99 lines
3.6 KiB
Groff
99 lines
3.6 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 1998 Doug Rabson
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 16, 1998
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.Dt DEVICE_ADD_CHILD 9
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.Os
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.Sh NAME
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.Nm device_add_child ,
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.Nm device_add_child_ordered
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.Nd "add a new device as a child of an existing device"
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/bus.h
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.Ft device_t
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.Fn device_add_child "device_t dev" "const char *name" "int unit"
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.Ft device_t
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.Fn device_add_child_ordered "device_t dev" "int order" "const char *name" "int unit"
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.Sh DESCRIPTION
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Create a new child device of
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.Fa dev .
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The
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.Fa name
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and
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.Fa unit
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arguments specify the name and unit number of the device.
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If the name is unknown then the caller should pass
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.Dv NULL .
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If the unit is unknown then the caller should pass
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.Dv -1
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and the system will choose the next available unit number.
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.Pp
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The name of the device is used to determine which drivers might be
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appropriate for the device. If a name is specified then only drivers
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of that name are probed. If no name is given then all drivers for the
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owning bus are probed.
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.Pp
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This allows busses which can uniquely identify device instances (such
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as PCI) to allow each driver to check each device instance for a
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match. For busses which rely on supplied probe hints where only one
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driver can have a change of probing the device, the driver name should
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specified as the device name.
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.Pp
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Normally unit numbers will be chosen automatically by the system and a
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unit number of
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.Dv -1
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should be given.
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When a specific unit number is desired (e.g. for wiring a particular
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piece of hardware to a pre-configured unit number), that unit should
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be passed. If the specified unit number is already allocated, a new
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unit will be allocated and a diagnostic message printed.
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.Pp
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If the devices attached to a bus must be probed in a specific order
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(e.g. for the ISA bus some devices are sensitive to failed probe attempts
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of unrelated drivers and therefore must be probed first),
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the
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.Fa order
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argument of
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.Xr device_add_child_ordered 9
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should be used to specify a partial ordering.
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The new device will be added before any existing device with a greater
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order.
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If
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.Xr device_add_child 9
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is used, then the new child will be added as if its order was zero.
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.Sh RETURN VALUES
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The new device if successful, NULL otherwise.
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.Sh SEE ALSO
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.Xr device 9
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.Sh AUTHORS
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This man page was written by
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.An Doug Rabson .
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