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