.\"
.\" Copyright (c) 2018 Oleksandr Tymoshenko <gonzo@FreeBSD.org>
.\"
.\" All rights reserved.
.\"
.\" 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.
.\"
.\" $FreeBSD: releng/12.2/share/man/man9/OF_device_from_xref.9 332642 2018-04-17 09:05:46Z trasz $
.\"
.Dd April 9, 2018
.Dt OF_DEVICE_FROM_XREF 9
.Os
.Sh NAME
.Nm OF_device_from_xref ,
.Nm OF_xref_from_device ,
.Nm OF_device_register_xref
.Nd "manage mappings between xrefs and devices"
.Sh SYNOPSIS
.In dev/ofw/ofw_bus.h
.In dev/ofw/ofw_bus_subr.h
.Ft int
.Fn OF_device_register_xref "phandle_t xref" "device_t dev"
.Ft device_t
.Fn OF_device_from_xref "phandle_t xref"
.Ft phandle_t
.Fn OF_xref_from_device "device_t dev"
.Sh DESCRIPTION
.Pp
When a device tree node references another node, the driver may
need to get a device_t instance associated with the referenced node.
For instance, an Ethernet driver accessing a PHY device.
To make this possible, the kernel maintains a table that
maps effective handles to device_t instances.
.Pp
.Fn OF_device_register_xref
adds a map entry from the effective phandle
.Fa xref
to device
.Fa dev .
If a mapping entry for
.Fa xref
already exists, it is replaced with the new one.
The function always returns 0.
.Pp
.Fn OF_device_from_xref
returns a device_t instance associated with the effective phandle
.Fa xref .
If no such mapping exists, the function returns NULL.
.Pp
.Fn OF_xref_from_device
returns the effective phandle associated with the device
.Fa dev .
If no such mapping exists, the function returns 0.
.Sh EXAMPLES
.Bd -literal
    static int
    acmephy_attach(device_t dev)
    {
        phandle_t node;

	/* PHY node is referenced from eth device, register it */
        node = ofw_bus_get_node(dev);
        OF_device_register_xref(OF_xref_from_node(node), dev);

        return (0);
    }
.Ed
.Sh SEE ALSO
.Xr OF_node_to_xref 9
.Sh AUTHORS
.An -nosplit
This manual page was written by
.An Oleksandr Tymoshenko Aq Mt gonzo@FreeBSD.org .