Add vehicle hal.

- vehicle hal is used for supporting car specific features.
- Each property can be written (=set), read (=get), or subscribed.
- Each property has configuration informaiton to tell what that property
  is and how it can be accessed.
- also adding dummy hal implementation.

bug: 25183740

Change-Id: Ib1cc1c11540f156db73552f2a18a8efb361002af
diff --git a/include/hardware/vehicle.h b/include/hardware/vehicle.h
new file mode 100644
index 0000000..267a910
--- /dev/null
+++ b/include/hardware/vehicle.h
@@ -0,0 +1,1492 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_VEHICLE_INTERFACE_H
+#define ANDROID_VEHICLE_INTERFACE_H
+
+#include <stdint.h>
+#include <sys/cdefs.h>
+#include <sys/types.h>
+#include <errno.h>
+
+#include <hardware/hardware.h>
+#include <cutils/native_handle.h>
+
+__BEGIN_DECLS
+
+/*****************************************************************************/
+
+#define VEHICLE_HEADER_VERSION          1
+#define VEHICLE_MODULE_API_VERSION_1_0  HARDWARE_MODULE_API_VERSION(1, 0)
+#define VEHICLE_DEVICE_API_VERSION_1_0  HARDWARE_DEVICE_API_VERSION_2(1, 0, VEHICLE_HEADER_VERSION)
+
+/**
+ * Vehicle HAL to provide interfaces to various Car related sensors. The HAL is
+ * designed in a property, value maping where each property has a value which
+ * can be "get", "set" and "(un)subscribed" to. Subscribing will require the
+ * user of this HAL to provide parameters such as sampling rate.
+ */
+
+
+/*
+ * The id of this module
+ */
+#define VEHICLE_HARDWARE_MODULE_ID  "vehicle"
+
+/**
+ *  Name of the vehicle device to open
+ */
+#define VEHICLE_HARDWARE_DEVICE     "vehicle_hw_device"
+
+/**
+ * Each vehicle property is defined with various annotations to specify the type of information.
+ * Annotations will be used by scripts to run some type check or generate some boiler-plate codes.
+ * Also the annotations are the specification for each property, and each HAL implementation should
+ * follow what is specified as annotations.
+ * Here is the list of annotations with explanation on what it does:
+ * @value_type: Type of data for this property. One of the value from vehicle_value_type should be
+ *              set here.
+ * @change_mode: How this property changes. Value set is from vehicle_prop_change_mode. Some
+ *               properties can allow either on change or continuous mode and it is up to HAL
+ *               implementation to choose which mode to use.
+ * @access: Define how this property can be accessed. read only, write only or R/W from
+ *          vehicle_prop_access
+ * @data_member: Name of member from vehicle_value union to access this data.
+ * @data_enum: enum type that should be used for the data.
+ * @unit: Unit of data. Should be from vehicle_unit_type.
+ * @config_string: Explains the usage of config_string in vehicle_prop_config. Property with
+ *                 this annotation is expected to have additional information in config_string
+ *                 for that property to work.
+ * @range_start, @range_end : define range of specific property values.
+ */
+//===== Vehicle Information ====
+
+/**
+ * Invalid property value used for argument where invalid property gives different result.
+ * @range_start
+ */
+#define VEHICLE_PROPERTY_INVALID (0x0)
+
+/**
+ * VIN of vehicle
+ * @value_type VEHICLE_VALUE_TYPE_STRING
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_STATIC
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member info_vin
+ */
+#define VEHICLE_PROPERTY_INFO_VIN                                   (0x00000100)
+
+/**
+ * Maker name of vehicle
+ * @value_type VEHICLE_VALUE_TYPE_STRING
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_STATIC
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member info_make
+ */
+#define VEHICLE_PROPERTY_INFO_MAKE                                  (0x00000101)
+
+/**
+ * Model of vehicle
+ * @value_type VEHICLE_VALUE_TYPE_STRING
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_STATIC
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member info_model
+ */
+#define VEHICLE_PROPERTY_INFO_MODEL                                 (0x00000102)
+
+/**
+ * Model year of vehicle.
+ * @value_type VEHICLE_VALUE_TYPE_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_STATIC
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member info_model_year
+ * @unit VEHICLE_UNIT_TYPE_YEAR
+ */
+#define VEHICLE_PROPERTY_INFO_MODEL_YEAR                           (0x00000103)
+
+/**
+ * Fuel capacity of the vehicle
+ * @value_type VEHICLE_VALUE_TYPE_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_STATIC
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member info_fuel_capacity
+ * @unit VEHICLE_UNIT_TYPE_VEHICLE_UNIT_TYPE_MILLILITER
+ */
+#define VEHICLE_PROPERTY_INFO_FUEL_CAPACITY                         (0x00000104)
+
+
+//==== Vehicle Performance Sensors ====
+
+/**
+ * Current odometer value of the vehicle
+ * @value_type VEHICLE_VALUE_TYPE_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member odometer
+ * @unit VEHICLE_UNIT_TYPE_KILOMETER
+ */
+#define VEHICLE_PROPERTY_PERF_ODOMETER                              (0x00000204)
+
+/**
+ * Speed of the vehicle
+ * @value_type VEHICLE_VALUE_TYPE_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member vehicle_speed
+ * @unit VEHICLE_UNIT_TYPE_METER_PER_SEC
+ */
+#define VEHICLE_PROPERTY_PERF_VEHICLE_SPEED                         (0x00000207)
+
+
+//==== Engine Sensors ====
+
+/**
+ * Temperature of engine coolant
+ * @value_type VEHICLE_VALUE_TYPE_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member engine_coolant_temperature
+ * @unit VEHICLE_UNIT_TYPE_CELCIUS
+ */
+#define VEHICLE_PROPERTY_ENGINE_COOLANT_TEMP                        (0x00000301)
+
+/**
+ * Temperature of engine oil
+ * @value_type VEHICLE_VALUE_TYPE_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member engine_oil_temperature
+ * @unit VEHICLE_UNIT_TYPE_CELCIUS
+ */
+#define VEHICLE_PROPERTY_ENGINE_OIL_TEMP                            (0x00000304)
+/**
+ * Engine rpm
+ * @value_type VEHICLE_VALUE_TYPE_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member engine_rpm
+ * @unit VEHICLE_UNIT_TYPE_RPM
+ */
+#define VEHICLE_PROPERTY_ENGINE_RPM                                 (0x00000305)
+
+//==== Event Sensors ====
+
+/**
+ * Currently selected gear
+ * @value_type VEHICLE_VALUE_TYPE_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member gear_selection
+ * @data_enum vehicle_gear
+ */
+#define VEHICLE_PROPERTY_GEAR_SELECTION                             (0x00000400)
+
+/**
+ * Current gear. In non-manual case, selected gear does not necessarily match the current gear
+ * @value_type VEHICLE_VALUE_TYPE_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member gear_current_gear
+ * @data_enum vehicle_gear
+ */
+#define VEHICLE_PROPERTY_CURRENT_GEAR                               (0x00000401)
+
+/**
+ * Parking brake state.
+ * @value_type VEHICLE_VALUE_TYPE_BOOLEAN
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member parking_brake
+ * @data_enum vehicle_boolean
+ */
+#define VEHICLE_PROPERTY_PARKING_BRAKE_ON                           (0x00000402)
+
+/**
+ * Driving status policy.
+ * @value_type VEHICLE_VALUE_TYPE_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member driving_status
+ * @data_enum vehicle_driving_status
+ */
+#define VEHICLE_PROPERTY_DRIVING_STATUS                             (0x00000404)
+
+/**
+ * Warning for fuel low level.
