388 lines
14 KiB
Groff
388 lines
14 KiB
Groff
.\" Copyright (c) 2001-2002 Maksim Yevmenkin <m_evmenkin@yahoo.com>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $Id: ng_hci.4,v 1.3 2003/05/21 19:37:35 max Exp $
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.\" $FreeBSD$
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.\"
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.Dd June 25, 2002
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.Dt NG_HCI 4
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.Os
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.Sh NAME
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.Nm ng_hci
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.Nd Netgraph node type that is also a Bluetooth Host Controller Interface
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(HCI) layer
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.Sh SYNOPSIS
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.In sys/types.h
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.In netgraph/bluetooth/include/ng_hci.h
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.Sh DESCRIPTION
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The
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.Nm hci
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node type is a Netgraph node type that implements Bluetooth Host Controller
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Interface (HCI) layer as per chapter H1 of the Bluetooth Specification Book
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v1.1.
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.Sh INTRODUCTION TO BLUETOOTH
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Bluetooth is a short-range radio link intended to replace the cable(s)
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connecting portable and/or fixed electronic devices.
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Bluetooth operates in the unlicensed ISM band at 2.4 GHz.
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The Bluetooth protocol uses a
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combination of circuit and packet switching.
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Bluetooth can support an
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asynchronous data channel, up to three simultaneous synchronous voice
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channels, or a channel which simultaneously supports asynchronous data
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and synchronous voice.
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Each voice channel supports a 64 kb/s synchronous
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(voice) channel in each direction.
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The asynchronous channel can support
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maximal 723.2 kb/s asymmetric (and still up to 57.6 kb/s in the return
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direction), or 433.9 kb/s symmetric.
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.Pp
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The Bluetooth system provides a point-to-point connection (only two
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Bluetooth units involved), or a point-to-multipoint connection.
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In the point-to-multipoint connection,
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the channel is shared among several Bluetooth units.
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Two or more units sharing the same channel form a
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.Dq piconet .
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One Bluetooth unit acts as the master of the piconet, whereas the other
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unit(s) acts as slave(s).
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Up to seven slaves can be active in the piconet.
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In addition, many more slaves can remain locked to the master in a so-called
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parked state.
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These parked slaves cannot be active on the channel, but remain
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synchronized to the master.
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Both for active and parked slaves, the channel
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access is controlled by the master.
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.Pp
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Multiple piconets with overlapping coverage areas form a
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.Dq scatternet .
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Each piconet can only have a single master.
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However, slaves can participate
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in different piconets on a time-division multiplex basis.
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In addition, a master in one piconet can be a slave in another piconet.
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The piconets shall not be frequency-synchronized.
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Each piconet has its own hopping channel.
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.Ss Time Slots
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The channel is divided into time slots, each 625 usec in length.
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The time
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slots are numbered according to the Bluetooth clock of the piconet master.
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The slot numbering ranges from 0 to 2^27 -1 and is cyclic with a cycle length
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of 2^27.
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In the time slots, master and slave can transmit packets.
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.Ss SCO Link
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The SCO link is a symmetric, point-to-point link between the master and a
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specific slave.
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The SCO link reserves slots and can therefore be considered
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as a circuit-switched connection between the master and the slave.
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The SCO link typically supports time-bounded information like voice.
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The master can
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support up to three SCO links to the same slave or to different slaves.
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A slave can support up to three SCO links from the same master, or two SCO
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links if the links originate from different masters.
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SCO packets are never retransmitted.
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.Ss ACL Link
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In the slots not reserved for SCO links, the master can exchange packets
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with any slave on a per-slot basis.
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The ACL link provides a packet-switched
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connection between the master and all active slaves participating in the
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piconet.
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Both asynchronous and isochronous services are supported.
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Between a master and a slave only a single ACL link can exist.
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For most ACL packets,
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packet retransmission is applied to assure data integrity.
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.Sh HOST CONTROLLER INTERFACE (HCI)
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The HCI provides a command interface to the baseband controller and link
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manager, and access to hardware status and control registers.
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This interface
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provides a uniform method of accessing the Bluetooth baseband capabilities.
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.Pp
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The HCI layer on the Host exchanges data and commands with the HCI firmware
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on the Bluetooth hardware.
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The Host Controller Transport Layer (i.e., physical
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bus) driver provides both HCI layers with the ability to exchange information
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with each other.
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.Pp
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The Host will receive asynchronous notifications of HCI events independent
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of which Host Controller Transport Layer is used.
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HCI events are used for
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notifying the Host when something occurs.
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When the Host discovers that an
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event has occurred it will then parse the received event packet to determine
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which event occurred.
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The next sections specify the HCI packet formats.
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.Ss HCI Command Packet
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.Bd -literal -offset indent
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#define NG_HCI_CMD_PKT 0x01
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typedef struct {
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uint8_t type; /* MUST be 0x1 */
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uint16_t opcode; /* OpCode */
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uint8_t length; /* parameter(s) length in bytes */
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} __attribute__ ((packed)) ng_hci_cmd_pkt_t;
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.Ed
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.Pp
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The HCI command packet is used to send commands to the Host Controller
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from the Host.
