xref: /freebsd/share/man/man9/OF_finddevice.9 (revision 4b9d6057)
1.\"
2.\" Copyright (c) 2018 Oleksandr Tymoshenko <gonzo@FreeBSD.org>
3.\"
4.\" All rights reserved.
5.\"
6.\" Redistribution and use in source and binary forms, with or without
7.\" modification, are permitted provided that the following conditions
8.\" are met:
9.\" 1. Redistributions of source code must retain the above copyright
10.\"    notice, this list of conditions and the following disclaimer.
11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\"    notice, this list of conditions and the following disclaimer in the
13.\"    documentation and/or other materials provided with the distribution.
14.\"
15.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25.\"
26.Dd April 9, 2018
27.Dt OF_FINDDEVICE 9
28.Os
29.Sh NAME
30.Nm OF_finddevice
31.Nd find node in device tree
32.Sh SYNOPSIS
33.In dev/ofw/ofw_bus.h
34.In dev/ofw/ofw_bus_subr.h
35.Ft phandle_t
36.Fn OF_finddevice "const char *path"
37.Sh DESCRIPTION
38.Fn OF_finddevice
39returns the phandle for the node specified by the
40.Fa path .
41Returns -1 if the path cannot be found in the tree.
42.Sh EXAMPLES
43.Bd -literal
44    phandle_t root, i2c;
45
46    root = OF_finddevice("/");
47    i2c = OF_finddevice("/soc/axi/i2c@a0e0000");
48    if (i2c != -1) {
49        ...
50    }
51.Ed
52.Sh SEE ALSO
53.Xr OF_child 9 ,
54.Xr OF_parent 9 ,
55.Xr OF_peer 9
56.Sh AUTHORS
57.An -nosplit
58This manual page was written by
59.An Oleksandr Tymoshenko Aq Mt gonzo@FreeBSD.org .
60.Sh CAVEATS
61The return value should only be checked with equality
62operators (equal to, not equal to) and not relational comparison
63(less than, greater than ).
64There is a discrepancy between IEEE 1275 standard and
65.Fx Ns 's
66internal representation of a phandle: IEEE 1275
67requires the return value of this function to be -1 if the path
68is not found.
69But phandle_t is an unsigned type, so it cannot
70be relationally compared with -1 or 0, this comparison
71is always true or always false.
72