+ * @value_type VEHICLE_VALUE_TYPE_BOOLEAN
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member is_fuel_level_low
+ * @data_enum vehicle_boolean
+ */
+#define VEHICLE_PROPERTY_FUEL_LEVEL_LOW                             (0x00000405)
+
+/**
+ * Night mode or not.
+ * @value_type VEHICLE_VALUE_TYPE_BOOLEAN
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member night_mode
+ * @data_enum vehicle_boolean
+ */
+#define VEHICLE_PROPERTY_NIGHT_MODE                                 (0x00000407)
+
+
+
+ //==== HVAC Properties ====
+
+/**
+ * Fan speed setting
+ * @value_type VEHICLE_VALUE_TYPE_ZONED_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member hvac.fan_speed
+ * @data_enum TODO
+ */
+#define VEHICLE_PROPERTY_HVAC_FAN_SPEED                             (0x00000500)
+
+/**
+ * Fan direction setting
+ * @value_type VEHICLE_VALUE_TYPE_ZONED_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member hvac.fan_direction
+ * @data_enum TODO
+ */
+#define VEHICLE_PROPERTY_HVAC_FAN_DIRECTION                         (0x00000501)
+
+/**
+ * HVAC current temperature.
+ * @value_type VEHICLE_VALUE_TYPE_ZONED_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member hvac.temperature_current
+ */
+#define VEHICLE_PROPERTY_HVAC_TEMPERATURE_CURRENT                   (0x00000502)
+
+/**
+ * HVAC, target temperature set.
+ * @value_type VEHICLE_VALUE_TYPE_ZONED_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member hvac.temperature_set
+ */
+#define VEHICLE_PROPERTY_HVAC_TEMPERATURE_SET                       (0x00000503)
+
+/**
+ * On/off defrost
+ * @value_type VEHICLE_VALUE_TYPE_ZONED_BOOLEAN
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member hvac.defrost_on
+ */
+#define VEHICLE_PROPERTY_HVAC_DEFROSTER                             (0x00000504)
+
+/**
+ * On/off AC
+ * @value_type VEHICLE_VALUE_TYPE_ZONED_BOOLEAN
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member hvac.ac_on
+ */
+#define VEHICLE_PROPERTY_HVAC_AC_ON                                 (0x00000505)
+
+/**
+ * Outside temperature
+ * @value_type VEHICLE_VALUE_TYPE_FLOAT
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE|VEHICLE_PROP_CHANGE_MODE_CONTINUOUS
+ * @access VEHICLE_PROP_ACCESS_READ
+ * @data_member outside_temperature
+ * @unit VEHICLE_UNIT_TYPE_CELCIUS
+ */
+#define VEHICLE_PROPERTY_ENV_OUTSIDE_TEMP                           (0x00000703)
+
+
+/*
+ * Radio features.
+ */
+/**
+ * Radio presets stored on the Car radio module. The data type used is int32
+ * array with the following fields:
+ * <ul>
+ *    <li> int32_array[0]: Preset number </li>
+ *    <li> int32_array[1]: Band type (see #RADIO_BAND_FM in
+ *    system/core/include/system/radio.h).
+ *    <li> int32_array[2]: Channel number </li>
+ *    <li> int32_array[3]: Sub channel number </li>
+ * </ul>
+ *
+ * NOTE: When getting a current preset config ONLY set preset number (i.e.
+ * int32_array[0]). For setting a preset other fields are required.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32_VEC4
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member int32_array
+ */
+#define VEHICLE_PROPERTY_RADIO_PRESET                               (0x0000801)
+
+/**
+ * Constants relevant to radio.
+ */
+enum vehicle_radio_consts {
+    /** Minimum value for the radio preset */
+    VEHICLE_RADIO_PRESET_MIN_VALUE = 1,
+};
+
+/**
+ * Represents audio focus state of Android side. Note that car's audio module will own audio
+ * focus and grant audio focus to Android side when requested by Android side. The focus has both
+ * per stream characteristics and global characteristics.
+ *
+ * Focus request (get of this property) will take the following form in int32_vec4:
+ *   int32_array[0]: vehicle_audio_focus_request_type
+ *   int32_array[1]: bit flags of streams requested by this focus request. There can be up to
+ *                   32 streams.
+ *   int32_array[2]: External focus state flags. For request, only flag like
+ *                   VEHICLE_AUDIO_EXT_FOCUS_CAR_PLAY_ONLY_FLAG can be used.
+ *                   This is for case like radio where android side app still needs to hold focus
+ *                   but playback is done outside Android.
+ * Note that each focus request can request multiple streams that is expected to be used for
+ * the current request. But focus request itself is global behavior as GAIN or GAIN_TRANSIENT
+ * expects all sounds played by car's audio module to stop. Note that stream already allocated to
+ * android before this focus request should not be affected by focus request.
+ *
+ * Focus response (set and subscription callback for this property) will take the following form:
+ *   int32_array[0]: vehicle_audio_focus_state_type
+ *   int32_array[1]: bit flags of streams allowed.
+ *   int32_array[2]: External focus state: bit flags of currently active audio focus in car
+ *                   side (outside Android). Active audio focus does not necessarily mean currently
+ *                   playing, but represents the state of having focus or waiting for focus
+ *                   (pause state).
+ *                   One or combination of flags from vehicle_audio_ext_focus_flag.
+ *                   0 means no active audio focus holder outside Android.
+ *                   The state will have following values for each vehicle_audio_focus_state_type:
+ *                   GAIN: 0 or VEHICLE_AUDIO_EXT_FOCUS_CAR_PLAY_ONLY when radio is active in
+ *                       Android side.
+ *                   GAIN_TRANSIENT: 0. Can be VEHICLE_AUDIO_EXT_FOCUS_CAR_PERMANENT or
+ *                       VEHICLE_AUDIO_EXT_FOCUS_CAR_TRANSIENT if android side has requested
+ *                       GAIN_TRANSIENT_MAY_DUCK and car side is ducking.
+ *                   LOSS: 0 when no focus is audio is active in car side.
+ *                       VEHICLE_AUDIO_EXT_FOCUS_CAR_PERMANENT when car side is playing something
+ *                       permanent.
+ *                   LOSS_TRANSIENT: always should be VEHICLE_AUDIO_EXT_FOCUS_CAR_TRANSIENT
+ *
+ * If car does not support VEHICLE_PROPERTY_AUDIO_FOCUS, focus is assumed to be granted always.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32_VEC3
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member int32_array
+ */
+#define VEHICLE_PROPERTY_AUDIO_FOCUS                                  (0x00000900)
+
+enum vehicle_audio_focus_request {
+    VEHICLE_AUDIO_FOCUS_REQUEST_GAIN = 0x1,
+    VEHICLE_AUDIO_FOCUS_REQUEST_GAIN_TRANSIENT = 0x2,
+    VEHICLE_AUDIO_FOCUS_REQUEST_GAIN_TRANSIENT_MAY_DUCK = 0x3,
+    VEHICLE_AUDIO_FOCUS_REQUEST_RELEASE = 0x4,
+};
+
+enum vehicle_audio_focus_state {
+    /**
+     * Android side has permanent focus and can play allowed streams.
+     */
+    VEHICLE_AUDIO_FOCUS_STATE_GAIN = 0x1,
+    /**
+     * Android side has transient focus and can play allowed streams.
+     */
+    VEHICLE_AUDIO_FOCUS_STATE_GAIN_TRANSIENT = 0x2,
+    /**
+     * Car audio module is playing guidance kind of sound outside Android. Android side can
+     * still play through allowed streams with ducking.
+     */
+    VEHICLE_AUDIO_FOCUS_STATE_LOSS_TRANSIENT_CAN_DUCK = 0x3,
+    /**
+     * Car audio module is playing transient sound outside Android. Android side should stop
+     * playing any sounds.
