sdk/fidl/fuchsia.hardware.i2c/i2c.fidl

// Copyright 2018 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.
@available(added=7)
library fuchsia.hardware.i2c;

using zx;

const MAX_TRANSFER_SIZE uint32 = 8196; // More than enough for I2C
const MAX_COUNT_SEGMENTS uint32 = 8; // Enough for all known transfer configurations.

// A previous `Device` is now removed.
@discoverable
protocol Device2 {
    /// Write and read segments of data for a particular I2C device.
    ///
    /// The `segments_is_write` vector specifies the type (write or read) of each segment.
    /// The `write_segments_data` vector of segments specifies the data to write for each write
    /// segment. Each segment itself is a vector of uint8s, so `write_segments_data` is a vector of
    /// vectors of uint8s.
    /// The `read_segments_length` vector specifies the length of the read segments. No entry may be
    /// larger than MAX_TRANSFER_SIZE.
    /// If there is no error, `read_segments_data` returns a vector of segments, with each segment
    /// data itself returned in vectors.
    ///
    /// For a simple I2C read, for instance 2 bytes write followed by one byte read,
    /// `segments_is_write` would be a vector with 2 elements: true, false and
    /// `write_segments_data` would be a vector with 1 element including the 2 bytes address of the
    /// read. Upon success `read_segments_data` would return a vector with one element, the byte
    /// read.
    Transfer(struct {
        segments_is_write vector<bool>:MAX_COUNT_SEGMENTS;
        write_segments_data vector<vector<uint8>:MAX_TRANSFER_SIZE>:MAX_COUNT_SEGMENTS;
        read_segments_length vector<uint32>:MAX_COUNT_SEGMENTS;
    }) -> (struct {
        read_segments_data vector<vector<uint8>:MAX_TRANSFER_SIZE>:MAX_COUNT_SEGMENTS;
    }) error zx.status;
};