
  @param  RemainingDevicePath  Optional parameter use to pick a specific child
                               device to start.

  @retval EFI_SUCCESS          This driver is added to ControllerHandle
  @retval EFI_DEVICE_ERROR     This driver could not be started due to a device error
  @retval other                This driver does not support this device

**/
EFI_STATUS
EFIAPI
SimpleNetworkDriverStart (
  IN EFI_DRIVER_BINDING_PROTOCOL  *This,
  IN EFI_HANDLE                   Controller,
  IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath
  )
{
  EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL  *Nii;
  EFI_DEVICE_PATH_PROTOCOL                   *NiiDevicePath;
  EFI_STATUS                                 Status;
  PXE_UNDI                                   *Pxe;
  SNP_DRIVER                                 *Snp;
  VOID                                       *Address;
  EFI_HANDLE                                 Handle;
  UINT8                                      BarIndex;
  PXE_STATFLAGS                              InitStatFlags;
  EFI_PCI_IO_PROTOCOL                        *PciIo;
  EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR          *BarDesc;
  BOOLEAN                                    FoundIoBar;
  BOOLEAN                                    FoundMemoryBar;

  DEBUG ((DEBUG_NET, "\nSnpNotifyNetworkInterfaceIdentifier()  "));

  Status = gBS->OpenProtocol (
                  Controller,
                  &gEfiDevicePathProtocolGuid,
                  (VOID **)&NiiDevicePath,
                  This->DriverBindingHandle,
                  Controller,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );

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

  Status = gBS->LocateDevicePath (
                  &gEfiPciIoProtocolGuid,
                  &NiiDevicePath,
                  &Handle
                  );

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

  Status = gBS->OpenProtocol (
                  Handle,
                  &gEfiPciIoProtocolGuid,
                  (VOID **)&PciIo,
                  This->DriverBindingHandle,
                  Controller,
                  EFI_OPEN_PROTOCOL_GET_PROTOCOL
                  );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Get the NII interface.
  //
  Status = gBS->OpenProtocol (
                  Controller,
                  &gEfiNetworkInterfaceIdentifierProtocolGuid_31,
                  (VOID **)&Nii,
                  This->DriverBindingHandle,
                  Controller,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );
  if (EFI_ERROR (Status)) {
    gBS->CloseProtocol (
           Controller,
           &gEfiDevicePathProtocolGuid,
           This->DriverBindingHandle,
           Controller
           );
    return Status;
  }

  DEBUG ((DEBUG_INFO, "Start(): UNDI3.1 found\n"));

  Pxe = (PXE_UNDI *)(UINTN)(Nii->Id);

  if (Calc8BitCksum (Pxe, Pxe->hw.Len) != 0) {
    DEBUG ((DEBUG_NET, "\n!PXE checksum is not correct.\n"));
    goto NiiError;
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_PROMISCUOUS_RX_SUPPORTED) != 0) {
    //
    //  We can get any packets.
    //
  } else if ((Pxe->hw.Implementation & PXE_ROMID_IMP_BROADCAST_RX_SUPPORTED) != 0) {
    //
    //  We need to be able to get broadcast packets for DHCP.
    //  If we do not have promiscuous support, we must at least have
    //  broadcast support or we cannot do DHCP!
    //
  } else {
    DEBUG ((DEBUG_NET, "\nUNDI does not have promiscuous or broadcast support."));
    goto NiiError;
  }

  //
  // OK, we like this UNDI, and we know snp is not already there on this handle
  // Allocate and initialize a new simple network protocol structure.
  //
  Status = PciIo->AllocateBuffer (
                    PciIo,
                    AllocateAnyPages,
                    EfiBootServicesData,
                    SNP_MEM_PAGES (sizeof (SNP_DRIVER)),
                    &Address,
                    0
                    );

  if (Status != EFI_SUCCESS) {
    DEBUG ((DEBUG_NET, "\nCould not allocate SNP_DRIVER structure.\n"));
    goto NiiError;
  }

  Snp = (SNP_DRIVER *)(UINTN)Address;

  ZeroMem (Snp, sizeof (SNP_DRIVER));

  Snp->PciIo     = PciIo;
  Snp->Signature = SNP_DRIVER_SIGNATURE;

  EfiInitializeLock (&Snp->Lock, TPL_NOTIFY);

