Processing of Bluetooth HCI event

The author's blog address: http://blog.sina.com.cn/samzhen1977
By Sam (zhufeng)
Sam_code@hotmail.com

 

 

1. When Bluetooth USB
When the USB interface is inserted into the dongle, the probe program in Driver/Bluetooth/hci_usb.c is called. PROBE will call
Hci_register_dev () --> tasklet_init (& hdev-> rx_task,
Hci_rx_task, (unsigned long) hdev );
Connect hci_rx_task () to rx_task-> func.

 

2. When Bluetooth USB dongle is inserted, hdev-> open =
Hci_usb_open; When USB
This function is called when the dongle is up. It calls hci_usb_intr_rx_submit () and registers urb to complete the processing process.
Hci_usb_rx_complete.

When urb appears, hci_usb_rx_complete->__ recv_frame ()
-> Hci_recv_frame ()-> hci_sched_rx (hdev);-> hci_sched_rx ()
-> Tasklet_schedule (& hdev-> rx_task)

Tasklet_schedule ():
Put this tasklet in
The head of the tasklet_vec linked list and wake up the background thread ksoftirqd. When the backend thread ksoftirqd runs the call _ do_softirq, the execution is interrupted.
Tasklet_action function corresponding to tasklet_softirq in softirq_vec vector table, and traverse tasklet_action
The tasklet_vec linked list calls each tasklet function to complete the Soft Interrupt operation.
That is, call hci_rx_task ()

That is, when urb exists, hci_rx_task () is finally called ()

When the package type is HCI event, call hci_event_packet ()
In hci_event_packet (), the system determines the event and processes it.

The following uses hci_ev_disconn_complete as an example to see how the event is processed. This event indicates that the connection is disconnected. Reason indicates the reason for disconnection.

Hci_ev_disconn_complete
Event is handled by the handler hci_disconn_complete_evt. The following describes in detail:

1. hci_dev_lock (): Use the spin lock to get the resource.

2. hci_conn_hash_lookup_handle (): Find the corresponding connection from the connection queue. Note: When an ACL or SOC connection exists, the connection will be added to the connection chain.
Table.

3. Change the connection state to bt_closed.

4. hci_proto_disconn_ind ():
Call disconn_ind () in the global variable hci_proto ().

Note: In L2CAP protocol
Hci_register_proto () is called during insmod. The global variable hci_proto is assigned a value.
Disconn_ind = l2cap_disconn_ind;

Therefore, when the HCI Layer gets disconnect, it will notify the L2CAP layer to delete the channel.

Because the state is changed to bt_closed
When the layer calls poll (and finally calls bt_sock_poll), it will find that pollhup is set.

In this way, The L2CAP application can know that the connection has been disconnected.