Android4.4 's Bluetooth finishing

The Bluetooth protocol stack on Android 4.4 uses the BRCM and Google co-developed bluedroid, instead of the previous BlueZ.

One, Bluetooth source distribution (based on Android 4.4)

1. Packages/apps/settings/src/com/android/settings/bluetooth

bluetooth Settings code

2. Packages/apps/bluetooth

BT application layer code, and BT profile (eg: a2dp,gatt,hdp,hfp,hid,map,opp,pan,pbap ... ) Upper Code

Packages/apps/bluetooth/jni

3. Frameworks/base/core/java/android/bluetooth

Framework layer-related Java code and AIDL

4. External/bluetooth/bluedroid

BRCM and Google co-developed the official Bluetooth protocol stack

5. Linux/kernel/drivers/bluetooth

6. Linux/kernel/net/bluetooth

7. The following is the recent project Intel platform

Hardware/broadcom/libbt

Hardware/libhardware

VENDOR/INTEL/FW/PRIVATE/BT Manufacturer BT Firmware

Second, Bluetooth common categories and related profiles

A2DP: Advanced Audio distribution Profiles Bluetooth audio transmission model agreement

Bluetooth stereo, and Bluetooth headset listen to the song about those, there is also a avrcp--(Audio/video Remote control Profile) audio/video remotely controlled configuration file, is used to listen to the song when paused, up and down songs selected

GATT: Generic Attribute Profile Common property profiles

The GATT is based on the ATT protocol, which has been specifically optimized for BLE devices, using as little data as possible in the transfer process. Each property has a unique UUID, and the properties are transferred as characteristics and services

Https://developer.bluetooth.org/TechnologyOverview/Pages/GATT.aspx

HDP: Bluetooth Health Device profile bluetooth® for medical applications

HFP : Hands-free profile and phone-related, Bluetooth answer, hang up the phone

HID : Human Interface Device

The protocol, characteristics and usage procedures of Bluetooth in human-computer interface device are defined. Typical applications include Bluetooth mouse, Bluetooth keyboard, Bluetooth gamepad, and more. The protocol is adapted from USB HID Protocol

MAP : Message Access Profile

OPP : Object Push Profile

PAN : Personal area Network profile

Describes how two or more Bluetooth devices form an instant network, and the network-related serial port feature (SPP), Dial-Up Networking function (DUN)

PBAP: Phonebook access profile phone book accessing protocol

Third, Enable Bluetooth

1. Service Startup:

Frameworks/base/services/java/com/android/server/systemserver.java

When the system starts, the Bluetooth service Management Bluetoothmanagerservice service is registered in Systemserver:

Bt Services

Other processes invoke the service through the binder mechanism, which belongs to the Integrated services management class, including Adapterservice startup, Bluetooth adapter adapter management, and so on.

2. Bluetoothadapter

The Bluetooth enable for Android is provided by Bluetoothadapter. You only need to call Bluetoothadapter.enable () to start Bluetooth. I'll analyze the process below

Frameworks/base/core/java/android/bluetooth/bluetoothadapter.java

Mmanagerservice.enable ()

Mmanagerservice is actually a proxy of Bluetoothadapter,

Getdefaultadapter

Bluetoothadapter

3. Bluetoothmanagerservice

Frameworks/base/services/java/com/android/server/bluetoothmanagerservice.java

Bluetoothmanagerservice:enable ()

Sendenablemsg

Sendenablemsg to Handlemessage processing, you can see case message_enable: Call the Handleenable

Handleenable

You can see that the mbluetooth.enable () is called.

4. Adapterservice,adapterstate

Packages/app/bluetooth/src/com/android/bluetooth/btservice/adapterservice.java

Adapterservice:enable ()

The use of statemachine here, it will be in the Adapterstate processmessage processing (StateMachine is the state machine, in different states, received the same event, do different things), direct search Uer_turn_ On you can see the following:

user_turn_on

The next step is to call the Adapterservice.processstart ()

Processstart

Setprofileservicestate (supportedprofileservices,bluetoothadapter.state_on); is used to turn on Bluetooth profile, which can be seen in log:

BT Profile Log

Then you can see: Madapterstatemachine.sendmessage (Madapterstatemachine.obtainmessage (adapterstate.started));

Handed over to the pendingcommandstate under the ProcessMessage treatment

Case STARTED

by Madapterservice.enablenative (); You can see/*package*/native Boolean enablenative ();

This is where the JNI comes in.

