audk/MdeModulePkg/Bus/Ata/AtaBusDxe/AtaPassThruExecute.c

/** @file
  This file implements ATA pass through transaction for ATA bus driver.

  This file implements the low level execution of ATA pass through transaction.
  It transforms the high level identity, read/write, reset command to ATA pass
  through command and protocol. 
    
  Copyright (c) 2009 - 2011, 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 "AtaBus.h"

//
// Look up table (UdmaValid, IsWrite) for EFI_ATA_PASS_THRU_CMD_PROTOCOL
//
EFI_ATA_PASS_THRU_CMD_PROTOCOL mAtaPassThruCmdProtocols[][2] = {
  {
    EFI_ATA_PASS_THRU_PROTOCOL_PIO_DATA_IN,
    EFI_ATA_PASS_THRU_PROTOCOL_PIO_DATA_OUT
  },
  {
    EFI_ATA_PASS_THRU_PROTOCOL_UDMA_DATA_IN,
    EFI_ATA_PASS_THRU_PROTOCOL_UDMA_DATA_OUT,
  }
};

//
// Look up table (UdmaValid, Lba48Bit, IsIsWrite) for ATA_CMD
//
UINT8 mAtaCommands[][2][2] = {
  {
    {
      ATA_CMD_READ_SECTORS,            // 28-bit LBA; PIO read
      ATA_CMD_WRITE_SECTORS            // 28-bit LBA; PIO write
    },
    {
      ATA_CMD_READ_SECTORS_EXT,        // 48-bit LBA; PIO read
      ATA_CMD_WRITE_SECTORS_EXT        // 48-bit LBA; PIO write
    }
  },
  {
    {
      ATA_CMD_READ_DMA,                // 28-bit LBA; DMA read
      ATA_CMD_WRITE_DMA                // 28-bit LBA; DMA write
    },
    {
      ATA_CMD_READ_DMA_EXT,            // 48-bit LBA; DMA read
      ATA_CMD_WRITE_DMA_EXT            // 48-bit LBA; DMA write
    }
  }
};

//
// Look up table (Lba48Bit) for maximum transfer block number
//
UINTN mMaxTransferBlockNumber[] = {
  MAX_28BIT_TRANSFER_BLOCK_NUM,
  MAX_48BIT_TRANSFER_BLOCK_NUM
};


/**
  Wrapper for EFI_ATA_PASS_THRU_PROTOCOL.PassThru().

  This function wraps the PassThru() invocation for ATA pass through function
  for an ATA device. It assembles the ATA pass through command packet for ATA
  transaction.

  @param[in, out]  AtaDevice   The ATA child device involved for the operation.
  @param[in, out]  TaskPacket  Pointer to a Pass Thru Command Packet. Optional, 
                               if it is NULL, blocking mode, and use the packet
                               in AtaDevice. If it is not NULL, non blocking mode,
                               and pass down this Packet.
  @param[in]       Event       If Event is NULL, then blocking I/O is performed.
                               If Event is not NULL and non-blocking I/O is
                               supported,then non-blocking I/O is performed,
                               and Event will be signaled when the write
                               request is completed.

  @return The return status from EFI_ATA_PASS_THRU_PROTOCOL.PassThru().

**/
EFI_STATUS
AtaDevicePassThru (
  IN OUT ATA_DEVICE                       *AtaDevice,
  IN OUT EFI_ATA_PASS_THRU_COMMAND_PACKET *TaskPacket, OPTIONAL
  IN OUT EFI_EVENT                        Event OPTIONAL
  )
{
  EFI_STATUS                              Status;
  EFI_ATA_PASS_THRU_PROTOCOL              *AtaPassThru;
  EFI_ATA_PASS_THRU_COMMAND_PACKET        *Packet;

