蓝牙inquiry流程之命令下发

Android 上面的蓝牙inquiry 是在设置界面，打开蓝牙就会自动搜索周边的蓝牙设备，其最终调用到协议栈的start_discovery接口，此篇文章分析该接口的调用流程以及与controller交互过程。

static int start_discovery(void)
{
    /* sanity check */
    if (interface_ready() == FALSE)
        return BT_STATUS_NOT_READY;
    return btif_dm_start_discovery();
}

 

bt_status_t btif_dm_start_discovery(void)
{
    tBTA_DM_INQ inq_params;
    tBTA_SERVICE_MASK services = 0;
    tBTA_DM_BLE_PF_FILT_PARAMS adv_filt_param;

#if (defined(BLE_INCLUDED) && (BLE_INCLUDED == TRUE))
    memset(&adv_filt_param, 0, sizeof(tBTA_DM_BLE_PF_FILT_PARAMS));
    /* Cleanup anything remaining on index 0 */
    BTA_DmBleScanFilterSetup(BTA_DM_BLE_SCAN_COND_DELETE, 0, &adv_filt_param, NULL,
                             bte_scan_filt_param_cfg_evt, 0);

    /* Add an allow-all filter on index 0*/
    adv_filt_param.dely_mode = IMMEDIATE_DELY_MODE;
    adv_filt_param.feat_seln = ALLOW_ALL_FILTER;
    adv_filt_param.filt_logic_type = BTA_DM_BLE_PF_FILT_LOGIC_OR;
    adv_filt_param.list_logic_type = BTA_DM_BLE_PF_LIST_LOGIC_OR;
    adv_filt_param.rssi_low_thres = LOWEST_RSSI_VALUE;
    adv_filt_param.rssi_high_thres = LOWEST_RSSI_VALUE;
    BTA_DmBleScanFilterSetup(BTA_DM_BLE_SCAN_COND_ADD, 0, &adv_filt_param, NULL,
                             bte_scan_filt_param_cfg_evt, 0);

    /* TODO: Do we need to handle multiple inquiries at the same time? */

    /* Set inquiry params and call API */
    inq_params.mode = BTA_DM_GENERAL_INQUIRY|BTA_BLE_GENERAL_INQUIRY;//设置inquiry模式，ble和bredr
#else
    inq_params.mode = BTA_DM_GENERAL_INQUIRY;
#endif
    inq_params.duration = BTIF_DM_DEFAULT_INQ_MAX_DURATION;//设置超时时间

    inq_params.max_resps = BTIF_DM_DEFAULT_INQ_MAX_RESULTS;//设置接收的最大的response数量
    inq_params.report_dup = TRUE;

    inq_params.filter_type = BTA_DM_INQ_CLR;//0
    /* TODO: Filter device by BDA needs to be implemented here */

    /* Will be enabled to TRUE once inquiry busy level has been received */
    btif_dm_inquiry_in_progress = FALSE;
    /* find nearby devices */
    BTA_DmSearch(&inq_params, services, bte_search_devices_evt);//执行搜索
    return BT_STATUS_SUCCESS;
}

 

上面代码的主要做的事情是，设置相关的搜索的参数，然后调用BTA_DmSearch(&inq_params, services, bte_search_devices_evt); 进行搜索。

我们这里再次整理一下 传入BTA_DmSearch的参数：

    inq_params.mode = BTA_DM_GENERAL_INQUIRY|BTA_BLE_GENERAL_INQUIRY;
    inq_params.duration = BTIF_DM_DEFAULT_INQ_MAX_DURATION;
    inq_params.max_resps = BTIF_DM_DEFAULT_INQ_MAX_RESULTS;
    inq_params.report_dup = TRUE;
    inq_params.filter_type = BTA_DM_INQ_CLR;//0

    tBTA_SERVICE_MASK services = 0;

    bte_search_devices_evt 是一个回调函数，实现也是在btif_dm.c，最终会被赋值给
    bta_dm_search_cb.p_search_cback = bte_search_devices_evt

