1The source tree contains the Device Tree Compiler (dtc) toolchain for 2working with device tree source and binary files and also libfdt, a 3utility library for reading and manipulating the binary format. 4 5DTC and LIBFDT are maintained by: 6 7David Gibson <david@gibson.dropbear.id.au> 8Jon Loeliger <loeliger@gmail.com> 9 10 11Python library 12-------------- 13 14A Python library is also available. To build this you will need to install 15swig and Python development files. On Debian distributions: 16 17 sudo apt-get install swig python3-dev 18 19The library provides an Fdt class which you can use like this: 20 21$ PYTHONPATH=../pylibfdt python3 22>>> import libfdt 23>>> fdt = libfdt.Fdt(open('test_tree1.dtb', mode='rb').read()) 24>>> node = fdt.path_offset('/subnode@1') 25>>> print(node) 26124 27>>> prop_offset = fdt.first_property_offset(node) 28>>> prop = fdt.get_property_by_offset(prop_offset) 29>>> print('%s=%s' % (prop.name, prop.as_str())) 30compatible=subnode1 31>>> node2 = fdt.path_offset('/') 32>>> print(fdt.getprop(node2, 'compatible').as_str()) 33test_tree1 34 35You will find tests in tests/pylibfdt_tests.py showing how to use each 36method. Help is available using the Python help command, e.g.: 37 38 $ cd pylibfdt 39 $ python3 -c "import libfdt; help(libfdt)" 40 41If you add new features, please check code coverage: 42 43 $ sudo apt-get install python3-coverage 44 $ cd tests 45 # It's just 'coverage' on most other distributions 46 $ python3-coverage run pylibfdt_tests.py 47 $ python3-coverage html 48 # Open 'htmlcov/index.html' in your browser 49 50 51The library can be installed with pip from a local source tree: 52 53 pip install . [--user|--prefix=/path/to/install_dir] 54 55Or directly from a remote git repo: 56 57 pip install git+git://git.kernel.org/pub/scm/utils/dtc/dtc.git@main 58 59The install depends on libfdt shared library being installed on the host system 60first. Generally, using --user or --prefix is not necessary and pip will use the 61default location for the Python installation which varies if the user is root or 62not. 63 64You can also install everything via make if you like, but pip is recommended. 65 66To install both libfdt and pylibfdt you can use: 67 68 make install [PREFIX=/path/to/install_dir] 69 70To disable building the python library, even if swig and Python are available, 71use: 72 73 make NO_PYTHON=1 74 75 76More work remains to support all of libfdt, including access to numeric 77values. 78 79 80Adding a new function to libfdt.h 81--------------------------------- 82 83The shared library uses libfdt/version.lds to list the exported functions, so 84add your new function there. Check that your function works with pylibfdt. If 85it cannot be supported, put the declaration in libfdt.h behind #ifndef SWIG so 86that swig ignores it. 87 88 89Tests 90----- 91 92Test files are kept in the tests/ directory. Use 'make check' to build and run 93all tests. 94 95If you want to adjust a test file, be aware that tree_tree1.dts is compiled 96and checked against a binary tree from assembler macros in trees.S. So 97if you change that file you must change tree.S also. 98 99 100Mailing list 101------------ 102The following list is for discussion about dtc and libfdt implementation 103mailto:devicetree-compiler@vger.kernel.org 104 105Core device tree bindings are discussed on the devicetree-spec list: 106mailto:devicetree-spec@vger.kernel.org 107