ng_h4(4)

NAME

ng_h4 - Netgraph node type that is also an H4 line disci

pline

SYNOPSIS

#include <sys/types.h>
#include <netgraph/bluetooth/include/ng_h4.h>

DESCRIPTION

The h4 node type is both a persistent Netgraph node type and

a H4 line
discipline. It implements a Bluetooth HCI UART transport

layer as per
chapter H4 of the Bluetooth Specification Book v1.1. A new

node is created when the corresponding line discipline, H4DISC, is reg

istered on a
tty device (see tty(4)).

The node has a single hook called hook. Incoming bytes re

ceived on the
tty device are re-assembled into HCI frames (according to

the length).
Full HCI frames are sent out on the hook. HCI frames re

ceived on hook
are transmitted out on the tty device. No modification to

the data is
performed in either direction. While the line discipline is

installed on
a tty, the normal read and write operations are unavailable,

returning
EIO.

Information about the node is available via the netgraph

ioctl(2) command
NGIOCGINFO. This command returns a struct nodeinfo similar

to the
NGM_NODEINFO netgraph(4) control message.

HOOKS

This node type supports the following hooks:

hook single HCI frame contained in single mbuf structure.

CONTROL MESSAGES

This node type supports the generic control messages, plus

the following:

NGM_H4_NODE_RESET

Reset the node.

NGM_H4_NODE_GET_STATE

Returns current receiving state for the node.

NGM_H4_NODE_GET_DEBUG

Returns an integer containing the current debug lev

el for the
node.

NGM_H4_NODE_SET_DEBUG

This command takes an integer argument and sets cur

rent debug
level for the node.

NGM_H4_NODE_GET_QLEN

Returns current length of outgoing queue for the

node.

NGM_H4_NODE_SET_QLEN

This command takes an integer argument and sets max

imum length of
outgoing queue for the node.

NGM_H4_NODE_GET_STAT

Returns various statistic information for the node,

such as: number of bytes (frames) sent, number of bytes (frames)

received and
number of input (output) errors.

NGM_H4_NODE_RESET_STAT

Reset all statistic counters to zero.

SHUTDOWN

This node shuts down when the corresponding device is closed

(or the line
discipline is uninstalled on the device).

SEE ALSO

ioctl(2), netgraph(4), tty(4), ngctl(8)

HISTORY

The h4 node type was implemented in FreeBSD 5.0.

AUTHORS

Maksim Yevmenkin <m_evmenkin@yahoo.com>

BUGS

This node still uses spltty(9) to lock tty layer. This is

wrong.

BSD June 14, 2002

BSD