AndroidAutomotive模块介绍（四）VehicleHal介绍_vehicle hal

技术文档

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 -ltotal 132-rw-r--r-- 1 users 375 Nov 9 2022 Android.bpdrwxrwxr-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 -ltotal 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.rcdrwxrwxr-x 4 users 4096 Jun 7 2022 commondrwxrwxr-x 3 users 4096 Jun 7 2022 impldrwxrwxr-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 libcc_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 implementationcc_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 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 props) generates (StatusCode status, vec 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 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 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 areaConfigs; // 包含每个区域的配置 /** Contains additional configuration parameters */ vec 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 int32Values; /** * This is used for properties of types VehiclePropertyType#FLOAT * and VehiclePropertyType#FLOAT_VEC */ vec floatValues; /** This is used for properties of type VehiclePropertyType#INT64 */ vec int64Values; /** This is used for properties of type VehiclePropertyType#BYTES */ vec 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
在这里插入图片描述

2.4.2 VehicleHal 启动序列图

下面是 VehicleHal 启动序列图
在这里插入图片描述

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：

#define LOG_TAG \"automotive.vehicle@2.0-service\"#include #include #include #include #include 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(); // 创建 EmulatedVehicleHal 对象 auto hal = std::make_unique(store.get()); // 创建 VehicleEmulator 对象 auto emulator = std::make_unique(hal.get()); // 创建 VehicleHalManager 对象 auto service = std::make_unique(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；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：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：

class EmulatedVehicleHal : public EmulatedVehicleHalIface { // EmulatedVehicleHalIface 继承了 VehicleHalpublic: 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 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 getAllProperties() const override; private: constexpr std::chrono::nanoseconds hertzToNanoseconds(float hz) const { return std::chrono::nanoseconds(static_cast(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& 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 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：

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 getAllProperties() const = 0; void registerEmulator(VehicleEmulator* emulator) { ALOGI(\"%s, emulator: %p\", __func__, emulator); std::lock_guard g(mEmulatorLock); mEmulator = emulator; }protected: VehicleEmulator* getEmulatorOrDie() { std::lock_guard 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 mSocketComm; std::unique_ptr 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：

/** * 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 getAllPropConfigs(getAllPropConfigs_cb _hidl_cb) override; Return getPropConfigs(const hidl_vec& properties, getPropConfigs_cb _hidl_cb) override; Return get(const VehiclePropValue& requestedPropValue,  get_cb _hidl_cb) override; Return set(const VehiclePropValue& value) override; Return subscribe(const sp& callback, const hidl_vec& options) override; Return unsubscribe(const sp& callback, int32_t propId) override; Return debugDump(debugDump_cb _hidl_cb = nullptr) override;private: using VehiclePropValuePtr = VehicleHal::VehiclePropValuePtr; // Returns true if needs to call again shortly. using RetriableAction = std::function; // --------------------------------------------------------------------------------------------- // 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& 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& callback);private: VehicleHal* mHal; // 保存 VehicleHal 对象 std::unique_ptr mConfigIndex; SubscriptionManager mSubscriptionManager; hidl_vec mHidlVecOfVehiclePropValuePool; ConcurrentQueue mEventQueue; BatchingConsumer mBatchingConsumer; VehiclePropValuePool mValueObjectPool;};

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。