Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
NG_HCI(4)	       FreeBSD Kernel Interfaces Manual		     NG_HCI(4)

NAME
     ng_hci -- Netgraph	node type that is also a Bluetooth Host	Controller
     Interface (HCI) layer

SYNOPSIS
     #include <sys/types.h>
     #include <netgraph/bluetooth/include/ng_hci.h>

DESCRIPTION
     The hci node type is a Netgraph node type that implements Bluetooth Host
     Controller	Interface (HCI)	layer as per chapter H1	of the Bluetooth Spec-
     ification Book v1.1.

INTRODUCTION TO	BLUETOOTH
     Bluetooth is a short-range	radio link intended to replace the cable(s)
     connecting	portable and/or	fixed electronic devices.  Bluetooth operates
     in	the unlicensed ISM band	at 2.4 GHz.  The Bluetooth protocol uses a
     combination of circuit and	packet switching.  Bluetooth can support an
     asynchronous data channel,	up to three simultaneous synchronous voice
     channels, or a channel which simultaneously supports asynchronous data
     and synchronous voice.  Each voice	channel	supports a 64 kb/s synchronous
     (voice) channel in	each direction.	 The asynchronous channel can support
     maximal 723.2 kb/s	asymmetric (and	still up to 57.6 kb/s in the return
     direction), or 433.9 kb/s symmetric.

     The Bluetooth system provides a point-to-point connection (only two Blue-
     tooth units involved), or a point-to-multipoint connection.  In the
     point-to-multipoint connection, the channel is shared among several Blue-
     tooth units.  Two or more units sharing the same channel form a
     ``piconet''.  One Bluetooth unit acts as the master of the	piconet,
     whereas the other unit(s) acts as slave(s).  Up to	seven slaves can be
     active in the piconet.  In	addition, many more slaves can remain locked
     to	the master in a	so-called parked state.	 These parked slaves cannot be
     active on the channel, but	remain synchronized to the master.  Both for
     active and	parked slaves, the channel access is controlled	by the master.

     Multiple piconets with overlapping	coverage areas form a ``scatternet''.
     Each piconet can only have	a single master.  However, slaves can partici-
     pate in different piconets	on a time-division multiplex basis.  In	addi-
     tion, a master in one piconet can be a slave in another piconet.  The
     piconets shall not	be frequency-synchronized.  Each piconet has its own
     hopping channel.

   Time	Slots
     The channel is divided into time slots, each 625 usec in length.  The
     time slots	are numbered according to the Bluetooth	clock of the piconet
     master.  The slot numbering ranges	from 0 to 2^27 -1 and is cyclic	with a
     cycle length of 2^27.  In the time	slots, master and slave	can transmit
     packets.

   SCO Link
     The SCO link is a symmetric, point-to-point link between the master and a
     specific slave.  The SCO link reserves slots and can therefore be consid-
     ered as a circuit-switched	connection between the master and the slave.
     The SCO link typically supports time-bounded information like voice.  The
     master can	support	up to three SCO	links to the same slave	or to differ-
     ent slaves.  A slave can support up to three SCO links from the same mas-
     ter, or two SCO links if the links	originate from different masters.  SCO
     packets are never retransmitted.

   ACL Link
     In	the slots not reserved for SCO links, the master can exchange packets
     with any slave on a per-slot basis.  The ACL link provides	a packet-
     switched connection between the master and	all active slaves participat-
     ing in the	piconet.  Both asynchronous and	isochronous services are sup-
     ported.  Between a	master and a slave only	a single ACL link can exist.
     For most ACL packets, packet retransmission is applied to assure data
     integrity.

HOST CONTROLLER	INTERFACE (HCI)
     The HCI provides a	command	interface to the baseband controller and link
     manager, and access to hardware status and	control	registers.  This
     interface provides	a uniform method of accessing the Bluetooth baseband
     capabilities.

     The HCI layer on the Host exchanges data and commands with	the HCI
     firmware on the Bluetooth hardware.  The Host Controller Transport	Layer
     (i.e., physical bus) driver provides both HCI layers with the ability to
     exchange information with each other.

     The Host will receive asynchronous	notifications of HCI events indepen-
     dent of which Host	Controller Transport Layer is used.  HCI events	are
     used for notifying	the Host when something	occurs.	 When the Host discov-
     ers that an event has occurred it will then parse the received event
     packet to determine which event occurred.	The next sections specify the
     HCI packet	formats.

   HCI Command Packet
	   #define NG_HCI_CMD_PKT 0x01
	   typedef struct {
		   u_int8_t  type;   /*	MUST be	0x1 */
		   u_int16_t opcode; /*	OpCode */
		   u_int8_t  length; /*	parameter(s) length in bytes */
	   } __attribute__ ((packed)) ng_hci_cmd_pkt_t;

     The HCI command packet is used to send commands to	the Host Controller
     from the Host.  When the Host Controller completes	most of	the commands,
     a Command Complete	event is sent to the Host.  Some commands do not
     receive a Command Complete	event when they	have been completed.  Instead,
     when the Host Controller receives one of these commands the Host Con-
     troller sends a Command Status event back to the Host when	it has begun
     to	execute	the command.  Later on,	when the actions associated with the
     command have finished, an event that is associated	with the sent command
     will be sent by the Host Controller to the	Host.

