Docs: Adding vehicle hal content + nav
Adding KY feedback
Adding Gina's feedback
Bug: 30283016
Change-Id: I373fa8d3ef8493352d432a4345c23400fff7b500
diff --git a/src/devices/automotive.jd b/src/devices/automotive.jd
new file mode 100644
index 0000000..cfcccc9
--- /dev/null
+++ b/src/devices/automotive.jd
@@ -0,0 +1,293 @@
+page.title=Automotive
+@jd:body
+
+<!--
+ Copyright 2016 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.
+-->
+<div id="qv-wrapper">
+ <div id="qv">
+ <h2>In this document</h2>
+ <ol id="auto-toc">
+ </ol>
+ </div>
+</div>
+
+<img style="float: right; margin: 0px 15px 15px 15px;"
+src="images/ape_fwk_hal_vehicle.png" alt="Android vehicle HAL icon"/>
+
+<p>Many car subsystems interconnect with each other and the in-vehicle
+infotainment (IVI) system via various bus topologies. The exact bus type and
+protocols vary widely between manufacturers (and even between different vehicle
+models of the same brand); examples include Controller Area Network (CAN) bus,
+Local Interconnect Network (LIN) bus, Media Oriented Systems Transport (MOST),
+as well as automotive-grade Ethernet and TCP/IP networks such as BroadR-Reach.
+</p>
+<p>Android Automotive has a hardware abstraction layer (HAL) that provides a
+consistent interface to the Android framework regardless of physical transport
+layer. This vehicle HAL is the interface for developing Android Automotive
+implementations.</p>
+<p>System integrators can implement a vehicle HAL module by connecting
+function-specific platform HAL interfaces (e.g. HVAC) with technology-specific
+network interfaces (e.g. CAN bus). Typical implementations may include a
+dedicated Microcontroller Unit (MCU) running a proprietary real-time operating
+system (RTOS) for CAN bus access or similar, which may be connected via a serial
+link to the CPU running Android Automotive. Instead of a dedicated MCU, it may
+also be possible to implement the bus access as a virtualized CPU. It is up to
+each partner to choose the architecture suitable for the hardware as long as the
+implementation fulfills the interface requirements for the vehicle HAL.</p>
+
+<h2 id=arch>Architecture</h2>
+<p>The vehicle HAL is the interface definition between the car and the vehicle
+network service:</p>
+
+<img src="images/vehicle_hal_arch.png" alt="Android vehicle HAL architecture">
+<p class="img-caption"><strong>Figure 1</strong>. Vehicle HAL and Android
+automotive architecture</p>
+
+<ul>
+<li><strong>Car API</strong>. Contains the APIs such as CarHvacManager,
+CarSensorManager, and CarCameraManager. For details on all supported APIs,
+refer to <code>/platform/packages/services/Car/car-lib</code>.</li>
+<li><strong>CarService</strong>. Located at
+<code>/platform/packages/services/Car/</code>.</li>
+<li><strong>VehicleNetworkService</strong>. Controls vehicle HAL with built-in
+security. Access restricted to system components only (non-system components
+such as third party apps should use car API instead). OEMs can control access
+using <code>vns_policy.xml</code> and <code>vendor_vns_policy.xml</code>.