  //
  // Assemble packet. If it is non blocking mode, the Ata driver should keep each 
  // subtask and clean them when the event is signaled.
  //
  if (TaskPacket != NULL) {
    Packet = TaskPacket;
    Packet->Asb = AllocateAlignedBuffer (AtaDevice, sizeof (*AtaDevice->Asb));
    CopyMem (Packet->Asb, AtaDevice->Asb, sizeof (*AtaDevice->Asb));
    Packet->Acb = AllocateCopyPool(sizeof (EFI_ATA_COMMAND_BLOCK), &AtaDevice->Acb);
  } else {
    Packet = &AtaDevice->Packet;
    Packet->Asb = AtaDevice->Asb;
    Packet->Acb = &AtaDevice->Acb;
  }

  AtaPassThru = AtaDevice->AtaBusDriverData->AtaPassThru;

  Status = AtaPassThru->PassThru (
                          AtaPassThru,
                          AtaDevice->Port,
                          AtaDevice->PortMultiplierPort,
                          Packet,
                          Event
                          );
  //
  // Ensure ATA pass through caller and callee have the same
  // interpretation of ATA pass through protocol. 
  //
  ASSERT (Status != EFI_INVALID_PARAMETER);
  ASSERT (Status != EFI_BAD_BUFFER_SIZE);

  return Status;
}


/**
  Wrapper for EFI_ATA_PASS_THRU_PROTOCOL.ResetDevice().

  This function wraps the ResetDevice() invocation for ATA pass through function
  for an ATA device. 

  @param  AtaDevice         The ATA child device involved for the operation.

  @return The return status from EFI_ATA_PASS_THRU_PROTOCOL.PassThru().

**/
EFI_STATUS
ResetAtaDevice (
  IN ATA_DEVICE                           *AtaDevice
  )
{
  EFI_ATA_PASS_THRU_PROTOCOL              *AtaPassThru;
  
  AtaPassThru = AtaDevice->AtaBusDriverData->AtaPassThru;
  
  return AtaPassThru->ResetDevice (
                        AtaPassThru,
                        AtaDevice->Port,
                        AtaDevice->PortMultiplierPort
                        );
}


/**
  Prints ATA model name to ATA device structure.

  This function converts ATA device model name from ATA identify data 
  to a string in ATA device structure. It needs to change the character
  order in the original model name string.

  @param  AtaDevice         The ATA child device involved for the operation.

**/
VOID
PrintAtaModelName (
  IN OUT ATA_DEVICE  *AtaDevice
  )
{
  UINTN   Index;
  CHAR8   *Source;
  CHAR16  *Destination;

  Source = AtaDevice->IdentifyData->ModelName;
  Destination = AtaDevice->ModelName;

  //
  // Swap the byte order in the original module name.
  //
  for (Index = 0; Index < MAX_MODEL_NAME_LEN; Index += 2) {
    Destination[Index]      = Source[Index + 1];
    Destination[Index + 1]  = Source[Index];
  }
  AtaDevice->ModelName[MAX_MODEL_NAME_LEN] = L'\0';
}


/**
  Gets ATA device Capacity according to ATA 6.

  This function returns the capacity of the ATA device if it follows
  ATA 6 to support 48 bit addressing.

  @param  AtaDevice         The ATA child device involved for the operation.

  @return The capacity of the ATA device or 0 if the device does not support
          48-bit addressing defined in ATA 6.

**/
EFI_LBA
GetAtapi6Capacity (
  IN ATA_DEVICE                 *AtaDevice
  )
{
  EFI_LBA                       Capacity;
  EFI_LBA                       TmpLba;
  UINTN                         Index;
  ATA_IDENTIFY_DATA             *IdentifyData;

  IdentifyData = AtaDevice->IdentifyData;
  if ((IdentifyData->command_set_supported_83 & BIT10) == 0) {
    //
    // The device doesn't support 48 bit addressing
    //
    return 0;
  }

  //
  // 48 bit address feature set is supported, get maximum capacity
  //
  Capacity = 0;
  for (Index = 0; Index < 4; Index++) {
    //
    // Lower byte goes first: word[100] is the lowest word, word[103] is highest
    //
    TmpLba = IdentifyData->maximum_lba_for_48bit_addressing[Index];
    Capacity |= LShiftU64 (TmpLba, 16 * Index);
  }

  return Capacity;
}


/**
  Identifies ATA device via the Identify data.

