1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1998 Doug Rabson 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd April 30, 2020 32.Dt DRIVER 9 33.Os 34.Sh NAME 35.Nm driver 36.Nd structure describing a device driver 37.Sh SYNOPSIS 38.Bd -literal 39#include <sys/param.h> 40#include <sys/kernel.h> 41#include <sys/bus.h> 42#include <sys/module.h> 43 44static int foo_probe(device_t); 45static int foo_attach(device_t); 46static int foo_detach(device_t); 47static int foo_frob(device_t, int, int); 48static int foo_twiddle(device_t, char *); 49 50static device_method_t foo_methods[] = { 51 /* Methods from the device interface */ 52 DEVMETHOD(device_probe, foo_probe), 53 DEVMETHOD(device_attach, foo_attach), 54 DEVMETHOD(device_detach, foo_detach), 55 56 /* Methods from the bogo interface */ 57 DEVMETHOD(bogo_frob, foo_frob), 58 DEVMETHOD(bogo_twiddle, foo_twiddle), 59 60 /* Terminate method list */ 61 DEVMETHOD_END 62}; 63 64static driver_t foo_driver = { 65 "foo", 66 foo_methods, 67 sizeof(struct foo_softc) 68}; 69 70static devclass_t foo_devclass; 71 72DRIVER_MODULE(foo, bogo, foo_driver, foo_devclass, NULL, NULL); 73.Ed 74.Sh DESCRIPTION 75Each driver in the kernel is described by a 76.Dv driver_t 77structure. 78The 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. 82Each driver will implement 83one or more sets of methods (called interfaces). 84The example driver 85implements the standard "driver" interface and the fictitious "bogo" 86interface. 87.Pp 88When a driver is registered with the system (by the 89.Dv DRIVER_MODULE 90macro, see 91.Xr DRIVER_MODULE 9 ) , 92it is added to the list of drivers contained in the devclass 93of its parent bus type. 94For instance all PCI drivers would be 95contained in the devclass named "pci" and all ISA drivers would be 96in the devclass named "isa". 97The reason the drivers are not held in the device object of the parent 98bus is to handle multiple instances of a given type of bus. 99The 100.Dv DRIVER_MODULE 101macro will also create the devclass with the name of the driver and 102can optionally call extra initialisation code in the driver by 103specifying an extra module event handler and argument as the last two 104arguments. 105.Sh SEE ALSO 106.Xr devclass 9 , 107.Xr device 9 , 108.Xr DEVICE_ATTACH 9 , 109.Xr DEVICE_DETACH 9 , 110.Xr DEVICE_IDENTIFY 9 , 111.Xr DEVICE_PROBE 9 , 112.Xr DEVICE_SHUTDOWN 9 , 113.Xr DRIVER_MODULE 9 114.Sh HISTORY 115The 116.Nm 117framework first appeared in 118.Fx 2.2.7 . 119.Sh AUTHORS 120This manual page was written by 121.An Doug Rabson . 122