/** @file

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

  Copyright (C) 2013, Red Hat, Inc.
  Copyright (c) 2006 - 2010, 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/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>

#include "VirtioNet.h"

/**
  Initialize a virtio ring for a specific transfer direction of the virtio-net
  device.

  This function may only be called by VirtioNetInitialize().

  @param[in,out] Dev       The VNET_DEV driver instance about to enter the
                           EfiSimpleNetworkInitialized state.
  @param[in]     Selector  Identifies the transfer direction (virtio queue) of
                           the network device.
  @param[out]    Ring      The virtio-ring inside the VNET_DEV structure,
                           corresponding to Selector.

  @retval EFI_UNSUPPORTED  The queue size reported by the virtio-net device is
                           too small.
  @return                  Status codes from VIRTIO_CFG_WRITE(),
                           VIRTIO_CFG_READ() and VirtioRingInit().
  @retval EFI_SUCCESS      Ring initialized.
*/

STATIC
EFI_STATUS
EFIAPI
VirtioNetInitRing (
  IN OUT VNET_DEV *Dev,
  IN     UINT16   Selector,
  OUT    VRING    *Ring
  )
{
  EFI_STATUS Status;
  UINT16     QueueSize;

  //
  // step 4b -- allocate selected queue
  //
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrQueueSelect, Selector);
  if (EFI_ERROR (Status)) {
    return Status;
  }
  Status = VIRTIO_CFG_READ (Dev, Generic.VhdrQueueSize, &QueueSize);
  if (EFI_ERROR (Status)) {
    return Status;
  }
  //
  // For each packet (RX and TX alike), we need two descriptors:
  // one for the virtio-net request header, and another one for the data
  //
  if (QueueSize < 2) {
    return EFI_UNSUPPORTED;
  }
  Status = VirtioRingInit (QueueSize, Ring);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // step 4c -- report GPFN (guest-physical frame number) of queue
  //
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrQueueAddress,
             (UINTN) Ring->Base >> EFI_PAGE_SHIFT);
  if (EFI_ERROR (Status)) {
    VirtioRingUninit (Ring);
  }
  return Status;
}


/**
  Set up static scaffolding for the VirtioNetTransmit() and
  VirtioNetGetStatus() SNP methods.

  This function may only be called by VirtioNetInitialize().

  The structures laid out and resources configured include:
  - fully populate the TX queue with a static pattern of virtio descriptor
    chains,
  - tracking of heads of free descriptor chains from the above,
  - one common virtio-net request header (never modified by the host) for all
    pending TX packets,
  - select polling over TX interrupt.

  @param[in,out] Dev       The VNET_DEV driver instance about to enter the
                           EfiSimpleNetworkInitialized state.

  @retval EFI_OUT_OF_RESOURCES  Failed to allocate the stack to track the heads
                                of free descriptor chains.
  @retval EFI_SUCCESS           TX setup successful.
*/

STATIC
EFI_STATUS
EFIAPI
VirtioNetInitTx (
  IN OUT VNET_DEV *Dev
  )
{
  UINTN PktIdx;

  Dev->TxMaxPending = (UINT16) MIN (Dev->TxRing.QueueSize / 2,
                                 VNET_MAX_PENDING);
  Dev->TxCurPending = 0;
  Dev->TxFreeStack  = AllocatePool (Dev->TxMaxPending *
                        sizeof *Dev->TxFreeStack);
  if (Dev->TxFreeStack == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  for (PktIdx = 0; PktIdx < Dev->TxMaxPending; ++PktIdx) {
    UINT16 DescIdx;

    DescIdx = (UINT16) (2 * PktIdx);
    Dev->TxFreeStack[PktIdx] = DescIdx;

    //
    // For each possibly pending packet, lay out the descriptor for the common
    // (unmodified by the host) virtio-net request header.
    //
    Dev->TxRing.Desc[DescIdx].Addr  = (UINTN) &Dev->TxSharedReq;
    Dev->TxRing.Desc[DescIdx].Len   = sizeof Dev->TxSharedReq;
    Dev->TxRing.Desc[DescIdx].Flags = VRING_DESC_F_NEXT;
    Dev->TxRing.Desc[DescIdx].Next  = (UINT16) (DescIdx + 1);

    //
    // The second descriptor of each pending TX packet is updated on the fly,
    // but it always terminates the descriptor chain of the packet.
    //
    Dev->TxRing.Desc[DescIdx + 1].Flags = 0;
  }

  //
  // virtio-0.9.5, Appendix C, Packet Transmission
  //
  Dev->TxSharedReq.Flags   = 0;
  Dev->TxSharedReq.GsoType = VIRTIO_NET_HDR_GSO_NONE;

  //
  // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device
  //
  MemoryFence ();
  Dev->TxLastUsed = *Dev->TxRing.Used.Idx;
  ASSERT (Dev->TxLastUsed == 0);

  //
  // want no interrupt when a transmit completes
  //
  *Dev->TxRing.Avail.Flags = (UINT16) VRING_AVAIL_F_NO_INTERRUPT;

  return EFI_SUCCESS;
}


/**
  Set up static scaffolding for the VirtioNetReceive() SNP method and enable
  live device operation.

