NAME
ng_h4 —
Netgraph node type that is also an H4
line discipline
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 registered on a tty device (see
tty(4)).
The node has a single hook called hook.
Incoming bytes received 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 received 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 level for the node.
NGM_H4_NODE_SET_DEBUG- This command takes an integer argument and sets current 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 maximum 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
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.