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.\" $FreeBSD: releng/12.2/share/man/man9/BUS_ADD_CHILD.9 332317 2018-04-09 05:48:12Z gonzo $
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.Dd April 8, 2018
.Dt BUS_ADD_CHILD 9
.Os
.Sh NAME
.Nm BUS_ADD_CHILD
.Nd "add a device node to the tree with a given priority"
.Sh SYNOPSIS
.In sys/param.h
.In sys/bus.h
.Ft device_t
.Fn BUS_ADD_CHILD "device_t dev" "int order" "const char *name" "int unit"
.Sh DESCRIPTION
The
.Fn BUS_ADD_CHILD
method
is used by the driver identify routine to add devices to the tree.
It can also be used to add children to buses that implement this
routine in other contexts, although the behavior is bus specific.
Please see
.Xr device_add_child 9
for more details.
The interface is the same as
.Xr device_add_child 9
however, the bus'
.Fn BUS_ADD_CHILD
is called.
.Pp
Buses implementing
.Fn BUS_ADD_CHILD
should insert the device into the tree using
.Xr device_add_child 9
before adding things such as their own ivars and resource lists to the device.
.Fn BUS_ADD_CHILD
is not called by
.Xr device_add_child 9 .
.Fn BUS_ADD_CHILD
instead calls
.Xr device_add_child 9 .
.Pp
A panic will result when called for a bus that does not implement
.Fn BUS_ADD_CHILD .
Some buses require a special bus-specific routine to be called instead
of
.Fn BUS_ADD_CHILD .
.Sh RETURN VALUES
The
.Fn BUS_ADD_CHILD
method returns
.Vt device_t
added to the tree, or
.Dv NULL
to indicate failure.
.Sh SEE ALSO
.Xr device 9 ,
.Xr device_add_child 9 ,
.Xr driver 9
.Sh AUTHORS
This manual page was written by
.An M. Warner Losh .