  This function may only be called as VirtioNetInitialize()'s final step.

  The structures laid out and resources configured include:
  - destination area for the host to write virtio-net request headers and
    packet data into,
  - select polling over RX interrupt,
  - fully populate the RX queue with a static pattern of virtio descriptor
    chains.

  @param[in,out] Dev       The VNET_DEV driver instance about to enter the
                           EfiSimpleNetworkInitialized state.

  @retval EFI_OUT_OF_RESOURCES  Failed to allocate RX destination area.
  @return                       Status codes from VIRTIO_CFG_WRITE().
  @retval EFI_SUCCESS           RX setup successful. The device is live and may
                                already be writing to the receive area.
*/

STATIC
EFI_STATUS
EFIAPI
VirtioNetInitRx (
  IN OUT VNET_DEV *Dev
  )
{
  EFI_STATUS Status;
  UINTN      RxBufSize;
  UINT16     RxAlwaysPending;
  UINTN      PktIdx;
  UINT16     DescIdx;
  UINT8      *RxPtr;

  //
  // For each incoming packet we must supply two descriptors:
  // - the recipient for the virtio-net request header, plus
  // - the recipient for the network data (which consists of Ethernet header
  //   and Ethernet payload).
  //
  RxBufSize = sizeof (VIRTIO_NET_REQ) +
              (Dev->Snm.MediaHeaderSize + Dev->Snm.MaxPacketSize);

  //
  // Limit the number of pending RX packets if the queue is big. The division
  // by two is due to the above "two descriptors per packet" trait.
  //
  RxAlwaysPending = (UINT16) MIN (Dev->RxRing.QueueSize / 2, VNET_MAX_PENDING);

  Dev->RxBuf = AllocatePool (RxAlwaysPending * RxBufSize);
  if (Dev->RxBuf == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  //
  // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device
  //
  MemoryFence ();
  Dev->RxLastUsed = *Dev->RxRing.Used.Idx;
  ASSERT (Dev->RxLastUsed == 0);

  //
  // virtio-0.9.5, 2.4.2 Receiving Used Buffers From the Device:
  // the host should not send interrupts, we'll poll in VirtioNetReceive()
  // and VirtioNetIsPacketAvailable().
  //
  *Dev->RxRing.Avail.Flags = (UINT16) VRING_AVAIL_F_NO_INTERRUPT;

  //
  // now set up a separate, two-part descriptor chain for each RX packet, and
  // link each chain into (from) the available ring as well
  //
  DescIdx = 0;
  RxPtr = Dev->RxBuf;
  for (PktIdx = 0; PktIdx < RxAlwaysPending; ++PktIdx) {
    //
    // virtio-0.9.5, 2.4.1.2 Updating the Available Ring
    // invisible to the host until we update the Index Field
    //
    Dev->RxRing.Avail.Ring[PktIdx] = DescIdx;

    //
    // virtio-0.9.5, 2.4.1.1 Placing Buffers into the Descriptor Table
    //
    Dev->RxRing.Desc[DescIdx].Addr  = (UINTN) RxPtr;
    Dev->RxRing.Desc[DescIdx].Len   = sizeof (VIRTIO_NET_REQ);
    Dev->RxRing.Desc[DescIdx].Flags = VRING_DESC_F_WRITE | VRING_DESC_F_NEXT;
    Dev->RxRing.Desc[DescIdx].Next  = (UINT16) (DescIdx + 1);
    RxPtr += Dev->RxRing.Desc[DescIdx++].Len;

    Dev->RxRing.Desc[DescIdx].Addr  = (UINTN) RxPtr;
    Dev->RxRing.Desc[DescIdx].Len   = (UINT32) (RxBufSize -
                                                sizeof (VIRTIO_NET_REQ));
    Dev->RxRing.Desc[DescIdx].Flags = VRING_DESC_F_WRITE;
    RxPtr += Dev->RxRing.Desc[DescIdx++].Len;
  }

  //
  // virtio-0.9.5, 2.4.1.3 Updating the Index Field
  //
  MemoryFence ();
  *Dev->RxRing.Avail.Idx = RxAlwaysPending;

  //
  // At this point reception may already be running. In order to make it sure,
  // kick the hypervisor. If we fail to kick it, we must first abort reception
  // before tearing down anything, because reception may have been already
  // running even without the kick.
  //
  // virtio-0.9.5, 2.4.1.4 Notifying the Device
  //
  MemoryFence ();
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrQueueNotify, VIRTIO_NET_Q_RX);

  if (EFI_ERROR (Status)) {
    VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, 0);
    FreePool (Dev->RxBuf);
  }

  return Status;
}


/**
  Resets a network adapter and allocates the transmit and receive buffers
  required by the network interface; optionally, also requests allocation  of
  additional transmit and receive buffers.

