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 15, 2017 30.Dt DEVICE_IDENTIFY 9 31.Os 32.Sh NAME 33.Nm DEVICE_IDENTIFY 34.Nd identify a device, register it 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 function for a device is only needed for devices on buses 42that cannot identify their children independently, e.g.\& the ISA bus. 43It is used to recognize the device (usually done by accessing non-ambiguous 44registers in the hardware) and to tell the kernel about it and thus 45creating a new device instance. 46.Pp 47.Xr BUS_ADD_CHILD 9 48is used to register the device as a child of the bus. 49The device's resources (such as IRQ and I/O ports) are registered 50with the kernel by calling 51.Fn bus_set_resource 52for each resource (refer to 53.Xr bus_set_resource 9 54for more information). 55.Pp 56Since the device tree and the device driver tree are disjoint, the 57.Fn DEVICE_IDENTIFY 58routine needs to take this into account. 59If you load and unload your device driver that has the identify 60routine, the child node has the potential for adding the same node 61multiple times unless specific measure are taken to preclude that 62possibility. 63.Sh EXAMPLES 64The following pseudo-code shows an example of a function that 65probes for a piece of hardware and registers it and its resource 66(an I/O port) with the kernel. 67.Bd -literal 68void 69foo_identify(driver_t *driver, device_t parent) 70{ 71 device_t child; 72 73 retrieve_device_information; 74 if (devices matches one of your supported devices && 75 not already in device tree) { 76 child = BUS_ADD_CHILD(parent, 0, "foo", DEVICE_UNIT_ANY); 77 bus_set_resource(child, SYS_RES_IOPORT, 0, FOO_IOADDR, 1); 78 } 79} 80.Ed 81.Sh SEE ALSO 82.Xr BUS_ADD_CHILD 9 , 83.Xr bus_set_resource 9 , 84.Xr device 9 , 85.Xr device_add_child 9 , 86.Xr DEVICE_ATTACH 9 , 87.Xr DEVICE_DETACH 9 , 88.Xr DEVICE_PROBE 9 , 89.Xr DEVICE_SHUTDOWN 9 90.Sh AUTHORS 91This manual page was written by 92.An Alexander Langer Aq Mt alex@FreeBSD.org . 93