  Snp->Snp.Revision       = EFI_SIMPLE_NETWORK_PROTOCOL_REVISION;
  Snp->Snp.Start          = SnpUndi32Start;
  Snp->Snp.Stop           = SnpUndi32Stop;
  Snp->Snp.Initialize     = SnpUndi32Initialize;
  Snp->Snp.Reset          = SnpUndi32Reset;
  Snp->Snp.Shutdown       = SnpUndi32Shutdown;
  Snp->Snp.ReceiveFilters = SnpUndi32ReceiveFilters;
  Snp->Snp.StationAddress = SnpUndi32StationAddress;
  Snp->Snp.Statistics     = SnpUndi32Statistics;
  Snp->Snp.MCastIpToMac   = SnpUndi32McastIpToMac;
  Snp->Snp.NvData         = SnpUndi32NvData;
  Snp->Snp.GetStatus      = SnpUndi32GetStatus;
  Snp->Snp.Transmit       = SnpUndi32Transmit;
  Snp->Snp.Receive        = SnpUndi32Receive;
  Snp->Snp.WaitForPacket  = NULL;

  Snp->Snp.Mode = &Snp->Mode;

  Snp->TxRxBufferSize = 0;
  Snp->TxRxBuffer     = NULL;

  Snp->RecycledTxBuf = AllocatePool (sizeof (UINT64) * SNP_TX_BUFFER_INCREASEMENT);
  if (Snp->RecycledTxBuf == NULL) {
    Status = EFI_OUT_OF_RESOURCES;
    goto Error_DeleteSNP;
  }

  Snp->MaxRecycledTxBuf   = SNP_TX_BUFFER_INCREASEMENT;
  Snp->RecycledTxBufCount = 0;

  if (Nii->Revision >= EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL_REVISION) {
    Snp->IfNum = Nii->IfNum;
  } else {
    Snp->IfNum = (UINT8)(Nii->IfNum & 0xFF);
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_HW_UNDI) != 0) {
    Snp->IsSwUndi           = FALSE;
    Snp->IssueUndi32Command = &IssueHwUndiCommand;
  } else {
    Snp->IsSwUndi = TRUE;

    if ((Pxe->sw.Implementation & PXE_ROMID_IMP_SW_VIRT_ADDR) != 0) {
      Snp->IssueUndi32Command = (ISSUE_UNDI32_COMMAND)(UINTN)Pxe->sw.EntryPoint;
    } else {
      Snp->IssueUndi32Command = (ISSUE_UNDI32_COMMAND)(UINTN)((UINT8)(UINTN)Pxe + Pxe->sw.EntryPoint);
    }
  }

  //
  // Allocate a global CPB and DB buffer for this UNDI interface.
  // we do this because:
  //
  // -UNDI 3.0 wants all the addresses passed to it (even the cpb and db) to be
  // within 2GB limit, create them here and map them so that when undi calls
  // v2p callback to check if the physical address is < 2gb, we will pass.
  //
  // -This is not a requirement for 3.1 or later UNDIs but the code looks
  // simpler if we use the same cpb, db variables for both old and new undi
  // interfaces from all the SNP interface calls (we don't map the buffers
  // for the newer undi interfaces though)
  // .
  // -it is OK to allocate one global set of CPB, DB pair for each UNDI
  // interface as EFI does not multi-task and so SNP will not be re-entered!
  //
  Status = PciIo->AllocateBuffer (
                    PciIo,
                    AllocateAnyPages,
                    EfiBootServicesData,
                    SNP_MEM_PAGES (4096),
                    &Address,
                    0
                    );

  if (Status != EFI_SUCCESS) {
    DEBUG ((DEBUG_NET, "\nCould not allocate CPB and DB structures.\n"));
    goto Error_DeleteSNP;
  }

  Snp->Cpb = (VOID *)(UINTN)Address;
  Snp->Db  = (VOID *)((UINTN)Address + 2048);

  //
  // Find the correct BAR to do IO.
  //
  // Enumerate through the PCI BARs for the device to determine which one is
  // the IO BAR.  Save the index of the BAR into the adapter info structure.
  // for regular 32bit BARs, 0 is memory mapped, 1 is io mapped
  //
  Snp->MemoryBarIndex = PCI_MAX_BAR;
  Snp->IoBarIndex     = PCI_MAX_BAR;
  FoundMemoryBar      = FALSE;
  FoundIoBar          = FALSE;
  for (BarIndex = 0; BarIndex < PCI_MAX_BAR; BarIndex++) {
    Status = PciIo->GetBarAttributes (
                      PciIo,
                      BarIndex,
                      NULL,
                      (VOID **)&BarDesc
                      );
    if (Status == EFI_UNSUPPORTED) {
      continue;
    } else if (EFI_ERROR (Status)) {
      goto Error_DeleteSNP;
    }

    if ((!FoundMemoryBar) && (BarDesc->ResType == ACPI_ADDRESS_SPACE_TYPE_MEM)) {
      Snp->MemoryBarIndex = BarIndex;
      FoundMemoryBar      = TRUE;
    } else if ((!FoundIoBar) && (BarDesc->ResType == ACPI_ADDRESS_SPACE_TYPE_IO)) {
      Snp->IoBarIndex = BarIndex;
      FoundIoBar      = TRUE;
    }

