AndroidAutomotive模块介绍(四)VehicleHal介绍

前言

前面的文章中,描述了 Android Automotive 的框架中应用、Framework 层服务等知识,本篇文章将会继续按照 Android Automotive 框架介绍 Vehicle Hal 层服务的内容。

上一篇:AndroidAutomotive模块介绍(三)CarService服务

正文

1、VehicleHal 介绍

本篇文档将对 Andorid Automotive 框架中 VehicleHal 层展开介绍。VehicleHal 即为车辆硬件抽象层的定义。可以理解为 Android Automotive OS 中的硬件抽象层接口,包括车辆属性和方法;各厂商制造商会根据定义的 Hal 接口,实现定制化的模块服务。

VehicleHal 是链接 Android Automotive Car Services 与制造商实现车辆控制服务进程的桥梁,通过标准化接口对上层提供服务,对于服务的实现依赖厂商的定制化,可以忽略汽车制造商的具体实现,也就是说 CarService 调用 VehicleHal 定义的标准接口,厂商实现这些接口。

2、VehicleHal 模块功能

2.1 rc 文件

VehicleHal 的代码路径为:android/hardware/interfaces/automotive/vehicle/2.0/default。路径下有 android.hardware.automotive.vehicle@2.0-service.rc 文件,在开机阶段通过此 rc 文件,将 VehicleHal 进程启动,下面来看下 android.hardware.automotive.vehicle@2.0-service.rc 文件的定义

service vendor.vehicle-hal-2.0 /vendor/bin/hw/android.hardware.automotive.vehicle@2.0-service
    class hal
    user vehicle_network
    group system inet

2.2 编译

对于 VehicleHal 的编译,可以对以下两个 Android.bp 文件介绍。

  • Hidl 接口编译
  • VehicleHal 服务编译

VehicleHal 定义的 Hal 接口编译介绍,Android.bp 文件路径为:android/hardware/interfaces/automotive/vehicle/2.0,目录结构如下:

ubuntu:android/hardware/interfaces/automotive/vehicle/2.0$ ls -l
total 132
-rw-r--r-- 1   users    375 Nov  9  2022 Android.bp
drwxrwxr-x 5   users   4096 Mar 22 13:55 default
-rw-r--r-- 1   users   2336 Nov  9  2022 IVehicleCallback.hal
-rw-r--r-- 1   users   3665 Nov  9  2022 IVehicle.hal
-rw-r--r-- 1   users 115184 Nov  9  2022 types.hal

下面是 Android.bp 文件的定义:

makefile 复制代码
// This file is autogenerated by hidl-gen -Landroidbp.

hidl_interface {
    name: "android.hardware.automotive.vehicle@2.0",
    root: "android.hardware",
    vndk: {
        enabled: true,
    },
    srcs: [
        "types.hal",
        "IVehicle.hal",
        "IVehicleCallback.hal",
    ],
    interfaces: [
        "android.hidl.base@1.0",
    ],
    gen_java: true,
}

编译文件中定义了 android.hardware.automotive.vehicle@2.0 HIDL 接口编译,包含三个文件 types.hal、IVehicle.hal、IVehicleCallback.hal 文件。

VehicleHal 服务编译介绍,Android.bp 文件路径为:android/hardware/interfaces/automotive/vehicle/2.0/default,目录结构如下:

ubuntu16:android/hardware/interfaces/automotive/vehicle/2.0/default$ ls -l
total 28
-rw-r--r-- 1   users 4705 Nov  9  2022 Android.bp
-rw-r--r-- 1   users  155 Nov  9  2022 android.hardware.automotive.vehicle@2.0-service.rc
drwxrwxr-x 4   users 4096 Jun  7  2022 common
drwxrwxr-x 3   users 4096 Jun  7  2022 impl
drwxrwxr-x 2   users 4096 Nov  9  2022 tests
-rw-r--r-- 1   users 1953 Nov  9  2022 VehicleService.cpp

Android.bp 文件定义如下:

makefile 复制代码
// Vehicle reference implementation lib
cc_library {
    name: "android.hardware.automotive.vehicle@2.0-manager-lib",
    vendor: true,
    defaults: ["vhal_v2_0_defaults"],
    srcs: [
        "common/src/Obd2SensorStore.cpp",
        "common/src/SubscriptionManager.cpp",
        "common/src/VehicleHalManager.cpp",
        "common/src/VehicleObjectPool.cpp",
        "common/src/VehiclePropertyStore.cpp",
        "common/src/VehicleUtils.cpp",
        "common/src/VmsUtils.cpp",
    ],
    local_include_dirs: ["common/include/vhal_v2_0"],
    export_include_dirs: ["common/include"],
}

// Vehicle default VehicleHAL implementation
cc_library_static {
    name: "android.hardware.automotive.vehicle@2.0-default-impl-lib",
    vendor: true,
    cflags: ["-Wno-unused-parameter", "-Wno-sign-compare"],
    defaults: ["vhal_v2_0_defaults"],
    srcs: [
        "impl/vhal_v2_0/CommConn.cpp",
        "impl/vhal_v2_0/EmulatedVehicleHal.cpp",
        "impl/vhal_v2_0/VehicleEmulator.cpp",
        "impl/vhal_v2_0/PipeComm.cpp",
        "impl/vhal_v2_0/SocketComm.cpp",
        "impl/vhal_v2_0/LinearFakeValueGenerator.cpp",
        "impl/vhal_v2_0/JsonFakeValueGenerator.cpp",
    ],
    local_include_dirs: ["common/include/vhal_v2_0"],
    export_include_dirs: ["impl"],
    whole_static_libs: ["android.hardware.automotive.vehicle@2.0-manager-lib"],
    shared_libs: [
        "libbase",
        "libprotobuf-cpp-lite",
    ],
    static_libs: [
        "libjsoncpp",
        "libqemu_pipe",
        "android.hardware.automotive.vehicle@2.0-libproto-native",
    ],
}

cc_binary {
    name: "android.hardware.automotive.vehicle@2.0-service",
    defaults: ["vhal_v2_0_defaults"],
    init_rc: ["android.hardware.automotive.vehicle@2.0-service.rc"],
    vendor: true,
    relative_install_path: "hw",
    srcs: ["VehicleService.cpp"],
    shared_libs: [
        "libbase",
        "libprotobuf-cpp-lite",
    ],
    static_libs: [
        "android.hardware.automotive.vehicle@2.0-manager-lib",
        "android.hardware.automotive.vehicle@2.0-default-impl-lib",
        "android.hardware.automotive.vehicle@2.0-libproto-native",
        "libjsoncpp",
        "libqemu_pipe",
    ],
}

