| commit | 3b02a94b486f998aa22d898b427820a805d0904f | [log] [tgz] |
|---|---|---|
| author | David Gibson <david@gibson.dropbear.id.au> | Sun May 14 16:27:27 2023 +1000 |
| committer | David Gibson <david@gibson.dropbear.id.au> | Sun May 14 16:27:27 2023 +1000 |
| tree | 53c96daf1faa51d372519fea1da871a558234dae | |
| parent | d4888958d64bd9b3e0e2e6582af665f9b81706c9 [diff] |
dtc: Correct invalid dts output with mixed phandles and integers The handling of "type preservation" dts output is based on the idea of "phandles with arguments" in properties, which isn't really a thing, other than a fairly common convention about how bindings are written. There's nothing preventing a binding which freely mixes phandles and other integers in an array of cells. Currently write_propval() handles this incorrectly: specifically the case of a phandle which follows a regular integer in a 32-bit cell array, but without a new '< >' delimited causing an extra TYPE_UINT32 marker to be inserted. In this case it omits the necessary space between the integer and the phandle reference, leading to output which can't be sent back into dtc and parsed. Correct this, and update tests to match. I think this is more or less correct for now, but really write_propval() is a big mess :(. 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.