ArmPkg/Include/Library/ArmMtlLib.h

/** @file

  Copyright (c) 2017-2018, Arm Limited. All rights reserved.

  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.

  System Control and Management Interface V1.0
    http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/
    DEN0056A_System_Control_and_Management_Interface.pdf
**/

#ifndef ARM_MTL_LIB_H_
#define ARM_MTL_LIB_H_

#include <Uefi/UefiBaseType.h>

// Ideally we don't need packed struct. However we can't rely on compilers.
#pragma pack(1)

typedef struct {
  UINT32 Reserved1;
  UINT32 ChannelStatus;
  UINT64 Reserved2;
  UINT32 Flags;
  UINT32 Length;
  UINT32 MessageHeader;

  // NOTE: Since EDK2 does not allow flexible array member [] we declare
  // here array of 1 element length. However below is used as a variable
  // length array.
  UINT32 Payload[1];    // size less object gives offset to payload.
} MTL_MAILBOX;

#pragma pack()

// Channel Type, Low-priority, and High-priority
typedef enum {
  MTL_CHANNEL_TYPE_LOW = 0,
  MTL_CHANNEL_TYPE_HIGH = 1
} MTL_CHANNEL_TYPE;

typedef struct {
  UINT64 PhysicalAddress;
  UINT32 ModifyMask;
  UINT32 PreserveMask;
} MTL_DOORBELL;

typedef struct {
  MTL_CHANNEL_TYPE ChannelType;
  MTL_MAILBOX      * CONST MailBox;
  MTL_DOORBELL     DoorBell;
} MTL_CHANNEL;

/** Wait until channel is free.

  @param[in] Channel                Pointer to a channel.
  @param[in] TimeOutInMicroSeconds  Time out in micro seconds.

  @retval EFI_SUCCESS               Channel is free.
  @retval EFI_TIMEOUT               Time out error.
**/
EFI_STATUS
MtlWaitUntilChannelFree (
  IN MTL_CHANNEL  *Channel,
  IN UINTN        TimeOutInMicroSeconds
  );

/** Return the address of the message payload.

  @param[in] Channel   Pointer to a channel.

  @retval UINT32*      Pointer to the payload.
**/
UINT32*
MtlGetChannelPayload (
  IN MTL_CHANNEL  *Channel
  );

/** Return pointer to a channel for the requested channel type.

  @param[in] ChannelType        ChannelType, Low or High priority channel.
                                MTL_CHANNEL_TYPE_LOW or
                                MTL_CHANNEL_TYPE_HIGH

  @param[out] Channel           Holds pointer to the channel.

  @retval EFI_SUCCESS           Pointer to channel is returned.
  @retval EFI_UNSUPPORTED       Requested channel type not supported.
**/
EFI_STATUS
MtlGetChannel (
  IN  MTL_CHANNEL_TYPE  ChannelType,
  OUT MTL_CHANNEL       **Channel
  );

/** Mark the channel busy and ring the doorbell.

  @param[in] Channel               Pointer to a channel.
  @param[in] MessageHeader         Message header.

  @param[out] PayloadLength        Message length.

  @retval EFI_SUCCESS              Message sent successfully.
  @retval EFI_DEVICE_ERROR         Channel is busy.
**/
EFI_STATUS
MtlSendMessage (
  IN  MTL_CHANNEL  *Channel,
  IN  UINT32       MessageHeader,
  OUT UINT32       PayloadLength
  );

/** Wait for a response on a channel.

  If channel is free after sending message, it implies SCP responded
  with a response on the channel.

  @param[in] Channel               Pointer to a channel.

  @retval EFI_SUCCESS              Message received successfully.
  @retval EFI_TIMEOUT              Time out error.
**/
EFI_STATUS
MtlReceiveMessage (
  IN  MTL_CHANNEL  *Channel,
  OUT UINT32       *MessageHeader,
  OUT UINT32       *PayloadLength
  );

#endif  /* ARM_MTL_LIB_H_ */