从 Android.bp 的定义中,VehicleHal 的服务名为 android.hardware.automotive.vehicle@2.0-service,启动 rc 文件是 android.hardware.automotive.vehicle@2.0-service.rc,入口文件是 VehicleService.cpp,依赖自定义相关模块主要有 android.hardware.automotive.vehicle@2.0-manager-lib、android.hardware.automotive.vehicle@2.0-default-impl-lib、android.hardware.automotive.vehicle@2.0-libproto-native。

android.hardware.automotive.vehicle@2.0-manager-lib 模块是 common 目录下的文件所编译的内容,主要是 VehicleHal 所以来的模块。

android.hardware.automotive.vehicle@2.0-default-impl-lib 模块是 impl 目录下的文件所编译的内容,主要是 VehicleHal 的功能实现模块。

android.hardware.automotive.vehicle@2.0-libproto-native 模块是 impl/vhal_v2_0/proto 目录下的文件所编译的内容,目录下的文件为 VehicleHalProto.proto 文件,是一种序列化存储数据的方式。

2.3 HIDL 接口

Android Automotive 框架中 Hal 层接口文件有三个,IVehicle.hal、IVehicleCallback.hal 和 types.hal 文件。IVehicle.hal 文件中定义了 Vehicle Hal 对外提供的接口;IVehicleCallback.hal 文件中定义了 VehicleHal 的回调接口;types.hal 文件定义了 Vehicle Hal 的属性定义。

Hidl 文件路径为:android/hardware/interfaces/automotive/vehicle/2.0。

2.3.1 IVehicle.hal

IVehicle.hal 文件中定义了 Vehicle Hal 对外提供的接口,上层 CarService 通过 IVehicle.hal 中定义的接口与 Vehicle Hal 通信。

package android.hardware.automotive.vehicle@2.0;

import IVehicleCallback;

interface IVehicle {
  /**
   * Returns a list of all property configurations supported by this vehicle
   * HAL.
   * 返回此车辆HAL支持的所有属性配置的列表
   */
  getAllPropConfigs() generates (vec<VehiclePropConfig> propConfigs);

  /**
   * Returns a list of property configurations for given properties.
   *
   * If requested VehicleProperty wasn't found it must return
   * StatusCode::INVALID_ARG, otherwise a list of vehicle property
   * configurations with StatusCode::OK
   * 返回给定属性的属性配置列表。
   * 如果请求的车辆属性没有找到,它必须返回StatusCode::INVALID_ARG,否则返回一个车辆属性配置列表,StatusCode::OK
   */
  getPropConfigs(vec<int32_t> props)
          generates (StatusCode status, vec<VehiclePropConfig> propConfigs);

  /**
   * Get a vehicle property value.
   *
   * For VehiclePropertyChangeMode::STATIC properties, this method must always
   * return the same value always.
   * For VehiclePropertyChangeMode::ON_CHANGE properties, it must return the
   * latest available value.
   *
   * Some properties like RADIO_PRESET requires to pass additional data in
   * GET request in VehiclePropValue object.
   *
   * If there is no data available yet, which can happen during initial stage,
   * this call must return immediately with an error code of
   * StatusCode::TRY_AGAIN.
   * 获取车辆属性值。
   * 对于 VehiclePropertyChangeMode::STATIC 的属性值,此方法会返回同一个值,不会改变。
   * 对于 VehiclePropertyChangeMode::ON_CHANGE 的属性值,此方法会返回最新值。
   */
  get(VehiclePropValue requestedPropValue)
          generates (StatusCode status, VehiclePropValue propValue);

  /**
   * Set a vehicle property value.
   *
   * Timestamp of data must be ignored for set operation.
   *
   * Setting some properties require having initial state available. If initial
   * data is not available yet this call must return StatusCode::TRY_AGAIN.
   * For a property with separate power control this call must return
   * StatusCode::NOT_AVAILABLE error if property is not powered on.
   * 设置车辆属性值。
   * 特殊场景:
   * 设置一些属性值需要其初始状态可用,如果初始状态不可用,需要返回 StatusCode::TRY_AGAIN。
   * 设置单独电源控制的属性,如果属性未上电,需要返回 StatusCode::TRY_AGAIN。
   */
  set(VehiclePropValue propValue) generates (StatusCode status);

  /**
   * Subscribes to property events.
   *
   * Clients must be able to subscribe to multiple properties at a time
   * depending on data provided in options argument.
   *
   * @param listener This client must be called on appropriate event.
   * @param options List of options to subscribe. SubscribeOption contains
   *                information such as property Id, area Id, sample rate, etc.
   * 订阅属性
   * 客户端可以一次订阅多个属性,这取决于 options 定义的参数。
   * 参数 SubscribeOptions 包含 属性id、区域id、采样率 等信息。
   */
  subscribe(IVehicleCallback callback, vec<SubscribeOptions> options)
          generates (StatusCode status);

  /**
   * Unsubscribes from property events.
   *
   * If this client wasn't subscribed to the given property, this method
   * must return StatusCode::INVALID_ARG.
   * 取消订阅属性
   * 如果客户端在此前没有对此属性进行订阅,则返回 StatusCode::INVALID_ARG。
   */
  unsubscribe(IVehicleCallback callback, int32_t propId)
          generates (StatusCode status);

  /**
   * Print out debugging state for the vehicle hal.
   *
   * The text must be in ASCII encoding only.
   *
   * Performance requirements:
   *
   * The HAL must return from this call in less than 10ms. This call must avoid
   * deadlocks, as it may be called at any point of operation. Any synchronization
   * primitives used (such as mutex locks or semaphores) must be acquired
   * with a timeout.
   *
   * 打印车辆的调试状态。
   */
  debugDump() generates (string s);
};
2.3.2 IVehicleCallback.hal

IVehicleCallback.hal 文件定义了 VehicleHal 的回调对象,上层 CarService 通过注册此回调对象以监听属性是否改变。VehicleHal 通过回调对象返回状态给到客户端。

package android.hardware.automotive.vehicle@2.0;

interface IVehicleCallback {

    /**
     * Event callback happens whenever a variable that the API user has
     * subscribed to needs to be reported. This may be based purely on
     * threshold and frequency (a regular subscription, see subscribe call's
     * arguments) or when the IVehicle#set method was called and the actual
     * change needs to be reported.
     *
     * These callbacks are chunked.
     *
     * @param values that has been updated.
     * 当需要报告客户端订阅的变量时,就会调用此回调函数。
     * 这可能基于常规按频率上报或者客户端调用 IVehicle#set 函数时调用。
     */
    oneway onPropertyEvent(vec<VehiclePropValue> propValues);

    /**
     * This method gets called if the client was subscribed to a property using
     * SubscribeFlags::EVENTS_FROM_ANDROID flag and IVehicle#set(...) method was called.
     *
     * These events must be delivered to subscriber immediately without any
     * batching.
     *
     * @param value Value that was set by a client.
     * 如果客户端使用 SubscribeFlags::EVENTS_FROM_ANDROID 标志订阅属性,并且调用 IVehicle#set 函数,则回调此方法。
     */
    oneway onPropertySet(VehiclePropValue propValue);

