Android bluedroid模块间关系

一图解百惑整个bluedroid可以分为两大模块：BTIF，BTEBTIF：提供bluedroid对外的接口BTE：bluedroid的内部处理，又细分为BTA，BTU，BTM和HCIBTA：bluedroid中各profile的逻辑实现和处理BTU：承接BTA与HCIBTM：蓝牙配对与链路管理HCI：读取或写入数据到蓝牙hw下面以实际例子来表现个模块间的协作tv与蓝牙音箱建立连接上层应用建立连接时候，会调用到btif_av.c中的connect函数btif_av.c

static bt_status_t connect(bt_bdaddr_t *bd_addr)
{
BTIF_TRACE_EVENT1("%s", __FUNCTION__);
CHECK_BTAV_INIT();

return btif_queue_connect(UUID_SERVCLASS_AUDIO_SOURCE, bd_addr, connect_int);
}

经过内部逻辑处理后，会调用到bta_av_api.c中的BTA_AvOpen函数

void BTA_AvOpen(BD_ADDR bd_addr, tBTA_AV_HNDL handle, BOOLEAN use_rc, tBTA_SEC sec_mask)
170 {
171     tBTA_AV_API_OPEN  *p_buf;
172
173     if ((p_buf = (tBTA_AV_API_OPEN *) GKI_getbuf(sizeof(tBTA_AV_API_OPEN))) != NULL)
174     {
175         p_buf->hdr.event = BTA_AV_API_OPEN_EVT;
176         p_buf->hdr.layer_specific   = handle;
177         bdcpy(p_buf->bd_addr, bd_addr);
178         p_buf->use_rc = use_rc;
179         p_buf->sec_mask = sec_mask;
180         p_buf->switch_res = BTA_AV_RS_NONE;
181         bta_sys_sendmsg(p_buf);
182     }
183 }

bta_sys_sendmsg最终会将消息发送btu_task.c中的btu_task线程处理

for (;;)
227     {
228         event = GKI_wait (0xFFFF, 0);
229
230         if (event & TASK_MBOX_0_EVT_MASK)
231         {
........
}
.
.
.
if (event & TASK_MBOX_2_EVT_MASK)
549         {
550             while ((p_msg = (BT_HDR *) GKI_read_mbox(TASK_MBOX_2)) != NULL)
551             {
552                 bta_sys_event(p_msg);
553             }
554         }

通过bta_sys_event，消息再次转入bta内部处理，最终经过协议栈a2dp和l2cap和BTM的管理，将建立连接的请求通过bte_main.c的bte_main_hci_send发送给hci处理

void bte_main_hci_send (BT_HDR *p_msg, UINT16 event)
506 {
507     UINT16 sub_event = event & BT_SUB_EVT_MASK;  /* local controller ID */
508
509     p_msg->event = event;
510
511
512     if((sub_event == LOCAL_BR_EDR_CONTROLLER_ID) || \
513        (sub_event == LOCAL_BLE_CONTROLLER_ID))
514     {
515         if (bt_hc_if)
516             bt_hc_if->transmit_buf((TRANSAC)p_msg, \
517                                        (char *) (p_msg + 1), \
518                                         p_msg->len);
519         else
520             GKI_freebuf(p_msg);
521     }
522     else
523     {
524         APPL_TRACE_ERROR0("Invalid Controller ID. Discarding message.");
525         GKI_freebuf(p_msg);
526     }
527 }

在hci中，数据被写入bt driver中

static int transmit_buf(TRANSAC transac, char *p_buf, int len)
338 {
339     utils_enqueue(&tx_q, (void *) transac);
340
341     bthc_signal_event(HC_EVENT_TX);
342
343     return BT_HC_STATUS_SUCCESS;
344 }

bt_hc_worker_thread负责处理hci事件：

            if (events & HC_EVENT_TX)529         {530             /*531              *  We will go through every packets in the tx queue.532              *  Fine to clear tx_cmd_pkts_pending.533              */534             tx_cmd_pkts_pending = FALSE;535             HC_BT_HDR * sending_msg_que[64];536             int sending_msg_count = 0;537             int sending_hci_cmd_pkts_count = 0;538             utils_lock();539             p_next_msg = tx_q.p_first;540             while (p_next_msg && sending_msg_count <541                             (int)sizeof(sending_msg_que)/sizeof(sending_msg_que[0]))542             {543                 if ((p_next_msg->event & MSG_EVT_MASK)==MSG_STACK_TO_HC_HCI_CMD)544                 {545                     /*546                      *  if we have used up controller's outstanding HCI command547                      *  credits (normally is 1), skip all HCI command packets in548                      *  the queue.549                      *  The pending command packets will be sent once controller550                      *  gives back us credits through CommandCompleteEvent or551                      *  CommandStatusEvent.552                      */553                     if ((tx_cmd_pkts_pending == TRUE) ||554                         (sending_hci_cmd_pkts_count >= num_hci_cmd_pkts))555                     {556                         tx_cmd_pkts_pending = TRUE;557                         p_next_msg = utils_getnext(p_next_msg);558                         continue;559                     }560                     sending_hci_cmd_pkts_count++;561                 }562563                 p_msg = p_next_msg;564                 p_next_msg = utils_getnext(p_msg);565                 utils_remove_from_queue_unlocked(&tx_q, p_msg);566                 sending_msg_que[sending_msg_count++] = p_msg;567             }utils_unlock();569             int i;570             for(i = 0; i < sending_msg_count; i++)571                 p_hci_if->send(sending_msg_que[i]);//将数据发送到bt driver中572             if (tx_cmd_pkts_pending == TRUE)573                 BTHCDBG("Used up Tx Cmd credits");574575         }