// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library ddk.protocol.shareddma;
using zx;

enum DmaType : uint32 {
    REGULAR = 0x1;
    CYCLIC = 0x2;
};

enum DmaState : uint32 {
    COMPLETED = 0x1;
    FAILED = 0x2;
};

[Layout = "ddk-callback"]
protocol DmaNotify {
    Callback(DmaState state) -> ();
};

[Layout = "ddk-protocol"]
protocol SharedDma {

    /// Initializes and provides a VMO for memory source or destination.
    /// Only supports device to memory and memory to device DMAs.
    /// The provided id is opaque and HW specific.  The id implicitly defines the direction of the
    /// DMA (biderectional DMAs are not supported yet).  Transfer sizes and alignment are
    /// managed within the shared DMA driver.
    InitializeAndGetBuffer(uint32 channel_id, DmaType type, uint32 size) ->
        (zx.status s, handle<vmo> vmo);

    /// Start DMA
    Start(uint32 channel_id);

    /// Stop DMA
    Stop(uint32 channel_id);

    /// Returns the current position within memory where is the DMA has written to or read from.
    GetBufferPosition(uint32 channel_id) -> (uint32 position);

    /// It must always be assumed that the DMA is in the process of transfering this amount
    /// of data (accounting for warp around) into or from memory, hence for:
    /// Device to memory DMAs, it is not safe to read this amount past the buffer position.
    /// Memory to device DMAs, it is not safe to write this amount before the buffer position.
    GetTransferSize(uint32 channel_id) -> (uint32 available_size);

    /// Specifies a callback for notifications of state change.
    SetNotifyCallback(uint32 channel_id, DmaNotify cb) -> (zx.status s);
};