+Located at <code>/platform/packages/services/Car/vehicle_network_service/</code>;
+for libraries to access the vehicle network, refer to
+<code>/platform/packages/services/Car/libvehiclenetwork/</code>.</li>
+<li><strong>Vehicle HAL</strong>. Interface that defines the properties OEMs can
+implement and contains property metadata (for example, whether the property is
+an int and which change modes are allowed). Located at
+<code>hardware/libhardware/include/hardware/vehicle.h</code>. For a basic
+reference implementation, refer to
+<code>hardware/libhardware/modules/vehicle/</code>.</li>
+</ul>
+
+<h2 id=prop>Vehicle properties</h2>
+<p>The vehicle HAL interface is based on accessing (read, write, subscribe) a
+property, which is an abstraction for a specific function. Properties can be
+read-only, write-only (used to pass information to vehicle HAL level), or read
+and write. Support of most properties is optional.</p>
+<p>Each property is uniquely identified by an int32 key and has a predefined
+type (<code>value_type</code>):</p>
+
+<ul>
+<li><code>INT32</code> (and array), <code>INT64</code>, <code>BOOLEAN</code>,
+<code>FLOAT</code> (and array), string, bytes.</li>
+<li>Zoned type has zone in addition to value.</li>
+</ul>
+
+<h3 id-=zone_type>Zone types</h3>
+<p>The vehicle HAL defines three zone types:</p>
+<ul>
+<li><code>vehicle_zone</code>: Zone based on rows.</li>
+<li><code>vehicle_seat</code>: Zone based on seats.</li>
+<li><code>vehicle_window</code>: Zone based on windows.</li>
+</ul>
+<p>Each zoned property should use pre-defined zone type. If necessary, you can
+use a custom zone type for each property (for details, see
+<a href=#prop_custom>Handling custom properties</a>).</p>
+
+<h3 id=prop_config>Configuring a property</h3>
+<p>Use <code>vehicle_prop_config_t</code> to provide configuration information
+for each property. Information includes:</p>
+<ul>
+<li><code>access</code> (r, w, rw)</li>
+<li><code>change_mode</code> (represents how property is monitored: on change vs
+continuous)</li>
+<li><code>min_value</code> (int32, float, int64), <code>max_value</code> (int32,
+float, int64)</li>
+<li><code>min_sample_rate</code>, <code>max_sample_rate</code></li>
+<li><code>permission_model</code></li>
+<li><code>prop</code> (Property ID, int)</li>
+<li><code>value_type</code></li>
+<li><code>zone_flags</code> (represents supported zones as bit flags)</li>
+</ul>
+<p>In addition, some properties have specific configuration flags to represent
+capability.</p>
+
+<h2 id=interfaces>HAL interfaces</h2>
+<p>The vehicle HAL uses the following interfaces:</p>
+<ul>
+<li><code>vehicle_prop_config_t const *(*list_properties)(..., int*
+num_properties)</code>. List configuration of all properties supported by the
+vehicle HAL. Only supported properties will be used by vehicle network service.
+</li>
+<li><code>(*get)(..., vehicle_prop_value_t *data)</code>. Read the current value
+of the property. For zoned property, each zone may have different value.</li>
+<li><code>(*set)(..., const vehicle_prop_value_t *data)</code>. Write a value to
+property. Result of write is defined per each property.</li>
+<li><code>(*subscribe)(..., int32_t prop, float sample_rate, int32_t
+zones)</code>.<ul>
+<li>Start monitoring property value's change. For zoned property, subscription
+applies to requested zones. Zones = 0 is used to request all zones supported.
+</li>
+<li>Vehicle HAL should call separate callback when the property's value changes
+(=on change) or in const interval (=continuous type).</ul></li>
+<li><code>(*release_memory_from_get)(struct vehicle_hw_device* device,
+vehicle_prop_value_t *data)</code>. Release memory allocated from get call.</ul>
+</li>
+</ul>
+
+<p>The vehicle HAL uses the following callback interfaces:</p>
+<ul>
+<li><code>(*vehicle_event_callback_fn)(const vehicle_prop_value_t
+*event_data)</code>. Notifies vehicle property's value change. Should be done
+only for subscribed properties.</li>
+<li><code>(*vehicle_error_callback_fn)(int32_t error_code, int32_t property,
+int32_t operation).</code> Return global vehicle HAL level error or error per
+each property. Global error causes HAL restart, which can lead to restarting
+other components, including applications.</li>
+</ul>
+
+<h2 id=zone_prop>Handling zone properties</h2>
+<p>A zoned property is equivalent to a collection of multiple properties where
+each sub property is accessible by specified zone value.</p>
+<ul>
+<li><code>get</code> call for zoned property always includes zone in request, so
+only the current value for the requested zone should be returned.</li>
+<li><code>set</code> call for zoned property always includes zone in request, so
+only the requested zone should be changed.</li>
+<li><code>subscribe</code> call includes flags of all zones subscribed. Events
+from un-subscribed zones should not be reported.</li>
+</ul>
+
+<h3 id=get>Get calls</h3>
+<p>During initialization, the value for the property may not be available yet as
+the matching vehicle network message has not yet been received. In such cases,
+the <code>get</code> call should return <code>-EAGAIN</code>. Some properties
+(such as HVAC) have separate on/off power property. Calling <code>get</code> for
+such a property (when powered off) should return a special value
+<code>(VEHICLE_INT_OUT_OF_RANGE_OFF/VEHICLE_FLOAT_OUT_OF_RANGE_OFF)</code>
+rather than returning an error.</p>
+<p>In addition, some properties (such as HVAC temperature) can have a value to
+indicate it is in max power mode rather than in specific temperature value. In
+such cases, use special values to represent such state.</p>
+<ul>
+<li>VEHICLE_INT_OUT_OF_RANGE_MAX/MIN</li>
+<li>VEHICLE_FLOAT_OUT_OF_RANGE_MAX/MIN</li>
+</ul>
+
+<p>Example: get HVAC Temperature</p>
+<img src="images/vehicle_hvac_get.png" alt="Vehicle HAL get HVAC example">
+<p class="img-caption"><strong>Figure 2</strong>. Get HVAC temperature (CD =
+CarService, VNS = VehicleNetworkService, VHAL = Vehicle HAL)</p>
+
+<h3 id=set>Set calls</h3>
+<p>A <code>set</code> call is an asynchronous operation involving event
+notification after a requested change is made. In a typical operation, a
+<code>set</code> call leads to making a change request across vehicle network.
