bluez/android

BlueZ for Android
*****************

Since Android 4.2 there exists a well standardized HAL interface that the
Bluetooth stack is expected to provide and which enables the easy replacement
of the stack of choice on Android. Android BlueZ is intended as a drop-in
replacement to Android provided Bluetooth stack.

More details about BlueZ for Android architecture and components can be found
in android/hal-apc-api.txt file.

Supported Android version: 4.4

===============================
Building and running on Android
===============================

Steps needed to build and run Android Open Source Project 4.4.2 with
integrated BlueZ.

Build requirements
==================

- GLib - Android 4.2 or later don't provide GLib and one must provide it in
'external/bluetooth/glib' folder of Android tree. Sample Android GLib port
is available at https://code.google.com/p/aosp-bluez.glib/

- Bionic support - Currently only 'master' branch available at
https://android.googlesource.com/platform/bionic provides all required
functionality and running BlueZ on release branch requires backporting missing
features (currently only epoll_create1 call for Android 4.4.2). Sample
Bionic for Android 4.4.2 with all required features backported is available at
https://code.google.com/p/aosp-bluez.platform-bionic/

Runtime requirements
====================

BlueZ HAL library requires 'bluetoothd' and 'bluetoothd-snoop' services to be
available on Android system. This can be done by defining following services in
init.rc file of targeted board:

service bluetoothd /system/bin/logwrapper /system/bin/bluetoothd
  class main
  group bluetooth net_admin
  disabled
  oneshot

service bluetoothd-snoop /system/bin/bluetoothd-snoop
  class main
  group bluetooth net_admin
  disabled
  oneshot

It is required that bluetooth user could start and stop bluetoothd and
bluetoothd-snoop services by setting 'ctl.start' or 'ctl.stop' property. This
can be achieved by whitelisting bluetooth user and bluetoothd and
bluetoothd-snoop services in init source code.

Required Android init system modifications can be found at
https://code.google.com/p/aosp-bluez.platform-system-core/

Some configuration changes like setting permissions, starting hciattach
services etc. are device specific. For convenience examples are provided at:
https://code.google.com/p/aosp-bluez.device-lge-mako/    (Nexus 4)
https://code.google.com/p/aosp-bluez.device-asus-flo/    (Nexus 7 2013)

Downloading and building
========================

Building for Android requires full Android AOSP source tree. Sample Android
4.4.2 tree with all required components present is available at
http://code.google.com/p/aosp-bluez/

This tree provides support for Nexus4 (target aosp_mako-userdebug) and
Nexus 7 2013 (target aosp_flo-userdebug). Tree does not provide binary blobs
needed to run Android on supported devices. Those can be obtained from
https://developers.google.com/android/nexus/drivers. Binary blobs needs to be
unpacked (EULA acceptance required) into 'vendor' directory of Android tree.

Downloading:
repo init -u https://code.google.com/p/aosp-bluez.platform-manifest -b kitkat
repo sync

Building:
source build/envsetup.sh
lunch aosp_mako-userdebug    or    lunch aosp_flo-userdebug
make -j8

Flashing:
adb reboot bootloader
fastboot flashall -w

After full build is done it is possible to rebuild only BlueZ:
'cd external/bluetooth/bluez/android/'
'mm' (or 'mm -B' to force rebuilding of all files)
'adb sync' to update target device.

Linux Kernel requirements
=========================
TODO add section about kernel requirements

=============================
Building and running on Linux
=============================

It is possible to build and test BlueZ for Android daemon on Linux (eg. PC).
Simply follow instructions available at README file in BlueZ top directory.
Android daemon binary is located at android/bluetoothd. See next section on
how to test Android daemon on Linux.

============
Testing tool
============

BT HAL test tools located in android/haltest is provided for HAL level testing
of both Android daemon and HAL library. Start it with '-n' parameter and type
'bluetooth init' in prompt to initialize HAL library. Running without parameter
will make haltest try to initialize all services after start. On Android
required bluetoothd service will be started automatically. On Linux it is
required to start android/bluetoothd manually before init command timeout or
use provided android/system-emulator, which takes care of launching daemon
automatically on HAL library initialization. To deinitialize HAL library and
stop daemon type 'bluetooth cleanup'. Type 'help' for more information. Tab
completion is also supported.

===========================
Implementation shortcomings
===========================

It is possible that some of HAL functionality is missing implementation due to
reasons like feature feasibility or necessity for latest Android Framework.
This sections provides list of such deficiencies. Note that HAL library is
always expected to fully implement HAL API so missing implementation might
happen only in daemon.

HAL Bluetooth
=============

methods:
dut_mode_send                      never called from Android Framework
le_test_mode                       never called from Android Framework
get_remote_service_record          never called from Android Framework

callbacks:
dut_mode_recv_cb
le_test_mode_cb

properties:
BT_PROPERTY_SERVICE_RECORD         not supported for adapter and device, for
                                   device this property is to be returned as
                                   response to get_remote_service_record,
                                   not sure what to return on get_property
                                   calls (records of all services?)

BT_PROPERTY_REMOTE_VERSION_INFO    information required by this property (LMP
                                   information) are not accessible from mgmt
                                   interface, also marking this property as
                                   settable is probably a typo in HAL header

Socket HAL
==========

Support only for BTSOCK_RFCOMM socket type.