 

我们看看BTA_DmSearch具体的实现，

/*******************************************************************************
**
** Function         BTA_DmSearch
**
** Description      This function searches for peer Bluetooth devices. It performs
**                  an inquiry and gets the remote name for devices. Service
**                  discovery is done if services is non zero
**
**
** Returns          void
**
*******************************************************************************/
void BTA_DmSearch(tBTA_DM_INQ *p_dm_inq, tBTA_SERVICE_MASK services, tBTA_DM_SEARCH_CBACK *p_cback)
{
    tBTA_DM_API_SEARCH    *p_msg;
    if ((p_msg = (tBTA_DM_API_SEARCH *) GKI_getbuf(sizeof(tBTA_DM_API_SEARCH))) != NULL)
    {
        memset(p_msg, 0, sizeof(tBTA_DM_API_SEARCH));
        p_msg->hdr.event = BTA_DM_API_SEARCH_EVT;
        memcpy(&p_msg->inq_params, p_dm_inq, sizeof(tBTA_DM_INQ));
        p_msg->services = services;
        p_msg->p_cback = p_cback;
        p_msg->rs_res  = BTA_DM_RS_NONE;
        bta_sys_sendmsg(p_msg);
    }

}

 

这里发现就是组装了一个msg，然后发送给btu 线程处理，这里整理一下发送给btu 线程的参数：

p_msg->hdr.event = BTA_DM_API_SEARCH_EVT;
memcpy(&p_msg->inq_params, p_dm_inq, sizeof(tBTA_DM_INQ)); 上面赋值的参数
p_msg->services = services;//service = 0
p_msg->p_cback = p_cback;//bte_search_devices_evt

p_msg->rs_res = BTA_DM_RS_NONE;

我们查找一下， BTA_DM_API_SEARCH_EVT 执行的函数：bta_dm_search_start 

/*******************************************************************************
**
** Function         bta_dm_search_start
**
** Description      Starts an inquiry
**
**
** Returns          void
**
*******************************************************************************/
void bta_dm_search_start (tBTA_DM_MSG *p_data)
{
    tBTM_INQUIRY_CMPL result;

#if (BLE_INCLUDED == TRUE && BTA_GATT_INCLUDED == TRUE)
    UINT16 len = (UINT16)(sizeof(tBT_UUID) * p_data->search.num_uuid);
    bta_dm_gattc_register();
#endif
    if (p_bta_dm_cfg->avoid_scatter &&
        (p_data->search.rs_res == BTA_DM_RS_NONE) && bta_dm_check_av(BTA_DM_API_SEARCH_EVT))
    {
        memcpy(&bta_dm_cb.search_msg, &p_data->search, sizeof(tBTA_DM_API_SEARCH));
        return;
    }

    BTM_ClearInqDb(NULL);
    /* save search params */
    bta_dm_search_cb.p_search_cback = p_data->search.p_cback;
    bta_dm_search_cb.services = p_data->search.services;

#if (BLE_INCLUDED == TRUE && BTA_GATT_INCLUDED == TRUE)
    utl_freebuf((void **)&bta_dm_search_cb.p_srvc_uuid);

    if ((bta_dm_search_cb.num_uuid = p_data->search.num_uuid) != 0 &&
         p_data->search.p_uuid != NULL)//如果在搜索的时候设置了uuid，那么也会将这个值copy给bta_dm_search_cb.p_srvc_uuid
    {
        bta_dm_search_cb.p_srvc_uuid = (tBT_UUID *)GKI_getbuf(len)
        memcpy(bta_dm_search_cb.p_srvc_uuid, p_data->search.p_uuid, len);
    }
#endif
    result.status = BTM_StartInquiry(   (tBTM_INQ_PARMS*)&p_data->search.inq_params,
                        bta_dm_inq_results_cb,//扫描到设备调用此函数
                        (tBTM_CMPL_CB*) bta_dm_inq_cmpl_cb);//扫描完成会调用到此函数

    if (result.status != BTM_CMD_STARTED)
    {
        result.num_resp = 0;
        bta_dm_inq_cmpl_cb ((void *)&result);//如果开始失败，直接调用回调函数汇报
    }
}