    /**
     * Set property value is usually asynchronous operation. Thus even if
     * client received StatusCode::OK from the IVehicle::set(...) this
     * doesn't guarantee that the value was successfully propagated to the
     * vehicle network. If such rare event occurs this method must be called.
     *
     * @param errorCode - any value from StatusCode enum.
     * @param property - a property where error has happened.
     * @param areaId - bitmask that specifies in which areas the problem has
     *                 occurred, must be 0 for global properties
     * 设置属性通常是异步操作,客户端调用 IVehicle#set 函数到接收到 StatusCode::OK 的返回值,也不能保证此属性成功传播到车辆网络,如果发生这种低概率的事件,则回调此方法。
     * @ errorCode:StatusCode 枚举中的任何值。
     * @ property:发生错误的属性。
     * @ areaId:指定问题发生在哪个区域的位掩码,对于全局属性必须为 0。
     */
    oneway onPropertySetError(StatusCode errorCode,
                              int32_t propId,
                              int32_t areaId);
};
2.3.3 types.hal

types.hal 中定义了 VehicleHal 的属性、结构等数据。

2.3.3.1 车辆属性 VehiclePropertyType

下面列举 types.hal 中定义的 VehiclePropertyType 属性:

package android.hardware.automotive.vehicle@2.0;

/**
 * Enumerates supported data type for VehicleProperty.
 * 枚举 VehicleProperty 支持的数据类型。
 * Used to create property ID in VehicleProperty enum.
 * 用于在 VehicleProperty enum 中创建属性 ID。
 */
enum VehiclePropertyType : int32_t { // VehicleProperty 的类型是 string、bool、还是 int32 等等
    STRING          = 0x00100000,
    BOOLEAN         = 0x00200000,
    INT32           = 0x00400000,
    INT32_VEC       = 0x00410000,
    INT64           = 0x00500000,
    INT64_VEC       = 0x00510000,
    FLOAT           = 0x00600000,
    FLOAT_VEC       = 0x00610000,
    BYTES           = 0x00700000,

    /**
     * Any combination of scalar or vector types. The exact format must be
     * provided in the description of the property.
     */
    MIXED           = 0x00e00000, // 这两个主要就是 VehicleProperty 用来进行或运算的。

    MASK            = 0x00ff0000
};
2.3.3.2 车辆区域属性 VehicleArea

下面是 types.hal 中定义的车辆区域属性:

/**
 * Vehicle Areas
 * Used to construct property IDs in the VehicleProperty enum.
 * 用于在VehicleProperty enum中构造属性id。
 *
 * Some properties may be associated with particular vehicle areas. For
 * example, VehicleProperty:DOOR_LOCK property must be associated with
 * particular door, thus this property must be marked with
 * VehicleArea:DOOR flag.
 * 某些属性可能与特定车辆区域相关。例如,VehicleProperty:DOOR_LOCK 属性必须与特定的门相关联,因此该属性必须标记为 VehicleArea: door 标志。
 *
 * Other properties may not be associated with particular vehicle area,
 * these kind of properties must have VehicleArea:GLOBAL flag.
 * 其他属性可能不与特定的车辆区域相关联,这些属性必须具有VehicleArea:GLOBAL标志。
 *
 * [Definition] Area: An area represents a unique element of an AreaType.
 *   For instance, if AreaType is WINDOW, then an area may be FRONT_WINDSHIELD.
 *
 * [Definition] AreaID: An AreaID is a combination of one or more areas,
 *   and is represented using a bitmask of Area enums. Different AreaTypes may
 *   not be mixed in a single AreaID. For instance, a window area cannot be
 *   combined with a seat area in an AreaID.
 *
 * Rules for mapping a zoned property to AreaIDs:
 *  - A property must be mapped to an array of AreaIDs that are impacted when
 *    the property value changes.
 *  - Each element in the array must represent an AreaID, in which, the
 *    property value can only be changed together in all the areas within
 *    an AreaID and never independently. That is, when the property value
 *    changes in one of the areas in an AreaID in the array, then it must
 *    automatically change in all other areas in the AreaID.
 *  - The property value must be independently controllable in any two
 *    different AreaIDs in the array.
 *  - An area must only appear once in the array of AreaIDs. That is, an
 *    area must only be part of a single AreaID in the array.
 *
 * [Definition] Global Property: A property that applies to the entire car
 *   and is not associated with a specific area. For example, FUEL_LEVEL,
 *   HVAC_STEERING_WHEEL_HEAT.
 *
 * Rules for mapping a global property to AreaIDs:
 *  - A global property must not be mapped to AreaIDs.
*/
enum VehicleArea : int32_t {
    GLOBAL      = 0x01000000, // 全局区域
    /** WINDOW maps to enum VehicleAreaWindow */
    WINDOW      = 0x03000000, // 窗户区域
    /** MIRROR maps to enum VehicleAreaMirror */
    MIRROR      = 0x04000000, // 反光镜区域
    /** SEAT maps to enum VehicleAreaSeat */
    SEAT        = 0x05000000, // 座椅区域
    /** DOOR maps to enum VehicleAreaDoor */
    DOOR        = 0x06000000, // 车门区域
    /** WHEEL maps to enum VehicleAreaWheel */
    WHEEL       = 0x07000000, // 车轮区域
    YFVehicleAreaTire = 0x08000000,
    MASK        = 0x0f000000,
};
2.3.3.3 车辆属性分组类型 VehiclePropertyGroup

下面是 types.hal 中定义的车辆属性分组类型:

/**
 * Enumerates property groups.
 * 车辆属性分组枚举
 *
 * Used to create property ID in VehicleProperty enum.
 * 用于在VehicleProperty enum中创建属性ID。
 */
enum VehiclePropertyGroup : int32_t { // AndroidO 之后的 treble,用于区分 android 原生的 property 和厂商的 property。
    /**
     * Properties declared in AOSP must use this flag.
     * AOSP 原生的属性标志
     */
    SYSTEM      = 0x10000000,

    /**
     * Properties declared by vendors must use this flag.
     * 厂商自定义的属性标志
     */
    VENDOR      = 0x20000000,

    MASK        = 0xf0000000,
};
2.3.3.4 车辆属性 VehicleProperty

下面是 types.hal 中定义的车辆属性

/**
 * Declares all vehicle properties. VehicleProperty has a bitwise structure.
 * Each property must have:
 *  - a unique id from range 0x0100 - 0xffff
 *  - associated data type using VehiclePropertyType
 *  - property group (VehiclePropertyGroup)
 *  - vehicle area (VehicleArea)
 *
 * Vendors are allowed to extend this enum with their own properties. In this
 * case they must use VehiclePropertyGroup:VENDOR flag when property is
 * declared.
 *
 * When a property's status field is not set to AVAILABLE:
 *  - IVehicle#set may return StatusCode::NOT_AVAILABLE.
 *  - IVehicle#get is not guaranteed to work.
 *
 * Properties set to values out of range must be ignored and no action taken
 * in response to such ill formed requests.
 */
enum VehicleProperty : int32_t {

