zircon/system/fidl/fuchsia-hardware-usb-peripheral-block/usb-peripheral-block.fidl

// 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.usb.peripheral.block;

using zx;

// Represents a simulated USB block device whose cache can be controlled.
// This allows for integration testing of USB mass storage devices
// both with and without caches.
[Layout = "Simple"]
protocol Device {
    // Enables writeback caching. This requires the device
    // to be disconnected at the time of the call. Calling it when the device is connected
    // will result in undefined behavior.
    // All writes will be buffered until a BLOCK_OP_FLUSH is received.
    EnableWritebackCache() -> (zx.status s);
    // Disables writeback caching. This requires the device to be disconnected at the time
    // of the call. Calling it when the device is connected will result in undefined behavior.
    // Disabling this cache will cause any writes to be written immediately to non-volatile storage
    // before returning to the caller.
    DisableWritebackCache() -> (zx.status s);
    // Sets writeback cache reporting behavior. This requires the device
    // to be disconnected at the time of the call. Calling it when the device is connected
    // will result in undefined behavior.
    // If report is set to true, the device will report its cache capability correctly to the
    // host. If set to false, the writeback caching capabilities will NOT be reported.
    // This can be used to test host drivers to ensure that they respond properly
    // when the device does not report its caching capabilities.
    SetWritebackCacheReported(bool report) -> (zx.status s);
};