 

上面的代码执行完，我们看看bta_dm_search_cb的各个结构的值：

 bta_dm_search_cb.p_search_cback = bte_search_devices_evt

bta_dm_search_cb.services = 0；

bta_dm_search_cb.num_uuid  =0；

bta_dm_search_cb.p_srvc_uuid = NULL;

下面继续看看BTM_StartInquiry 的实现，这里可以简单分析一下，传入的三个参数：

第一个参数是，上面组装的inquiry相关的设置。

第二个参数是 扫描到设备调用

第三个参数是 扫描完成 （inquiry complete）的时候调用

/*******************************************************************************
**
** Function         BTM_StartInquiry
**
** Description      This function is called to start an inquiry.
**
** Parameters:      p_inqparms - pointer to the inquiry information
**                      mode - GENERAL or LIMITED inquiry, BR/LE bit mask seperately
**                      duration - length in 1.28 sec intervals (If '0', the inquiry is CANCELLED)
**                      max_resps - maximum amount of devices to search for before ending the inquiry
**                      filter_cond_type - BTM_CLR_INQUIRY_FILTER, BTM_FILTER_COND_DEVICE_CLASS, or
**                                         BTM_FILTER_COND_BD_ADDR
**                      filter_cond - value for the filter (based on filter_cond_type)
**
**                  p_results_cb   - Pointer to the callback routine which gets called
**                                upon receipt of an inquiry result. If this field is
**                                NULL, the application is not notified.
**
**                  p_cmpl_cb   - Pointer to the callback routine which gets called
**                                upon completion.  If this field is NULL, the
**                                application is not notified when completed.
** Returns          tBTM_STATUS
**                  BTM_CMD_STARTED if successfully initiated
**                  BTM_BUSY if already in progress
**                  BTM_ILLEGAL_VALUE if parameter(s) are out of range
**                  BTM_NO_RESOURCES if could not allocate resources to start the command
**                  BTM_WRONG_MODE if the device is not up.
**
*******************************************************************************/
tBTM_STATUS BTM_StartInquiry (tBTM_INQ_PARMS *p_inqparms, tBTM_INQ_RESULTS_CB *p_results_cb,
                              tBTM_CMPL_CB *p_cmpl_cb)
{
    tBTM_STATUS  status = BTM_CMD_STARTED;
    tBTM_INQUIRY_VAR_ST *p_inq = &btm_cb.btm_inq_vars;
        p_inq->scan_type = INQ_GENERAL;
...
    /* Save the inquiry parameters to be used upon the completion of setting/clearing the inquiry filter */
    p_inq->inqparms = *p_inqparms;//保存inquiry的参数
    /* Initialize the inquiry variables */
    p_inq->state = BTM_INQ_ACTIVE_STATE;//active
    p_inq->p_inq_cmpl_cb = p_cmpl_cb;
    p_inq->p_inq_results_cb = p_results_cb;
    p_inq->inq_cmpl_info.num_resp = 0;         /* Clear the results counter */
    p_inq->inq_active = p_inqparms->mode;//0x11

/* start LE inquiry here if requested */
    if ((p_inqparms->mode & BTM_BLE_INQUIRY_MASK))
    {
         if ((status = btm_ble_start_inquiry((UINT8)(p_inqparms->mode & BTM_BLE_INQUIRY_MASK),
                                            p_inqparms->duration)) != BTM_CMD_STARTED)
        {
            BTM_TRACE_ERROR("Err Starting LE Inquiry.");
            p_inq->inqparms.mode &= ~ BTM_BLE_INQUIRY_MASK;
        }
#if (!defined(BTA_HOST_INTERLEAVE_SEARCH) || BTA_HOST_INTERLEAVE_SEARCH == FALSE)
        p_inqparms->mode &= ~BTM_BLE_INQUIRY_MASK;//开始inquiry之后，mode参数置0
#endif
    }

