OF_finddevice.9

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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
.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 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 .
.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.