    FreePool (BarDesc);

    if (FoundMemoryBar && FoundIoBar) {
      break;
    }
  }

  Status = PxeStart (Snp);

  if (Status != EFI_SUCCESS) {
    goto Error_DeleteSNP;
  }

  Snp->Cdb.OpCode  = PXE_OPCODE_GET_INIT_INFO;
  Snp->Cdb.OpFlags = PXE_OPFLAGS_NOT_USED;

  Snp->Cdb.CPBsize = PXE_CPBSIZE_NOT_USED;
  Snp->Cdb.CPBaddr = PXE_DBADDR_NOT_USED;

  Snp->Cdb.DBsize = (UINT16)sizeof (Snp->InitInfo);
  Snp->Cdb.DBaddr = (UINT64)(UINTN)(&Snp->InitInfo);

  Snp->Cdb.StatCode  = PXE_STATCODE_INITIALIZE;
  Snp->Cdb.StatFlags = PXE_STATFLAGS_INITIALIZE;

  Snp->Cdb.IFnum   = Snp->IfNum;
  Snp->Cdb.Control = PXE_CONTROL_LAST_CDB_IN_LIST;

  DEBUG ((DEBUG_NET, "\nSnp->undi.get_init_info()  "));

  (*Snp->IssueUndi32Command)((UINT64)(UINTN)&Snp->Cdb);

  //
  // Save the INIT Stat Code...
  //
  InitStatFlags = Snp->Cdb.StatFlags;

  if (Snp->Cdb.StatCode != PXE_STATCODE_SUCCESS) {
    DEBUG ((DEBUG_NET, "\nSnp->undi.init_info()  %xh:%xh\n", Snp->Cdb.StatFlags, Snp->Cdb.StatCode));
    PxeStop (Snp);
    goto Error_DeleteSNP;
  }

  //
  //  Initialize simple network protocol mode structure
  //
  Snp->Mode.State               = EfiSimpleNetworkStopped;
  Snp->Mode.HwAddressSize       = Snp->InitInfo.HWaddrLen;
  Snp->Mode.MediaHeaderSize     = Snp->InitInfo.MediaHeaderLen;
  Snp->Mode.MaxPacketSize       = Snp->InitInfo.FrameDataLen;
  Snp->Mode.NvRamAccessSize     = Snp->InitInfo.NvWidth;
  Snp->Mode.NvRamSize           = Snp->InitInfo.NvCount * Snp->Mode.NvRamAccessSize;
  Snp->Mode.IfType              = Snp->InitInfo.IFtype;
  Snp->Mode.MaxMCastFilterCount = Snp->InitInfo.MCastFilterCnt;
  Snp->Mode.MCastFilterCount    = 0;

  switch (InitStatFlags & PXE_STATFLAGS_CABLE_DETECT_MASK) {
    case PXE_STATFLAGS_CABLE_DETECT_SUPPORTED:
      Snp->CableDetectSupported = TRUE;
      break;

    case PXE_STATFLAGS_CABLE_DETECT_NOT_SUPPORTED:
    default:
      Snp->CableDetectSupported = FALSE;
  }

  switch (InitStatFlags & PXE_STATFLAGS_GET_STATUS_NO_MEDIA_MASK) {
    case PXE_STATFLAGS_GET_STATUS_NO_MEDIA_SUPPORTED:
      Snp->MediaStatusSupported = TRUE;
      break;

    case PXE_STATFLAGS_GET_STATUS_NO_MEDIA_NOT_SUPPORTED:
    default:
      Snp->MediaStatusSupported = FALSE;
  }

  if (Snp->CableDetectSupported || Snp->MediaStatusSupported) {
    Snp->Mode.MediaPresentSupported = TRUE;
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_STATION_ADDR_SETTABLE) != 0) {
    Snp->Mode.MacAddressChangeable = TRUE;
  } else {
    Snp->Mode.MacAddressChangeable = FALSE;
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_MULTI_FRAME_SUPPORTED) != 0) {
    Snp->Mode.MultipleTxSupported = TRUE;
  } else {
    Snp->Mode.MultipleTxSupported = FALSE;
  }

