293 lines
9.8 KiB
Groff
293 lines
9.8 KiB
Groff
.\" $NetBSD: autoconf.9,v 1.8 2001/12/13 19:29:32 gmcgarry Exp $
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.\"
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.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Gregory McGarry.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd June 17, 2001
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.Dt AUTOCONF 9
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.Os
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.Sh NAME
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.Nm autoconf ,
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.Nm config_search ,
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.Nm config_found_sm ,
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.Nm config_found ,
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.Nm config_attach ,
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.Nm config_detach ,
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.Nm config_activate ,
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.Nm config_deactivate ,
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.Nm config_defer ,
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.Nm config_interrupts ,
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.Nm config_pending_incr ,
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.Nm config_pending_decr
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.Nd autoconfiguration framework
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.Sh SYNOPSIS
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.Fd #include <sys/param.h>
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.Fd #include <sys/device.h>
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.Fd #include <sys/error.h>
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.Ft struct cfdata *
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.Fn config_search "cfmatch_t func" "struct device *parent" "void *aux"
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.Ft struct device *
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.Fn config_found_sm "struct device *parent" "void *aux" "cfprint_t print" \
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"cfmatch_t submatch"
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.Ft struct device *
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.Fn config_found "struct device *parent" "void *aux" "cfprint_t print"
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.Ft struct device *
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.Fn config_attach "struct device *parent" "struct cfdata *cf" "void *aux" \
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"cfprint_t print"
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.Ft int
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.Fn config_detach "struct device *dev" "int flags"
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.Ft int
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.Fn config_activate "struct device *dev"
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.Ft int
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.Fn config_deactivate "struct device *dev"
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.Ft int
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.Fn config_defer "struct device *dev" "void (*func)(struct device *)"
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.Ft void
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.Fn config_interrupts "struct device *dev" "void (*func)(struct device *)"
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.Ft void
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.Fn config_pending_incr
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.Ft void
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.Fn config_pending_decr
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.Sh DESCRIPTION
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Autoconfiguration is the process of matching hardware devices with an
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appropriate device driver. In its most basic form, autoconfiguration
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consists of the recursive process of finding and attaching all devices
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on a bus, including other busses.
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.Pp
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The autoconfiguration framework supports
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.Em direct configuration
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where the bus driver can determine the devices present. The
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autoconfiguration framework also supports
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.Em indirect configuration
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where the drivers must probe the bus looking the presence of a device.
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Direct configuration is preferred since it can find hardware
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regardless of the presence of proper drivers.
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.Pp
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The autoconfiguration process occurs at system bootstrap and is driven
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by a table generated from a
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.Do
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machine description
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.Dc
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file by
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.Xr config 8 .
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For a description of the
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.Xr config 8
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.Do
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device definition
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.Dc
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language, see
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.Xr config 9 .
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.Pp
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Each device must have a name consisting of an alphanumeric string that
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ends with a unit number. The unit number identifies an instance of
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the driver. Device data structures are allocated dynamically during
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autoconfiguration, giving a unique address for each instance.
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.Sh FUNCTIONS
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.Bl -tag -width compact
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.It Fn config_search "func" "parent" "aux"
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Performs indirect configuration of physical devices.
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.Fn config_search
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iterates over all potential children, calling the given
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function
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.Fa func
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for each one. If
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.Fa func
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is NULL,
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.Fn config_search
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applies each child's match function instead. The argument
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.Fa parent
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is the pointer to the parent's device structure. The given
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.Fa aux
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argument describes the device that has been found and is simply passed
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on through
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.Fa func
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to the child.
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.Fn config_search
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returns a pointer to the best-matched child or NULL otherwise.
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.Pp
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The role of
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.Fa func
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is to call
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the match function for each device and call
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.Fn config_attach
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for any positive matches. If
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.Fa func
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is NULL, then the parent should record the return value from
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.Fn config_search
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and call
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.Fn config_attach
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itself.
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.Pp
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Note that this function is designed so that it can be used to apply an
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arbitrary function to all potential children. In this case callers
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may choose to ignore the return value.
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.It Fn config_found_sm "parent" "aux" "print" "submatch"
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Performs direct configuration on a physical device.
