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.Dd March 27, 2003 26.Dt BUS_CHILD_PRESENT 9 27.Os 28.Sh NAME 29.Nm bus_child_present 30.Nd "ask the bus driver to see if this device is still really present" 31.Sh SYNOPSIS 32.In sys/param.h 33.In sys/bus.h 34.Pp 35.In machine/bus.h 36.In sys/rman.h 37.In machine/resource.h 38.Ft int 39.Fn bus_child_present "device_t dev" 40.Sh DESCRIPTION 41The 42.Fn bus_child_present 43function requests that the parent device driver of 44.Fa dev 45check to see if the 46hardware represented by 47.Fa dev 48is still physically accessible at this time. 49While the notion of accessible varies from bus to bus, generally 50hardware that is not accessible cannot be accessed via the 51.Fn bus_space* 52methods that would otherwise be used to access the device. 53.Pp 54This does not ask the question 55.Dq does this device have children? 56which can better be answered by 57.Xr device_get_children 9 . 58.Sh RETURN VALUES 59A zero return value indicates that the device is not present in the 60system. 61A non-zero return value indicates that the device is present in the 62system, or that the state of the device cannot be determined. 63.Sh EXAMPLES 64This is some example code. 65It only calls stop when the 66.Xr dc 4 67device is actually present. 68.Bd -literal -offset indent 69device_t dev; 70dc_softc *sc; 71 72sc = device_get_softc(dev); 73if (bus_child_present(dev)) 74 dc_stop(sc); 75.Ed 76.Sh SEE ALSO 77.Xr device 9 , 78.Xr driver 9 79.Sh AUTHORS 80This manual page was written by 81.An Warner Losh Aq Mt imp@FreeBSD.org . 82