/** @file

  Implementation of the SNP.Transmit() function and its private helpers if any.

  Copyright (C) 2013, Red Hat, Inc.
  Copyright (c) 2006 - 2013, 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 which 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 <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/UefiBootServicesTableLib.h>

#include "VirtioNet.h"

/**
  Places a packet in the transmit queue of a network interface.

  @param  This       The protocol instance pointer.
  @param  HeaderSize The size, in bytes, of the media header to be filled in by
                     the Transmit() function. If HeaderSize is non-zero, then
                     it must be equal to This->Mode->MediaHeaderSize and the
                     DestAddr and Protocol parameters must not be NULL.
  @param  BufferSize The size, in bytes, of the entire packet (media header and
                     data) to be transmitted through the network interface.
  @param  Buffer     A pointer to the packet (media header followed by data) to
                     be transmitted. This parameter cannot be NULL. If
                     HeaderSize is zero, then the media header in Buffer must
                     already be filled in by the caller. If HeaderSize is
                     non-zero, then the media header will be filled in by the
                     Transmit() function.
  @param  SrcAddr    The source HW MAC address. If HeaderSize is zero, then
                     this parameter is ignored. If HeaderSize is non-zero and
                     SrcAddr is NULL, then This->Mode->CurrentAddress is used
                     for the source HW MAC address.
  @param  DestAddr   The destination HW MAC address. If HeaderSize is zero,
                     then this parameter is ignored.
  @param  Protocol   The type of header to build. If HeaderSize is zero, then
                     this parameter is ignored. See RFC 1700, section "Ether
                     Types", for examples.

  @retval EFI_SUCCESS           The packet was placed on the transmit queue.
  @retval EFI_NOT_STARTED       The network interface has not been started.
  @retval EFI_NOT_READY         The network interface is too busy to accept
                                this transmit request.
  @retval EFI_BUFFER_TOO_SMALL  The BufferSize parameter is too small.
  @retval EFI_INVALID_PARAMETER One or more of the parameters has an
                                unsupported value.
  @retval EFI_DEVICE_ERROR      The command could not be sent to the network
                                interface.
  @retval EFI_UNSUPPORTED       This function is not supported by the network
                                interface.

**/

EFI_STATUS
EFIAPI
VirtioNetTransmit (
  IN EFI_SIMPLE_NETWORK_PROTOCOL *This,
  IN UINTN                       HeaderSize,
  IN UINTN                       BufferSize,
  IN /* +OUT! */ VOID            *Buffer,
  IN EFI_MAC_ADDRESS             *SrcAddr  OPTIONAL,
  IN EFI_MAC_ADDRESS             *DestAddr OPTIONAL,
  IN UINT16                      *Protocol OPTIONAL
  )
{
  VNET_DEV   *Dev;
  EFI_TPL    OldTpl;
  EFI_STATUS Status;
  UINT16     DescIdx;
  UINT16     AvailIdx;

  if (This == NULL || BufferSize == 0 || Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Dev = VIRTIO_NET_FROM_SNP (This);
  OldTpl = gBS->RaiseTPL (TPL_CALLBACK);
  switch (Dev->Snm.State) {
  case EfiSimpleNetworkStopped:
    Status = EFI_NOT_STARTED;
    goto Exit;
  case EfiSimpleNetworkStarted:
    Status = EFI_DEVICE_ERROR;
    goto Exit;
  default:
    break;
  }

  if (BufferSize < Dev->Snm.MediaHeaderSize) {
    Status = EFI_BUFFER_TOO_SMALL;
    goto Exit;
  }
  if (BufferSize > Dev->Snm.MediaHeaderSize + Dev->Snm.MaxPacketSize) {
    Status = EFI_INVALID_PARAMETER;
    goto Exit;
  }

  //
  // check if we have room for transmission
  //
  ASSERT (Dev->TxCurPending <= Dev->TxMaxPending);
  if (Dev->TxCurPending == Dev->TxMaxPending) {
    Status = EFI_NOT_READY;
    goto Exit;
  }

  //
  // the caller may want us to fill in the media header:
  // dst MAC, src MAC, Ethertype
  //
  if (HeaderSize != 0) {
    UINT8 *Ptr;

    if (HeaderSize != Dev->Snm.MediaHeaderSize ||
        DestAddr == NULL || Protocol == NULL) {
      Status = EFI_INVALID_PARAMETER;
      goto Exit;
    }
    Ptr = Buffer;
    ASSERT (SIZE_OF_VNET (Mac) <= sizeof (EFI_MAC_ADDRESS));

    CopyMem (Ptr, DestAddr, SIZE_OF_VNET (Mac));
    Ptr += SIZE_OF_VNET (Mac);

    CopyMem (Ptr,
      (SrcAddr == NULL) ? &Dev->Snm.CurrentAddress : SrcAddr,
      SIZE_OF_VNET (Mac));
    Ptr += SIZE_OF_VNET (Mac);

    *Ptr++ = (UINT8) (*Protocol >> 8);
    *Ptr++ = (UINT8) *Protocol;

    ASSERT ((UINTN) (Ptr - (UINT8 *) Buffer) == Dev->Snm.MediaHeaderSize);
  }

  //
  // virtio-0.9.5, 2.4.1 Supplying Buffers to The Device
  //
  DescIdx = Dev->TxFreeStack[Dev->TxCurPending++];
  Dev->TxRing.Desc[DescIdx + 1].Addr  = (UINTN) Buffer;
  Dev->TxRing.Desc[DescIdx + 1].Len   = (UINT32) BufferSize;

  //
  // the available index is never written by the host, we can read it back
  // without a barrier
  //
  AvailIdx = *Dev->TxRing.Avail.Idx;
  Dev->TxRing.Avail.Ring[AvailIdx++ % Dev->TxRing.QueueSize] = DescIdx;

  MemoryFence ();
  *Dev->TxRing.Avail.Idx = AvailIdx;

  MemoryFence ();
  Status = Dev->VirtIo->SetQueueNotify (Dev->VirtIo, VIRTIO_NET_Q_TX);

Exit:
  gBS->RestoreTPL (OldTpl);
  return Status;
}