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

     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.