fdt: Allow stacked overlays phandle references
This patch enables an overlay to refer to a previous overlay's
labels by performing a merge of symbol information at application
time.
In a nutshell it allows an overlay to refer to a symbol that a previous
overlay has defined. It requires both the base and all the overlays
to be compiled with the -@ command line switch so that symbol
information is included.
base.dts
--------
/dts-v1/;
/ {
foo: foonode {
foo-property;
};
};
$ dtc -@ -I dts -O dtb -o base.dtb base.dts
bar.dts
-------
/dts-v1/;
/plugin/;
/ {
fragment@1 {
target = <&foo>;
__overlay__ {
overlay-1-property;
bar: barnode {
bar-property;
};
};
};
};
$ dtc -@ -I dts -O dtb -o bar.dtb bar.dts
baz.dts
-------
/dts-v1/;
/plugin/;
/ {
fragment@1 {
target = <&bar>;
__overlay__ {
overlay-2-property;
baz: baznode {
baz-property;
};
};
};
};
$ dtc -@ -I dts -O dtb -o baz.dtb baz.dts
Applying the overlays:
$ fdtoverlay -i base.dtb -o target.dtb bar.dtb baz.dtb
Dumping:
$ fdtdump target.dtb
/ {
foonode {
overlay-1-property;
foo-property;
linux,phandle = <0x00000001>;
phandle = <0x00000001>;
barnode {
overlay-2-property;
phandle = <0x00000002>;
linux,phandle = <0x00000002>;
bar-property;
baznode {
phandle = <0x00000003>;
linux,phandle = <0x00000003>;
baz-property;
};
};
};
__symbols__ {
baz = "/foonode/barnode/baznode";
bar = "/foonode/barnode";
foo = "/foonode";
};
};
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Simon Glass <sjg@chromium.org>
1 file changed