.\" -*- nroff -*- .\" .\" Copyright (c) 1998 Doug Rabson .\" .\" All rights reserved. .\" .\" This program is free software. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd February 5, 2025 .Dt DEVICE_PROBE_AND_ATTACH 9 .Os .Sh NAME .Nm device_attach , .Nm device_detach , .Nm device_probe , .Nm device_probe_and_attach .Nd manage device's connection to a device driver .Sh SYNOPSIS .In sys/param.h .In sys/bus.h .Ft int .Fn device_attach "device_t dev" .Ft int .Fn device_detach "device_t dev" .Ft int .Fn device_probe "device_t dev" .Ft int .Fn device_probe_and_attach "device_t dev" .Sh DESCRIPTION These functions manage the relationship between a device and device drivers. .Pp .Fn device_probe invokes the .Xr DEVICE_PROBE 9 method of each suitable driver and to find the driver with the best match for .Fa dev . If a matching driver is found, .Fa dev is set to the .Dv DS_ALIVE state and zero is returned. If .Fa dev is already attached to a device driver or has been disabled via .Xr device_disable 9 , then it will not be probed and -1 is returned. .Pp .Fn device_attach fully attaches a device driver to .Fa dev . This function prints a description of the device and invokes the .Xr DEVICE_ATTACH 9 method. If the .Xr DEVICE_ATTACH 9 method succeeds, .Fa dev is set to the .Dv DS_ATTACHED state and zero is returned. If the .Xr DEVICE_ATTACH 9 method fails, .Xr BUS_CHILD_DETACHED 9 is called and an error value is returned. .Pp If the device name and unit are disabled by a hint, .Fn device_attach disables the device, demotes it to the .Dv DS_NOTPRESENT state, and returns .Dv ENXIO . The device retains its device name and unit and can be re-enabled via .Xr devctl 8 . .Pp .Fn device_probe_and_attach is a wrapper function around .Fn device_probe and .Fn device_attach that fully initialises a device. If .Fa dev is already attached or disabled, .Fn device_probe_and_attach leaves the device unchanged and returns zero. Otherwise, .Fn device_probe is used to identify a device driver for .Fa dev and .Fn device_attach finalizes attaching the driver to .Fa dev . Device drivers should generally use this function to initialize a device rather than direct calls to .Fn device_probe and .Fn device_attach . .Pp .Fn device_detach detaches the device driver from .Fa dev . This function invokes the .Xr DEVICE_DETACH 9 method to tear down device driver state for .Fa dev . If the method fails, its error value is returned and .Fa dev remains attached. If the method succeeds, otherwise, .Xr BUS_CHILD_DETACHED 9 is called, the device is set to the .Dv DS_NOTPRESENT state, and zero is returned. If a device is busy, .Fn device_detach fails with .Dv EBUSY and leaving .Fa dev unchanged. .Sh RETURN VALUES Zero is returned on success, otherwise an appropriate error is returned. In addition, .Fn device_probe returns -1 if .Fa dev is disabled or already attached. .Sh SEE ALSO .Xr devctl 8 , .Xr BUS_CHILD_DETACHED 9 , .Xr device 9 , .Xr DEVICE_ATTACH 9 , .Xr DEVICE_DETACH 9 , .Xr DEVICE_PROBE 9 , .Xr driver 9 .Sh AUTHORS This manual page was written by .An Doug Rabson .