AndroidAutomotive模块介绍（四）VehicleHal介绍

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已于 2025-04-24 15:45:22 修改 · 置顶 · 1.7k 阅读

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于 2025-04-23 16:18:45 首次发布

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

Android Vehicle HAL架构-腾讯云开发者社区-腾讯云

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：

// 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：

// 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 Th

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