freebsd-nq/share/man/man9/DEVICE_PROBE.9

.\" -*- nroff -*-
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.\" Copyright (c) 1998 Doug Rabson
.\"
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.\" This program is free software.
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.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.Dd January 6, 2005
.Dt DEVICE_PROBE 9
.Os
.Sh NAME
.Nm DEVICE_PROBE
.Nd probe for device existence
.Sh SYNOPSIS
.In sys/param.h
.In sys/bus.h
.Ft int
.Fn DEVICE_PROBE "device_t dev"
.Sh DESCRIPTION
The
.Fn DEVICE_PROBE
method should probe to see if the device is present.
It should return 0 if the device exists,
.Er ENXIO
if it cannot be found.
If some other error happens during the probe (such as a memory
allocation failure), an appropriate error code should be returned.
For
cases where more than one driver matches a device, a priority value can
be returned.
In this case, success codes are values less than or equal
to zero with the highest value representing the best match.
Failure
codes are represented by positive values and the regular
.Ux
error
codes should be used for the purpose.
.Pp
If a driver returns a success code which is less than zero, it must
not assume that it will be the same driver which is attached to the
device.
In particular, it must not assume that any values stored in
the softc structure will be available for its attach method and any
resources allocated during probe must be released and re-allocated
if the attach method is called.
In addition it is an absolute requirement that the probe routine have
no side effects whatsoever.
The probe routine may be called more than once before the attach
routine is called.
.Pp
If a success code of zero is
returned, the driver can assume that it will be the one attached, but
must not hold any resources when the probe routine returns.
A driver may assume that the softc is preserved when it returns
a success code of zero.
.Sh RETURN VALUES
A value equal to or less than zero indicates success, greater than
zero indicates an error (errno).
For values equal to or less than
zero: zero indicates highest priority, no further probing is done;
for a value less than zero, the lower the value the lower the
priority, e.g.\& -100 indicates a lower priority than -50.
.Sh SEE ALSO
.Xr device 9 ,
.Xr DEVICE_ATTACH 9 ,
.Xr DEVICE_DETACH 9 ,
.Xr DEVICE_IDENTIFY 9 ,
.Xr DEVICE_SHUTDOWN 9
.Sh AUTHORS
This man page was written by
.An Doug Rabson .
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.\" -- nroff --`
			`.\"`
			`.\" Copyright (c) 1998 Doug Rabson`
			`.\"`
			`.\" All rights reserved.`
			`.\"`
			`.\" This program is free software.`
			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
			`.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES`
			`.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.`
			`.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,`
			`.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT`
			`.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,`
			`.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY`
			`.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT`
			`.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF`
			`.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.`
			`.\"`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.\"`
Use .Fn function_name MFC after: 3 days 2005-01-06 17:25:11 +00:00			`.Dd January 6, 2005`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.Dt DEVICE_PROBE 9`
mdoc(7) police: removed HISTORY info from the .Os call. 2001-07-10 15:31:11 +00:00			`.Os`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.Sh NAME`
			`.Nm DEVICE_PROBE`
			`.Nd probe for device existence`
			`.Sh SYNOPSIS`
mdoc(7) police: Use the new .In macro for #include statements. 2001-10-01 16:09:29 +00:00			`.In sys/param.h`
			`.In sys/bus.h`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.Ft int`
			`.Fn DEVICE_PROBE "device_t dev"`
			`.Sh DESCRIPTION`
Use .Fn function_name MFC after: 3 days 2005-01-06 17:25:11 +00:00			`The`
			`.Fn DEVICE_PROBE`
			`method should probe to see if the device is present.`
mdoc(7) police: Er macro usage cleanup. 2000-11-22 16:11:48 +00:00			`It should return 0 if the device exists,`
			`.Er ENXIO`
			`if it cannot be found.`
Remove more single-space hard sentence breaks. 2000-03-02 14:54:02 +00:00			`If some other error happens during the probe (such as a memory`
			`allocation failure), an appropriate error code should be returned.`
			`For`
Update the comments on values than can be returned by DEVICE_PROBE. DEVICE_PROBE can return priorities. Reviewed by: Doug Rabson <dfr@nlsystems.com> 1999-06-17 19:22:12 +00:00			`cases where more than one driver matches a device, a priority value can`