+     */
+    VEHICLE_AUDIO_FOCUS_STATE_LOSS_TRANSIENT = 0x4,
+    /**
+     * Android side has lost focus and cannot play any sound.
+     */
+    VEHICLE_AUDIO_FOCUS_STATE_LOSS = 0x5,
+    /**
+     * car audio module is playing safety critical sound, and Android side cannot request focus
+     * until the current state is finished. car audio module should restore it to the previous
+     * state when it can allow Android to play.
+     */
+    VEHICLE_AUDIO_FOCUS_STATE_LOSS_TRANSIENT_EXLCUSIVE = 0x6,
+};
+
+/**
+ * Flags to represent multiple streams by combining these.
+ */
+enum vehicle_audio_stream_flag {
+    VEHICLE_AUDIO_STREAM_STREAM0_FLAG = (0x1<<0),
+    VEHICLE_AUDIO_STREAM_STREAM1_FLAG = (0x1<<1),
+    VEHICLE_AUDIO_STREAM_STREAM2_FLAG = (0x1<<2),
+};
+
+/**
+ * Represents stream number (always 0 to N -1 where N is max number of streams).
+ * Can be used for audio related property expecting one stream.
+ */
+enum vehicle_audio_stream {
+    VEHICLE_AUDIO_STREAM0 = 0,
+    VEHICLE_AUDIO_STREAM1 = 1,
+};
+
+/**
+ * Flag to represent external focus state (outside Android).
+ */
+enum vehicle_audio_ext_focus_flag {
+    /**
+     * No external focus holder.
+     */
+    VEHICLE_AUDIO_EXT_FOCUS_NONE_FLAG = 0x0,
+    /**
+     * Car side (outside Android) has component holding GAIN kind of focus state.
+     */
+    VEHICLE_AUDIO_EXT_FOCUS_CAR_PERMANENT_FLAG = 0x1,
+    /**
+     * Car side (outside Android) has component holding GAIN_TRANSIENT kind of focus state.
+     */
+    VEHICLE_AUDIO_EXT_FOCUS_CAR_TRANSIENT_FLAG = 0x2,
+    /**
+     * Car side is expected to play something while focus is held by Android side. One example
+     * can be radio attached in car side. But Android's radio app still should have focus,
+     * and Android side should be in GAIN state, but media stream will not be allocated to Android
+     * side and car side can play radio any time while this flag is active.
+     */
+    VEHICLE_AUDIO_EXT_FOCUS_CAR_PLAY_ONLY_FLAG = 0x4,
+};
+
+/**
+ * Index in int32_array for VEHICLE_PROPERTY_AUDIO_FOCUS property.
+ */
+enum vehicle_audio_focus_index {
+    VEHICLE_AUDIO_FOCUS_INDEX_FOCUS = 0,
+    VEHICLE_AUDIO_FOCUS_INDEX_STREAMS = 1,
+    VEHICLE_AUDIO_FOCUS_INDEX_EXTERNAL_FOCUS_STATE = 2,
+};
+
+/**
+ * Property to control audio volume of each stream.
+ *
+ * Data type looks like:
+ *   int32_array[0] : stream number (not bit flag) like VEHICLE_AUDIO_STREAM0.
+ *   int32_array[1] : volume level, valid range is 0 to int32_max_value defined in config.
+ *                    0 will be mute state. int32_min_value in config should be always 0.
+ *   int32_array[2] : One of vehicle_audio_volume_state.
+ *
+ * This property requires per stream based get. HAL implementation should check stream number
+ * in get call to return the right volume.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32_VEC3
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member int32_array
+ */
+#define VEHICLE_PROPERTY_AUDIO_VOLUME                                 (0x00000901)
+
+/**
+ * enum to represent audio volume state.
+ */
+enum vehicle_audio_volume_state {
+    VEHICLE_AUDIO_VOLUME_STATE_OK            = 0,
+    /**
+     * Audio volume has reached volume limit set in VEHICLE_PROPERTY_AUDIO_VOLUME_LIMIT
+     * and user's request to increase volume further is not allowed.
+     */
+    VEHICLE_AUDIO_VOLUME_STATE_LIMIT_REACHED = 1,
+};
+
+/**
+ * Index in int32_array for VEHICLE_PROPERTY_AUDIO_VOLUME property.
+ */
+enum vehicle_audio_volume_index {
+    VEHICLE_AUDIO_VOLUME_INDEX_STREAM = 0,
+    VEHICLE_AUDIO_VOLUME_INDEX_VOLUME = 1,
+    VEHICLE_AUDIO_VOLUME_INDEX_STATE = 2,
+};
+
+/**
+ * Property for handling volume limit set by user. This limits maximum volume that can be set
+ * per each volume.
+ *   int32_array[0] : stream number (not bit flag) like VEHICLE_AUDIO_STREAM0.
+ *   int32_array[1] : maximum volume set to the stream. If there is no restriction, this value
+ *                    will be  bigger than VEHICLE_PROPERTY_AUDIO_VOLUME's max value.
+ *
+ * If car does not support this feature, this property should not be populated by HAL.
+ * This property requires per stream based get. HAL implementation should check stream number
+ * in get call to return the right volume.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32_VEC2
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member int32_array
+ */
+#define VEHICLE_PROPERTY_AUDIO_VOLUME_LIMIT                           (0x00000902)
+
+/**
+ * Index in int32_array for VEHICLE_PROPERTY_AUDIO_VOLUME_LIMIT property.
+ */
+enum vehicle_audio_volume_limit_index {
+    VEHICLE_AUDIO_VOLUME_LIMIT_INDEX_STREAM = 0,
+    VEHICLE_AUDIO_VOLUME_LIMIT_INDEX_MAX_VOLUME = 1,
+};
+
+/**
+ * Property to share audio routing policy of android side. This property is set at the beginning
+ * to pass audio policy in android side down to vehicle HAL and car audio module.
+ * This can be used as a hint to adjust audio policy or other policy decision.
+ *
+ *   int32_array[0] : audio stream where the audio for the application context will be routed
+ *                    by default. Note that this is the default setting from system, but each app
+ *                    may still use different audio stream for whatever reason.
+ *   int32_array[1] : All application contexts that will be sent through the physical stream. Flag
+ *                    is defined in vehicle_app_context_flag.
+
+ * Setting of this property will be done for all available physical streams based on audio H/W
+ * variant information acquired from VEHICLE_PROPERTY_AUDIO_HW_VARIANT property.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32_VEC2
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_WRITE
+ * @data_member int32_array
+ */
+#define VEHICLE_PROPERTY_AUDIO_ROUTING_POLICY                         (0x00000903)
+
+/**
+ * Index in int32_array for VEHICLE_PROPERTY_AUDIO_ROUTING_POLICY property.
+ */
+enum vehicle_audio_routing_policy_index {
+    VEHICLE_AUDIO_ROUTING_POLICY_INDEX_STREAM = 0,
+    VEHICLE_AUDIO_ROUTING_POLICY_INDEX_CONTEXTS = 1,
+};
+
+/**
+* Property to return audio H/W variant type used in this car. This allows android side to
+* support different audio policy based on H/W variant used. Note that other components like
+* CarService may need overlay update to support additional variants. If this property does not
+* exist, default audio policy will be used.
+*
+* @value_type VEHICLE_VALUE_TYPE_INT32
+* @change_mode VEHICLE_PROP_CHANGE_MODE_STATIC
+* @access VEHICLE_PROP_ACCESS_READ
+* @data_member int32_value
+*/
+#define VEHICLE_PROPERTY_AUDIO_HW_VARIANT                             (0x00000904)
+
+/**
+ * Flag to be used in vehicle_prop_config.config_flags for VEHICLE_PROPERTY_AUDIO_HW_VARIANT.
