/** @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
**/

#include <Uefi/UefiBaseType.h>
#include <Uefi/UefiSpec.h>
#include <Library/ArmLib.h>
#include <Library/ArmMtlLib.h>
#include <Library/DebugLib.h>
#include <Library/IoLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/PcdLib.h>
#include <Library/UefiBootServicesTableLib.h>

#include "ArmJunoMtlPrivateLib.h"

// Each channel has a shared mailbox and a doorbell register.
STATIC CONST MTL_CHANNEL Channels[NUM_CHANNELS] = {
    // Low priority channel.
    {
      MTL_CHANNEL_TYPE_LOW,
      (MTL_MAILBOX*)(MTL_MAILBOX_BASE),
      DOORBELL_LOW
    },
    // High priority channel
    {
      MTL_CHANNEL_TYPE_HIGH,
      (MTL_MAILBOX*)(MTL_MAILBOX_BASE + MTL_MAILBOX_HIGH_PRIORITY_OFFSET),
      DOORBELL_HIGH
    }
  };

/** 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
  )
{
  while (TimeOutInMicroSeconds != 0) {
    // If channel is free then we have received the reply.
    if (Channel->MailBox->ChannelStatus == MTL_CHANNEL_FREE) {
      return EFI_SUCCESS;
    }
    if (TimeOutInMicroSeconds < MTL_POLL_WAIT_TIME) {
      gBS->Stall (TimeOutInMicroSeconds);
      break;
    }
    // Wait for some arbitrary time.
    gBS->Stall (MTL_POLL_WAIT_TIME);
    TimeOutInMicroSeconds -= MTL_POLL_WAIT_TIME;
  }

  // No response from SCP.
  if (Channel->MailBox->ChannelStatus != MTL_CHANNEL_FREE) {
    ASSERT (FALSE);
    return EFI_TIMEOUT;
  }

  return EFI_SUCCESS;
}

/** 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 Channel->MailBox->Payload;
}

/** 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
  )
{
  if (ChannelType != MTL_CHANNEL_TYPE_LOW
    && ChannelType != MTL_CHANNEL_TYPE_HIGH) {
    return EFI_UNSUPPORTED;
  }

  *Channel = (MTL_CHANNEL*)&Channels[ChannelType];

  return EFI_SUCCESS;
}

/** 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
  )
{
  MTL_MAILBOX *MailBox = Channel->MailBox;

  if (Channel->MailBox->ChannelStatus != MTL_CHANNEL_FREE) {
    return EFI_DEVICE_ERROR;
  }

  // Mark the channel busy before ringing doorbell.
  Channel->MailBox->ChannelStatus = MTL_CHANNEL_BUSY;
  ArmDataSynchronizationBarrier ();

  MailBox->Flags         = MTL_POLL;
  MailBox->MessageHeader = MessageHeader;

  // Add length of message header.
  MailBox->Length = PayloadLength + sizeof (MessageHeader);

  // Ring the doorbell. It sets SET bit of the MHU register.
  MmioWrite32 (
    Channel->DoorBell.PhysicalAddress,
    Channel->DoorBell.ModifyMask
    );

  return EFI_SUCCESS;
}

/** 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
  )
{
  EFI_STATUS Status;

  MTL_MAILBOX *MailBox = Channel->MailBox;

  Status = MtlWaitUntilChannelFree (Channel, RESPONSE_TIMEOUT);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  *MessageHeader = MailBox->MessageHeader;

  // Deduct message header length.
  *PayloadLength = MailBox->Length - sizeof (*MessageHeader);

  return EFI_SUCCESS;
}