  @param  This              The protocol instance pointer.
  @param  ExtraRxBufferSize The size, in bytes, of the extra receive buffer
                            space that the driver should allocate for the
                            network interface. Some network interfaces will not
                            be able to use the extra buffer, and the caller
                            will not know if it is actually being used.
  @param  ExtraTxBufferSize The size, in bytes, of the extra transmit buffer
                            space that the driver should allocate for the
                            network interface. Some network interfaces will not
                            be able to use the extra buffer, and the caller
                            will not know if it is actually being used.

  @retval EFI_SUCCESS           The network interface was initialized.
  @retval EFI_NOT_STARTED       The network interface has not been started.
  @retval EFI_OUT_OF_RESOURCES  There was not enough memory for the transmit
                                and receive buffers.
  @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
VirtioNetInitialize (
  IN EFI_SIMPLE_NETWORK_PROTOCOL *This,
  IN UINTN                       ExtraRxBufferSize  OPTIONAL,
  IN UINTN                       ExtraTxBufferSize  OPTIONAL
  )
{
  VNET_DEV   *Dev;
  EFI_TPL    OldTpl;
  EFI_STATUS Status;
  UINT8      NextDevStat;
  UINT32     Features;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  if (ExtraRxBufferSize > 0 || ExtraTxBufferSize > 0) {
    return EFI_UNSUPPORTED;
  }

  Dev = VIRTIO_NET_FROM_SNP (This);
  OldTpl = gBS->RaiseTPL (TPL_CALLBACK);
  if (Dev->Snm.State != EfiSimpleNetworkStarted) {
    Status = EFI_NOT_STARTED;
    goto InitFailed;
  }

  //
  // In the EfiSimpleNetworkStarted state the virtio-net device has status
  // value 0 (= reset) -- see the state diagram, the full call chain to
  // the end of VirtioNetGetFeatures() (considering we're here now),
  // the DeviceFailed label below, and VirtioNetShutdown().
  //
  // Accordingly, the below is a subsequence of the steps found in the
  // virtio-0.9.5 spec, 2.2.1 Device Initialization Sequence.
  //
  NextDevStat = VSTAT_ACK;    // step 2 -- acknowledge device presence
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);
  if (EFI_ERROR (Status)) {
    goto InitFailed;
  }

  NextDevStat |= VSTAT_DRIVER; // step 3 -- we know how to drive it
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);
  if (EFI_ERROR (Status)) {
    goto DeviceFailed;
  }

  //
  // step 4a -- retrieve features. Note that we're past validating required
  // features in VirtioNetGetFeatures().
  //
  Status = VIRTIO_CFG_READ (Dev, Generic.VhdrDeviceFeatureBits, &Features);
  if (EFI_ERROR (Status)) {
    goto DeviceFailed;
  }
  ASSERT (Features & VIRTIO_NET_F_MAC);
  ASSERT (Dev->Snm.MediaPresentSupported ==
    !!(Features & VIRTIO_NET_F_STATUS));

  //
  // step 4b, 4c -- allocate and report virtqueues
  //
  Status = VirtioNetInitRing (Dev, VIRTIO_NET_Q_RX, &Dev->RxRing);
  if (EFI_ERROR (Status)) {
    goto DeviceFailed;
  }

  Status = VirtioNetInitRing (Dev, VIRTIO_NET_Q_TX, &Dev->TxRing);
  if (EFI_ERROR (Status)) {
    goto ReleaseRxRing;
  }

  //
  // step 5 -- keep only the features we want
  //
  Features &= VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS;
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrGuestFeatureBits, Features);
  if (EFI_ERROR (Status)) {
    goto ReleaseTxRing;
  }

  //
  // step 6 -- virtio-net initialization complete
  //
  NextDevStat |= VSTAT_DRIVER_OK;
  Status = VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, NextDevStat);
  if (EFI_ERROR (Status)) {
    goto ReleaseTxRing;
  }

  Status = VirtioNetInitTx (Dev);
  if (EFI_ERROR (Status)) {
    goto AbortDevice;
  }

  //
  // start receiving
  //
  Status = VirtioNetInitRx (Dev);
  if (EFI_ERROR (Status)) {
    goto ReleaseTxAux;
  }

  Dev->Snm.State = EfiSimpleNetworkInitialized;
  gBS->RestoreTPL (OldTpl);
  return EFI_SUCCESS;

ReleaseTxAux:
  VirtioNetShutdownTx (Dev);

AbortDevice:
  VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, 0);

ReleaseTxRing:
  VirtioRingUninit (&Dev->TxRing);

ReleaseRxRing:
  VirtioRingUninit (&Dev->RxRing);

DeviceFailed:
  //
  // restore device status invariant for the EfiSimpleNetworkStarted state
  //
  VIRTIO_CFG_WRITE (Dev, Generic.VhdrDeviceStatus, 0);

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