   HCI Event Packet
	   #define NG_HCI_EVENT_PKT 0x04
	   typedef struct {
		   u_int8_t type;   /* MUST be 0x4 */
		   u_int8_t event;  /* event */
		   u_int8_t length; /* parameter(s) length in bytes */
	   } __attribute__ ((packed)) ng_hci_event_pkt_t;

     The HCI event packet is used by the Host Controller to notify the Host
     when events occur.

   HCI ACL Data	Packet
	   #define NG_HCI_ACL_DATA_PKT 0x02
	   typedef struct {
		   u_int8_t  type;	 /* MUST be 0x2	*/
		   u_int16_t con_handle; /* connection handle +	PB + BC	flags */
		   u_int16_t length;	 /* payload length in bytes */
	   } __attribute__ ((packed)) ng_hci_acldata_pkt_t;

     HCI ACL data packets are used to exchange ACL data	between	the Host and
     Host Controller.

   HCI SCO Data	Packet
	   #define NG_HCI_SCO_DATA_PKT 0x03
	   typedef struct {
		   u_int8_t  type;	 /* MUST be 0x3	*/
		   u_int16_t con_handle; /* connection handle +	reserved bits */
		   u_int8_t  length;	 /* payload length in bytes */
	   } __attribute__ ((packed)) ng_hci_scodata_pkt_t;

     HCI SCO data packets are used to exchange SCO data	between	the Host and
     Host Controller.

HCI INITIALIZATION
     On	initialization,	HCI control application	must issue the following HCI
     commands (in any order).

     Read_BD_ADDR
	     To	obtain BD_ADDR of the Bluetooth	unit.

     Read_Local_Supported_Features
	     To	obtain the list	of features supported by Bluetooth unit.

     Read_Buffer_Size
	     To	determine the maximum size of HCI ACL and SCO HCI data packets
	     (excluding	header)	that can be sent from the Host to the Host
	     Controller.  There	are also two additional	return parameters that
	     specify the total number of HCI ACL and SCO data packets that the
	     Host Controller can have waiting for transmission in its buffers.

     As	soon as	HCI initialization has been successfully performed, HCI	con-
     trol application must turn	on ``inited'' bit for the node.	 Once HCI node
     has been initialized all upstream hooks will receive a NGM_HCI_NODE_UP
     Netgraph message defined as follows.

	   #define NGM_HCI_NODE_UP 112 /* HCI -> Upper */
	   typedef struct {
		   u_int16_t pkt_size; /* max. ACL/SCO packet size (w/o	hdr) */
		   u_int16_t num_pkts; /* ACL/SCO packet queue size */
		   u_int16_t reserved; /* place	holder */
		   bdaddr_t  bdaddr;   /* bdaddr */
	   } ng_hci_node_up_ep;

HCI FLOW CONTROL
     HCI layer performs	flow control on	baseband connection basis (i.e., ACL
     and SCO link).  Each baseband connection has ``connection handle''	and
     queue of outgoing data packets.  Upper layers protocols are allowed to
     send up to	(num_pkts - pending) packets at	one time.  HCI layer will send
     NGM_HCI_SYNC_CON_QUEUE Netgraph messages to inform	upper layers about
     current queue state for each connection handle.  The
     NGM_HCI_SYNC_CON_QUEUE Netgraph message is	defined	as follows.

	   #define NGM_HCI_SYNC_CON_QUEUE 113 /* HCI ->	Upper */
	   typedef struct {
		   u_int16_t con_handle; /* connection handle */
		   u_int16_t completed;	 /* number of completed	packets	*/
	   } ng_hci_sync_con_queue_ep;

HOOKS
     This node type supports the following hooks:

     drv     Bluetooth Host Controller Transport Layer hook.  Single HCI
	     packet contained in single	mbuf structure.

     acl     Upper layer protocol/node is connected to the hook.  Single HCI
	     ACL data packet contained in single mbuf structure.

     sco     Upper layer protocol/node is connected to the hook.  Single HCI
	     SCO data packet contained in single mbuf structure.

     raw     Raw hook.	Every HCI frame	(including HCI command frame) that
	     goes in or	out will be delivered to the hook.  Usually the	Blue-
	     tooth raw HCI socket layer	is connected to	the hook.  Single HCI
	     frame contained in	single mbuf structure.

BLUETOOTH UPPER	LAYER PROTOCOLS	INTERFACE (LP CONTROL MESSAGES)
     NGM_HCI_LP_CON_REQ
	     Requests the lower	protocol to create a connection.  If a physi-
	     cal link to the remote device does	not exist, this	message	must
	     be	sent to	the lower protocol (baseband) to establish the physi-
	     cal connection.