+ */
+enum vehicle_audio_hw_variant_config_flag {
+    /**
+     * This is a flag to disable the default behavior of not sending focus request for radio module.
+     * By default, when radio app request audio focus, that focus request is filtered out and
+     * is not sent to car audio module as radio is supposed to be played by car radio module and
+     * android side should have have audio focus for media stream.
+     * But in some H/W, radio may be directly played from android side, and in that case,
+     * android side should take focus for media stream. This flag should be enabled in such case.
+     */
+    VEHICLE_AUDIO_HW_VARIANT_FLAG_PASS_RADIO_AUDIO_FOCUS_FLAG = 0x1,
+};
+
+/**
+ * Property to control power state of application processor.
+ *
+ * It is assumed that AP's power state is controller by separate power controller.
+ *
+ * For configuration information, vehicle_prop_config.config_flags can have bit flag combining
+ * values in vehicle_ap_power_state_config_type.
+ *
+ * For get / notification, data type looks like this:
+ *   int32_array[0] : vehicle_ap_power_state_type
+ *   int32_array[1] : additional parameter relevant for each state. should be 0 if not used.
+ * For set, data type looks like this:
+ *   int32_array[0] : vehicle_ap_power_state_set_type
+ *   int32_array[1] : additional parameter relevant for each request. should be 0 if not used.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32_VEC2
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member int32_array
+ */
+#define VEHICLE_PROPERTY_AP_POWER_STATE                               (0x00000A00)
+
+enum vehicle_ap_power_state_config_flag {
+    /**
+     * AP can enter deep sleep state. If not set, AP will always shutdown from
+     * VEHICLE_AP_POWER_STATE_SHUTDOWN_PREPARE power state.
+     */
+    VEHICLE_AP_POWER_STATE_CONFIG_ENABLE_DEEP_SLEEP_FLAG = 0x1,
+
+    /**
+     * The power controller can power on AP from off state after timeout specified in
+     * VEHICLE_AP_POWER_SET_SHUTDOWN_READY message.
+     */
+    VEHICLE_AP_POWER_STATE_CONFIG_SUPPORT_TIMER_POWER_ON_FLAG = 0x2,
+};
+
+enum vehicle_ap_power_state {
+    /** vehicle HAL will never publish this state to AP */
+    VEHICLE_AP_POWER_STATE_OFF = 0,
+    /** vehicle HAL will never publish this state to AP */
+    VEHICLE_AP_POWER_STATE_DEEP_SLEEP = 1,
+    /** AP is on but display should be off. */
+    VEHICLE_AP_POWER_STATE_ON_DISP_OFF = 2,
+    /** AP is on with display on. This state allows full user interaction. */
+    VEHICLE_AP_POWER_STATE_ON_FULL = 3,
+    /**
+     * The power controller has requested AP to shutdown. AP can either enter sleep state or start
+     * full shutdown. AP can also request postponing shutdown by sending
+     * VEHICLE_AP_POWER_SET_SHUTDOWN_POSTPONE message. The power controller should change power
+     * state to this state to shutdown system.
+     *
+     * int32_array[1] : one of enum_vehicle_ap_power_state_shutdown_param_type
+     */
+    VEHICLE_AP_POWER_STATE_SHUTDOWN_PREPARE = 4,
+};
+
+enum vehicle_ap_power_state_shutdown_param {
+    /** AP should shutdown immediately. Postponing is not allowed. */
+    VEHICLE_AP_POWER_SHUTDOWN_PARAM_SHUTDOWN_IMMEDIATELY = 1,
+    /** AP can enter deep sleep instead of shutting down completely. */
+    VEHICLE_AP_POWER_SHUTDOWN_PARAM_CAN_SLEEP = 2,
+    /** AP can only shutdown with postponing allowed. */
+    VEHICLE_AP_POWER_SHUTDOWN_PARAM_SHUTDOWN_ONLY = 3,
+};
+
+enum vehicle_ap_power_set_state {
+    /**
+     * AP has finished boot up, and can start shutdown if requested by power controller.
+     */
+    VEHICLE_AP_POWER_SET_BOOT_COMPLETE = 0x1,
+    /**
+     * AP is entering deep sleep state. How this state is implemented may vary depending on
+     * each H/W, but AP's power should be kept in this state.
+     */
+    VEHICLE_AP_POWER_SET_DEEP_SLEEP_ENTRY = 0x2,
+    /**
+     * AP is exiting from deep sleep state, and is in VEHICLE_AP_POWER_STATE_SHUTDOWN_PREPARE state.
+     * The power controller may change state to other ON states based on the current state.
+     */
+    VEHICLE_AP_POWER_SET_DEEP_SLEEP_EXIT = 0x3,
+    /**
+     * int32_array[1]: Time to postpone shutdown in ms. Maximum value can be 5000 ms.
+     *                 If AP needs more time, it will send another POSTPONE message before
+     *                 the previous one expires.
+     */
+    VEHICLE_AP_POWER_SET_SHUTDOWN_POSTPONE = 0x4,
+    /**
+     * AP is starting shutting down. When system completes shutdown, everything will stop in AP
+     * as kernel will stop all other contexts. It is responsibility of vehicle HAL or lower level
+     * to synchronize that state with external power controller. As an example, some kind of ping
+     * with timeout in power controller can be a solution.
+     *
+     * int32_array[1]: Time to turn on AP in secs. Power controller may turn on AP after specified
+     *                 time so that AP can run tasks like update. If it is set to 0, there is no
+     *                 wake up, and power controller may not necessarily support wake-up.
+     *                 If power controller turns on AP due to timer, it should start with
+     *                 VEHICLE_AP_POWER_STATE_ON_DISP_OFF state, and after receiving
+     *                 VEHICLE_AP_POWER_SET_BOOT_COMPLETE, it shall do state transition to
+     *                 VEHICLE_AP_POWER_STATE_SHUTDOWN_PREPARE.
+     */
+    VEHICLE_AP_POWER_SET_SHUTDOWN_START = 0x5,
+    /**
+     * User has requested to turn off headunit's display, which is detected in android side.
+     * The power controller may change the power state to VEHICLE_AP_POWER_STATE_ON_DISP_OFF.
+     */
+    VEHICLE_AP_POWER_SET_DISPLAY_OFF = 0x6,
+    /**
+     * User has requested to turn on headunit's display, most probably from power key input which
+     * is attached to headunit. The power controller may change the power state to
+     * VEHICLE_AP_POWER_STATE_ON_FULL.
+     */
+    VEHICLE_AP_POWER_SET_DISPLAY_ON = 0x7,
+};
+
+/**
+ * Property to represent brightness of the display. Some cars have single control for
+ * the brightness of all displays and this property is to share change in that control.
+ *
+ * If this is writable, android side can set this value when user changes display brightness
+ * from Settings. If this is read only, user may still change display brightness from Settings,
+ * but that will not be reflected to other displays.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_READ|VEHICLE_PROP_ACCESS_READ_WRITE
+ * @data_member int32
+ */
+#define VEHICLE_PROPERTY_DISPLAY_BRIGHTNESS                        (0x00000A01)
+
+
+/**
+ * Index in int32_array for VEHICLE_PROPERTY_AP_POWER_STATE property.
+ */
+enum vehicle_ap_power_state_index {
+    VEHICLE_AP_POWER_STATE_INDEX_STATE = 0,
+    VEHICLE_AP_POWER_STATE_INDEX_ADDITIONAL = 1,
+};
+
+/**
+* Property to report bootup reason for the current power on. This is a static property that will
+* not change for the whole duration until power off. For example, even if user presses power on
+* button after automatic power on with door unlock, bootup reason should stay with
+* VEHICLE_AP_POWER_BOOTUP_REASON_USER_UNLOCK.