  This function identifies the ATA device and initializes the Media information in 
  Block IO protocol interface.

  @param  AtaDevice         The ATA child device involved for the operation.

  @retval EFI_UNSUPPORTED   The device is not a valid ATA device (hard disk).
  @retval EFI_SUCCESS       The device is successfully identified and Media information
                            is correctly initialized.

**/
EFI_STATUS
IdentifyAtaDevice (
  IN OUT ATA_DEVICE                 *AtaDevice
  )
{
  ATA_IDENTIFY_DATA                 *IdentifyData;
  EFI_BLOCK_IO_MEDIA                *BlockMedia;
  EFI_LBA                           Capacity;
  UINT16                            PhyLogicSectorSupport;
  UINT16                            UdmaMode;

  IdentifyData = AtaDevice->IdentifyData;

  if ((IdentifyData->config & BIT15) != 0) {
    //
    // This is not an hard disk
    //
    return EFI_UNSUPPORTED;
  }

  DEBUG ((EFI_D_INFO, "AtaBus - Identify Device (%x %x)\n", (UINTN)AtaDevice->Port, (UINTN)AtaDevice->PortMultiplierPort));

  //
  // Check whether the WORD 88 (supported UltraDMA by drive) is valid
  //
  if ((IdentifyData->field_validity & BIT2) != 0) {
    UdmaMode = IdentifyData->ultra_dma_mode;
    if ((UdmaMode & (BIT0 | BIT1 | BIT2 | BIT3 | BIT4 | BIT5 | BIT6)) != 0) {
      //
      // If BIT0~BIT6 is selected, then UDMA is supported
      //
      AtaDevice->UdmaValid = TRUE;
    }
  }

  Capacity = GetAtapi6Capacity (AtaDevice);
  if (Capacity > MAX_28BIT_ADDRESSING_CAPACITY) {
    //
    // Capacity exceeds 120GB. 48-bit addressing is really needed
    //
    AtaDevice->Lba48Bit = TRUE;
  } else {
    //
    // This is a hard disk <= 120GB capacity, treat it as normal hard disk
    //
    Capacity = ((UINT32)IdentifyData->user_addressable_sectors_hi << 16) | IdentifyData->user_addressable_sectors_lo;
    AtaDevice->Lba48Bit = FALSE;
  }

  //
  // Block Media Information:
  //
  BlockMedia = &AtaDevice->BlockMedia;
  BlockMedia->LastBlock = Capacity - 1;
  BlockMedia->IoAlign = AtaDevice->AtaBusDriverData->AtaPassThru->Mode->IoAlign;
  //
  // Check whether Long Physical Sector Feature is supported
  //
  PhyLogicSectorSupport = IdentifyData->phy_logic_sector_support;
  if ((PhyLogicSectorSupport & (BIT14 | BIT15)) == BIT14) {
    //
    // Check whether one physical block contains multiple physical blocks
    //
    if ((PhyLogicSectorSupport & BIT13) != 0) {
      BlockMedia->LogicalBlocksPerPhysicalBlock = (UINT32) (1 << (PhyLogicSectorSupport & 0x000f));
      //
      // Check lowest alignment of logical blocks within physical block
      //
      if ((IdentifyData->alignment_logic_in_phy_blocks & (BIT14 | BIT15)) == BIT14) {
        BlockMedia->LowestAlignedLba = (EFI_LBA) ((BlockMedia->LogicalBlocksPerPhysicalBlock - ((UINT32)IdentifyData->alignment_logic_in_phy_blocks & 0x3fff)) %
          BlockMedia->LogicalBlocksPerPhysicalBlock);
      }
    }
    //
    // Check logical block size
    //
    if ((PhyLogicSectorSupport & BIT12) != 0) {
      BlockMedia->BlockSize = (UINT32) (((IdentifyData->logic_sector_size_hi << 16) | IdentifyData->logic_sector_size_lo) * sizeof (UINT16));
    }
    AtaDevice->BlockIo.Revision = EFI_BLOCK_IO_PROTOCOL_REVISION2;
  }
  //
  // Get ATA model name from identify data structure. 
  //
  PrintAtaModelName (AtaDevice);

  return EFI_SUCCESS;
}


/**
  Discovers whether it is a valid ATA device.

