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.Dd April 19, 2022 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/kernel.h> 39#include <sys/bus.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 48static device_method_t foo_methods[] = { 49 /* Methods from the device interface */ 50 DEVMETHOD(device_probe, foo_probe), 51 DEVMETHOD(device_attach, foo_attach), 52 DEVMETHOD(device_detach, foo_detach), 53 54 /* Methods from the bogo interface */ 55 DEVMETHOD(bogo_frob, foo_frob), 56 DEVMETHOD(bogo_twiddle, foo_twiddle), 57 58 /* Terminate method list */ 59 DEVMETHOD_END 60}; 61 62static driver_t foo_driver = { 63 "foo", 64 foo_methods, 65 sizeof(struct foo_softc) 66}; 67 68DRIVER_MODULE(foo, bogo, foo_driver, NULL, NULL); 69.Ed 70.Sh DESCRIPTION 71Each driver in the kernel is described by a 72.Dv driver_t 73structure. 74The structure contains the name of the device, a pointer 75to a list of methods, an indication of the kind of device which the 76driver implements and the size of the private data which the driver 77needs to associate with a device instance. 78Each driver will implement 79one or more sets of methods (called interfaces). 80The example driver 81implements the standard "driver" interface and the fictitious "bogo" 82interface. 83.Pp 84When a driver is registered with the system (by the 85.Dv DRIVER_MODULE 86macro, see 87.Xr DRIVER_MODULE 9 ) , 88it is added to the list of drivers contained in the devclass 89of its parent bus type. 90For instance all PCI drivers would be 91contained in the devclass named "pci" and all ISA drivers would be 92in the devclass named "isa". 93The reason the drivers are not held in the device object of the parent 94bus is to handle multiple instances of a given type of bus. 95The 96.Dv DRIVER_MODULE 97macro will also create the devclass with the name of the driver and 98can optionally call extra initialisation code in the driver by 99specifying an extra module event handler and argument as the last two 100arguments. 101.Sh SEE ALSO 102.Xr devclass 9 , 103.Xr device 9 , 104.Xr DEVICE_ATTACH 9 , 105.Xr DEVICE_DETACH 9 , 106.Xr DEVICE_IDENTIFY 9 , 107.Xr DEVICE_PROBE 9 , 108.Xr DEVICE_SHUTDOWN 9 , 109.Xr DRIVER_MODULE 9 110.Sh HISTORY 111The 112.Nm 113framework first appeared in 114.Fx 2.2.7 . 115.Sh AUTHORS 116This manual page was written by 117.An Doug Rabson . 118