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When the Host Controller completes most of the commands,
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a Command Complete event is sent to the Host.
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Some commands do not receive
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a Command Complete event when they have been completed.
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Instead, when the
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Host Controller receives one of these commands the Host Controller sends
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a Command Status event back to the Host when it has begun to execute the
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command.
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Later on, when the actions associated with the command have finished,
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an event that is associated with the sent command will be sent by the Host
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Controller to the Host.
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.Ss HCI Event Packet
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.Bd -literal -offset indent
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#define NG_HCI_EVENT_PKT 0x04
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typedef struct {
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uint8_t type; /* MUST be 0x4 */
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uint8_t event; /* event */
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uint8_t length; /* parameter(s) length in bytes */
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} __attribute__ ((packed)) ng_hci_event_pkt_t;
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.Ed
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.Pp
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The HCI event packet is used by the Host Controller to notify the Host
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when events occur.
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.Ss HCI ACL Data Packet
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.Bd -literal -offset indent
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#define NG_HCI_ACL_DATA_PKT 0x02
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typedef struct {
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uint8_t type; /* MUST be 0x2 */
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uint16_t con_handle; /* connection handle + PB + BC flags */
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uint16_t length; /* payload length in bytes */
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} __attribute__ ((packed)) ng_hci_acldata_pkt_t;
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.Ed
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.Pp
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HCI ACL data packets are used to exchange ACL data between the Host and
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Host Controller.
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.Ss HCI SCO Data Packet
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.Bd -literal -offset indent
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#define NG_HCI_SCO_DATA_PKT 0x03
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typedef struct {
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uint8_t type; /* MUST be 0x3 */
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uint16_t con_handle; /* connection handle + reserved bits */
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uint8_t length; /* payload length in bytes */
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} __attribute__ ((packed)) ng_hci_scodata_pkt_t;
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.Ed
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.Pp
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HCI SCO data packets are used to exchange SCO data between the Host and
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Host Controller.
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.Sh HCI INITIALIZATION
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On initialization, HCI control application must issue the following HCI
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commands (in any order).
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.Bl -tag -width foo
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.It Dv Read_BD_ADDR
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To obtain BD_ADDR of the Bluetooth unit.
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.It Dv Read_Local_Supported_Features
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To obtain the list of features supported by Bluetooth unit.
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.It Dv Read_Buffer_Size
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To determine the maximum size of HCI ACL and SCO HCI data packets (excluding
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header) that can be sent from the Host to the Host Controller.
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There are also
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two additional return parameters that specify the total number of HCI ACL and
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SCO data packets that the Host Controller can have waiting for transmission in
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its buffers.
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.El
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.Pp
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As soon as HCI initialization has been successfully performed, HCI control
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application must turn on
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.Dq inited
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bit for the node.
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Once HCI node has been initialized all upstream hooks
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will receive a
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.Dv NGM_HCI_NODE_UP
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Netgraph message defined as follows.
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.Bd -literal -offset indent
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#define NGM_HCI_NODE_UP 112 /* HCI -> Upper */
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typedef struct {
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uint16_t pkt_size; /* max. ACL/SCO packet size (w/o hdr) */
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uint16_t num_pkts; /* ACL/SCO packet queue size */
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uint16_t reserved; /* place holder */
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bdaddr_t bdaddr; /* bdaddr */
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} ng_hci_node_up_ep;
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.Ed
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.Sh HCI FLOW CONTROL
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HCI layer performs flow control on baseband connection basis (i.e., ACL and
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SCO link).
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Each baseband connection has
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.Dq "connection handle"
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and queue of outgoing data packets.
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Upper layers protocols are allowed to
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send up to
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.Dv ( num_pkts
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\-
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.Dv pending )
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packets at one time.
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HCI layer will send
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.Dv NGM_HCI_SYNC_CON_QUEUE
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Netgraph messages to inform upper layers about current queue state for each
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connection handle.
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The
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.Dv NGM_HCI_SYNC_CON_QUEUE
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Netgraph message is defined as follows.
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.Bd -literal -offset indent
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#define NGM_HCI_SYNC_CON_QUEUE 113 /* HCI -> Upper */
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typedef struct {
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uint16_t con_handle; /* connection handle */
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uint16_t completed; /* number of completed packets */
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} ng_hci_sync_con_queue_ep;
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.Ed
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.Sh HOOKS
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This node type supports the following hooks:
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.Bl -tag -width ".Va drv"
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.It Va drv
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Bluetooth Host Controller Transport Layer hook.
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Single HCI packet contained in single
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.Vt mbuf
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structure.
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.It Va acl
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Upper layer protocol/node is connected to the hook.
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Single HCI ACL data packet contained in single
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.Vt mbuf
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structure.
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.It Va sco
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Upper layer protocol/node is connected to the hook.
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Single HCI SCO data packet contained in single
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.Vt mbuf
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structure.
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.It Va raw
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Raw hook.
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Every HCI frame (including HCI command frame) that goes in
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or out will be delivered to the hook.
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Usually the Bluetooth raw HCI socket layer is connected to the hook.