  Snp->Mode.ReceiveFilterMask = EFI_SIMPLE_NETWORK_RECEIVE_UNICAST;

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_PROMISCUOUS_MULTICAST_RX_SUPPORTED) != 0) {
    Snp->Mode.ReceiveFilterMask |= EFI_SIMPLE_NETWORK_RECEIVE_PROMISCUOUS_MULTICAST;
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_PROMISCUOUS_RX_SUPPORTED) != 0) {
    Snp->Mode.ReceiveFilterMask |= EFI_SIMPLE_NETWORK_RECEIVE_PROMISCUOUS;
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_BROADCAST_RX_SUPPORTED) != 0) {
    Snp->Mode.ReceiveFilterMask |= EFI_SIMPLE_NETWORK_RECEIVE_BROADCAST;
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_FILTERED_MULTICAST_RX_SUPPORTED) != 0) {
    Snp->Mode.ReceiveFilterMask |= EFI_SIMPLE_NETWORK_RECEIVE_MULTICAST;
  }

  if ((Pxe->hw.Implementation & PXE_ROMID_IMP_PROMISCUOUS_MULTICAST_RX_SUPPORTED) != 0) {
    Snp->Mode.ReceiveFilterMask |= EFI_SIMPLE_NETWORK_RECEIVE_PROMISCUOUS_MULTICAST;
  }

  Snp->Mode.ReceiveFilterSetting = 0;

  //
  //  need to get the station address to save in the mode structure. we need to
  // initialize the UNDI first for this.
  //
  Snp->TxRxBufferSize = Snp->InitInfo.MemoryRequired;
  Status              = PxeInit (Snp, PXE_OPFLAGS_INITIALIZE_DO_NOT_DETECT_CABLE);

  if (EFI_ERROR (Status)) {
    PxeStop (Snp);
    goto Error_DeleteSNP;
  }

  Status = PxeGetStnAddr (Snp);

  if (Status != EFI_SUCCESS) {
    DEBUG ((DEBUG_ERROR, "\nSnp->undi.get_station_addr() failed.\n"));
    PxeShutdown (Snp);
    PxeStop (Snp);
    goto Error_DeleteSNP;
  }

  Snp->Mode.MediaPresent = FALSE;

  //
  // We should not leave UNDI started and initialized here. this DriverStart()
  // routine must only find and attach the SNP interface to UNDI layer that it
  // finds on the given handle!
  // The UNDI layer will be started when upper layers call Snp->start.
  // How ever, this DriverStart() must fill up the snp mode structure which
  // contains the MAC address of the NIC. For this reason we started and
  // initialized UNDI here, now we are done, do a shutdown and stop of the
  // UNDI interface!
  //
  PxeShutdown (Snp);
  PxeStop (Snp);

  if (PcdGetBool (PcdSnpCreateExitBootServicesEvent)) {
    //
    // Create EXIT_BOOT_SERIVES Event
    //
    Status = gBS->CreateEventEx (
                    EVT_NOTIFY_SIGNAL,
                    TPL_CALLBACK,
                    SnpNotifyExitBootServices,
                    Snp,
                    &gEfiEventExitBootServicesGuid,
                    &Snp->ExitBootServicesEvent
                    );
    if (EFI_ERROR (Status)) {
      goto Error_DeleteSNP;
    }
  }

  //
  //  add SNP to the undi handle
  //
  Status = gBS->InstallProtocolInterface (
                  &Controller,
                  &gEfiSimpleNetworkProtocolGuid,
                  EFI_NATIVE_INTERFACE,
                  &(Snp->Snp)
                  );

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

  PciIo->FreeBuffer (
           PciIo,
           SNP_MEM_PAGES (4096),
           Snp->Cpb
           );

Error_DeleteSNP:

  if (Snp->RecycledTxBuf != NULL) {
    FreePool (Snp->RecycledTxBuf);
  }

  PciIo->FreeBuffer (
           PciIo,
           SNP_MEM_PAGES (sizeof (SNP_DRIVER)),
           Snp
           );
NiiError:
  gBS->CloseProtocol (
         Controller,
         &gEfiNetworkInterfaceIdentifierProtocolGuid_31,
         This->DriverBindingHandle,
         Controller
         );

  gBS->CloseProtocol (
         Controller,
         &gEfiDevicePathProtocolGuid,
         This->DriverBindingHandle,
         Controller
         );

  //
  // If we got here that means we are in error state.
  //
  if (!EFI_ERROR (Status)) {
    Status = EFI_DEVICE_ERROR;
  }

  return Status;
}

/**
  Stop this driver on ControllerHandle. This service is called by the
  EFI boot service DisconnectController(). In order to
  make drivers as small as possible, there are a few calling
  restrictions for this service. DisconnectController()
  must follow these calling restrictions. If any other agent wishes
  to call Stop() it must also follow these calling restrictions.

