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.\" -*- nroff -*-
.\"
.\" Copyright (c) 2003 M. Warner Losh
.\"
.\" All rights reserved.
.\"
.\" This program is free software.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd March 27, 2003
.Dt BUS_CHILD_PRESENT 9
.Os
.Sh NAME
.Nm bus_child_present
.Nd "ask the bus driver to see if this device is still really present"
.Sh SYNOPSIS
.In sys/param.h
.In sys/bus.h
.Pp
.In machine/bus.h
.In sys/rman.h
.In machine/resource.h
.Ft int
.Fn bus_child_present "device_t dev"
.Sh DESCRIPTION
The
.Fn bus_child_present
function requests that the parent device driver of
.Fa dev
check to see if the
hardware represented by
.Fa dev
is still physically accessible at this time.
While the notion of accessible varies from bus to bus, generally
hardware that is not accessible cannot be accessed via the
.Fn bus_space*
methods that would otherwise be used to access the device.
.Pp
This does not ask the question
.Dq does this device have children?
which can better be answered by
.Xr device_get_children 9 .
.Sh RETURN VALUES
A zero return value indicates that the device is not present in the
system.
A non-zero return value indicates that the device is present in the
system, or that the state of the device cannot be determined.
.Sh EXAMPLES
This is some example code.
It only calls stop when the
.Xr dc 4
device is actually present.
.Bd -literal -offset indent
device_t dev;
dc_softc *sc;
sc = device_get_softc(dev);
if (bus_child_present(dev))
dc_stop(sc);
.Ed
.Sh SEE ALSO
.Xr device 9 ,
.Xr driver 9
.Sh AUTHORS
This manual page was written by
.An Warner Losh Aq imp@FreeBSD.org .
|
