tools/bazel/generate_dts_build_files.py

# Copyright 2026 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.

import argparse
import os
from pathlib import Path


def _get_parent_filegroup_name(dir: Path, zephyr_root: Path):
    parent_path = dir.parent
    parent_relative_path = parent_path.relative_to(zephyr_root)
    # E.g. '//arm/nxp'
    return '//' + str(parent_relative_path).replace('\\', '/')


def create_build_files(dts_root, output_root):
    """Walks the directory tree from the given dts_root downwards and creates
    BUILD.bazel files. Each directory's filegroup includes the filegroup
    from its parent directory.
    """
    abs_dts_root = Path(dts_root).resolve()
    zephyr_root = abs_dts_root.parent
    if zephyr_root.name != 'zephyr':
        raise ValueError(
            f'Error: {abs_dts_root} does not seem to be in a valid Zephyr tree.'
        )

    for root, dirs, files in os.walk(dts_root, topdown=True):
        current_path = Path(root)

        # We don't generate anything for zephyr/dts/ root.
        if current_path == abs_dts_root:
            continue

        # We don't generate anything for zephyr/dts/bindings and its child
        # directories. Those are handled separately, possibly by another
        # script.
        if current_path.is_relative_to(abs_dts_root / 'bindings'):
            continue

        filegroup_name = current_path.name

        # --- Construct the srcs attribute value ---
        srcs_parts = []
        if any(f.endswith('.dtsi') for f in files):
            srcs_parts.append('glob(["*.dtsi"])')

        if any(f.endswith('.h') for f in files):
            srcs_parts.append('glob(["*.h"])')

        # Include parent filegroup, if parent directory is not zephyr/dts/ root.
        abs_root = current_path.resolve()
        if abs_root.parent != abs_dts_root:
            parent_filegroup_name = _get_parent_filegroup_name(
                abs_root, zephyr_root
            )
            srcs_parts.append(f'["{parent_filegroup_name}"]')

        if not srcs_parts:
            srcs_value = '[]'
        else:
            srcs_value = ' + '.join(srcs_parts)

        # --- Generate BUILD.bazel content ---
        content = f'''# SPDX-License-Identifier: Apache-2.0

# Auto-generated using scripts in zephyr-bazel.

package(default_visibility = ["//visibility:public"])

filegroup(
    name = "{filegroup_name}",
    srcs = {srcs_value},
)
'''

        # --- Write the file ---
        relative_dir = current_path.relative_to(abs_dts_root)
        output_dir = Path(output_root) / relative_dir
        output_dir.mkdir(parents=True, exist_ok=True)
        output_file = output_dir / 'BUILD.bazel'

        try:
            with open(output_file, 'w') as f:
                f.write(content)
            print(f'Wrote {output_file}')
        except IOError as e:
            print(f'Error: Could not write to {output_file}. {e}')


def main():
    parser = argparse.ArgumentParser(
        description='Generate BUILD.bazel files for dts directories.'
    )
    parser.add_argument(
        '--dts_root', required=True, help='The root directory of the dts files.'
    )
    parser.add_argument(
        '--output_dir',
        required=True,
        help=(
            'Output directory to hold converted BUILD.bazel files, '
            'should end in "dts"'
        ),
    )
    args = parser.parse_args()
    create_build_files(args.dts_root, args.output_dir)


if __name__ == '__main__':
    main()