+*
+* int32_value should be vehicle_ap_power_bootup_reason.
+*
+* @value_type VEHICLE_VALUE_TYPE_INT32
+* @change_mode VEHICLE_PROP_CHANGE_MODE_STATIC
+* @access VEHICLE_PROP_ACCESS_READ
+* @data_member int32_value
+*/
+#define VEHICLE_PROPERTY_AP_POWER_BOOTUP_REASON                     (0x00000A02)
+
+/**
+ * Enum to represent bootup reason.
+ */
+enum vehicle_ap_power_bootup_reason {
+    /**
+     * Power on due to user's pressing of power key or rotating of ignition switch.
+     */
+    VEHICLE_AP_POWER_BOOTUP_REASON_USER_POWER_ON = 0,
+    /**
+     * Automatic power on triggered by door unlock or any other kind of automatic user detection.
+     */
+    VEHICLE_AP_POWER_BOOTUP_REASON_USER_UNLOCK   = 1,
+    /**
+     * Automatic power on triggered by timer. This only happens when AP has asked wake-up after
+     * certain time through time specified in VEHICLE_AP_POWER_SET_SHUTDOWN_START.
+     */
+    VEHICLE_AP_POWER_BOOTUP_REASON_TIMER         = 2,
+};
+
+/**
+ * Property to share currently active application context in android side.
+ * This can be used as a hint to adjust audio policy or other policy decision. Note that there
+ * can be multiple context active at the same time.
+ *
+ * @value_type VEHICLE_VALUE_TYPE_INT32
+ * @change_mode VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+ * @access VEHICLE_PROP_ACCESS_WRITE
+ * @data_member int32
+ */
+#define VEHICLE_PROPERTY_APP_CONTEXT                        (0x00000B00)
+/**
+ * Flags to tell the current application context. The same flag is used in
+ */
+enum vehicle_app_context_flag {
+    /** Music playback is currently active. */
+    VEHICLE_APP_CONTEXT_MUSIC_FLAG = 0x1,
+    /** Navigation is currently running. */
+    VEHICLE_APP_CONTEXT_NAVIGATION_FLAG = 0x2,
+    /** Voice command session is currently running. */
+    VEHICLE_APP_CONTEXT_VOICE_COMMAND_FLAG = 0x4,
+    /** Voice call is currently active. */
+    VEHICLE_APP_CONTEXT_CALL_FLAG = 0x8,
+    /** Alarm is active. This may be only used in VEHICLE_PROPERTY_AUDIO_ROUTING_POLICY. */
+    VEHICLE_APP_CONTEXT_ALARM_FLAG = 0x10,
+    /**
+     * Notification sound is active. This may be only used in VEHICLE_PROPERTY_AUDIO_ROUTING_POLICY.
+     */
+    VEHICLE_APP_CONTEXT_NOTIFICATION_FLAG = 0x20,
+    /**
+     * Context unknown. Only used for VEHICLE_PROPERTY_AUDIO_ROUTING_POLICY to represent default
+     * stream for unknown contents.
+     */
+    VEHICLE_APP_CONTEXT_UNKNOWN_FLAG = 0x40,
+};
+
+/**
+ *  H/W specific, non-standard property can be added as necessary. Such property should use
+ *  property number in range of [VEHICLE_PROPERTY_CUSTOM_START, VEHICLE_PROPERTY_CUSTOM_END].
+ *  Definition of property in this range is completely up to each HAL implementation.
+ *  For such property, it is recommended to fill vehicle_prop_config.config_string with some
+ *  additional information to help debugging. For example, company XYZ's custom extension may
+ *  include config_string of "com.XYZ.some_further_details".
+ *  @range_start
+ */
+#define VEHICLE_PROPERTY_CUSTOM_START                       (0xf0000000)
+/** @range_end */
+#define VEHICLE_PROPERTY_CUSTOM_END                         (0xf7ffffff)
+
+/**
+ * Property range allocated for system's internal usage like testing. HAL should never declare
+ * property in this range.
+ * @range_start
+ */
+#define VEHICLE_PROPERTY_INTERNAL_START                     (0xf8000000)
+/**
+ * @range_end
+ */
+#define VEHICLE_PROPERTY_INTERNAL_END                       (0xf8ffffff)
+
+/**
+ * Value types for various properties.
+ */
+enum vehicle_value_type {
+    VEHICLE_VALUE_TYPE_SHOUD_NOT_USE            = 0x00, // value_type should never set to 0.
+    VEHICLE_VALUE_TYPE_STRING                   = 0x01,
+    VEHICLE_VALUE_TYPE_BYTES                    = 0x02,
+    VEHICLE_VALUE_TYPE_BOOLEAN                  = 0x03,
+    VEHICLE_VALUE_TYPE_ZONED_INT32              = 0x04,
+    VEHICLE_VALUE_TYPE_ZONED_FLOAT              = 0x05,
+    VEHICLE_VALUE_TYPE_ZONED_BOOLEAN            = 0x06,
+    VEHICLE_VALUE_TYPE_INT64                    = 0x07,
+    VEHICLE_VALUE_TYPE_FLOAT                    = 0x10,
+    VEHICLE_VALUE_TYPE_FLOAT_VEC2               = 0x11,
+    VEHICLE_VALUE_TYPE_FLOAT_VEC3               = 0x12,
+    VEHICLE_VALUE_TYPE_FLOAT_VEC4               = 0x13,
+    VEHICLE_VALUE_TYPE_INT32                    = 0x20,
+    VEHICLE_VALUE_TYPE_INT32_VEC2               = 0x21,
+    VEHICLE_VALUE_TYPE_INT32_VEC3               = 0x22,
+    VEHICLE_VALUE_TYPE_INT32_VEC4               = 0x23,
+};
+
+/**
+ * Units used for int or float type with no attached enum types.
+ */
+enum vehicle_unit_type {
+    VEHICLE_UNIT_TYPE_SHOULD_NOT_USE        = 0x00000000,
+    // speed related items
+    VEHICLE_UNIT_TYPE_METER_PER_SEC         = 0x00000001,
+    VEHICLE_UNIT_TYPE_RPM                   = 0x00000002,
+    VEHICLE_UNIT_TYPE_HZ                    = 0x00000003,
+    // kind of ratio
+    VEHICLE_UNIT_TYPE_PERCENTILE            = 0x00000010,
+    // length
+    VEHICLE_UNIT_TYPE_MILLIMETER            = 0x00000020,
+    VEHICLE_UNIT_TYPE_METER                 = 0x00000021,
+    VEHICLE_UNIT_TYPE_KILOMETER             = 0x00000023,
+    // temperature
+    VEHICLE_UNIT_TYPE_CELCIUS               = 0x00000030,
+    // volume
+    VEHICLE_UNIT_TYPE_MILLILITER            = 0x00000040,
+    // time
+    VEHICLE_UNIT_TYPE_NANO_SECS             = 0x00000050,
+    VEHICLE_UNOT_TYPE_SECS                  = 0x00000053,
+    VEHICLE_UNIT_TYPE_YEAR                  = 0x00000059,
+};
+
+/**
+ * Error code used in HAL implemnentation. Follows utils/Errors.h
+ */
+enum vehicle_error_code {
+    VEHICLE_NO_ERROR    = 0x0,
+    VEHICLE_ERROR_UNKNOWN       = (-2147483647 - 1), // INT32_MIN value
+    VEHICLE_ERROR_NO_MEMORY           = -12, //ENOMEM
+    VEHICLE_ERROR_INVALID_OPERATION   = -38, //ENOSYS
+    VEHICLE_ERROR_BAD_VALUE           = -22, //EINVAL
+    VEHICLE_ERROR_BAD_TYPE            = (VEHICLE_ERROR_UNKNOWN + 1),
+    VEHICLE_ERROR_NAME_NOT_FOUND      = -2, //ENOENT
+    VEHICLE_ERROR_PERMISSION_DENIED   = -1, //EPERM
+    VEHICLE_ERROR_NO_INIT             = -19, //ENODEV
+    VEHICLE_ERROR_ALREADY_EXISTS      = -17, //EEXIST
+    VEHICLE_ERROR_DEAD_OBJECT         = -32, //EPIPE
+    VEHICLE_ERROR_FAILED_TRANSACTION  = (VEHICLE_ERROR_UNKNOWN + 2),
+    VEHICLE_ERROR_BAD_INDEX           = -75, //EOVERFLOW
+    VEHICLE_ERROR_NOT_ENOUGH_DATA     = -61, //ENODATA
+    VEHICLE_ERROR_WOULD_BLOCK         = -11, //EWOULDBLOCK
+    VEHICLE_ERROR_TIMED_OUT           = -110, //ETIMEDOUT
+    VEHICLE_ERROR_UNKNOWN_TRANSACTION = -74, //EBADMSG
+    VEHICLE_FDS_NOT_ALLOWED     = (VEHICLE_ERROR_UNKNOWN + 7),
+};
+
+/**
+ * This describes how value of property can change.