    /** Undefined property. */
    INVALID = 0x00000000,

    /**
     * VIN of vehicle
     * 车辆 VIN 码
     *
     * @change_mode VehiclePropertyChangeMode:STATIC
     * @access VehiclePropertyAccess:READ
     */
    INFO_VIN = (
        0x0100
        | VehiclePropertyGroup:SYSTEM // 原生属性
        | VehiclePropertyType:STRING // 属性值是 String 类型
        | VehicleArea:GLOBAL), // 全局属性

    /**
     * Model of vehicle
     * 车辆型号
     *
     * @change_mode VehiclePropertyChangeMode:STATIC
     * @access VehiclePropertyAccess:READ
     */
    INFO_MODEL = (
        0x0102
        | VehiclePropertyGroup:SYSTEM // 原生属性
        | VehiclePropertyType:STRING // 属性值是 String 类型
        | VehicleArea:GLOBAL), // 全局属性
...
};
2.3.3.5 车辆座位占用状态 VehicleSeatOccupancyState

下面是 types.hal 中定义的车辆座位占用状态值

/**
 * Used by seat occupancy to enumerate the current occupancy state of the seat.
 * 由座位占用使用,以枚举座位的当前占用状态
 */
enum  VehicleSeatOccupancyState : int32_t {

    UNKNOWN = 0,
    VACANT = 1, // 空闲
    OCCUPIED = 2 // 占用
};
2.3.3.6 灯光状态属性 VehicleLightState

下面是 types.hal 中定义的灯光状态属性

/**
 * Used by lights state properties to enumerate the current state of the lights.
 * 由灯光状态属性使用,枚举灯光的当前状态。
 * Most XXX_LIGHTS_STATE properties will only report ON and OFF states.  Only
 * the HEADLIGHTS_STATE property will report DAYTIME_RUNNING.
 * 大多数 XXX_LIGHTS_STATE 属性将只报告 ON 和 OFF 状态。只有 headlight_state 属性会报告 DAYTIME_RUNNING。
 */
enum  VehicleLightState : int32_t {

    OFF = 0,
    ON = 1,
    DAYTIME_RUNNING = 2
};
2.3.3.7 车灯开关属性 VehicleLightSwitch

下面是 types.hal 中定义的车灯开关属性

/**
 * Used by lights switch properties to enumerate user selected switch setting.
 * 由灯开关属性使用,枚举用户选择的开关设置。
 * XXX_LIGHTS_SWITCH properties report the switch settings that the user
 * selects.  The switch setting may be decoupled from the state reported if the
 * user selects AUTOMATIC.
 * XXX_LIGHTS_SWITCH 属性报告用户选择的开关设置。如果用户选择 AUTOMATIC,开关设置可能与报告的状态分离。
 */
enum VehicleLightSwitch : int32_t {
    OFF = 0,
    ON = 1,
    /**
     * Daytime running lights mode.  Most cars automatically use DRL but some
     * cars allow the user to activate them manually.
     * 日间行车灯模式。大多数汽车自动使用DRL,但有些汽车允许用户手动激活它们。
     */
    DAYTIME_RUNNING = 2,
    /**
     * Allows the vehicle ECU to set the lights automatically
     * 允许车辆ECU自动设置灯光
     */
    AUTOMATIC = 0x100,
};
2.3.3.8 车辆充电连接线类型 EvConnectorType

下面是 types.hal 中定义的车辆充电连接线类型属性

/**
 * Used by INFO_EV_CONNECTOR_TYPE to enumerate the type of connectors
 * available to charge the vehicle.
 * 由 INFO_EV_CONNECTOR_TYPE 使用,枚举可用于给车辆充电的连接器类型。
 */
enum EvConnectorType : int32_t {
    /**
     * Default type if the vehicle does not know or report the EV connector
     * type.
     * 如果车辆不知道或不报告EV连接器类型,则默认类型
     */
    UNKNOWN = 0,
    IEC_TYPE_1_AC = 1,              // aka Yazaki
    IEC_TYPE_2_AC = 2,              // aka Mennekes
    IEC_TYPE_3_AC = 3,              // aka Scame
    IEC_TYPE_4_DC = 4,              // aka CHAdeMO
    IEC_TYPE_1_CCS_DC = 5,          // aka Combo 1
    IEC_TYPE_2_CCS_DC = 6,          // aka Combo 2
    TESLA_ROADSTER = 7,
    TESLA_HPWC = 8,
    TESLA_SUPERCHARGER = 9,
    GBT_AC = 10,
    GBT_DC = 11,

    /**
     * Connector type to use when no other types apply. Before using this
     * value, work with Google to see if the EvConnectorType enum can be
     * extended with an appropriate value.
     */
    OTHER = 101,
};
2.3.3.9 端口位置属性 PortLocationType

下面是 types.hal 中定义的用于枚举燃油门或燃油口位置属性。

/**
 * Used by INFO_FUEL_DOOR_LOCATION/INFO_CHARGE_PORT_LOCATION to enumerate fuel door or
 * ev port location.
 * 用于描述 INFO_FUEL_DOOR_LOCATION 和 INFO_CHARGE_PORT_LOCATION 信号的燃油门或燃油口位置。
 */
enum PortLocationType : int32_t {
    /**
     * Default type if the vehicle does not know or report the Fuel door
     * and ev port location.
     */
    UNKNOWN = 0,
    FRONT_LEFT = 1,
    FRONT_RIGHT = 2,
    REAR_RIGHT = 3,
    REAR_LEFT = 4,
    FRONT = 5,
    REAR = 6,
};
2.3.3.10 风扇方向属性 VehicleHvacFanDirection

下面是 types.hal 中定义的风扇方向属性。

/**
 * Bit flags for fan direction
 * 风扇方向的位标志
 */
enum VehicleHvacFanDirection : int32_t {
    FACE = 0x1,
    FLOOR = 0x2,
    DEFROST = 0x4,
};
2.3.3.11 车辆油量属性 VehicleOilLevel

下面是 types.hal 中定义的车辆油量属性。

enum VehicleOilLevel : int32_t {
    /**
     * Oil level values
     */
    CRITICALLY_LOW = 0,
    LOW = 1,
    NORMAL = 2,
    HIGH = 3,
    ERROR = 4,
};
2.3.3.12 车辆输入事件属性 VehicleHwKeyInputAction

下面是 types.hal 中定义的车辆输入事件属性。

enum VehicleHwKeyInputAction : int32_t {
    /** Key down */
    ACTION_DOWN = 1, // 输入事件按下

    /** Key up */
    ACTION_UP = 0, // 输入事件抬起
};
2.3.3.13 车辆属性修改模式 VehiclepropertyChangeMode

下面是 types.hal 中定义的属性是否可以改变的配置。

/**
 * This describes how value of property can change.
 * 描述属性是否可以改变
 */
enum VehiclePropertyChangeMode : int32_t {
    /**
     * Property of this type must never be changed. Subscription is not supported
     * for these properties.
     * STATIC 表示属性不可修改
     */
    STATIC = 0x00,