  This function issues ATA_CMD_IDENTIFY_DRIVE command to the ATA device to identify it.
  If the command is executed successfully, it then identifies it and initializes
  the Media information in Block IO protocol interface.

  @param  AtaDevice         The ATA child device involved for the operation.

  @retval EFI_SUCCESS       The device is successfully identified and Media information
                            is correctly initialized.
  @return others            Some error occurs when discovering the ATA device. 

**/
EFI_STATUS
DiscoverAtaDevice (
  IN OUT ATA_DEVICE                 *AtaDevice
  )
{
  EFI_STATUS                        Status;
  EFI_ATA_COMMAND_BLOCK             *Acb;
  EFI_ATA_PASS_THRU_COMMAND_PACKET  *Packet;
  UINTN                             Retry;

  //
  // Prepare for ATA command block.
  //
  Acb = ZeroMem (&AtaDevice->Acb, sizeof (*Acb));
  Acb->AtaCommand = ATA_CMD_IDENTIFY_DRIVE;
  Acb->AtaDeviceHead = (UINT8) (BIT7 | BIT6 | BIT5 | (AtaDevice->PortMultiplierPort << 4));

  //
  // Prepare for ATA pass through packet.
  //
  Packet = ZeroMem (&AtaDevice->Packet, sizeof (*Packet));
  Packet->InDataBuffer = AtaDevice->IdentifyData;
  Packet->InTransferLength = sizeof (*AtaDevice->IdentifyData);
  Packet->Protocol = EFI_ATA_PASS_THRU_PROTOCOL_PIO_DATA_IN;
  Packet->Length   = EFI_ATA_PASS_THRU_LENGTH_BYTES | EFI_ATA_PASS_THRU_LENGTH_SECTOR_COUNT;
  Packet->Timeout  = ATA_TIMEOUT;

  Retry = MAX_RETRY_TIMES;
  do {
    Status = AtaDevicePassThru (AtaDevice, NULL, NULL);
    if (!EFI_ERROR (Status)) {
      //
      // The command is issued successfully
      //
      Status = IdentifyAtaDevice (AtaDevice);
      if (!EFI_ERROR (Status)) {
        return Status;
      }
    }
  } while (Retry-- > 0);

  return Status;
}

/**
  Transfer data from ATA device.

  This function performs one ATA pass through transaction to transfer data from/to
  ATA device. It chooses the appropriate ATA command and protocol to invoke PassThru
  interface of ATA pass through.

  @param[in, out]  AtaDevice       The ATA child device involved for the operation.
  @param[in, out]  TaskPacket      Pointer to a Pass Thru Command Packet. Optional, 
                                   if it is NULL, blocking mode, and use the packet
                                   in AtaDevice. If it is not NULL, non blocking mode,
                                   and pass down this Packet.
  @param[in, out]  Buffer          The pointer to the current transaction buffer.
  @param[in]       StartLba        The starting logical block address to be accessed.
  @param[in]       TransferLength  The block number or sector count of the transfer.
  @param[in]       IsWrite         Indicates whether it is a write operation.
  @param[in]       Event           If Event is NULL, then blocking I/O is performed.
                                   If Event is not NULL and non-blocking I/O is
                                   supported,then non-blocking I/O is performed,
                                   and Event will be signaled when the write
                                   request is completed.

  @retval EFI_SUCCESS       The data transfer is complete successfully.
  @return others            Some error occurs when transferring data. 

