1.\" Copyright (c) 1998 Doug Rabson 2.\" 3.\" All rights reserved. 4.\" 5.\" This program is free software. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" $FreeBSD: src/share/man/man9/DEVICE_PROBE.9,v 1.4.2.6 2001/12/17 11:30:18 ru Exp $ 28.\" $DragonFly: src/share/man/man9/DEVICE_PROBE.9,v 1.5 2008/11/09 10:27:47 swildner Exp $ 29.\" 30.Dd June 16, 1998 31.Dt DEVICE_PROBE 9 32.Os 33.Sh NAME 34.Nm DEVICE_PROBE 35.Nd probe for device existence 36.Sh SYNOPSIS 37.In sys/param.h 38.In sys/bus.h 39.Ft int 40.Fn DEVICE_PROBE "device_t dev" 41.Sh DESCRIPTION 42This device method should probe to see if the device is present. 43It should return 0 if the device exists, 44.Er ENXIO 45if it cannot be found. 46If some other error happens during the probe (such as a memory 47allocation failure), an appropriate error code should be returned. 48For 49cases where more than one driver matches a device, a priority value can 50be returned. In this case, success codes are values less than or equal 51to zero with the highest value representing the best match. Failure 52codes are represented by positive values and the regular unix error 53codes should be used for the purpose. 54.Pp 55If a driver returns a success code which is less than zero, it must 56not assume that it will be the same driver which is attached to the 57device. 58In particular, it must not assume that any values stored in 59the softc structure will be available for its attach method and any 60resources allocated during probe must be released and re-allocated 61if the attach method is called. 62If a success code of zero is 63returned, the driver can assume that it will be the one attached. 64.Pp 65Devices which implement busses should use this method to probe for 66the existence of devices attached to the bus and add them as 67children. 68If this is combined with the use of 69.Xr bus_generic_attach 9 70the child devices will be automatically probed and attached. 71.Sh RETURN VALUES 72A value equal to or less than zero indicates success, greater than 73zero indicates an error 74.Va ( errno ) . 75For values equal to or less than 76zero: zero indicates highest priority, no further probing is done; 77for a value less than zero, the lower the value the lower the 78priority, e.g. -100 indicates a lower priority than -50. 79.Sh SEE ALSO 80.Xr device 9 , 81.Xr DEVICE_ATTACH 9 82.Sh AUTHORS 83This man page was written by 84.An Doug Rabson . 85