+When the change is performed by the electronic control unit (ECU) owning the
+property, the updated value is returned through vehicle network and the vehicle
+HAL sends an updated value as an event to vehicle network service (VNS).</p>
+<p>Some <code>set</code> calls may require initial data to be ready but during
+initialization, such data may not be available yet. In such cases, the
+<code>set</code> call should return <code>-EAGAIN</code>. Some properties with
+separate power on /off should return <code>-ESHUTDOWN</code> when the property
+is powered off and set cannot be done.</p>
+<p>Until <code>set</code> is made effective, <code>get</code> does not
+necessarily return the same value as what is set. The exception is a property
+with change mode of <code>VEHICLE_PROP_CHANGE_MODE_ON_SET.</code> This property
+notifies change only when it is set by external component outside Android (for
+example, clock properties such as <code>VEHICLE_PROPERTY_UNIX_TIME</code>).</p>
+
+<p>Example: set HVAC Temperature</p>
+<img src="images/vehicle_hvac_set.png" alt="Vehicle HAL set HVAC example">
+<p class="img-caption"><strong>Figure 3</strong>. Set HVAC temperature (CD =
+CarService, VNS = VehicleNetworkService, VHAL = Vehicle HAL)</p>
+
+<h2 id=prop_custom>Handling custom properties</h2>
+<p>To support partner-specific needs, the vehicle HAL allows custom properties
+that are restricted to system apps. Use the following guidelines when working
+with custom properties:</p>
+<ul>
+<li>Key should be in [<code>VEHICLE_PROPERTY_CUSTOM_START,
+VEHICLE_PROPERTY_CUSTOM_END</code>] range. Other ranges are reserved for future
+extension; using such ranges can cause conflicts in future Android releases.</li>
+<li>Use only defined <code>value_type</code>. BYTES type allows passing raw
+data, so this is enough in most cases. Sending big data frequently through
+custom properties can slow down the whole vehicle network access, so be careful
+when you add a big payload.</li>
+<li>Add access policy into <code>vendor_vns_policy.xml</code> (otherwise, all
+access will be rejected).</li>
+<li>Access via <code>VendorExtensionManager</code> (for Java components) or
+via Vehicle Network Service API (for native). Do not modify other car APIs as it
+can lead to compatibility issues in the future.</li>
+</ul>
+
+<h2 id=prop_hvac>Handling HVAC properties</h2>
+<p>You can use the vehicle HAL to control HVAC by setting HVAC-related
+properties. Most HVAC properties are zoned properties, but a few are non-zoned
+(global) properties. Example properties defined include:</p>
+<ul>
+<li><code>VEHICLE_PROPERTY_HVAC_TEMPERATURE_SET</code> (set temperature per each
+zone).</li>
+<li><code>VEHICLE_PROPERTY_HVAC_RECIRC_ON</code> (control recirculation per each
+zone).</li>
+</ul>
+<p>For full list of HVAC properties, search for
+<code>VEHICLE_PROPERTY_HVAC_*</code> in <code>vehicle.h</code>.</p>
+
+<h2 id=prop_sensor>Handling sensor properties</h2>
+<p>Vehicle HAL sensor properties represent real sensor data or policy
+information such as driving status. Some sensor information (such as driving
+status and day/night mode) is accessible by any app without restriction as the
+data is mandatory to build a safe vehicle application. Other sensor information
+(such as vehicle speed) is more sensitive and requires specific permissions that
+users can manage.</p>
+<p>Supported sensor properties include:</p>
+<ul>
+<li><code>DRIVING_STATUS</code> (should support). Represents allowed operations
+in the current driving state. This information is used to block unsafe
+applications while driving.</li>
+<li><code>NIGHT_MODE</code> (should support). Determines day/night mode of
+display.</li>
+<li><code>GEAR_SELECTION/CURRENT_GEAR</code>. Gear selected by driver vs.