    /**
     * Properties of this type must report when there is a change.
     * IVehicle#get call must return the current value.
     * Set operation for this property is assumed to be asynchronous. When the
     * property is read (using IVehicle#get) after IVehicle#set, it may still
     * return old value until underlying H/W backing this property has actually
     * changed the state. Once state is changed, the property must dispatch
     * changed value as event.
     * ON_CHANGE 表示属性必须在改变时报告
     */
    ON_CHANGE = 0x01,

    /**
     * Properties of this type change continuously and require a fixed rate of
     * sampling to retrieve the data.  Implementers may choose to send extra
     * notifications on significant value changes.
     * CONTINUOUS 属性在不断变化,需要固定的速率来检索数据
     */
    CONTINUOUS = 0x02,
};
2.3.3.14 车辆属性访问 VehiclePropertyAccess

下面是 types.hal 中定义的车辆属性访问配置。

/**
 * Property config defines the capabilities of it. User of the API
 * must first get the property config to understand the output from get()
 * commands and also to ensure that set() or events commands are in sync with
 * the expected output.
 * 属性定义功能访问模式。
 */
enum VehiclePropertyAccess : int32_t {
    NONE = 0x00,

    READ = 0x01, // 只读
    WRITE = 0x02, // 只写
    READ_WRITE = 0x03, // 读写
};
2.3.3.15 车辆属性状态 VehiclePropertyStatus

下面是 types.hal 中定义的车辆属性状态。

/**
 * Property status is a dynamic value that may change based on the vehicle state.
 * 属性状态是一个动态值,可能会根据车辆状态而改变。
 */
enum VehiclePropertyStatus : int32_t {
    /** Property is available and behaving normally */
    AVAILABLE   = 0x00, // 属性可用且运行正常
    /**
     * A property in this state is not available for reading and writing.  This
     * is a transient state that depends on the availability of the underlying
     * implementation (e.g. hardware or driver). It MUST NOT be used to
     * represent features that this vehicle is always incapable of.  A get() of
     * a property in this state MAY return an undefined value, but MUST
     * correctly describe its status as UNAVAILABLE A set() of a property in
     * this state MAY return NOT_AVAILABLE. The HAL implementation MUST ignore
     * the value of the status field when writing a property value coming from
     * Android.
     */
    UNAVAILABLE = 0x01, // 处于此状态的属性不可用于读写。这是一种瞬态,依赖于底层实现的可用性(例如硬件或驱动程序)。
    /** There is an error with this property. */
    ERROR       = 0x02,
};
2.3.3.16 汽车齿轮属性 VehicleGear

下面是 types.hal 中定义的汽车齿轮属性。

/**
 * Various gears which can be selected by user and chosen in system.
 * 各种齿轮可由用户选择,并在系统中选择。
 */
enum VehicleGear : int32_t {
    GEAR_NEUTRAL = 0x0001,
    GEAR_REVERSE = 0x0002,
    GEAR_PARK = 0x0004,
    GEAR_DRIVE = 0x0008,
    GEAR_1 = 0x0010,
    GEAR_2 = 0x0020,
    GEAR_3 = 0x0040,
    GEAR_4 = 0x0080,
    GEAR_5 = 0x0100,
    GEAR_6 = 0x0200,
    GEAR_7 = 0x0400,
    GEAR_8 = 0x0800,
    GEAR_9 = 0x1000,
};
2.3.3.17 汽车座椅区域属性 VehicleAreaSeat

下面是 types.hal 中定义的汽车座椅区域属性。

/**
 * Various Seats in the car.
 * 汽车里的各种座位。
 */
enum VehicleAreaSeat : int32_t {
    ROW_1_LEFT   = 0x0001,
    ROW_0_CENTER = 0x0002,
    ROW_1_RIGHT  = 0x0004,
    ROW_2_LEFT   = 0x0010,
    ROW_2_CENTER = 0x0020,
    ROW_2_RIGHT  = 0x0040,
    ROW_3_LEFT   = 0x0100,
    ROW_3_CENTER = 0x0200,
    ROW_3_RIGHT  = 0x0400
};
2.3.3.18 汽车玻璃区域属性 VehicleAreaWindow

下面是 types.hal 中定义的汽车玻璃区域属性。

/**
 * Various windshields/windows in the car.
 * 汽车的各种挡风玻璃/窗户。
 */
enum VehicleAreaWindow : int32_t {
    FRONT_WINDSHIELD  = 0x00000001, // 前挡风玻璃
    REAR_WINDSHIELD   = 0x00000002, // 后挡风玻璃
    ROW_1_LEFT        = 0x00000010,
    ROW_1_RIGHT       = 0x00000040,
    ROW_2_LEFT        = 0x00000100,
    ROW_2_RIGHT       = 0x00000400,
    ROW_3_LEFT        = 0x00001000,
    ROW_3_RIGHT       = 0x00004000,

    ROOF_TOP_1        = 0x00010000,
    ROOF_TOP_2        = 0x00020000,

};
2.3.3.19 车辆门区域属性 VehicleAreaDoor

下面是 types.hal 中定义的车辆门区域属性。

enum VehicleAreaDoor : int32_t {
    ROW_1_LEFT = 0x00000001,
    ROW_1_RIGHT = 0x00000004,
    ROW_2_LEFT = 0x00000010,
    ROW_2_RIGHT = 0x00000040,
    ROW_3_LEFT = 0x00000100,
    ROW_3_RIGHT = 0x00000400,
    HOOD = 0x10000000,
    REAR = 0x20000000,
};
2.3.3.20 车辆镜子区域属性 VehicleAreaMirror

下面是 types.hal 中定义的车辆镜子区域属性。

enum VehicleAreaMirror : int32_t {
    DRIVER_LEFT = 0x00000001,
    DRIVER_RIGHT = 0x00000002,
    DRIVER_CENTER = 0x00000004,
};
2.3.3.21 车辆转向灯属性 VehicleTurnSignal

下面是 types.hal 中定义的车辆转向灯属性。

enum VehicleTurnSignal : int32_t {
    NONE = 0x00,
    RIGHT = 0x01,
    LEFT = 0x02,
};
2.3.3.22 车辆区域配置结构体 VehicleAreaConfig

下面是 types.hal 中定义的车辆区域配置结构体。

struct VehicleAreaConfig {
    /**
     * Area id is ignored for VehiclePropertyGroup:GLOBAL properties.
     * 对于全局属性,忽略 Area 区域 id。
     */
    int32_t areaId;

    /**
     * If the property has @data_enum, leave the range to zero.
     *
     * Range will be ignored in the following cases:
     *    - The VehiclePropertyType is not INT32, INT64 or FLOAT.
     *    - Both of min value and max value are zero.
     */

    int32_t minInt32Value;
    int32_t maxInt32Value;

    int64_t minInt64Value;
    int64_t maxInt64Value;

    float minFloatValue;
    float maxFloatValue;
};
2.3.3.23 车辆属性配置 VehiclePropConfig