     NGM_HCI_LP_DISCON_REQ
	     Requests the lower	protocol (baseband) to terminate a connection.

     NGM_HCI_LP_CON_CFM
	     Confirms success or failure of the	NGM_HCI_LP_CON_REQ request to
	     establish a lower layer (baseband)	connection.  This includes
	     passing the authentication	challenge if authentication is
	     required to establish the physical	link.

     NGM_HCI_LP_CON_IND
	     Indicates the lower protocol (baseband) has successfully estab-
	     lished incoming connection.

     NGM_HCI_LP_CON_RSP
	     A response	accepting or rejecting the previous connection indica-
	     tion request.

     NGM_HCI_LP_DISCON_IND
	     Indicates the lower protocol (baseband) has terminated connec-
	     tion.  This could be a response to	NGM_HCI_LP_DISCON_REQ or a
	     timeout event.

     NGM_HCI_LP_QOS_REQ
	     Requests the lower	protocol (baseband) to accommodate a particu-
	     lar QoS parameter set.

     NGM_HCI_LP_QOS_CFM
	     Confirms success or failure of the	request	for a given quality of
	     service.

     NGM_HCI_LP_QOS_IND
	     Indicates the lower protocol (baseband) has detected a violation
	     of	the QoS	agreement.

NETGRAPH CONTROL MESSAGES
     This node type supports the generic control messages, plus	the following:

     NGM_HCI_NODE_GET_STATE
	     Returns current state for the node.

     NGM_HCI_NODE_INIT
	     Turn on ``inited''	bit for	the node.

     NGM_HCI_NODE_GET_DEBUG
	     Returns an	integer	containing the current debug level for the
	     node.

     NGM_HCI_NODE_SET_DEBUG
	     This command takes	an integer argument and	sets current debug
	     level for the node.

     NGM_HCI_NODE_GET_BUFFER
	     Returns current state of data buffers.

     NGM_HCI_NODE_GET_BDADDR
	     Returns BD_ADDR as	cached in the node.

     NGM_HCI_NODE_GET_FEATURES
	     Returns the list of features supported by hardware	(as cached by
	     the node).

     NGM_HCI_NODE_GET_NEIGHBOR_CACHE
	     Returns content of	the neighbor cache.

     NGM_HCI_NODE_FLUSH_NEIGHBOR_CACHE
	     Remove all	neighbor cache entries.

     NGM_HCI_NODE_GET_CON_LIST
	     Returns list of active baseband connections (i.e.,	ACL and	SCO
	     links).

     NGM_HCI_NODE_GET_STAT
	     Returns various statistic counters.

     NGM_HCI_NODE_RESET_STAT
	     Resets all	statistic counters to zero.

     NGM_HCI_NODE_SET_LINK_POLICY_SETTINGS_MASK
	     Sets current link policy settings mask.  After the	new ACL	con-
	     nection is	created	the HCI	node will try set link policy for the
	     ACL connection.  By default, every	supported Link Manager (LM)
	     mode will be enabled.  User can override this by setting link
	     policy settings mask which	specifies LM modes to be enabled.

     NGM_HCI_NODE_GET_LINK_POLICY_SETTINGS_MASK
	     Returns current link policy settings mask.

     NGM_HCI_NODE_SET_PACKET_MASK
	     Sets current packet mask.	When new baseband (ACL or SCO) connec-
	     tion is created the HCI node will specify every packet type sup-
	     ported by the device.  User can override this by setting packet
	     mask which	specifies packet types to be used for new baseband
	     connections.

     NGM_HCI_NODE_GET_PACKET_MASK
	     Returns current packet mask.

     NGM_HCI_NODE_SET_ROLE_SWITCH
	     Sets the value of the role	switch.	 Role switch is	enabled	when
	     this value	is not zero.  This is the default state.  Note that
	     actual role switch	at Bluetooth link level	will only be performed
	     if	hardware supports role switch and it was enabled.

     NGM_HCI_NODE_GET_ROLE_SWITCH
	     Returns the value of the role switch for the node.

SHUTDOWN
     This node shuts down upon receipt of a NGM_SHUTDOWN control message, or
     when all hooks have been disconnected.

SEE ALSO
     netgraph(4), hccontrol(8),	ngctl(8)

HISTORY
     The hci node type was implemented in FreeBSD 5.0.

AUTHORS
     Maksim Yevmenkin <m_evmenkin@yahoo.com>

BUGS
     Most likely.  Please report if found.

FreeBSD	10.1			 June 25, 2002			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | INTRODUCTION TO BLUETOOTH | HOST CONTROLLER INTERFACE (HCI) | HCI INITIALIZATION | HCI FLOW CONTROL | HOOKS | BLUETOOTH UPPER LAYER PROTOCOLS INTERFACE (LP CONTROL MESSAGES) | NETGRAPH CONTROL MESSAGES | SHUTDOWN | SEE ALSO | HISTORY | AUTHORS | BUGS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=ng_hci&sektion=4&manpath=FreeBSD+9.0-RELEASE>

home | help