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