**/
EFI_STATUS
TransferAtaDevice (
  IN OUT ATA_DEVICE                       *AtaDevice,
  IN OUT EFI_ATA_PASS_THRU_COMMAND_PACKET *TaskPacket, OPTIONAL
  IN OUT VOID                             *Buffer,
  IN EFI_LBA                              StartLba,
  IN UINT32                               TransferLength,
  IN BOOLEAN                              IsWrite, 
  IN EFI_EVENT                            Event OPTIONAL
  )
{
  EFI_ATA_COMMAND_BLOCK             *Acb;
  EFI_ATA_PASS_THRU_COMMAND_PACKET  *Packet;

  //
  // Ensure AtaDevice->UdmaValid, AtaDevice->Lba48Bit and IsWrite are valid boolean values 
  //
  ASSERT ((UINTN) AtaDevice->UdmaValid < 2);
  ASSERT ((UINTN) AtaDevice->Lba48Bit < 2);
  ASSERT ((UINTN) IsWrite < 2);
  //
  // Prepare for ATA command block.
  //
  Acb = ZeroMem (&AtaDevice->Acb, sizeof (*Acb));
  Acb->AtaCommand = mAtaCommands[AtaDevice->UdmaValid][AtaDevice->Lba48Bit][IsWrite];
  Acb->AtaSectorNumber = (UINT8) StartLba;
  Acb->AtaCylinderLow = (UINT8) RShiftU64 (StartLba, 8);
  Acb->AtaCylinderHigh = (UINT8) RShiftU64 (StartLba, 16);
  Acb->AtaDeviceHead = (UINT8) (BIT7 | BIT6 | BIT5 | (AtaDevice->PortMultiplierPort << 4));
  Acb->AtaSectorCount = (UINT8) TransferLength;
  if (AtaDevice->Lba48Bit) {
    Acb->AtaSectorNumberExp = (UINT8) RShiftU64 (StartLba, 24);
    Acb->AtaCylinderLowExp = (UINT8) RShiftU64 (StartLba, 32);
    Acb->AtaCylinderHighExp = (UINT8) RShiftU64 (StartLba, 40);
    Acb->AtaSectorCountExp = (UINT8) (TransferLength >> 8);
  } else {
    Acb->AtaDeviceHead = (UINT8) (Acb->AtaDeviceHead | RShiftU64 (StartLba, 24));
  }

  //
  // Prepare for ATA pass through packet.
  //
  if (TaskPacket != NULL) {
    Packet = ZeroMem (TaskPacket, sizeof (*Packet));
  } else {
    Packet = ZeroMem (&AtaDevice->Packet, sizeof (*Packet));
  }

  if (IsWrite) {
    Packet->OutDataBuffer = Buffer;
    Packet->OutTransferLength = TransferLength;
  } else {
    Packet->InDataBuffer = Buffer;
    Packet->InTransferLength = TransferLength;
  }

  Packet->Protocol = mAtaPassThruCmdProtocols[AtaDevice->UdmaValid][IsWrite];
  Packet->Length = EFI_ATA_PASS_THRU_LENGTH_SECTOR_COUNT;
  Packet->Timeout  = ATA_TIMEOUT;

  return AtaDevicePassThru (AtaDevice, TaskPacket, Event);
}

/**
  Free SubTask. 

  @param[in, out]  Task      Pointer to task to be freed.

**/
VOID
EFIAPI 
FreeAtaSubTask (
  IN ATA_BUS_ASYN_TASK  *Task
  )
{
  if (Task->Packet.Asb != NULL) {
    FreeAlignedBuffer (Task->Packet.Asb, sizeof (Task->Packet.Asb));
  }
  if (Task->Packet.Acb != NULL) {
    FreePool (Task->Packet.Acb);
  }

  FreePool (Task);
}

/**
  Call back funtion when the event is signaled.

  @param[in]  Event     The Event this notify function registered to.
  @param[in]  Context   Pointer to the context data registerd to the
                        Event.