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.Fn config_found_sm
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is called by the parent and in turn calls the
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.Fa submatch
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function to call the match function as
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determined by the configuration table. If
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.Fa submatch
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is NULL, the driver match functions are called directly. The argument
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.Fa parent
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is the pointer to the parent's device structure. The given
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.Fa aux
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argument describes the device that has been found. The
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.Em softc
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structure for the matched device will be allocated, and the
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appropriate driver attach function will be called. If the device is
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matched, the system prints the name of the child and parent devices,
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and then calls the
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.Fa print
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function to produce addition information if desired. If no driver
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takes a match, the same
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.Fa print
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function is called to complain. The print function is called with the
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.Fa aux
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argument and, if the matches failed, the full name (including unit
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number) of the parent device, otherwise NULL. The
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.Fa print
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function must return an integer value.
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.Pp
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Two special strings,
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.Do
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not configured
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.Dc
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and
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.Do
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unsupported
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.Dc
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will be appended automatically to non-driver reports if the return
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value is UNCONF or UNSUPP respectively; otherwise the function should
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return the value QUIET.
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.Pp
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.Fn config_found_sm
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returns a pointer to the attached device's
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.Em softc
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structure if the device is attached, NULL otherwise. Most callers can
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ignore this value, since the system will already have printed a
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diagnostic.
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.It Fn config_found "parent" "aux" "print"
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This function is equivalent to calling
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.Fn config_found_sm "parent" "aux" "print" "submatch"
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with
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.Fa submatch
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set to NULL and is provided for compatibility with older drivers.
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.It Fn config_attach "parent" "cf" "aux" "print"
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Attach a found device. Allocates the memory for the
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.Em softc
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structure and calls the drivers attach function according to the
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configuration table.
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If successful,
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.Fn config_attach
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returns the
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.Em softc .
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If unsuccessful, it returns NULL.
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.It Fn config_detach "dev" "flags"
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Called by the parent to detach the child device. The second argument
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.Em flags
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contains detachment flags. Valid values are DETACH_FORCE (force
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detachment (eg. because of hardware removal) and DETACH_QUIET (do not
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print a notice).
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.Fn config_detach
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returns zero if successful and an error code otherwise.
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.Fn config_detach
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is always called from a thread context, allowing
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.Xr sleep 9
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to be called while the device detaches itself.
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.It Fn config_activate "dev"
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Called by the parent to activate the child device
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.Fa dev .
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It is called to activate resources and initialise other kernel
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subsystems (such as the network subsystem).
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.Fn config_activate
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is called from interrupt contect after the device has been attached.
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.It Fn config_deactivate "dev"
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Called by the parent to deactivate the child device
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.Fa dev .
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.Fn config_deactivate
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is called from interrupt context to immediately relinquish resources
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and notify dependent kernel subsystems that the device is about to be
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detached. At some later point
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.Fn config_detach
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will be called to finalise the removal of the device.
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.It Fn config_defer "dev" "func"
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Called by the child to defer the remainder of its configuration until
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all its parent's devices have been attached. At this point, the
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function
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.Fa func
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is called with the argument
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.Fa dev .
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.It Fn config_interrupts "struct device *dev" "void (*func)(struct device *)"
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Called by the child to defer the remainder of its configuration until
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interrupts are enabled. At this point, the function
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.Fa func
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is called with the argument
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.Fa dev .
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.It Fn config_pending_incr
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Increment the
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.Va config_pending
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semaphore. It is used to account for deferred configurations before
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mounting the root file system.
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.It Fn config_pending_decr
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Decrement the
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.Va config_pending
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semaphore. It is used to account for deferred configurations before
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mounting the root file system.
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.El
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.Sh CODE REFERENCES
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This section describes places within the
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.Nx
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source tree where actual code implementing or utilising the
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autoconfiguration framework can be found. All pathnames are relative
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to
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.Pa /usr/src .
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.Pp
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The autoconfiguration framework itself is implemented within the file
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.Pa sys/kern/subr_autoconf.c .
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Data structures and function prototypes for the framework are located in
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.Pa sys/sys/device.h .
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.Sh SEE ALSO
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.Xr config 8 ,
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.Xr config 9 ,
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.Xr driver 9
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.Sh HISTORY
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Autoconfiguration first appeared in
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.Bx 4.1 .
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The autoconfiguration framework was completely revised in
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.Bx 4.4 .
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The detach and activate/deactivate interfaces appeared in
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.Nx 1.5 .
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