+actual gear.</li>
+<li><code>VEHICLE_SPEED</code>. Vehicle speed. Protected with permission.</li>
+<li><code>ODOMETER</code>. Current odometer reading. Protected with permission.
+</li>
+<li><code>FUEL_LEVEL</code>. Current fuel level in %.</li>
+<li><code>FUEL_LEVEL_LOW</code>. Fuel level is low or not (boolean).</li>
+</ul>
+
+<h2 id=security>Security</h2>
+<p>The vehicle HAL supports three levels of security for accessing data:</p>
+<ul>
+<li>System only (controlled by <code>vns_policy.xml</code>)</li>
+<li>Accessible to app with permission (through car service)</li>
+<li>Accessible without permission (through car service)</li>
+</ul>
+<p>Direct access to vehicle properties is allowed only to selected system
+components with vehicle network service acting as the gatekeeper. Most
+applications go through additional gatekeeping by car service (for example, only
+system applications can control HVAC as it requires system permission granted
+only to system apps).</p>
+
+<h2 id=validation>Validation</h2>
+<p>AOSP includes the following testing resources for use in development:</p>
+<ul>
+<li><code>hardware/libhardware/tests/vehicle/vehicle-hal-tool.c</code>.
+Command-line native tool to load vehicle HAL and do simple operations. Useful
+for getting the system up and running in the early stages of development.</li>
+<li><code>packages/services/Car/tests/carservice_test/</code>. Contains car
+service testing with mocked vehicle HAL properties. For each property, expected
+behavior is implemented in the test. This can be a good starting point to
+understand expected behavior.</li>
+<li><code>hardware/libhardware/modules/vehicle/</code>. A basic reference
+implementation.</li>
+</ul>
diff --git a/src/devices/devices_toc.cs b/src/devices/devices_toc.cs
index 862d6f5..0dc2b03 100644
--- a/src/devices/devices_toc.cs
+++ b/src/devices/devices_toc.cs
@@ -128,6 +128,7 @@
<li><a href="<?cs var:toroot ?>devices/audio/tv.html">TV Audio</a></li>
</ul>
</li>
+ <li><a href="<?cs var:toroot ?>devices/automotive.html">Automotive</a></li>
<li><a href="<?cs var:toroot ?>devices/bluetooth.html">Bluetooth</a></li>
<li class="nav-section">
<div class="nav-section-header">
diff --git a/src/devices/images/ape_fwk_hal_vehicle.png b/src/devices/images/ape_fwk_hal_vehicle.png
new file mode 100644
index 0000000..500934d
--- /dev/null
+++ b/src/devices/images/ape_fwk_hal_vehicle.png
Binary files differ
diff --git a/src/devices/images/vehicle_hal_arch.png b/src/devices/images/vehicle_hal_arch.png
new file mode 100644
index 0000000..8c8a6ab
--- /dev/null
+++ b/src/devices/images/vehicle_hal_arch.png
Binary files differ
diff --git a/src/devices/images/vehicle_hvac_get.png b/src/devices/images/vehicle_hvac_get.png
new file mode 100644
index 0000000..1006db6
--- /dev/null
+++ b/src/devices/images/vehicle_hvac_get.png
Binary files differ
diff --git a/src/devices/images/vehicle_hvac_set.png b/src/devices/images/vehicle_hvac_set.png
new file mode 100644
index 0000000..fcf4683
--- /dev/null
+++ b/src/devices/images/vehicle_hvac_set.png
Binary files differ
