1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 2003 M. Warner Losh <imp@FreeBSD.org> 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 15.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 18.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd March 27, 2003 28.Dt BUS_CHILD_PRESENT 9 29.Os 30.Sh NAME 31.Nm bus_child_present 32.Nd "ask the bus driver to see if this device is still really present" 33.Sh SYNOPSIS 34.In sys/param.h 35.In sys/bus.h 36.Pp 37.In machine/bus.h 38.In sys/rman.h 39.In machine/resource.h 40.Ft int 41.Fn bus_child_present "device_t dev" 42.Sh DESCRIPTION 43The 44.Fn bus_child_present 45function requests that the parent device driver of 46.Fa dev 47check to see if the 48hardware represented by 49.Fa dev 50is still physically accessible at this time. 51While the notion of accessible varies from bus to bus, generally 52hardware that is not accessible cannot be accessed via the 53.Fn bus_space* 54methods that would otherwise be used to access the device. 55.Pp 56This does not ask the question 57.Dq does this device have children? 58which can better be answered by 59.Xr device_get_children 9 . 60.Sh RETURN VALUES 61A zero return value indicates that the device is not present in the 62system. 63A non-zero return value indicates that the device is present in the 64system, or that the state of the device cannot be determined. 65.Sh EXAMPLES 66This is some example code. 67It only calls stop when the 68.Xr dc 4 69device is actually present. 70.Bd -literal -offset indent 71device_t dev; 72dc_softc *sc; 73 74sc = device_get_softc(dev); 75if (bus_child_present(dev)) 76 dc_stop(sc); 77.Ed 78.Sh SEE ALSO 79.Xr device 9 , 80.Xr driver 9 81.Sh AUTHORS 82This manual page was written by 83.An Warner Losh Aq Mt imp@FreeBSD.org . 84