下面是 types.hal 中定义的车辆属性配置。

struct VehiclePropConfig { // Vehicle Property 的配置
    /** Property identifier */
    int32_t prop; // property 标识符

    /**
     * Defines if the property is read or write or both.
     */
    VehiclePropertyAccess access; // 定义属性是读还是写,还是两者兼而有之

    /**
     * Defines the change mode of the property.
     */
    VehiclePropertyChangeMode changeMode; // 定义属性的更改模式

    /**
     * Contains per-area configuration.
     */
    vec<VehicleAreaConfig> areaConfigs; // 包含每个区域的配置

    /** Contains additional configuration parameters */
    vec<int32_t> configArray; // 包含其他配置参数

    /**
     * Some properties may require additional information passed over this
     * string. Most properties do not need to set this.
     */
    string configString; // 某些属性可能需要通过该字符串传递额外的信息

    /**
     * Min sample rate in Hz.
     * Must be defined for VehiclePropertyChangeMode::CONTINUOUS
     */
    float minSampleRate; // 最小采样率(Hz)

    /**
     * Must be defined for VehiclePropertyChangeMode::CONTINUOUS
     * Max sample rate in Hz.
     */
    float maxSampleRate; // 最大采样率(Hz)
};
2.3.3.24 车辆属性值 VehiclePropValue

下面是 types.hal 中定义的车辆属性值。

/**
 * Encapsulates the property name and the associated value. It
 * is used across various API calls to set values, get values or to register for
 * events.
 * 封装属性名和关联值。它在各种 API 调用中用于设置值、获取值或注册事件。
 */
struct VehiclePropValue {
    /** Time is elapsed nanoseconds since boot */
    int64_t timestamp; // 从 boot 开始的时间

    /**
     * Area type(s) for non-global property it must be one of the value from
     * VehicleArea* enums or 0 for global properties.
     * 对于非全局属性,区域类型必须是VehicleArea*枚举中的值之一;对于全局属性必须是0。
     */
    int32_t areaId;

    /** Property identifier */
    int32_t prop; // 属性标识符

    /** Status of the property */
    VehiclePropertyStatus status; // 属性状态

    /**
     * Contains value for a single property. Depending on property data type of
     * this property (VehiclePropetyType) one field of this structure must be filled in.
     * 包含单个属性的值。根据该属性的属性数据类型(vehiclepetytype),必须填充该结构的一个字段。
     */
    struct RawValue {
        /**
         * This is used for properties of types VehiclePropertyType#INT
         * and VehiclePropertyType#INT_VEC
         */
        vec<int32_t> int32Values;

        /**
         * This is used for properties of types VehiclePropertyType#FLOAT
         * and VehiclePropertyType#FLOAT_VEC
         */
        vec<float> floatValues;

        /** This is used for properties of type VehiclePropertyType#INT64 */
        vec<int64_t> int64Values;

        /** This is used for properties of type VehiclePropertyType#BYTES */
        vec<uint8_t> bytes;

        /** This is used for properties of type VehiclePropertyType#STRING */
        string stringValue;
    };

    RawValue value;
};

2.4 启动流程

2.4.1 VehicleHal 类图

下面是 VehicleHal 的类图

2.4.2 VehicleHal 启动序列图

下面是 VehicleHal 启动序列图

2.4.3 VehicleHal 启动流程
2.4.3.1 VehicleService.cpp

VehicleHal 的入口文件是 VehicleService.cpp。路径为:android/hardware/interfaces/automotive/vehicle/2.0/default。下面是 VehicleService.cpp 的内容:

cpp 复制代码
#define LOG_TAG "automotive.vehicle@2.0-service"
#include <android/log.h>
#include <hidl/HidlTransportSupport.h>

#include <iostream>

#include <vhal_v2_0/VehicleHalManager.h>
#include <vhal_v2_0/EmulatedVehicleHal.h>

using namespace android;
using namespace android::hardware;
using namespace android::hardware::automotive::vehicle::V2_0;

int main(int /* argc */, char* /* argv */ []) {
    // 创建 VehiclePropertyStore 对象
    auto store = std::make_unique<VehiclePropertyStore>();
    // 创建 EmulatedVehicleHal 对象
    auto hal = std::make_unique<impl::EmulatedVehicleHal>(store.get());
    // 创建 VehicleEmulator 对象
    auto emulator = std::make_unique<impl::VehicleEmulator>(hal.get());
    // 创建 VehicleHalManager 对象
    auto service = std::make_unique<VehicleHalManager>(hal.get());

    configureRpcThreadpool(4, true /* callerWillJoin */);

    // 注册 VehicleService 服务
    ALOGI("Registering as service...");
    status_t status = service->registerAsService();

    if (status != OK) {
        ALOGE("Unable to register vehicle service (%d)", status);
        return 1;
    }

    ALOGI("Ready");
    joinRpcThreadpool();

    return 1;
}

从 VehicleService.cpp 中可以发现,主要初始化了 Vehicle 相关服务类,并注册 Vehicle 服务。下面可以来简单跟踪下各类的功能。

2.4.3.2 VehiclePropertyStore.cpp

VehiclePropertyStore 类是用于封装与存储和访问配置、存储和修改车辆属性值相关的工作。内部主要维护一个 PropertyMap mPropertyValues,PropertyMap = std::map<RecordId, VehiclePropValue>;用于通过 RecordId 保存对应的 VehiclePropValue 值。

VehiclePropValue.h :

android/hardware/interfaces/automotive/vehicle/2.0/default/common/include/vhal_v2_0/VehiclePropertyStore.h

VehiclePropertyStore.cpp :

android/hardware/interfaces/automotive/vehicle/2.0/default/common/src/VehiclePropertyStore.cpp

车辆属性在 VehiclePropertyStore 是存储在有序的 Map 集合中,这样可以更加方便的获取属性的值。VehiclePropertyStore 的使用是线程安全的,方法间使用同步阻塞保证线程安全。

下面是 VehiclePropertyStore.h 头文件的内容:

cpp 复制代码
class VehiclePropertyStore {
public:
    /* Function that used to calculate unique token for given VehiclePropValue */
    using TokenFunction = std::function<int64_t(const VehiclePropValue& value)>;

private:
    // 定义 RecordConfig 结构体
    struct RecordConfig {
        VehiclePropConfig propConfig;
        TokenFunction tokenFunction;
    };

    // 定义 RecordId 结构体
    struct RecordId {
        int32_t prop; // propid
        int32_t area; // areaid
        int64_t token;

        bool operator==(const RecordId& other) const;
        bool operator<(const RecordId& other) const;
    };

