ZT 4.3 android bluetooth hfp分析

4.3 android bluetooth hfp分析

2013-08-20 20:16 592人阅读 评论(3) 收藏 举报

所有程序执行的代码都是有入口的，在这里我们暂时分析一种情景，蓝牙打开着，蓝牙耳机连接。

在设置界面点击蓝牙耳机操作：

packages/apps/Settings/src/com/android/settings/bluetooth/BluetoothDevicePreference.java

void onClicked() {
    int bondState = mCachedDevice.getBondState();

    if (mCachedDevice.isConnected()) {
        askDisconnect();
    } else if (bondState == BluetoothDevice.BOND_BONDED) { //已经配对，但是未连接
        <span style="color:#ff0000;">mCachedDevice.connect(true);</span>
    } else if (bondState == BluetoothDevice.BOND_NONE) { //没有配对
        <span style="color:#ff0000;">pair();</span>
    }
}

mCachedDevice.connect(true);方法会直接调用CachedBluetoothDevice.java的connect的方法。

packages/apps/Settings/src/com/android/settings/bluetooth/CachedBluetoothDevice.java

   void connect(boolean connectAllProfiles) {
        if (!ensurePaired()) {  //配对处理暂时不关注
            return;
        }
        mConnectAttempted = SystemClock.elapsedRealtime();
        connectWithoutResettingTimer(connectAllProfiles);
    }

代码执行到connectWithoutResettingTimer，注释就不粘贴了。 

    private void connectWithoutResettingTimer(boolean connectAllProfiles) {
         ......
        // Reset the only-show-one-error-dialog tracking variable
        mIsConnectingErrorPossible = true;
        int preferredProfiles = 0;
        for (LocalBluetoothProfile profile : mProfiles) {
            if (connectAllProfiles ? profile.isConnectable() : profile.isAutoConnectable()) {
                if (profile.isPreferred(mDevice)) {
                    ++preferredProfiles;
                    connectInt(profile);
                }
            }
        }
        if (DEBUG) Log.d(TAG, "Preferred profiles = " + preferredProfiles);

        if (preferredProfiles == 0) {
            connectAutoConnectableProfiles();
        }
    }

不同的协议实现类，继承于LocalBluetoothProfile，以HeadsetProfile为例。

synchronized void connectInt(LocalBluetoothProfile profile) {
    if (!ensurePaired()) {
        return;
    }
    if (<span style="color:#ff0000;">profile.connect(mDevice)</span>) {
        if (Utils.D) {
            Log.d(TAG, "Command sent successfully:CONNECT " + describe(profile));
        }
        return;
    }
    Log.i(TAG, "Failed to connect " + profile.toString() + " to " + mName);
}

这个方法中,profile.connnect()，直接调用 HeadsetProfile的connnect()，其实headset/handsfree 是共用同一个service。

packages/apps/Settings/src/com/android/settings/bluetooth/HeadsetProfile.java

public boolean connect(BluetoothDevice device) {
    if (mService == null) return false;
    List<BluetoothDevice> sinks = mService.getConnectedDevices();
    if (sinks != null) {//断开所有连接
        for (BluetoothDevice sink : sinks) {
            mService.disconnect(sink);
        }
    }
    return mService.connect(device);
}

mService.connect 直接进入framwork层，调用Bluetooth Headset server的api。

frameworks/base/core/java/android/bluetooth/BluetoothHeadset.java

public boolean connect(BluetoothDevice device) {
    if (DBG) log("connect(" + device + ")");
    if (mService != null && isEnabled() &&
        isValidDevice(device)) {
        try {
            return mService.connect(device);
        } catch (RemoteException e) {
            Log.e(TAG, Log.getStackTraceString(new Throwable()));
            return false;
        }
    }
    if (mService == null) Log.w(TAG, "Proxy not attached to service");
    return false;
}

framework 中转了一下，利用Binder机制再次进入Bluetooth模块。

frameworks/base/core/java/android/bluetooth/IBluetoothHeadset.aidl，实现类是

packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetService.java
注意顺序:Setting->framewrok->Bluetooth

public boolean connect(BluetoothDevice device) {
    HeadsetService service = getService();
    if (service == null) return false;
    return service.connect(device);
}

IBluetoothHeadset.Sub仅仅是一个连接，什么都不做直接进入HeadsetService.java的connect 方法。

    public boolean connect(BluetoothDevice device) {
        enforceCallingOrSelfPermission(BLUETOOTH_ADMIN_PERM,
                                       "Need BLUETOOTH ADMIN permission");

        if (getPriority(device) == BluetoothProfile.PRIORITY_OFF) {
            return false;
        }
        int connectionState = mStateMachine.getConnectionState(device);
        if (connectionState == BluetoothProfile.STATE_CONNECTED ||
            connectionState == BluetoothProfile.STATE_CONNECTING) {
            return false;
        }
        mStateMachine.sendMessage(HeadsetStateMachine.CONNECT, device);//万恶的状态机开始工作
        return true;
    }

