sdk/banjo/fuchsia.hardware.spiimpl/spi-impl.banjo

// 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 fuchsia.hardware.spiimpl;

using zx;

/// Low-level protocol for spi drivers.
[BanjoLayout = "ddk-protocol"]
protocol SpiImpl {
    /// Returns the number of chip select lines available or provided by the driver instance.
    /// To be used as a limit on the acceptable values for the `chip_select' field in the Exchange()
    /// and ExchangeVmo() methods.
    GetChipSelectCount() -> (uint32 count);

    /// Perform a SPI bus transaction of the specified length. Either txdata or rxdata may be
    /// NULL, in which case the transaction will be half-duplex in the appropriate direction.
    /// Regardless, both vectors must have the same length.
    Exchange(uint32 chip_select, vector<uint8> txdata) -> (zx.status status, vector<uint8> rxdata);

    RegisterVmo(uint32 chip_select, uint32 vmo_id, zx.handle:VMO vmo, uint64 offset, uint64 size)
            -> (zx.status status);
    UnregisterVmo(uint32 chip_select, uint32 vmo_id) -> (zx.status status, zx.handle:VMO vmo);

    TransmitVmo(uint32 chip_select, uint32 vmo_id, uint64 offset, uint64 size)
            -> (zx.status status);
    ReceiveVmo(uint32 chip_select, uint32 vmo_id, uint64 offset, uint64 size)
            -> (zx.status status);
    ExchangeVmo(uint32 chip_select, uint32 tx_vmo_id, uint64 tx_offset, uint32 rx_vmo_id,
                uint64 rx_offset, uint64 size) -> (zx.status status);
};