1.\" Copyright (c) 1998 Doug Rabson 2.\" 3.\" All rights reserved. 4.\" 5.\" This program is free software. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" $FreeBSD: src/share/man/man9/driver.9,v 1.3.2.3 2001/08/17 13:08:54 ru Exp $ 28.\" 29.Dd February 20, 2013 30.Dt DRIVER 9 31.Os 32.Sh NAME 33.Nm driver 34.Nd structure describing a device driver 35.Sh SYNOPSIS 36.Bd -literal 37#include <sys/param.h> 38#include <sys/bus.h> 39#include <sys/kernel.h> 40#include <sys/module.h> 41 42static int foo_probe(device_t); 43static int foo_attach(device_t); 44static int foo_detach(device_t); 45static int foo_frob(device_t, int, int); 46static int foo_twiddle(device_t, char *); 47 48struct foo_softc { 49}; 50 51static device_method_t foo_methods[] = { 52 /* Methods from the device interface */ 53 DEVMETHOD(device_probe, foo_probe), 54 DEVMETHOD(device_attach, foo_attach), 55 DEVMETHOD(device_detach, foo_detach), 56 57 /* Methods from the bogo interface */ 58 DEVMETHOD(bogo_frob, foo_frob), 59 DEVMETHOD(bogo_twiddle, foo_twiddle), 60 61 /* Terminate method list */ 62 DEVMETHOD_END 63}; 64 65static driver_t foo_driver = { 66 "foo", 67 foo_methods, 68 sizeof(struct foo_softc) 69}; 70 71static devclass_t foo_devclass; 72 73DRIVER_MODULE(foo, bogo, foo_driver, foo_devclass, NULL, NULL); 74.Ed 75.Sh DESCRIPTION 76Each driver in the kernel is described by a 77.Vt driver_t 78structure. The structure contains the name of the device, a pointer 79to a list of methods, an indication of the kind of device which the 80driver implements and the size of the private data which the driver 81needs to associate with a device instance. Each driver will implement 82one or more sets of methods (called interfaces). The example driver 83implements the standard "driver" interface and the fictitious "bogo" 84interface. 85.Pp 86When a driver is registered with the system (by the 87.Dv DRIVER_MODULE 88macro, see 89.Xr DRIVER_MODULE 9 ) , 90it is added to the list of drivers contained in the devclass 91of its parent bus type. For instance all PCI drivers would be 92contained in the devclass named "pci" and all ISA drivers would be 93in the devclass named "isa". 94The reason the drivers are not held in the device object of the parent 95bus is to handle multiple instances of a given type of bus. 96The 97.Dv DRIVER_MODULE 98macro will also create the devclass with the name of the driver and 99can optionally call extra initialisation code in the driver by 100specifying an extra module event handler and argument as the last two 101arguments. 102.Sh SEE ALSO 103.Xr devclass 9 , 104.Xr device 9 , 105.Xr DRIVER_MODULE 9 106.Sh AUTHORS 107This man page was written by 108.An Doug Rabson . 109