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Single HCI frame contained in single
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.Vt mbuf
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structure.
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.El
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.Sh BLUETOOTH UPPER LAYER PROTOCOLS INTERFACE (LP CONTROL MESSAGES)
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.Bl -tag -width foo
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.It Dv NGM_HCI_LP_CON_REQ
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Requests the lower protocol to create a connection.
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If a physical link
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to the remote device does not exist, this message must be sent to the lower
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protocol (baseband) to establish the physical connection.
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.It Dv NGM_HCI_LP_DISCON_REQ
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Requests the lower protocol (baseband) to terminate a connection.
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.It Dv NGM_HCI_LP_CON_CFM
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Confirms success or failure of the
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.Dv NGM_HCI_LP_CON_REQ
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request to establish a lower layer (baseband) connection.
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This includes passing the authentication challenge if authentication is
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required to establish the physical link.
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.It Dv NGM_HCI_LP_CON_IND
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Indicates the lower protocol (baseband) has successfully established
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incoming connection.
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.It Dv NGM_HCI_LP_CON_RSP
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A response accepting or rejecting the previous connection indication request.
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.It Dv NGM_HCI_LP_DISCON_IND
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Indicates the lower protocol (baseband) has terminated connection.
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This could be a response to
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.Dv NGM_HCI_LP_DISCON_REQ
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or a timeout event.
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.It Dv NGM_HCI_LP_QOS_REQ
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Requests the lower protocol (baseband) to accommodate a particular QoS
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parameter set.
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.It Dv NGM_HCI_LP_QOS_CFM
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Confirms success or failure of the request for a given quality of service.
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.It Dv NGM_HCI_LP_QOS_IND
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Indicates the lower protocol (baseband) has detected a violation of the QoS
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agreement.
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.El
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.Sh NETGRAPH CONTROL MESSAGES
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This node type supports the generic control messages, plus the following:
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.Bl -tag -width foo
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.It Dv NGM_HCI_NODE_GET_STATE
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Returns current state for the node.
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.It Dv NGM_HCI_NODE_INIT
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Turn on
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.Dq inited
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bit for the node.
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.It Dv NGM_HCI_NODE_GET_DEBUG
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Returns an integer containing the current debug level for the node.
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.It Dv NGM_HCI_NODE_SET_DEBUG
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This command takes an integer argument and sets current debug level
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for the node.
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.It Dv NGM_HCI_NODE_GET_BUFFER
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Returns current state of data buffers.
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.It Dv NGM_HCI_NODE_GET_BDADDR
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Returns BD_ADDR as cached in the node.
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.It Dv NGM_HCI_NODE_GET_FEATURES
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Returns the list of features supported by hardware (as cached by the node).
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.It Dv NGM_HCI_NODE_GET_NEIGHBOR_CACHE
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Returns content of the neighbor cache.
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.It Dv NGM_HCI_NODE_FLUSH_NEIGHBOR_CACHE
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Remove all neighbor cache entries.
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.It Dv NGM_HCI_NODE_GET_CON_LIST
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Returns list of active baseband connections (i.e., ACL and SCO links).
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.It Dv NGM_HCI_NODE_GET_STAT
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Returns various statistic counters.
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.It Dv NGM_HCI_NODE_RESET_STAT
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Resets all statistic counters to zero.
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.It NGM_HCI_NODE_SET_LINK_POLICY_SETTINGS_MASK
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Sets current link policy settings mask.
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After the new ACL connection is
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created the HCI node will try set link policy for the ACL connection.
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By default, every supported Link Manager (LM) mode will be enabled.
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User can
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override this by setting link policy settings mask which specifies LM
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modes to be enabled.
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.It NGM_HCI_NODE_GET_LINK_POLICY_SETTINGS_MASK
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Returns current link policy settings mask.
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.It NGM_HCI_NODE_SET_PACKET_MASK
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Sets current packet mask.
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When new baseband (ACL or SCO) connection is
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created the HCI node will specify every packet type supported by the device.
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User can override this by setting packet mask which specifies packet types
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to be used for new baseband connections.
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.It NGM_HCI_NODE_GET_PACKET_MASK
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Returns current packet mask.
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.It NGM_HCI_NODE_SET_ROLE_SWITCH
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Sets the value of the role switch.
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Role switch is enabled when this value is not zero.
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This is the default state.
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Note that actual role switch at Bluetooth link level will only be performed if
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hardware supports role switch and it was enabled.
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.It NGM_HCI_NODE_GET_ROLE_SWITCH
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Returns the value of the role switch for the node.
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.El
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.Sh SHUTDOWN
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This node shuts down upon receipt of a
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.Dv NGM_SHUTDOWN
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control message, or
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when all hooks have been disconnected.
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.Sh SEE ALSO
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.Xr netgraph 4 ,
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.Xr hccontrol 8 ,
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.Xr ngctl 8
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.Sh HISTORY
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The
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.Nm hci
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node type was implemented in
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.Fx 5.0 .
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.Sh AUTHORS
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.An Maksim Yevmenkin Aq Mt m_evmenkin@yahoo.com
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.Sh BUGS
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Most likely.
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Please report if found.
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