+ */
+enum vehicle_prop_change_mode {
+    /**
+     * Property of this type will *never* change. This property will not support subscription, but
+     * will support get
+     */
+    VEHICLE_PROP_CHANGE_MODE_STATIC         = 0x00,
+    /**
+     * Property of this type will be reported when there is a change. get should return the
+     * current value.
+     */
+    VEHICLE_PROP_CHANGE_MODE_ON_CHANGE      = 0x01,
+    /**
+     * Property of this type change continuously and requires fixed rate of sampling to retrieve
+     * the data.
+     */
+    VEHICLE_PROP_CHANGE_MODE_CONTINUOUS     = 0x02,
+};
+
+/**
+ * Property config defines the capabilities of it. User of the API
+ * should 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.
+ */
+enum vehicle_prop_access {
+    VEHICLE_PROP_ACCESS_READ  = 0x01,
+    VEHICLE_PROP_ACCESS_WRITE = 0x02,
+    VEHICLE_PROP_ACCESS_READ_WRITE = 0x03
+};
+
+/**
+ * These permissions define how the OEMs want to distribute their information and security they
+ * want to apply. On top of these restrictions, android will have additional
+ * 'app-level' permissions that the apps will need to ask the user before the apps have the
+ * information.
+ * This information should be kept in vehicle_prop_config.permission_model.
+ */
+enum vehicle_permission_model {
+    /**
+     * No special restriction, but each property can still require specific android app-level
+     * permission.
+     */
+    VEHICLE_PERMISSION_NO_RESTRICTION = 0,
+    /** Signature only. Only APKs signed with OEM keys are allowed. */
+    VEHICLE_PERMISSION_OEM_ONLY = 0x1,
+    /** System only. APKs built-in to system  can access the property. */
+    VEHICLE_PERMISSION_SYSTEM_APP_ONLY = 0x2,
+    /** Equivalent to “system|signature” */
+    VEHICLE_PERMISSION_OEM_OR_SYSTEM_APP = 0x3
+};
+
+/**
+ * Car states.
+ *
+ * The driving states determine what features of the UI will be accessible.
+ */
+enum vehicle_driving_status {
+    VEHICLE_DRIVING_STATUS_UNRESTRICTED      = 0x00,
+    VEHICLE_DRIVING_STATUS_NO_VIDEO          = 0x01,
+    VEHICLE_DRIVING_STATUS_NO_KEYBOARD_INPUT = 0x02,
+    VEHICLE_DRIVING_STATUS_NO_VOICE_INPUT    = 0x04,
+    VEHICLE_DRIVING_STATUS_NO_CONFIG         = 0x08,
+    VEHICLE_DRIVING_STATUS_LIMIT_MESSAGE_LEN = 0x10
+};
+
+/**
+ * Various gears which can be selected by user and chosen in system.
+ */
+enum vehicle_gear {
+    // Gear selections present in both automatic and manual cars.
+    VEHICLE_GEAR_NEUTRAL    = 0x0001,
+    VEHICLE_GEAR_REVERSE    = 0x0002,
+
+    // Gear selections (mostly) present only in automatic cars.
+    VEHICLE_GEAR_PARKING    = 0x0004,
+    VEHICLE_GEAR_DRIVE      = 0x0008,
+    VEHICLE_GEAR_L          = 0x0010,
+
+    // Other possible gear selections (maybe present in manual or automatic
+    // cars).
+    VEHICLE_GEAR_1          = 0x0010,
+    VEHICLE_GEAR_2          = 0x0020,
+    VEHICLE_GEAR_3          = 0x0040,
+    VEHICLE_GEAR_4          = 0x0080,
+    VEHICLE_GEAR_5          = 0x0100,
+    VEHICLE_GEAR_6          = 0x0200,
+    VEHICLE_GEAR_7          = 0x0400,
+    VEHICLE_GEAR_8          = 0x0800,
+    VEHICLE_GEAR_9          = 0x1000
+};
+
+
+/**
+ * Various zones in the car.
+ *
+ * Zones are used for Air Conditioning purposes and divide the car into physical
+ * area zones.
+ */
+enum vehicle_zone {
+    VEHICLE_ZONE_ROW_1_LEFT    = 0x00000001,
+    VEHICLE_ZONE_ROW_1_CENTER  = 0x00000002,
+    VEHICLE_ZONE_ROW_1_RIGHT   = 0x00000004,
+    VEHICLE_ZONE_ROW_1_ALL     = 0x00000008,
+    VEHICLE_ZONE_ROW_2_LEFT    = 0x00000010,
+    VEHICLE_ZONE_ROW_2_CENTER  = 0x00000020,
+    VEHICLE_ZONE_ROW_2_RIGHT   = 0x00000040,
+    VEHICLE_ZONE_ROW_2_ALL     = 0x00000080,
+    VEHICLE_ZONE_ROW_3_LEFT    = 0x00000100,
+    VEHICLE_ZONE_ROW_3_CENTER  = 0x00000200,
+    VEHICLE_ZONE_ROW_3_RIGHT   = 0x00000400,
+    VEHICLE_ZONE_ROW_3_ALL     = 0x00000800,
+    VEHICLE_ZONE_ROW_4_LEFT    = 0x00001000,
+    VEHICLE_ZONE_ROW_4_CENTER  = 0x00002000,
+    VEHICLE_ZONE_ROW_4_RIGHT   = 0x00004000,
+    VEHICLE_ZONE_ROW_4_ALL     = 0x00008000,
+    VEHICLE_ZONE_ALL           = 0x80000000,
+};
+
+/**
+ * Various Seats in the car.
+ */
+enum vehicle_seat {
+    VEHICLE_SEAT_DRIVER_LHD        = 0x0001,
+    VEHICLE_SEAT_DRIVER_RHD        = 0x0002,
+    VEHICLE_SEAT_ROW_1_PASSENGER_1 = 0x0010,
+    VEHICLE_SEAT_ROW_1_PASSENGER_2 = 0x0020,
+    VEHICLE_SEAT_ROW_1_PASSENGER_3 = 0x0040,
+    VEHICLE_SEAT_ROW_2_PASSENGER_1 = 0x0100,
+    VEHICLE_SEAT_ROW_2_PASSENGER_2 = 0x0200,
+    VEHICLE_SEAT_ROW_2_PASSENGER_3 = 0x0400,
+    VEHICLE_SEAT_ROW_3_PASSENGER_1 = 0x1000,
+    VEHICLE_SEAT_ROW_3_PASSENGER_2 = 0x2000,
+    VEHICLE_SEAT_ROW_3_PASSENGER_3 = 0x4000
+};
+
+/**
+ * Various windshields/windows in the car.
