// 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.

library fuchsia.hardware.usb.device;

using zx;

/// sizeof(usb_device_descriptor_t)
const uint32 DEVICE_DESC_SIZE = 18;

/// UINT16_MAX
const uint32 MAX_CONFIG_DESC_SIZE = 65536;

/// See GetStringDescriptor description below
const uint32 MAX_STRING_DESC_SIZE = 384;

[Layout = "Simple"]
protocol Device {
    /// Returns the speed of the USB device as a usb_speed_t value.
    GetDeviceSpeed() -> (uint32 speed);

    /// Returns the device's USB device descriptor.
    GetDeviceDescriptor() -> (array<uint8>:DEVICE_DESC_SIZE desc);

    /// Returns the total size of the USB configuration descriptor for the given configuration.
    GetConfigurationDescriptorSize(uint8 config) -> (zx.status s, uint16 size);

    /// Returns the device's USB configuration descriptor for the given configuration.
    GetConfigurationDescriptor(uint8 config) -> (zx.status s,
                                                 vector<uint8>:MAX_CONFIG_DESC_SIZE desc);

    /// Fetches a string descriptor from the USB device.
    ///
    /// desc_id          :   The ID of the string descriptor to fetch, or 0 to fetch
    ///                      the language table instead.
    ///
    /// lang_id          :   The language ID of the string descriptor to fetch.
    ///                      If no matching language ID is present in the device's language
    ///                      ID table, the first entry of the language ID table will
    ///                      be substituted.
    /// actual_lang_id   :   The actual language ID of the string fetched, or 0 for
    ///                      the language ID table.
    ///
    /// The worst case size for the payload of a language ID table should be 252
    /// bytes, meaning that a 256 byte buffer should always be enough to hold any
    /// language ID table.
    ///
    /// The worst case size for a UTF-8 encoded string descriptor payload should be
    /// 378 bytes (126 UTF-16 code units with a worst case expansion factor of 3)
    GetStringDescriptor(uint8 desc_id, uint16 lang_id) -> (zx.status s,
                                                           string:MAX_STRING_DESC_SIZE desc,
                                                           uint16 actual_lang_id);

    /// Selects an alternate setting for an interface on a USB device.
    SetInterface(uint8 interface_number, uint8 alt_setting) -> (zx.status s);

    /// Returns an implementation specific device ID for a USB device.
    /// For informational purposes only.
    GetDeviceId() -> (uint32 device_id);

    /// Returns the implementation specific device ID for the hub that a USB device is connected to.
    /// For informational purposes only.
    GetHubDeviceId() -> (uint32 hub_device_id);

    /// Returns the device's current configuration.
    GetConfiguration() -> (uint8 configuration);

    /// Sets the device's current configuration.
    SetConfiguration(uint8 configuration) -> (zx.status s);
};