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

2、VehicleHal 模块功能

2.1 rc 文件

service vendor.vehicle-hal-2.0 /vendor/bin/hw/android.hardware.automotive.vehicle@2.0-serviceclass haluser vehicle_networkgroup system inet

2.2 编译

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

// 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,
}

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

// 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",],
}

2.3 HIDL 接口

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 YazakiIEC_TYPE_2_AC = 2,              // aka MennekesIEC_TYPE_3_AC = 3,              // aka ScameIEC_TYPE_4_DC = 4,              // aka CHAdeMOIEC_TYPE_1_CCS_DC = 5,          // aka Combo 1IEC_TYPE_2_CCS_DC = 6,          // aka Combo 2TESLA_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：

#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：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 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：

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：

/*** 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 VehicleHalvoid onHalEvent(VehiclePropValuePtr  v);void onHalPropertySetError(StatusCode errorCode, int32_t property,int32_t areaId);// ---------------------------------------------------------------------------------------------// This method will be called from BatchingConsumer threadvoid 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;
};

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。

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