+ */
+enum vehicle_window {
+    VEHICLE_WINDOW_FRONT_WINDSHIELD = 0x0001,
+    VEHICLE_WINDOW_REAR_WINDSHIELD  = 0x0002,
+    VEHICLE_WINDOW_ROOF_TOP         = 0x0004,
+    VEHICLE_WINDOW_ROW_1_LEFT       = 0x0010,
+    VEHICLE_WINDOW_ROW_1_RIGHT      = 0x0020,
+    VEHICLE_WINDOW_ROW_2_LEFT       = 0x0100,
+    VEHICLE_WINDOW_ROW_2_RIGHT      = 0x0200,
+    VEHICLE_WINDOW_ROW_3_LEFT       = 0x1000,
+    VEHICLE_WINDOW_ROW_3_RIGHT      = 0x2000,
+};
+
+enum vehicle_turn_signal {
+    VEHICLE_SIGNAL_NONE         = 0x00,
+    VEHICLE_SIGNAL_RIGHT        = 0x01,
+    VEHICLE_SIGNAL_LEFT         = 0x02,
+    VEHICLE_SIGNAL_EMERGENCY    = 0x04
+};
+
+/*
+ * Boolean type.
+ */
+enum vehicle_boolean {
+    VEHICLE_FALSE = 0x00,
+    VEHICLE_TRUE  = 0x01
+};
+
+typedef int32_t vehicle_boolean_t;
+
+/**
+ * Vehicle string.
+ *
+ * Defines a UTF8 encoded sequence of bytes that should be used for string
+ * representation throughout.
+ */
+typedef struct vehicle_str {
+    uint8_t* data;
+    int32_t len;
+} vehicle_str_t;
+
+/**
+ * Vehicle byte array.
+ * This is for passing generic raw data.
+ */
+typedef vehicle_str_t vehicle_bytes_t;
+
+typedef struct vehicle_zoned_int32 {
+    union {
+        int32_t zone;
+        int32_t seat;
+        int32_t window;
+    };
+    int32_t value;
+} vehicle_zoned_int32_t;
+
+typedef struct vehicle_zoned_float {
+    union {
+        int32_t zone;
+        int32_t seat;
+        int32_t window;
+    };
+    float value;
+} vehicle_zoned_float_t;
+
+typedef struct vehicle_zoned_boolean {
+    union {
+        int32_t zone;
+        int32_t seat;
+        int32_t window;
+    };
+    vehicle_boolean_t value;
+} vehicle_zoned_boolean_t;
+
+
+typedef struct vehicle_prop_config {
+    int32_t prop;
+
+    /**
+     * Defines if the property is read or write. Value should be one of
+     * enum vehicle_prop_access.
+     */
+    int32_t access;
+
+    /**
+     * Defines if the property is continuous or on-change. Value should be one
+     * of enum vehicle_prop_change_mode.
+     */
+    int32_t change_mode;
+
+    /**
+     * Type of data used for this property. This type is fixed per each property.
+     * Check vehicle_value_type for allowed value.
+     */
+    int32_t value_type;
+
+    /**
+     * Define necessary permission model to access the data.
+     */
+    int32_t permission_model;
+    /**
+     * Some of the properties may have associated zones (such as hvac), in these
+     * cases the config should contain an ORed value for the associated zone.
+     */
+    union {
+        /**
+         * For generic configuration information
+         */
+        int32_t config_flags;
+
+        /**
+         * The value is derived by ORing one or more of enum vehicle_zone members.
+         */
+        int32_t vehicle_zone_flags;
+        /** The value is derived by ORing one or more of enum vehicle_seat members. */
+        int32_t vehicle_seat_flags;
+        /** The value is derived by ORing one or more of enum vehicle_window members. */
+        int32_t vehicle_window_flags;
+
+        /** The number of presets that are stored by the radio module. Pass 0 if
+         * there are no presets available. The range of presets is defined to be
+         * from 1 (see VEHICLE_RADIO_PRESET_MIN_VALUE) to vehicle_radio_num_presets.
+         */
+        int32_t vehicle_radio_num_presets;
+    };
+
+    /**
+     * Some properties may require additional information passed over this string. Most properties
+     * do not need to set this and in that case, config_string.data should be NULL and
+     * config_string.len should be 0.
+     */
+    vehicle_str_t config_string;
+
+    /**
+     * Specify minimum allowed value for the property. This is necessary for property which does
+     * not have specified enum.
+     */
+    union {
+        float float_min_value;
+        int32_t int32_min_value;
+        int64_t int64_min_value;
+    };
+
+    /**
+     * Specify maximum allowed value for the property. This is necessary for property which does
+     * not have specified enum.
+     */
+    union {
+        float float_max_value;
+        int32_t int32_max_value;
+        int64_t int64_max_value;
+    };
+
+    /**
+     * Min sample rate in Hz. Should be 0 for sensor type of VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+     */
+    float min_sample_rate;
+    /**
+     * Max sample rate in Hz. Should be 0 for sensor type of VEHICLE_PROP_CHANGE_MODE_ON_CHANGE
+     */
+    float max_sample_rate;
+    /**
+     * Place holder for putting HAL implementation specific data. Usage is wholly up to HAL
+     * implementation.
+     */
+    void* hal_data;
+} vehicle_prop_config_t;
+
+/**
+ * HVAC property fields.
+ *
+ * Defines various HVAC properties which are packed into vehicle_hvac_t (see
+ * below). We define these properties outside in global scope so that HAL
+ * implementation and HAL users (JNI) can typecast vehicle_hvac correctly.
+ */
+typedef vehicle_zoned_int32_t vehicle_hvac_fan_speed_t;
+
+typedef vehicle_zoned_int32_t vehicle_hvac_fan_direction_t;
+
+typedef vehicle_zoned_float_t vehicle_hvac_zone_temperature_t;
+
+//TODO Typical seat heat/cooling is done in fixed steps. Needs better definition.
+//typedef struct vehicle_hvac_seat_temperature {
+//    // Value should be one of enum vehicle_seat.
+//    int32_t seat;
+//    float temperature;
+//} vehicle_hvac_heated_seat_temperature_t;
+
+typedef vehicle_zoned_boolean_t vehicle_hvac_defrost_on_t;
+
+typedef vehicle_zoned_boolean_t vehicle_hvac_ac_on_t;
+
+typedef struct vehicle_hvac {
+    /**
+     * Define one structure for each possible HVAC property.
+     * NOTES:
+     * a) Zone is defined in enum vehicle_zone.
+     * b) Fan speed is a number from (0 - 6) where 6 is the highest speed. (TODO define enum)
+     * c) Temperature is a floating point Celcius scale.
+     * d) Direction is defined in enum vehicle_fan_direction.
+     *
+     * The HAL should create #entries number of vehicle_hvac_properties and
+     * assign it to "properties" variable below.
+     */
+    union {
+        vehicle_hvac_fan_speed_t fan_speed;
+        vehicle_hvac_fan_direction_t fan_direction;
+        vehicle_hvac_ac_on_t ac_on;
+
+        vehicle_hvac_zone_temperature_t temperature_current;
+        vehicle_hvac_zone_temperature_t temperature_set;
+
+        //TODO Heated seat.
+        //vehicle_hvac_heated_seat_t heated_seat;
+
+        vehicle_hvac_defrost_on_t defrost_on;
+    };
+} vehicle_hvac_t;
+
+/*
+ * Defines how the values for various properties are represented.