    /* BR/EDR inquiry portion */
...
    /* Before beginning the inquiry the current filter must be cleared, so initiate the command */
    if ((status = btm_set_inq_event_filter (p_inqparms->filter_cond_type,
                                            &p_inqparms->filter_cond)) != BTM_CMD_STARTED)//这里没有看到BRRDR的扫描，而只有这个清楚过滤的函数，那我可以想象，肯定是这个函数做完之后会自动开始bredr设备的inquiry
        p_inq->state = BTM_INQ_INACTIVE_STATE;
    return (status);
}

上面的代码主要做了三件事：

1. 将一些参数保存在tBTM_INQUIRY_VAR_ST *p_inq = &btm_cb.btm_inq_vars  这个结构。
   1. p_inq->scan_type = INQ_GENERAL;
   2. p_inq->inqparms = *p_inqparms;
   3. p_inq->state = BTM_INQ_ACTIVE_STATE;
   4. p_inq->p_inq_cmpl_cb = p_cmpl_cb;
   5. p_inq->p_inq_results_cb = p_results_cb;

   6. p_inq->inq_cmpl_info.num_resp = 0; /* Clear the results counter */

   7. p_inq->inq_active = p_inqparms->mode = 0x11（BLE|BREDR）
2. 做BLE 的inquiry ：btm_ble_start_inquiry((UINT8)(p_inqparms->mode & BTM_BLE_INQUIRY_MASK),p_inqparms->duration)
3. 做BREDR的inquiry：btm_set_inq_event_filter (p_inqparms->filter_cond_type,&p_inqparms->filter_cond)

btm_ble_start_inquiry

tBTM_STATUS btm_ble_start_inquiry (UINT8 mode, UINT8   duration)
{
    tBTM_STATUS status = BTM_CMD_STARTED;
    tBTM_BLE_CB *p_ble_cb = &btm_cb.ble_ctr_cb;
    tBTM_INQUIRY_VAR_ST      *p_inq = &btm_cb.btm_inq_vars;
...
    if (!BTM_BLE_IS_SCAN_ACTIVE(p_ble_cb->scan_activity))//如果没有scan 正在进行，开始scan
    {
        btsnd_hcic_ble_set_scan_params(BTM_BLE_SCAN_MODE_ACTI,//active scan
                                        BTM_BLE_LOW_LATENCY_SCAN_INT,
                                        BTM_BLE_LOW_LATENCY_SCAN_WIN,
                                        btm_cb.ble_ctr_cb.addr_mgnt_cb.own_addr_type,
                                        SP_ADV_ALL);
#if (defined BLE_PRIVACY_SPT && BLE_PRIVACY_SPT == TRUE)
        /* enable IRK list */
        btm_ble_enable_resolving_list_for_platform(BTM_BLE_RL_SCAN);
#endif
        p_ble_cb->inq_var.scan_duplicate_filter  = BTM_BLE_DUPLICATE_DISABLE;
        status = btm_ble_start_scan();//开始scan
    }
    else if ((p_ble_cb->inq_var.scan_interval != BTM_BLE_LOW_LATENCY_SCAN_INT) ||
            (p_ble_cb->inq_var.scan_window != BTM_BLE_LOW_LATENCY_SCAN_WIN)) {//如果已经有正在scan的行为，先停掉当前的scan，启动新的scan
        btsnd_hcic_ble_set_scan_enable(BTM_BLE_SCAN_DISABLE, BTM_BLE_DUPLICATE_ENABLE);
        btsnd_hcic_ble_set_scan_params(BTM_BLE_SCAN_MODE_ACTI,
                                        BTM_BLE_LOW_LATENCY_SCAN_INT,
                                        BTM_BLE_LOW_LATENCY_SCAN_WIN,
                                        btm_cb.ble_ctr_cb.addr_mgnt_cb.own_addr_type,
                                        SP_ADV_ALL);
        btsnd_hcic_ble_set_scan_enable(BTM_BLE_SCAN_ENABLE, BTM_BLE_DUPLICATE_DISABLE);
    }
    if (status == BTM_CMD_STARTED)
    {
        p_inq->inq_active |= mode;//置位
        p_ble_cb->scan_activity |= mode;
        if (duration != 0)
        {
            /* start inquiry timer */
            btu_start_timer (&p_inq->inq_timer_ent, BTU_TTYPE_BLE_INQUIRY, duration);//开始定时器，当定时器时间到的时候会 disable scan
        }
    }
    return status;
}