  @param  This              Protocol instance pointer.
  @param  ControllerHandle  Handle of device to stop driver on
  @param  NumberOfChildren  Number of Handles in ChildHandleBuffer. If number of
                            children is zero stop the entire bus driver.
  @param  ChildHandleBuffer List of Child Handles to Stop.

  @retval EFI_SUCCESS       This driver is removed ControllerHandle
  @retval other             This driver was not removed from this device

**/
EFI_STATUS
EFIAPI
SimpleNetworkDriverStop (
  IN  EFI_DRIVER_BINDING_PROTOCOL  *This,
  IN  EFI_HANDLE                   Controller,
  IN  UINTN                        NumberOfChildren,
  IN  EFI_HANDLE                   *ChildHandleBuffer
  )
{
  EFI_STATUS                   Status;
  EFI_SIMPLE_NETWORK_PROTOCOL  *SnpProtocol;
  SNP_DRIVER                   *Snp;
  EFI_PCI_IO_PROTOCOL          *PciIo;

  //
  // Get our context back.
  //
  Status = gBS->OpenProtocol (
                  Controller,
                  &gEfiSimpleNetworkProtocolGuid,
                  (VOID **)&SnpProtocol,
                  This->DriverBindingHandle,
                  Controller,
                  EFI_OPEN_PROTOCOL_GET_PROTOCOL
                  );

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

  Snp = EFI_SIMPLE_NETWORK_DEV_FROM_THIS (SnpProtocol);

  Status = gBS->UninstallProtocolInterface (
                  Controller,
                  &gEfiSimpleNetworkProtocolGuid,
                  &Snp->Snp
                  );

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

  if (PcdGetBool (PcdSnpCreateExitBootServicesEvent)) {
    //
    // Close EXIT_BOOT_SERVICES Event
    //
    gBS->CloseEvent (Snp->ExitBootServicesEvent);
  }

  Status = gBS->CloseProtocol (
                  Controller,
                  &gEfiNetworkInterfaceIdentifierProtocolGuid_31,
                  This->DriverBindingHandle,
                  Controller
                  );

  Status = gBS->CloseProtocol (
                  Controller,
                  &gEfiDevicePathProtocolGuid,
                  This->DriverBindingHandle,
                  Controller
                  );

  PxeShutdown (Snp);
  PxeStop (Snp);

  FreePool (Snp->RecycledTxBuf);

  PciIo = Snp->PciIo;
  PciIo->FreeBuffer (
           PciIo,
           SNP_MEM_PAGES (4096),
           Snp->Cpb
           );

  PciIo->FreeBuffer (
           PciIo,
           SNP_MEM_PAGES (sizeof (SNP_DRIVER)),
           Snp
           );

  return Status;
}

//
// Simple Network Protocol Driver Global Variables
//
EFI_DRIVER_BINDING_PROTOCOL  gSimpleNetworkDriverBinding = {
  SimpleNetworkDriverSupported,
  SimpleNetworkDriverStart,
  SimpleNetworkDriverStop,
  0xa,
  NULL,
  NULL
};

/**
  The SNP driver entry point.

  @param ImageHandle       The driver image handle.
  @param SystemTable       The system table.

  @retval EFI_SUCCESS      Initialization routine has found UNDI hardware,
                           loaded it's ROM, and installed a notify event for
                           the Network Identifier Interface Protocol
                           successfully.
  @retval Other            Return value from HandleProtocol for
                           DeviceIoProtocol or LoadedImageProtocol

**/
EFI_STATUS
EFIAPI
InitializeSnpNiiDriver (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  return EfiLibInstallDriverBindingComponentName2 (
           ImageHandle,
           SystemTable,
           &gSimpleNetworkDriverBinding,
           ImageHandle,
           &gSimpleNetworkComponentName,
           &gSimpleNetworkComponentName2
           );
}