Mdoc Janitor: * Fix hard sentence breaks. * Correct use of a period in DELAY(9). 2003-10-23 01:31:25 +00:00			`be returned.`
			`In this case, success codes are values less than or equal`
			`to zero with the highest value representing the best match.`
			`Failure`
mdoc(7) police: macroize UNIX. 2002-03-18 10:43:49 +00:00			`codes are represented by positive values and the regular`
			`.Ux`
			`error`
Update the comments on values than can be returned by DEVICE_PROBE. DEVICE_PROBE can return priorities. Reviewed by: Doug Rabson <dfr@nlsystems.com> 1999-06-17 19:22:12 +00:00			`codes should be used for the purpose.`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.Pp`
Update the comments on values than can be returned by DEVICE_PROBE. DEVICE_PROBE can return priorities. Reviewed by: Doug Rabson <dfr@nlsystems.com> 1999-06-17 19:22:12 +00:00			`If a driver returns a success code which is less than zero, it must`
			`not assume that it will be the same driver which is attached to the`
Remove more single-space hard sentence breaks. 2000-03-02 14:54:02 +00:00			`device.`
			`In particular, it must not assume that any values stored in`
Update the comments on values than can be returned by DEVICE_PROBE. DEVICE_PROBE can return priorities. Reviewed by: Doug Rabson <dfr@nlsystems.com> 1999-06-17 19:22:12 +00:00			`the softc structure will be available for its attach method and any`
			`resources allocated during probe must be released and re-allocated`
Remove more single-space hard sentence breaks. 2000-03-02 14:54:02 +00:00			`if the attach method is called.`
Document more clearly that a probe routine: Should have no side effects Must not hold resources when it returns May be called multiple times if it returns < 0. Remove the bad advise that the probe routine should look for children for devices that implement busses. This is more properly reserved for the attach routine. 2004-04-11 06:37:21 +00:00			`In addition it is an absolute requirement that the probe routine have`
			`no side effects whatsoever.`
			`The probe routine may be called more than once before the attach`
			`routine is called.`
Update the comments on values than can be returned by DEVICE_PROBE. DEVICE_PROBE can return priorities. Reviewed by: Doug Rabson <dfr@nlsystems.com> 1999-06-17 19:22:12 +00:00			`.Pp`
Document more clearly that a probe routine: Should have no side effects Must not hold resources when it returns May be called multiple times if it returns < 0. Remove the bad advise that the probe routine should look for children for devices that implement busses. This is more properly reserved for the attach routine. 2004-04-11 06:37:21 +00:00			`If a success code of zero is`
			`returned, the driver can assume that it will be the one attached, but`
			`must not hold any resources when the probe routine returns.`
Be explicit that a driver may assume softc is preserved when returning 0 2004-08-11 21:52:31 +00:00			`A driver may assume that the softc is preserved when it returns`
			`a success code of zero.`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.Sh RETURN VALUES`
Update the comments on values than can be returned by DEVICE_PROBE. DEVICE_PROBE can return priorities. Reviewed by: Doug Rabson <dfr@nlsystems.com> 1999-06-17 19:22:12 +00:00			`A value equal to or less than zero indicates success, greater than`
Mechanically kill hard sentence breaks and double whitespaces. 2004-07-03 18:29:24 +00:00			`zero indicates an error (errno).`
			`For values equal to or less than`
Update the comments on values than can be returned by DEVICE_PROBE. DEVICE_PROBE can return priorities. Reviewed by: Doug Rabson <dfr@nlsystems.com> 1999-06-17 19:22:12 +00:00			`zero: zero indicates highest priority, no further probing is done;`
Spelling: s/then/than/ where appropriate. 2002-12-24 16:52:31 +00:00			`for a value less than zero, the lower the value the lower the`
Mechanically kill hard sentence breaks and double whitespaces. 2004-07-03 18:29:24 +00:00			`priority, e.g.\& -100 indicates a lower priority than -50.`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.Sh SEE ALSO`
			`.Xr device 9 ,`
Document more clearly that a probe routine: Should have no side effects Must not hold resources when it returns May be called multiple times if it returns < 0. Remove the bad advise that the probe routine should look for children for devices that implement busses. This is more properly reserved for the attach routine. 2004-04-11 06:37:21 +00:00			`.Xr DEVICE_ATTACH 9 ,`
Cross references between the DEVICE_*(9) manual pages. 2001-03-10 19:53:38 +00:00			`.Xr DEVICE_DETACH 9 ,`
			`.Xr DEVICE_IDENTIFY 9 ,`
			`.Xr DEVICE_SHUTDOWN 9`
Add manpages for the new device framework. 1998-09-03 21:52:05 +00:00			`.Sh AUTHORS`
			`This man page was written by`
			`.An Doug Rabson .`