 上面的代码的逻辑非常的简单，需要留意一下就是 p_inq->inq_active |= mode 和 p_ble_cb->scan_activity |= mode;

现在Ble 的扫描就开始了，持续时间10s = 10*1000ms，定时器超时时间到了之后会取消scan。

从上面我们还可以看出从inquiry 下发的ble scan的优先级还是很高，它会停掉当前的scan的行为。如果此时后台有observe 行为，也会被停掉。

btm_set_inq_event_filter

static tBTM_STATUS btm_set_inq_event_filter (UINT8 filter_cond_type,
                                             tBTM_INQ_FILT_COND *p_filt_cond)
{
...
    btm_cb.btm_inq_vars.inqfilt_active = TRUE;设置了标志位

    /* Filter the inquiry results for the specified condition type and value */
    if (btsnd_hcic_set_event_filter(HCI_FILTER_INQUIRY_RESULT, filter_cond_type,
                                    p_cond, condition_length))

        return (BTM_CMD_STARTED);
    else
        return (BTM_NO_RESOURCES);
}

 上面主要是发送了HCI_FILTER_INQUIRY_RESULT ，以及设置了状态位：btm_cb.btm_inq_vars.inqfilt_active = TRUE

搜索的行为肯定是在这个函数的完成事件中进行的。

static void btu_hcif_hdl_command_complete (UINT16 opcode, UINT8 *p, UINT16 evt_len,
                                           void *p_cplt_cback)
{
    switch (opcode)
    {
        case HCI_INQUIRY_CANCEL:
            /* Tell inquiry processing that we are done */
            btm_process_cancel_complete(HCI_SUCCESS, BTM_BR_INQUIRY_MASK);
            break;
        case HCI_SET_EVENT_FILTER:
            btm_event_filter_complete (p);//执行此函数
            break;

void btm_event_filter_complete (UINT8 *p)
{
    UINT8            hci_status;
    tBTM_STATUS      status;
    tBTM_INQUIRY_VAR_ST *p_inq = &btm_cb.btm_inq_vars;
    tBTM_CMPL_CB   *p_cb = p_inq->p_inqfilter_cmpl_cb;
...
    /* Only process the inquiry filter; Ignore the connection filter until it
       is used by the upper layers */
    if (p_inq->inqfilt_active == TRUE ) //在命令下发的时候已经设置
    {
        /* Extract the returned status from the buffer */
        STREAM_TO_UINT8 (hci_status, p);
        if (hci_status != HCI_SUCCESS)
        {
            /* If standalone operation, return the error status; if embedded in the inquiry, continue the inquiry */
            BTM_TRACE_WARNING ("BTM Warning: Set Event Filter Failed (HCI returned 0x%x)", hci_status);
            status = BTM_ERR_PROCESSING;
        }
        else
            status = BTM_SUCCESS;