很讨厌android状态机，感觉把java搞成了非面向对象，进入状态机代码实现：

packages/apps/Bluetooth/src/com/android/bluetooth/hfp/HeadsetStateMachine.java

记住当前为 未连接状态，所以应该进入 Disconnected的状态，Disconnected的processMessage方法中：

switch(message.what) {
    case CONNECT:
        BluetoothDevice device = (BluetoothDevice) message.obj;
        broadcastConnectionState(device, BluetoothProfile.STATE_CONNECTING,
                       BluetoothProfile.STATE_DISCONNECTED);

        if (!<span style="color:#ff0000;">connectHfpNative(getByteAddress(device)) </span>) {
            broadcastConnectionState(device, BluetoothProfile.STATE_DISCONNECTED,
                           BluetoothProfile.STATE_CONNECTING);
            break;
        }

        synchronized (HeadsetStateMachine.this) {
            mTargetDevice = device;
            transitionTo(mPending);
        }

connectHfpNative 连接，jni 方法 简单了。

packagesappsluetoothjniCom_android_bluetooth_hfp.cpp

{"connectHfpNative", "([B)Z", (void *) connectHfpNative},

static jboolean connectHfpNative(JNIEnv *env, jobject object, jbyteArray address) {
jbyte *addr;
bt_status_t status;

ALOGI("%s: sBluetoothHfpInterface: %p", __FUNCTION__, sBluetoothHfpInterface);
if (!sBluetoothHfpInterface) return JNI_FALSE;

addr = env->GetByteArrayElements(address, NULL);
if (!addr) {
    jniThrowIOException(env, EINVAL);
    return JNI_FALSE;
}

<span style="color:#ff0000;">if ((status = sBluetoothHfpInterface->connect((bt_bdaddr_t *)addr)) != BT_STATUS_SUCCESS) {</span>
    ALOGE("Failed HF connection, status: %d", status);
}
env->ReleaseByteArrayElements(address, addr, 0);
return (status == BT_STATUS_SUCCESS) ? JNI_TRUE : JNI_FALSE;

关键函数是sBluetoothHfpInterface->connect((bt_bdaddr_t *)addr)， connect定义在 hardware/libhardware/include/hardware/bt_hf.h,

但是实现却在：external/bluetooth/bluedroid/btif/src/btif_hf.c 中实现

#include <hardware/bt_hf.h>
static bt_status_t connect( bt_bdaddr_t *bd_addr )
{
    CHECK_BTHF_INIT();
    return btif_queue_connect(UUID_SERVCLASS_AG_HANDSFREE, bd_addr, connect_int);
}

看定义，直接连接handsfree

#define UUID_SERVCLASS_AG_HANDSFREE             0X111F  /* Handsfree profile */

btif_queue_connect的定义在下面文件中定义

external/bluetooth/bluedroid/btif/src/btif_profile_queue.c

进入bt_status_t btif_queue_connect看定义：

bt_status_t btif_queue_connect(uint16_t uuid, const bt_bdaddr_t *bda,
                        btif_connect_cb_t *connect_cb)
{
    connect_node_t node;
    memset(&node, 0, sizeof(connect_node_t));
    memcpy(&(node.bda), bda, sizeof(bt_bdaddr_t));
    node.uuid = uuid;
    node.p_cb = connect_cb;

    return btif_transfer_context(queue_int_handle_evt, BTIF_QUEUE_CONNECT_EVT,
                          (char*)&node, sizeof(connect_node_t), NULL);
}

btif_transfer_context定义在如下文件中

external/bluetooth/bluedroid/btif/src/btif_core.c

btif_transfer_context内容就不粘贴了，里面发送消息，调用

external/bluetooth/bluedroid/gki/common/gki_buffer.c

void GKI_send_msg (UINT8 task_id, UINT8 mbox, void *msg)

GKI_send_msg发送一条GKI信息到BTA，GKI_send_msg有三个参数，第一个参数是线程id,也作为task id， 通过bta_sys_init获得，第二个参数是mailbox id,第三个是上一步封装好的p_msg

GKI_send_msg 首先对p_msg进一步封装成event，通过链表存到mailbox id对应的任务队列中，调用external/bluetooth/bluedroid/gki/ulinux/gki_ulinux.c :: GKI_send_event

进行发送。

GKI_send_event设置事件掩码

gki_cb.com.OSWaitEvt[task_id] |= event;， 

通过pthread_cond_signal(&gki_cb.os.thread_evt_cond[task_id]);通知另外线程。

这样，在另外一个等待线程函数中gki_ulinux.c :: GKI_wait可以返回了。