commit | 267efc7d469477927baa5c0e540d91cb51ca25bf | [log] [tgz] |
---|---|---|
author | Thierry Reding <treding@nvidia.com> | Fri Dec 13 15:14:38 2024 +0100 |
committer | David Gibson <david@gibson.dropbear.id.au> | Wed Dec 18 15:56:51 2024 +1100 |
tree | 37b2e2979056ab6c26656affbf279f7d0d8b4c5c | |
parent | 755db115355b101dea144eca5c272fdfa15e900f [diff] |
checks: Warn about missing #address-cells for interrupt parents The device tree specification (v0.4) suggests that #address-cells is mandatory for interrupt parent nodes. If this property is missing, Linux will default to the value of 0. A number of device tree files rely on Linux' fallback and don't specify an explicit #address-cells as suggested by the specification. This can cause issues when these device trees are passed to software with a more pedantic interpretation of the DT spec. Add a warning when this case is detected so that device tree files can be fixed. Reported-by: Brad Griffis <bgriffis@nvidia.com> Signed-off-by: Thierry Reding <treding@nvidia.com> Reviewed-by: Rob Herring (Arm) <robh@kernel.org> Message-ID: <20241213141438.3616902-1-thierry.reding@gmail.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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:
A Python library wrapping libfdt 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
The library can be installed with pip from a local source tree:
$ pip install . [--user|--prefix=/path/to/install_dir]
Or directly from a remote git repo:
$ pip install git+git://git.kernel.org/pub/scm/utils/dtc/dtc.git@main
The install depends on libfdt shared library being installed on the host system first. Generally, using --user
or --prefix
is not necessary and pip will use the default location for the Python installation which varies if the user is root or not.
You can also install everything via make if you like, but pip is recommended.
To install both libfdt and pylibfdt you can use:
$ make install [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.