freebsd-skq/share/man/man9/OF_finddevice.9
gonzo 88d57fa15c [man] Add documentation for OpenFirmware API
Add man pages for following OpenFirmware functions:

OF_child, OF_parent, OF_peer, OF_device_from_xref,
OF_device_register_xref, OF_xref_from_device, OF_getprop,
OF_getencprop, OF_getencprop_alloc, OF_getprop_alloc, OF_getproplen,
OF_hasprop, OF_nextprop, OF_prop_free, OF_searchencprop,
OF_searchprop, OF_setprop

Edited by:	wblock
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D14511
2018-04-09 22:23:45 +00:00

75 lines
2.5 KiB
Groff

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.Dd April 9, 2018
.Dt OF_FINDDEVICE 9
.Os
.Sh NAME
.Nm OF_finddevice
.Nd find node in device tree
.Sh SYNOPSIS
.In dev/ofw/ofw_bus.h
.In dev/ofw/ofw_bus_subr.h
.Ft phandle_t
.Fn OF_finddevice "const char *path"
.Sh DESCRIPTION
.Pp
.Fn OF_finddevice
returns the phandle for the node specified by the
.Fa path .
Returns -1 if the path cannot be found in the tree.
.Sh CAVEATS
The return value should only be checked with equality
operators (equal to, not equal to) and not relational comparison
(less than, greater than ).
There is a discrepancy between IEEE 1275 standard and
.Fx Ns 's
internal representation of a phandle: IEEE 1275
requires the return value of this function to be -1 if the path
is not found.
But phandle_t is an unsigned type, so it cannot
be relationally compared with -1 or 0, this comparison
is always true or always false.
.Sh EXAMPLES
.Bd -literal
phandle_t root, i2c;
root = OF_finddevice("/");
i2c = OF_finddevice("/soc/axi/i2c@a0e0000");
if (i2c != -1) {
...
}
.Ed
.Sh SEE ALSO
.Xr OF_child 9
.Xr OF_parent 9
.Xr OF_peer 9
.Sh AUTHORS
.An -nosplit
This manual page was written by
.An Oleksandr Tymoshenko Aq Mt gonzo@FreeBSD.org .