        /* If the set filter was initiated externally (via BTM_SetInqEventFilter), call the
           callback function to notify the initiator that it has completed */
        if (p_inq->state == BTM_INQ_INACTIVE_STATE)//此时是active状态
        {
            p_inq->inqfilt_active = FALSE;
            if (p_cb)
                (*p_cb) (&status);
        }
        else    /* An inquiry is active (the set filter command was internally generated),
                   process the next state of the process (Set a new filter or start the inquiry). */
        {
            if(status != BTM_SUCCESS)
            {
                /* Process the inquiry complete (Error Status) */
                btm_process_inq_complete (BTM_ERR_PROCESSING, (UINT8)(p_inq->inqparms.mode & BTM_BR_INQUIRY_MASK));

                /* btm_process_inq_complete() does not restore the following settings on periodic inquiry */
                p_inq->inqfilt_active = FALSE;
                p_inq->inq_active = BTM_INQUIRY_INACTIVE;
                p_inq->state = BTM_INQ_INACTIVE_STATE;

                return;
            }

            /* Check to see if a new filter needs to be set up */
            if (p_inq->state == BTM_INQ_CLR_FILT_STATE)
            {
                if ((status = btm_set_inq_event_filter (p_inq->inqparms.filter_cond_type, &p_inq->inqparms.filter_cond)) == BTM_CMD_STARTED)
                {
                    p_inq->state = BTM_INQ_SET_FILT_STATE;
                }
                else    /* Error setting the filter: Call the initiator's callback function to indicate a failure */
                {
                    p_inq->inqfilt_active = FALSE;

                    /* Process the inquiry complete (Error Status) */
                    btm_process_inq_complete (BTM_ERR_PROCESSING, (UINT8)(p_inq->inqparms.mode & BTM_BR_INQUIRY_MASK));
                }
            }
            else    /* Initiate the Inquiry or Periodic Inquiry */
            {
                p_inq->state = BTM_INQ_ACTIVE_STATE;//处于该状态
                p_inq->inqfilt_active = FALSE;//设置false
                btm_initiate_inquiry (p_inq);//开始扫描
            }
        }
    }
}

 

上面代码的做的主要的事情:

p_inq->state = BTM_INQ_ACTIVE_STATE;
p_inq->inqfilt_active = FALSE;
btm_initiate_inquiry (p_inq);

继续看btm_initiate_inquiry的实现：

static void btm_initiate_inquiry (tBTM_INQUIRY_VAR_ST *p_inq)
{
    const LAP       *lap;
    tBTM_INQ_PARMS  *p_inqparms = &p_inq->inqparms;
    btm_acl_update_busy_level (BTM_BLI_INQ_EVT);
...
    lap = (p_inq->inq_active & BTM_LIMITED_INQUIRY_ACTIVE) ? &limited_inq_lap : &general_inq_lap;//设置LAP

    {
        btm_clr_inq_result_flt();//清数据库
        /* Allocate memory to hold bd_addrs responding */
        if ((p_inq->p_bd_db = (tINQ_BDADDR *)GKI_getbuf(GKI_MAX_BUF_SIZE)) != NULL)
        {
            p_inq->max_bd_entries = (UINT16)(GKI_MAX_BUF_SIZE / sizeof(tINQ_BDADDR));
            memset(p_inq->p_bd_db, 0, GKI_MAX_BUF_SIZE);
/*            BTM_TRACE_DEBUG("btm_initiate_inquiry: memory allocated for %d bdaddrs",
                              p_inq->max_bd_entries); */
        }

        if (!btsnd_hcic_inquiry(*lap, p_inqparms->duration, 0))//发送inquiry 命令
            btm_process_inq_complete (BTM_NO_RESOURCES, (UINT8)(p_inqparms->mode & BTM_BR_INQUIRY_MASK));
    }
}

 

 上面代码中，重点就是btsnd_hcic_inquiry(*lap, p_inqparms->duration, 0) 

其实现就是向controller 发送inquiry 的命令。这里注意其duration参数是10，对应的实际的值是10*1.28s,在12.8秒之后会有inquiry complete 事件传上来。

对于inquiry 的命令发送流程就分析到这里。

转载于:https://www.cnblogs.com/libs-liu/p/9229253.html