// Copyright 2021 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.nvram;

using zx;

/// Maximum amount of data that can be transferred in a single transaction.
const NVRAM_MAX uint32 = 256;

/// A device that contains some small amount of non-volatile storage.
protocol Device {
    /// Get the size of the NVRAM NVRAM.
    GetSize() -> (struct {
        size uint32;
    });

    /// Read |size| bytes of data starting at |offset|.
    /// Returns ZX_ERR_OUT_OF_RANGE if the data extends past the end of the
    /// nvram.
    Read(struct {
        offset uint32;
        size uint32;
    }) -> (struct {
        data vector<uint8>:NVRAM_MAX;
    }) error zx.status;

    /// Write |data| starting at |offset|.
    /// Returns ZX_ERR_OUT_OF_RANGE if the data extends past the end of the
    /// nvram.
    Write(struct {
        offset uint32;
        data vector<uint8>:NVRAM_MAX;
    }) -> (struct {}) error zx.status;
};