**/
VOID
EFIAPI 
AtaNonBlockingCallBack (
  IN EFI_EVENT                Event,
  IN VOID                     *Context
  )
{
  ATA_BUS_ASYN_TASK *Task;

  Task = (ATA_BUS_ASYN_TASK *) Context;
  gBS->CloseEvent (Event);

  //
  // Check the command status.
  // If there is error during the sub task source allocation, the error status
  // should be returned to the caller directly, so here the Task->Token may already
  // be deleted by the caller and no need to update the status.
  //
  if ((!(*Task->IsError)) && (Task->Packet.Asb->AtaStatus & 0x01) == 0x01) {
    Task->Token->TransactionStatus = EFI_DEVICE_ERROR;
  }
  DEBUG ((
    DEBUG_INFO, 
    "NON-BLOCKING EVENT FINISHED!- STATUS = %r\n", 
    Task->Token->TransactionStatus
    ));

  //
  // Reduce the SubEventCount, till it comes to zero.
  //
  (*Task->UnsignalledEventCount) --;
  DEBUG ((DEBUG_INFO, "UnsignalledEventCount = %x\n", *Task->UnsignalledEventCount));

  //
  // Remove the SubTask from the Task list.
  //
  RemoveEntryList (&Task->TaskEntry);
  if ((*Task->UnsignalledEventCount) == 0) {
    //
    // All Sub tasks are done, then signal the upper layyer event.
    // Except there is error during the sub task source allocation.
    //
    if (!(*Task->IsError)) {
      gBS->SignalEvent (Task->Token->Event);
      DEBUG ((DEBUG_INFO, "Signal Up Level Event UnsignalledEventCount = %x!\n", *Task->UnsignalledEventCount));
    }
    
    FreePool (Task->UnsignalledEventCount);
    FreePool (Task->IsError);
  }

  DEBUG ((
    DEBUG_INFO, 
    "PACKET INFO: Write=%s, Lenght=%x, LowCylinder=%x, HighCylinder=%x,SectionNumber=%x",
    Task->Packet.OutDataBuffer != NULL ? L"YES" : L"NO",
    Task->Packet.OutDataBuffer != NULL ? Task->Packet.OutTransferLength : Task->Packet.InTransferLength,
    Task->Packet.Acb->AtaCylinderLow,
    Task->Packet.Acb->AtaCylinderHigh,
    Task->Packet.Acb->AtaSectorCount
    ));

  //
  // Free the buffer of SubTask.
  //
  FreeAtaSubTask (Task);
}

/**
  Read or write a number of blocks from ATA device.

  This function performs ATA pass through transactions to read/write data from/to
  ATA device. It may separate the read/write request into several ATA pass through
  transactions.

  @param[in, out]  AtaDevice       The ATA child device involved for the operation.
  @param[in, out]  Buffer          The pointer to the current transaction buffer.
  @param[in]       StartLba        The starting logical block address to be accessed.
  @param[in]       NumberOfBlocks  The block number or sector count of the transfer.
  @param[in]       IsWrite         Indicates whether it is a write operation.
  @param[in, out]  Token           A pointer to the token associated with the transaction.

  @retval EFI_SUCCESS       The data transfer is complete successfully.
  @return others            Some error occurs when transferring data. 

**/
EFI_STATUS 
AccessAtaDevice(
  IN OUT ATA_DEVICE                 *AtaDevice,
  IN OUT UINT8                      *Buffer,
  IN EFI_LBA                        StartLba,
  IN UINTN                          NumberOfBlocks,
  IN BOOLEAN                        IsWrite,
  IN OUT EFI_BLOCK_IO2_TOKEN        *Token
  )
{
  EFI_STATUS                        Status;
  UINTN                             MaxTransferBlockNumber;
  UINTN                             TransferBlockNumber;
  UINTN                             BlockSize;
  UINTN                             *EventCount;
  UINTN                             TempCount;
  ATA_BUS_ASYN_TASK                 *Task;
  EFI_EVENT                         SubEvent;
  UINTN                             Index;
  BOOLEAN                           *IsError;
  EFI_TPL                           OldTpl;

  SubEvent  = NULL;
  TempCount = 0;
  Status    = EFI_SUCCESS;

  EventCount = AllocateZeroPool (sizeof (UINTN));
  if (EventCount == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }
  
  IsError = AllocateZeroPool (sizeof (BOOLEAN));
  if (IsError == NULL) {
    goto EXIT;
  }
  *IsError = FALSE;

