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 [email protected] Jon Loeliger [email protected]
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 python3-dev
The library provides an Fdt class which you can use like this:
$ PYTHONPATH=../pylibfdt python3
import libfdt fdt = libfdt.Fdt(open('test_tree1.dtb', mode='rb').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=%s' % (prop.name, prop.as_str())) compatible=subnode1 node2 = fdt.path_offset('/') print(fdt.getprop(node2, 'compatible').as_str()) 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
$ python3 -c "import libfdt; help(libfdt)"
If you add new features, please check code coverage:
$ sudo apt-get install python3-coverage
$ cd tests
# It's just 'coverage' on most other distributions
$ python3-coverage run pylibfdt_tests.py
$ python3-coverage html
# Open 'htmlcov/index.html' in your browser
To install the library via the normal setup.py method, use:
./pylibfdt/setup.py install [--prefix=/path/to/install_dir]
If --prefix is not provided, the default prefix is used, typically '/usr' or '/usr/local'. See Python's distutils documentation for details. You can also install via the Makefile if you like, but the above is more common.
To install both libfdt and pylibfdt you can use:
make install [SETUP_PREFIX=/path/to/install_dir] \
[PREFIX=/path/to/install_dir]
To disable building the python library, even if swig and Python are available, use:
make NO_PYTHON=1
More work remains to support all of libfdt, including access to numeric values.
git clone https://git.kernel.org/pub/scm/utils/dtc/dtc.git dtc-1.6.1 -b v1.6.1
cd dtc-1.6.1/
make NO_PYTHON=1
Test files are kept in the tests/ directory. Use 'make check' to build and run all tests.
If you want to adjust a test file, be aware that tree_tree1.dts is compiled and checked against a binary tree from assembler macros in trees.S. So if you change that file you must change tree.S also.
The following list is for discussion about dtc and libfdt implementation mailto:[email protected]
Core device tree bindings are discussed on the devicetree-spec list: mailto:[email protected]