8c63b2db53
epoch(9). In one instance, remove a trailing whitespace while here. Submitted by: gbergling_gmail.com Approved by: bcr Differential Revision: https://reviews.freebsd.org/D24243
122 lines
3.8 KiB
Groff
122 lines
3.8 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 April 30, 2020
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.Dt DRIVER 9
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.Os
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.Sh NAME
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.Nm driver
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.Nd structure describing a device driver
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.Sh SYNOPSIS
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.Bd -literal
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/bus.h>
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#include <sys/module.h>
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static int foo_probe(device_t);
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static int foo_attach(device_t);
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static int foo_detach(device_t);
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static int foo_frob(device_t, int, int);
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static int foo_twiddle(device_t, char *);
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static device_method_t foo_methods[] = {
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/* Methods from the device interface */
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DEVMETHOD(device_probe, foo_probe),
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DEVMETHOD(device_attach, foo_attach),
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DEVMETHOD(device_detach, foo_detach),
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/* Methods from the bogo interface */
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DEVMETHOD(bogo_frob, foo_frob),
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DEVMETHOD(bogo_twiddle, foo_twiddle),
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/* Terminate method list */
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DEVMETHOD_END
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};
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static driver_t foo_driver = {
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"foo",
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foo_methods,
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sizeof(struct foo_softc)
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};
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static devclass_t foo_devclass;
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DRIVER_MODULE(foo, bogo, foo_driver, foo_devclass, NULL, NULL);
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.Ed
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.Sh DESCRIPTION
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Each driver in the kernel is described by a
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.Dv driver_t
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structure.
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The structure contains the name of the device, a pointer
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to a list of methods, an indication of the kind of device which the
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driver implements and the size of the private data which the driver
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needs to associate with a device instance.
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Each driver will implement
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one or more sets of methods (called interfaces).
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The example driver
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implements the standard "driver" interface and the fictitious "bogo"
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interface.
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.Pp
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When a driver is registered with the system (by the
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.Dv DRIVER_MODULE
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macro, see
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.Xr DRIVER_MODULE 9 ) ,
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it is added to the list of drivers contained in the devclass
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of its parent bus type.
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For instance all PCI drivers would be
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contained in the devclass named "pci" and all ISA drivers would be
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in the devclass named "isa".
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The reason the drivers are not held in the device object of the parent
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bus is to handle multiple instances of a given type of bus.
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The
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.Dv DRIVER_MODULE
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macro will also create the devclass with the name of the driver and
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can optionally call extra initialisation code in the driver by
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specifying an extra module event handler and argument as the last two
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arguments.
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.Sh HISTORY
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The
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.Nm
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framework first appeared in
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.Fx 2.2.7 .
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.Sh SEE ALSO
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.Xr devclass 9 ,
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.Xr device 9 ,
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.Xr DEVICE_ATTACH 9 ,
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.Xr DEVICE_DETACH 9 ,
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.Xr DEVICE_IDENTIFY 9 ,
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.Xr DEVICE_PROBE 9 ,
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.Xr DEVICE_SHUTDOWN 9 ,
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.Xr DRIVER_MODULE 9
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.Sh AUTHORS
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This manual page was written by
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.An Doug Rabson .
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