  //
  // Initial the return status for Non Blocking.
  //
  if (Token != NULL && Token->Event != NULL) {
    Token->TransactionStatus = EFI_SUCCESS;
  }
  //
  // Ensure AtaDevice->Lba48Bit is a valid boolean value 
  //
  ASSERT ((UINTN) AtaDevice->Lba48Bit < 2);
  MaxTransferBlockNumber = mMaxTransferBlockNumber[AtaDevice->Lba48Bit];
  BlockSize              = AtaDevice->BlockMedia.BlockSize;

  TempCount     = (NumberOfBlocks + MaxTransferBlockNumber - 1) / MaxTransferBlockNumber;
  *EventCount   = TempCount;
  Index         = 0;

  do {
    if (NumberOfBlocks > MaxTransferBlockNumber) {
      TransferBlockNumber = MaxTransferBlockNumber;
      NumberOfBlocks     -= MaxTransferBlockNumber;
    } else  {
      TransferBlockNumber = NumberOfBlocks;
      NumberOfBlocks  = 0;
    }

    //
    // Create sub event for the sub Ata task. Non-Blocking Mode.
    //
    if (Token != NULL && Token->Event != NULL) {
      OldTpl = gBS->RaiseTPL (TPL_NOTIFY);
      Task   = AllocateZeroPool (sizeof (ATA_BUS_ASYN_TASK));
      if (Task == NULL) {
        //
        // If resource allocation fail, reduce the total sub event counts.
        //
        *EventCount              = (*EventCount) - (TempCount - Index);
        *IsError                 = TRUE;
        Token->TransactionStatus = EFI_OUT_OF_RESOURCES;
        Status                   = EFI_OUT_OF_RESOURCES;

        gBS->RestoreTPL (OldTpl);
        goto EXIT;
      }

      Task->UnsignalledEventCount = EventCount;
      Task->Token                 = Token;
      Task->IsError               = IsError;

      InsertTailList (&AtaDevice->AtaTaskList, &Task->TaskEntry);

      Status = gBS->CreateEvent (
                      EVT_NOTIFY_SIGNAL,
                      TPL_NOTIFY,
                      AtaNonBlockingCallBack,
                      Task,
                      &SubEvent
                      );
      //
      // If resource allocation fail, the un-signalled event count should equal to
      // the original one minus the unassigned subtasks number.
      //
      if (EFI_ERROR (Status)) {
        *EventCount = (*EventCount) - (TempCount - Index);
        *IsError    = TRUE;
        gBS->RestoreTPL (OldTpl);
        goto EXIT;
      }
      Index++;
      gBS->RestoreTPL (OldTpl); 

      DEBUG ((EFI_D_INFO, "NON-BLOCKING SET EVENT START: WRITE = %d\n", IsWrite));
      Status = TransferAtaDevice (AtaDevice, &Task->Packet, Buffer, StartLba, (UINT32) TransferBlockNumber, IsWrite, SubEvent);
      DEBUG ((
        EFI_D_INFO,
        "NON-BLOCKING SET EVENT END:StartLba=%x, TransferBlockNumbers=%x, Status=%r\n",
        StartLba,
        TransferBlockNumber,
        Status
        ));
    }else {
      //
      // Blocking Mode.
      //
      DEBUG ((EFI_D_INFO, "BLOCKING BLOCK I/O START: WRITE = %d\n", IsWrite));
      Status = TransferAtaDevice (AtaDevice, NULL, Buffer, StartLba, (UINT32) TransferBlockNumber, IsWrite, NULL);
      DEBUG ((
        EFI_D_INFO,
        "BLOCKING BLOCK I/O FINISHE - StartLba = %x; TransferBlockNumbers = %x, status = %r\n", 
        StartLba,
        TransferBlockNumber,
        Status
        ));
    }

    if (EFI_ERROR (Status)) {
      goto EXIT;
    }

    StartLba += TransferBlockNumber;
    Buffer   += TransferBlockNumber * BlockSize;
  } while (NumberOfBlocks > 0);

EXIT:

  if (*EventCount == 0) {
    FreePool (EventCount);
    FreePool (IsError);
  }

  return Status;
}