    // 定义 RecordId 和 vehiclePropValue 对应的 Map 集合
    using PropertyMap = std::map<RecordId, VehiclePropValue>;
    using PropertyMapRange = std::pair<PropertyMap::const_iterator, PropertyMap::const_iterator>;

public:
    // 注册 Property 函数
    void registerProperty(const VehiclePropConfig& config, TokenFunction tokenFunc = nullptr);

    /* Stores provided value. Returns true if value was written returns false if config for
     * example wasn't registered. */
    // 写入 VehiclePropValue 值
    bool writeValue(const VehiclePropValue& propValue, bool updateStatus);

    // 移除 VehiclePropValue 值
    void removeValue(const VehiclePropValue& propValue);
    // 通过 propId 移除 VehiclePropValue 值
    void removeValuesForProperty(int32_t propId);

    // 获取所有的 VehiclePropValue 值
    std::vector<VehiclePropValue> readAllValues() const;
    std::vector<VehiclePropValue> readValuesForProperty(int32_t propId) const;
    std::unique_ptr<VehiclePropValue> readValueOrNull(const VehiclePropValue& request) const;
    std::unique_ptr<VehiclePropValue> readValueOrNull(int32_t prop, int32_t area = 0,
                                                      int64_t token = 0) const;

    // 获取所有的 VehiclePropConfig 值
    std::vector<VehiclePropConfig> getAllConfigs() const;
    // 根据 propId 获取 VehiclePropConfig 值
    const VehiclePropConfig* getConfigOrNull(int32_t propId) const;
    const VehiclePropConfig* getConfigOrDie(int32_t propId) const;

private:
    RecordId getRecordIdLocked(const VehiclePropValue& valuePrototype) const;
    const VehiclePropValue* getValueOrNullLocked(const RecordId& recId) const;
    PropertyMapRange findRangeLocked(int32_t propId) const;

private:
    using MuxGuard = std::lock_guard<std::mutex>;
    mutable std::mutex mLock;
    std::unordered_map<int32_t /* VehicleProperty */, RecordConfig> mConfigs;

    PropertyMap mPropertyValues;  // Sorted map of RecordId : VehiclePropValue.
};
2.4.3.3 EmulatedVehicleHal

EmulatedVehicleHal 的文件路径如下:

EmulatedVehicleHal.h 路径为:

android/hardware/interfaces/automotive/vehicle/2.0/default/impl/vhal_v2_0/EmulatedVehicleHal.h

EmulatedVehicleHal.cpp 路径为:

android/hardware/interfaces/automotive/vehicle/2.0/defaultandroid/hardware/interfaces/automotive/vehicle/2.0/default/impl/vhal_v2_0/EmulatedVehicleHal.cpp

EmulatedVehicleHal 可以理解为 VehicleHal 功能的真正实施类,EmulatedVehicleHal 实现了 EmulatedVehicleHalIface 和 VehicleHal 的功能。上层的 Binder 在 Hal 层的流转后,最终是通过 EmulatedVehicleHal 去处理的。下面是 EmulatedVehicleHal 头文件的内容:

cpp 复制代码
class EmulatedVehicleHal : public EmulatedVehicleHalIface { // EmulatedVehicleHalIface 继承了 VehicleHal
public:
    EmulatedVehicleHal(VehiclePropertyStore* propStore);
    ~EmulatedVehicleHal() = default;
    
    //  Methods from VehicleHal
    // 实现了 VehicleHal 接口功能,上层的 Binder 调用会调用到这里
    void onCreate() override;
    std::vector<VehiclePropConfig> listProperties() override;
    VehiclePropValuePtr get(const VehiclePropValue& requestedPropValue,
                            StatusCode* outStatus) override;
    StatusCode set(const VehiclePropValue& propValue) override;
    StatusCode subscribe(int32_t property, float sampleRate) override;
    StatusCode unsubscribe(int32_t property) override;

    //  Methods from EmulatedVehicleHalIface
    // 实现了 EmulatedVehicleHalIface 接口功能
    bool setPropertyFromVehicle(const VehiclePropValue& propValue) override;
    std::vector<VehiclePropValue> getAllProperties() const override;
    
private:
    constexpr std::chrono::nanoseconds hertzToNanoseconds(float hz) const {
        return std::chrono::nanoseconds(static_cast<int64_t>(1000000000L / hz));
    }   
    
    StatusCode handleGenerateFakeDataRequest(const VehiclePropValue& request);
    void onFakeValueGenerated(const VehiclePropValue& value);
    VehiclePropValuePtr createApPowerStateReq(VehicleApPowerStateReq req, int32_t param);
    VehiclePropValuePtr createHwInputKeyProp(VehicleHwKeyInputAction action, int32_t keyCode,
                                             int32_t targetDisplay); 
                                             
    void onContinuousPropertyTimer(const std::vector<int32_t>& properties);
    bool isContinuousProperty(int32_t propId) const;
    void initStaticConfig();
    void initObd2LiveFrame(const VehiclePropConfig& propConfig);
    void initObd2FreezeFrame(const VehiclePropConfig& propConfig);
    StatusCode fillObd2FreezeFrame(const VehiclePropValue& requestedPropValue,
                                   VehiclePropValue* outValue);
    StatusCode fillObd2DtcInfo(VehiclePropValue* outValue);
    StatusCode clearObd2FreezeFrames(const VehiclePropValue& propValue);

    /* Private members */
    VehiclePropertyStore* mPropStore;
    std::unordered_set<int32_t> mHvacPowerProps;
    RecurrentTimer mRecurrentTimer;
    GeneratorHub mGeneratorHub;
};
2.4.3.4 VehicleEmulator

VehicleEmulator 的文件路径如下:

VehicleEmulator.h 的文件路径为:android/hardware/interfaces/automotive/vehicle/2.0/default/impl/vhal_v2_0/VehicleEmulator.h

VehicleEmulator.cpp 的文件路径为:

android/hardware/interfaces/automotive/vehicle/2.0/default/impl/vhal_v2_0/VehicleEmulator.cpp

VehicleEmulator 的解释是通过 ADB 或 Pipe 从主机端提供控制接口来模拟车辆。

VehicleEmulator 可以理解为通过 SPI 通信与 MCU 芯片建立通信,连通车身 Can 网络来获取车辆的信号的处理类。厂商基于 VehicleEmulator 的功能搭建厂商自身的车身通信功能,例如通过 DBus 与 MCU 通信,获取来自 MCU 的车身数据;MCU 通过 Can 网络获取车身其他固件,例如空调、座椅等其他 ECU 件的数据。

下面是 VehicleEmulator.h 文件的内容:

cpp 复制代码
class VehicleEmulator;  // Forward declaration.