5. JNI Invocation

Enablenative () is in Packages/apps/bluetooth/jni/com_android_bluetooth_btservice_adapterservice.cpp

Enablenative

static const bt_interface_t *sbluetoothinterface = NULL;

bt_interface_t definition

bt_interface_t defined in HARDWARE/LIBHARDWARE/INCLUDE/HARDWARE/BLUETOOTH.H

Sbluetoothinterface is initialized in Classinitnative (), this function probably does the following things:

1), Registered Java callback function (that is, the current layer has turned on Bluetooth, and then to notify the upper level, Bluetooth has been turned on, the Java layer can send Bluetooth open broadcast. ）

2), initialize the HAL interface of the Bluetooth module.

3), Get Sbluetoothinterface

6. Bluedroid->bluetooth.c

External/bluetooth/bluedroid/btif/src/bluetooth.c

Sbluetoothinterface->enable (); will be transferred to the bottom.

Bluetooth:enable ()

Next Call: external/bluetooth/bluedroid/btif/src/btif_core.c

Btif_enable_bluetooth

External/bluetooth/bluedroid/main/bte_main.c

Bte_main_enable

Bte_hci_enable

Let's take a look at the bt_hc_if->set_power, and do some initialization bluedroid before.

by Bt_hc_if->set_power (bt_hc_chip_pwr_on), it can be seen that:

Static bt_hc_interface_t *bt_hc_if=null;

Below is the initialization of the BT_HC_IF

Bte_main_in_hw_init

External/bluetooth/bluedroid/hci/src/bt_hci_bdroid.c

Bt_hc_get_interface

Bluetoothhclibinterface

The above can be seen set_power

Set_power

Can be seen, Bt_vnd_if->op (Bt_vnd_op_power_ctrl, &pwr_state);

External/bluetooth/bluedroid/hci/src/bt_hw.c

bt_vendor_interface_t *bt_vnd_if=null;

BT_VND_IF initialization:

Init_vnd_if

The init_vnd_if () function can be seen in fact as a libbt-vendor.so interface. This is the library of vendor (chip maker)

Vendor is the chip supplier, after they do a piece of Bluetooth chip, need to provide some hardware-related actions, such as power up and down, set the baud rate and so on. However, these operations are generally not open to unlicensed. Bluedroid provides a unified interface bt_vendor_interface_t, the provider only need to implement the interface definition of Bluetooth-related operations can be handed to bluedroid to do the rest of the matter

The following is mainly Broadcom for example, we enter/hardware/inside:

$ find. -name android.mk |xargs grep LIBBT
./broadcom/libbt/android.mk:local_module: = Libbt-vendor
./broadcom/libbt/android.mk:local_module: = Libbt-vendor
./broadcom/libbt/android.mk:local_src_files: = $ (Ti_bt_vendor_path)/libbt-vendor-ti.c
./qcom/bt/android.mk:include $ (call All-named-subdir-makefiles,libbt-vendor)
./qcom/bt/libbt-vendor/android.mk:local_module: = Libbt-vendor

Or

$ GREP-NR Bt_vnd_op_power_ctrl
Broadcom/libbt/src/bt_vendor_brcm.c:147:case Bt_vnd_op_power_ctrl:
broadcom/libbt/src/bt_vendor_brcm.c:149:btvnddbg ("Op:bt_vnd_op_power_ctrl");
Qcom/bt/libbt-vendor/src/bt_vendor_qcom.c:105:case Bt_vnd_op_power_ctrl:

In BROADCOM/LIBBT/SRC/BT_VENDOR_BRCM.C

Op

Upio_set_bluetooth_power

static char *rfkill_state_path = NULL;

The Rfkill_state_path is initialized below.

Init_rfkill

The original was written in the Rfkill_state_path (/sys/class/rfkill/rfkill[x]/state) virtual device 1

Shell@android:/sys/class/rfkill/rfkill0 $ cat State
0//indicates Bluetooth is off

Shell@android:/sys/class/rfkill/rfkill0 $ cat State

1//Turn on Bluetooth to see

Rfkill is a standard wireless controlled virtual device under Linux, and Linux also provides Rfkill commands to view and control all registered wireless devices. They generate the corresponding virtual devices in/dev/(PC Linux) or/sys/class (typically Android).

Combining the log and bluetoothhclibinterface definitions below the Set_power, you can see the next proload->bthc_signal_event in the called Bluetoothhclibinterface ( Hc_event_preload)->bt_hc_worker_thread-"Userial_open (userial_port_1)->bt_vnd_if->op (BT_VND_OP_USERIAL _open, &fd_array);->userial_vendor_open ((TUSERIAL_CFG *) &userial_init_cfg);

Next up is hardware.c.

hw_config_start-"Hw_config_cback

Some of the logs are as follows:

Log

Below is the log of the Bluetooth-enabled logcat in minicom

Logcat

REF:

http://blog.csdn.net/baimy1985/article/details/8892410

http://my.oschina.net/u/1436933/blog/192060

http://blog.csdn.net/yutao52shi/article/details/12690353