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.Dd February 8, 2012 30.Dt DEVICE_PROBE 9 31.Os 32.Sh NAME 33.Nm DEVICE_PROBE 34.Nd probe for device existence 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/bus.h 38.Ft int 39.Fn DEVICE_PROBE "device_t dev" 40.Sh DESCRIPTION 41The 42.Fn DEVICE_PROBE 43method 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. 52In this case, success codes are values less than or equal 53to zero with the highest value representing the best match. 54Failure 55codes are represented by positive values and the regular 56.Ux 57error 58codes should be used for the purpose. 59.Pp 60If a driver returns a success code which is less than zero, it must 61not assume that it will be the same driver which is attached to the 62device. 63In particular, it must not assume that any values stored in 64the softc structure will be available for its attach method and any 65resources allocated during probe must be released and re-allocated 66if the attach method is called. 67In addition it is an absolute requirement that the probe routine have 68no side effects whatsoever. 69The probe routine may be called more than once before the attach 70routine is called. 71.Pp 72If a success code of zero is 73returned, the driver can assume that it will be the one attached, but 74must not hold any resources when the probe routine returns. 75A driver may assume that the softc is preserved when it returns 76a success code of zero. 77.Sh RETURN VALUES 78A value equal to or less than zero indicates success, greater than 79zero indicates an error (errno). 80For values equal to or less than 81zero: zero indicates highest priority, no further probing is done; 82for a value less than zero, the lower the value the lower the 83priority, e.g.\& -100 indicates a lower priority than -50. 84.Pp 85The following values are used by convention to indicate different 86strengths of matching in a probe routine. 87Except as noted, these are just suggested values, and there's nothing 88magical about them. 89.Bl -tag -width BUS_PROBE_NOWILDCARD 90.It BUS_PROBE_SPECIFIC 91The device that cannot be reprobed, and that no 92possible other driver may exist (typically legacy drivers who don't follow 93all the rules, or special needs drivers). 94.It BUS_PROBE_VENDOR 95The device is supported by a vendor driver. 96This is for source or binary drivers that are not yet integrated into the 97.Fx 98tree. 99Its use in the base OS is prohibited. 100.It BUS_PROBE_DEFAULT 101The device is a normal device matching some plug and play ID. 102This is 103the normal return value for drivers to use. 104It is intended that nearly all of the drivers in the tree should return 105this value. 106.It BUS_PROBE_LOW_PRIORITY 107The driver is a legacy driver, or an otherwise less desirable driver 108for a given plug and play ID. 109The driver has special requirements like when there are two drivers 110that support overlapping series of hardware devices. 111In this case the one that supports the older part of the line would 112return this value, while the one that supports the newer ones would 113return BUS_PROBE_DEFAULT. 114.It BUS_PROBE_GENERIC 115The driver matches the type of device generally. 116This allows drivers to match all serial ports generally, with specialized 117drivers matching particular types of serial ports that need special 118treatment for some reason. 119.It BUS_PROBE_HOOVER 120The driver matches all unclaimed devices on a bus. 121The 122.Xr ugen 4 123device is one example. 124.It BUS_PROBE_NOWILDCARD 125The driver expects its parent to tell it which children to manage 126and no probing is really done. 127The device only matches if its parent bus specifically said to use 128this driver. 129.El 130.Sh SEE ALSO 131.Xr device 9 , 132.Xr DEVICE_ATTACH 9 , 133.Xr DEVICE_DETACH 9 , 134.Xr DEVICE_IDENTIFY 9 , 135.Xr DEVICE_SHUTDOWN 9 136.Sh AUTHORS 137This manual page was written by 138.An Doug Rabson . 139