1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 2001 Alexander Langer 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 January 9, 2025 30.Dt DEVICE_IDENTIFY 9 31.Os 32.Sh NAME 33.Nm DEVICE_IDENTIFY 34.Nd identify new child devices and register them 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/bus.h 38.Ft void 39.Fn DEVICE_IDENTIFY "driver_t *driver" "device_t parent" 40.Sh DESCRIPTION 41The identify method of a device driver is used to add devices that cannot be 42enumerated by the standard method on a bus device. 43Devices can be enumerated in various ways including accessing non-ambiguous 44device registers and parsing firmware tables. 45Software-only pseudo devices are also often enumerated via identify methods. 46.Pp 47For each newly identified device, 48a new device instance should be created by invoking the 49.Xr BUS_ADD_CHILD 9 50method. 51If the identify method is able to discover other properties about the new 52device, those should also be set. 53For example, device resources should be added to the device by calling 54.Xr bus_set_resource 9 55for each resource. 56.Pp 57An identify method might be invoked multiple times. 58If a device driver is unloaded and loaded, 59the identify method will be called a second time after being reloaded. 60As a result, the identify method should avoid duplicate devices. 61Devices added by identify methods typically use a fixed device name 62in which case 63.Xr device_find_child 9 64can be used to detect existing devices. 65.Sh EXAMPLES 66The following pseudo-code shows an example of a function that 67probes for a piece of hardware and registers it and its resource 68(an I/O port) with the parent bus device. 69.Bd -literal 70void 71foo_identify(driver_t *driver, device_t parent) 72{ 73 device_t child; 74 75 retrieve_device_information; 76 if (devices matches one of your supported devices && 77 device_get_child(parent, "foo", DEVICE_UNIT_ANY) == NULL) { 78 child = BUS_ADD_CHILD(parent, 0, "foo", DEVICE_UNIT_ANY); 79 bus_set_resource(child, SYS_RES_IOPORT, 0, FOO_IOADDR, 1); 80 } 81} 82.Ed 83.Sh SEE ALSO 84.Xr BUS_ADD_CHILD 9 , 85.Xr bus_set_resource 9 , 86.Xr device 9 , 87.Xr device_find_child 9 88.Sh AUTHORS 89This manual page was written by 90.An Alexander Langer Aq Mt alex@FreeBSD.org . 91