=== Device tree

`platform_device.c` together with its kernel and QEMU forks contains a minimal runnable example.

Good format descriptions:

* https://www.raspberrypi.org/documentation/configuration/device-tree.md

Minimal example

....
/dts-v1/;

/ {
    a;
};
....

Check correctness with:

....
dtc a.dts
....

Separate nodes are simply merged by node path, e.g.:

....
/dts-v1/;

/ {
    a;
};

/ {
    b;
};
....

then `dtc a.dts` gives:

....
/dts-v1/;

/ {
        a;
        b;
};
....