+ *
+ * There are two ways to populate and access the fields:
+ * a) Using the individual fields. Use this mechanism (see
+ * info_manufacture_date, fuel_capacity fields etc).
+ * b) Using the union accessors (see uint32_value, float_value etc).
+ *
+ * To add a new field make sure that it does not exceed the total union size
+ * (defined in int_array) and it is one of the vehicle_value_type. Then add the
+ * field name with its unit to union. If the field type is not yet defined (as
+ * of this draft, we don't use int64_t) then add that type to vehicle_value_type
+ * and have an accessor (so for int64_t it will be int64_t int64_value).
+ */
+typedef union vehicle_value {
+    /** Define the max size of this structure. */
+    int32_t int32_array[4];
+    float float_array[4];
+
+    // Easy accessors for union members (HAL implementation SHOULD NOT USE these
+    // fields while populating, use the property specific fields below instead).
+    int32_t int32_value;
+    int64_t int64_value;
+    float float_value;
+    vehicle_str_t str_value;
+    vehicle_bytes_t bytes_value;
+    vehicle_boolean_t boolean_value;
+    vehicle_zoned_int32_t zoned_int32_value;
+    vehicle_zoned_float_t zoned_float_value;
+    vehicle_zoned_boolean_t zoned_boolean_value;
+
+    // Vehicle Information.
+    vehicle_str_t info_vin;
+    vehicle_str_t info_make;
+    vehicle_str_t info_model;
+    int32_t info_model_year;
+
+    // Represented in milliliters.
+    float info_fuel_capacity;
+
+    float vehicle_speed;
+    float odometer;
+
+    // Engine sensors.
+
+    // Represented in milliliters.
+    //float engine_coolant_level;
+    // Represented in celcius.
+    float engine_coolant_temperature;
+    // Represented in a percentage value.
+    //float engine_oil_level;
+    // Represented in celcius.
+    float engine_oil_temperature;
+    float engine_rpm;
+
+    // Event sensors.
+    // Value should be one of enum vehicle_gear_selection.
+    int32_t gear_selection;
+    // Value should be one of enum vehicle_gear.
+    int32_t gear_current_gear;
+    // Value should be one of enum vehicle_boolean.
+    int32_t parking_brake;
+    // If cruise_set_speed > 0 then cruise is ON otherwise cruise is OFF.
+    // Unit: meters / second (m/s).
+    //int32_t cruise_set_speed;
+    // Value should be one of enum vehicle_boolean.
+    int32_t is_fuel_level_low;
+    // Value should be one of enum vehicle_driving_status.
+    int32_t driving_status;
+    int32_t night_mode;
+    // Value should be one of emum vehicle_turn_signal.
+    int32_t turn_signals;
+    // Value should be one of enum vehicle_boolean.
+    //int32_t engine_on;
+
+    // HVAC properties.
+    vehicle_hvac_t hvac;
+
+    float outside_temperature;
+} vehicle_value_t;
+
+/*
+ * 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.
+ */
+typedef struct vehicle_prop_value {
+    /* property identifier */
+    int32_t prop;
+
+    /* value type of property for quick conversion from union to appropriate
+     * value. The value must be one of enum vehicle_value_type.
+     */
+    int32_t value_type;
+
+    /** time is elapsed nanoseconds since boot */
+    int64_t timestamp;
+
+    vehicle_value_t value;
+} vehicle_prop_value_t;
+
+/*
+ * 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 set()
+ * command is executed and the actual change needs to be reported.
+ *
+ * event_data is OWNED by the HAL and should be copied before the callback
+ * finishes.
+ */
+typedef int (*vehicle_event_callback_fn)(const vehicle_prop_value_t *event_data);
+
+
+/**
+ * Represent the operation where the current error has happened.
+ */
+enum vehicle_property_operation {
+    /** Generic error to this property which is not tied to any operation. */
+    VEHICLE_OPERATION_GENERIC = 0,
+    /** Error happened while handling property set. */
+    VEHICLE_OPERATION_SET = 1,
+    /** Error happened while handling property get. */
+    VEHICLE_OPERATION_GET = 2,
+    /** Error happened while handling property subscription. */
+    VEHICLE_OPERATION_SUBSCRIBE = 3,
+};
+
+/*
+ * Suggests that an error condition has occured. error_code should be one of
+ * enum vehicle_error_code.
+ *
+ * @param error_code Error code. It should be one of enum vehicle_error_code.
+ *                   See error code for details.
+ * @parm property Note a property where error has happened. If this is generic error, property
+ *                should be VEHICLE_PROPERTY_INVALID.
+ * @param operation Represent the operation where the error has happened. Should be one of
+ *                  vehicle_property_operation.
+ */
+typedef int (*vehicle_error_callback_fn)(int32_t error_code, int32_t property, int32_t operation);
+
+/************************************************************************************/
+
+/*
+ * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
+ * and the fields of this data structure must begin with hw_module_t
+ * followed by module specific information.
+ */
+typedef struct vehicle_module {
+    struct hw_module_t common;
+} vehicle_module_t;
+
+
+typedef struct vehicle_hw_device {
+    struct hw_device_t common;
+
+    /**
+     * After calling open on device the user should register callbacks for event and error
+     * functions.
+     */
+    int (*init)(struct vehicle_hw_device* device,
+                vehicle_event_callback_fn event_fn, vehicle_error_callback_fn err_fn);
+    /**
+     * Before calling close the user should destroy the registered callback
+     * functions.
+     * In case the unsubscribe() call is not called on all properties before
+     * release() then release() will unsubscribe the properties itself.
+     */
+    int (*release)(struct vehicle_hw_device* device);
+
+    /**
+     * Enumerate all available properties. The list is returned in "list".
+     * @param num_properties number of properties contained in the retuned array.
+     * @return array of property configs supported by this car. Note that returned data is const
+     *         and caller cannot modify it. HAL implementation should keep this memory until HAL
+     *         is released to avoid copying this again.
+     */
+    vehicle_prop_config_t const *(*list_properties)(struct vehicle_hw_device* device,
+            int* num_properties);
+
+    /**
+     * Get a vehicle property value immediately. data should be allocated
+     * properly.
+     * The caller of the API OWNS the data field.
+     * Caller will only set data->prop and HAL implementation needs to fill all entries properly.
+     * For pointer type, HAL implementation should allocate necessary memory and caller is
+     * responsible for freeing memory for the pointer.
+     * For VEHICLE_PROP_CHANGE_MODE_STATIC type of property, get should return the same value
+     * always.
+     * For VEHICLE_PROP_CHANGE_MODE_ON_CHANGE type of property, it should return the latest value.
+     */
+    int (*get)(struct vehicle_hw_device* device, vehicle_prop_value_t *data);
+
+    /**
+     * Set a vehicle property value.  data should be allocated properly and not
+     * NULL.
+     * The caller of the API OWNS the data field.
+     * timestamp of data will be ignored for set operation.
+     */
+    int (*set)(struct vehicle_hw_device* device, const vehicle_prop_value_t *data);
+
+    /**
+     * Subscribe to events.
+     * Depending on output of list_properties if the property is:
+     * a) on-change: sample_rate should be set to 0.
+     * b) supports frequency: sample_rate should be set from min_sample_rate to
+     * max_sample_rate.
+     * Subscribing to properties in-correctly may result in error callbacks and
+     * will depend on HAL implementation.
+     * @param device
+     * @param prop
+     * @param sample_rate
+     */
+    int (*subscribe)(struct vehicle_hw_device* device, int32_t prop, float sample_rate);
+
+    /** Cancel subscription on a property. */
+    int (*unsubscribe)(struct vehicle_hw_device* device, int32_t prop);
+} vehicle_hw_device_t;
+
+__END_DECLS
+
+#endif  // ANDROID_VEHICLE_INTERFACE_H