File:  [DragonFly] / src / share / man / man9 / driver.9
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Remove '-*- nroff -*-'.

Lets make a habit not to put editor-related magic into our base
files.  They are redundant and useless.

.\" 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.
.\"
.\" $FreeBSD: src/share/man/man9/driver.9,v 1.3.2.3 2001/08/17 13:08:54 ru Exp $
.\" $DragonFly: src/share/man/man9/driver.9,v 1.3 2004/06/01 11:36:53 hmp Exp $
.\"
.Dd June 16, 1998
.Dt DRIVER 9
.Os
.Sh NAME
.Nm driver
.Nd structure describing a device driver
.Sh SYNOPSIS
.Bd -literal
#include <sys/param.h>
#include <sys/bus.h>

static int foo_probe(device_t);
static int foo_attach(device_t);
static int foo_detach(device_t);
static int foo_frob(device_t, int, int);
static int foo_twiddle(device_t, char *);

static struct device_method foo_methods[] = {
	/* Methods from the device interface */
	DEVMETHOD(device_probe,		foo_probe),
	DEVMETHOD(device_attach,	foo_attach),
	DEVMETHOD(device_detach,	foo_detach),

	/* Methods from the bogo interface */
	DEVMETHOD(bogo_frob,		foo_frob),
	DEVMETHOD(bogo_twiddle,		foo_twiddle),

	/* Terminate method list */
	{ 0, 0 }
};

static driver_t foo_driver {
	"foo",
	foo_methods,
	DRIVER_TYPE_MISC,
	sizeof(struct foo_softc),
};

static devclass_t foo_devclass;

DRIVER_MODULE(foo, bogo, foo_driver, foo_devclass, 0, 0);
.Ed
.Sh DESCRIPTION
Each driver in the kernel is described by a
.Dv driver_t
structure.  The structure contains the name of the device, a pointer
to a list of methods, an indication of the kind of device which the
driver implements and the size of the private data which the driver
needs to associate with a device instance.  Each driver will implement
one or more sets of methods (called interfaces).  The example driver
implements the standard "driver" interface and the fictitious "bogo"
interface.
.Pp
When a driver is registered with the system (by the
.Dv DRIVER_MODULE
macro, see
.Xr DRIVER_MODULE 9 ) ,
it is added to the list of drivers contained in the devclass
of its parent bus type.  For instance all PCI drivers would be
contained in the devclass named "pci" and all ISA drivers would be
in the devclass named "isa".
The reason the drivers are not held in the device object of the parent
bus is to handle multiple instances of a given type of bus.
The
.Dv DRIVER_MODULE
macro will also create the devclass with the name of the driver and
can optionally call extra initialisation code in the driver by
specifying an extra module event handler and argument as the last two
arguments.
.Sh SEE ALSO
.Xr devclass 9 ,
.Xr device 9 ,
.Xr DRIVER_MODULE 9
.Sh AUTHORS
This man page was written by
.An Doug Rabson .