/** Extension of VehicleHal that used by VehicleEmulator. */
// 定义 EmulatedVehicleHalIface 类,扩展 VehicleHal 接口。
class EmulatedVehicleHalIface : public VehicleHal {
public:
    virtual bool setPropertyFromVehicle(const VehiclePropValue& propValue) = 0;
    virtual std::vector<VehiclePropValue> getAllProperties() const = 0;

    void registerEmulator(VehicleEmulator* emulator) {
        ALOGI("%s, emulator: %p", __func__, emulator);
        std::lock_guard<std::mutex> g(mEmulatorLock);
        mEmulator = emulator;
    }

protected:
    VehicleEmulator* getEmulatorOrDie() {
        std::lock_guard<std::mutex> g(mEmulatorLock);
        if (mEmulator == nullptr) abort();
        return mEmulator;
    }

private:
    mutable std::mutex mEmulatorLock;
    VehicleEmulator* mEmulator;
};

/**
 * Emulates vehicle by providing controlling interface from host side either through ADB or Pipe.
 */
// 定义 VehicleEmulator 类,通过 socket、pipe 模拟车辆
class VehicleEmulator : public MessageProcessor {
   public:
    VehicleEmulator(EmulatedVehicleHalIface* hal);
    virtual ~VehicleEmulator();

    void doSetValueFromClient(const VehiclePropValue& propValue);
    void processMessage(emulator::EmulatorMessage const& rxMsg,
                        emulator::EmulatorMessage& respMsg) override;

   private:
    friend class ConnectionThread;
    using EmulatorMessage = emulator::EmulatorMessage;

    void doGetConfig(EmulatorMessage const& rxMsg, EmulatorMessage& respMsg);
    void doGetConfigAll(EmulatorMessage const& rxMsg, EmulatorMessage& respMsg);
    void doGetProperty(EmulatorMessage const& rxMsg, EmulatorMessage& respMsg);
    void doGetPropertyAll(EmulatorMessage const& rxMsg, EmulatorMessage& respMsg);
    void doSetProperty(EmulatorMessage const& rxMsg, EmulatorMessage& respMsg);
    void populateProtoVehicleConfig(emulator::VehiclePropConfig* protoCfg,
                                    const VehiclePropConfig& cfg);
    void populateProtoVehiclePropValue(emulator::VehiclePropValue* protoVal,
                                       const VehiclePropValue* val);

private:
    EmulatedVehicleHalIface* mHal;
    std::unique_ptr<SocketComm> mSocketComm;
    std::unique_ptr<PipeComm> mPipeComm;
};
2.4.3.5 VehicleHalManager

VehicleHalManager 的文件路径如下:

VehicleHalManager.h 文件路径为:android/hardware/interfaces/automotive/vehicle/2.0/default/common/include/vhal_v2_0/VehicleHalManager.h

VehicleHalManager.cpp 文件路径为:

android/hardware/interfaces/automotive/vehicle/2.0/default/common/src/VehicleHalManager.cpp

VehicleHalManager 类是 IVehicle HIDL 接口和厂商实现之间的一个代理。VehicleHalManager 直接继承了 IVehicle,上层调用 Hild 接口时,会最先调用到此类中,VehicleHalManager 在初始化时获取 VehicleHal 对象,厂商需要实现 VehicleHal 类以提供 VehicleHal 的功能。

下面是 VehicleHalManager.h 文件的内容:

cpp 复制代码
/**
 * This class is a thick proxy between IVehicle HIDL interface and vendor's implementation.
 *
 * It has some boilerplate code like batching and caching property values, checking permissions,
 * etc. Vendors must implement VehicleHal class.
 */
// VehicleHalManager 继承 IVehicle 类,提供 Hidl 接口调用
class VehicleHalManager : public IVehicle {
public:
    // 构造函数需要传入 VehicleHal 类对象,具体 Hidl 接口功能实现由 VehicleHal 提供
    VehicleHalManager(VehicleHal* vehicleHal)
        : mHal(vehicleHal),
          mSubscriptionManager(std::bind(&VehicleHalManager::onAllClientsUnsubscribed,
                                         this, std::placeholders::_1)) {
        init();
    }

    virtual ~VehicleHalManager();

    void init();

    // ---------------------------------------------------------------------------------------------
    // Methods derived from IVehicle 实现 Hidl 接口函数
    Return<void> getAllPropConfigs(getAllPropConfigs_cb _hidl_cb)  override;
    Return<void> getPropConfigs(const hidl_vec<int32_t>& properties,
                                getPropConfigs_cb _hidl_cb)  override;
    Return<void> get(const VehiclePropValue& requestedPropValue,
                     get_cb _hidl_cb)  override;
    Return<StatusCode> set(const VehiclePropValue& value)  override;
    Return<StatusCode> subscribe(const sp<IVehicleCallback>& callback,
                                const hidl_vec<SubscribeOptions>& options)  override;
    Return<StatusCode> unsubscribe(const sp<IVehicleCallback>& callback,
                                   int32_t propId)  override;
    Return<void> debugDump(debugDump_cb _hidl_cb = nullptr) override;

private:
    using VehiclePropValuePtr = VehicleHal::VehiclePropValuePtr;
    // Returns true if needs to call again shortly.
    using RetriableAction = std::function<bool()>;

    // ---------------------------------------------------------------------------------------------
    // Events received from VehicleHal
    void onHalEvent(VehiclePropValuePtr  v);
    void onHalPropertySetError(StatusCode errorCode, int32_t property,
                               int32_t areaId);

    // ---------------------------------------------------------------------------------------------
    // This method will be called from BatchingConsumer thread
    void onBatchHalEvent(const std::vector<VehiclePropValuePtr >& values);

    void handlePropertySetEvent(const VehiclePropValue& value);

    const VehiclePropConfig* getPropConfigOrNull(int32_t prop) const;

    bool checkWritePermission(const VehiclePropConfig &config) const;
    bool checkReadPermission(const VehiclePropConfig &config) const;
    void onAllClientsUnsubscribed(int32_t propertyId);

    static bool isSubscribable(const VehiclePropConfig& config,
                               SubscribeFlags flags);
    static bool isSampleRateFixed(VehiclePropertyChangeMode mode);
    static float checkSampleRate(const VehiclePropConfig& config,
                                 float sampleRate);
    static ClientId getClientId(const sp<IVehicleCallback>& callback);
private:
    VehicleHal* mHal;  // 保存 VehicleHal 对象
    std::unique_ptr<VehiclePropConfigIndex> mConfigIndex;
    SubscriptionManager mSubscriptionManager;

    hidl_vec<VehiclePropValue> mHidlVecOfVehiclePropValuePool;

    ConcurrentQueue<VehiclePropValuePtr> mEventQueue;
    BatchingConsumer<VehiclePropValuePtr> mBatchingConsumer;
    VehiclePropValuePool mValueObjectPool;
};

3、总结

本篇主要描述了 Android 原生的 Automotive 框架中 VehicleHal 的逻辑。简单来说,VehicleHal 层主要是完成了对上层 Hidl 接口功能的实现,具体实现依赖厂商的逻辑,从框架上是封装了厂商的 VechielHal 实现,提供车辆网络信号的设置和获取功能。

上一篇:AndroidAutomotive模块介绍(三)CarService服务

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