platform_external_dtc/README

The source tree contains the Device Tree Compiler (dtc) toolchain for
working with device tree source and binary files and also libfdt, a
utility library for reading and manipulating the binary format.

DTC and LIBFDT are maintained by:

David Gibson <david@gibson.dropbear.id.au>
Jon Loeliger <jdl@jdl.com>


Python library
--------------

A Python library is also available. To build this you will need to install
swig and Python development files. On Debian distributions:

   sudo apt-get install swig python-dev

The library provides an Fdt class which you can use like this:

$ PYTHONPATH=../pylibfdt python
>>> import libfdt
>>> fdt = libfdt.Fdt(open('test_tree1.dtb').read())
>>> node = fdt.path_offset('/subnode@1')
>>> print node
124
>>> prop_offset = fdt.first_property_offset(node)
>>> prop = fdt.get_property_by_offset(prop_offset)
>>> print '%s=%r' % (prop.name, prop.value)
compatible=bytearray(b'subnode1\x00')
>>> print '%s=%s' % (prop.name, prop.value)
compatible=subnode1
>>> node2 = fdt.path_offset('/')
>>> print fdt.getprop(node2, 'compatible')
test_tree1

You will find tests in tests/pylibfdt_tests.py showing how to use each
method. Help is available using the Python help command, e.g.:

    $ cd pylibfdt
    $ python -c "import libfdt; help(libfdt)"

If you add new features, please check code coverage:

    $ sudo apt-get install python-pip python-pytest
    $ sudo pip install coverage
    $ cd tests
    $ coverage run pylibfdt_tests.py
    $ coverage html
    # Open 'htmlcov/index.html' in your browser


More work remains to support all of libfdt, including access to numeric
values.


Mailing list
------------
The following list is for discussion about dtc and libfdt implementation
mailto:devicetree-compiler@vger.kernel.org

Core device tree bindings are discussed on the devicetree-spec list:
mailto:devicetree-spec@vger.kernel.org