scripts: add tool to list bus-related bindings

scripts/dts/README.txt

@@ -1,4 +1,4 @@
 This directory used to contain the edtlib.py and dtlib.py libraries
 and tests, alongside the gen_defines.py script that uses them for
 converting DTS to the C macros used by Zephyr.
 
@@ -30,3 +30,8 @@
 Eventually, as APIs stabilize, the python-devicetree code in this
 repository will disappear, and a standalone repository will be the
 'main' one.
+
+Additional utilities in this directory include helper scripts for
+exploring the binding metadata.  For example, ``list_bus_nodes.py``
+summarizes bindings that define a bus or appear on one, making it
+easier to review the supported bus topologies.

scripts/dts/list_bus_nodes.py

@@ -0,0 +1,150 @@
+#!/usr/bin/env python3
+"""Utility for listing bindings that define or use buses."""
+
+from __future__ import annotations
+
+import argparse
+import csv
+import sys
+from pathlib import Path
+from typing import Iterable, List, Sequence, Tuple
+
+
+SCRIPT_DIR = Path(__file__).resolve().parent
+REPO_ROOT = SCRIPT_DIR.parent.parent
+PYTHON_DEVICETREE = SCRIPT_DIR / "python-devicetree" / "src"
+
+# Ensure the in-tree python-devicetree sources are preferred.
+sys.path.insert(0, str(PYTHON_DEVICETREE))
+
+try:
+    from devicetree.edtlib import Binding, bindings_from_paths  # type: ignore  # noqa: E402
+except ModuleNotFoundError as exc:  # pragma: no cover - environment guard
+    if exc.name == "yaml":
+        raise SystemExit(
+            "PyYAML is required to load bindings. Install it with 'pip install PyYAML'."
+        ) from exc
+    raise
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description=(
+            "List bindings that declare a bus or appear on a bus, including "
+            "their child-binding definitions."
+        )
+    )
+    default_root = REPO_ROOT / "dts" / "bindings"
+    parser.add_argument(
+        "--bindings-root",
+        type=Path,
+        default=default_root,
+        help=(
+            "Root directory to search for binding YAML files (default: %(default)s)."
+        ),
+    )
+    parser.add_argument(
+        "--csv",
+        action="store_true",
+        help="Emit the table as comma-separated values instead of padded text.",
+    )
+    return parser.parse_args()
+
+
+def find_binding_files(root: Path) -> List[Path]:
+    if not root.is_dir():
+        raise SystemExit(f"Bindings root '{root}' does not exist or is not a directory")
+
+    files = {
+        path.resolve()
+        for suffix in ("*.yaml", "*.yml")
+        for path in root.rglob(suffix)
+        if path.is_file()
+    }
+    if not files:
+        raise SystemExit(f"No binding YAML files found under '{root}'")
+    return sorted(files)
+
+
+def relative_label(path: Path, root: Path, depth: int) -> str:
+    try:
+        rel = path.resolve().relative_to(root.resolve())
+    except ValueError:
+        rel = path.name
+
+    if depth == 0:
+        return str(rel)
+    if depth == 1:
+        suffix = "child-binding"
+    else:
+        suffix = f"child-binding depth {depth}"
+    return f"{rel} ({suffix})"
+
+
+def collect_binding_rows(binding: Binding, root: Path, depth: int = 0) -> List[Tuple[str, str, str]]:
+    rows: List[Tuple[str, str, str]] = []
+    binding_path = Path(binding.path) if binding.path else None
+
+    if binding_path is not None and (binding.buses or binding.on_bus):
+        label = relative_label(binding_path, root, depth)
+        buses = ", ".join(binding.buses) if binding.buses else ""
+        on_bus = binding.on_bus or ""
+        rows.append((label, buses, on_bus))
+
+    if binding.child_binding is not None:
+        rows.extend(collect_binding_rows(binding.child_binding, root, depth + 1))
+
+    return rows
+
+
+def sort_rows(rows: Iterable[Tuple[str, str, str]]) -> List[Tuple[str, str, str]]:
+    return sorted(rows, key=lambda row: row[0])
+
+
+def emit_csv(rows: Sequence[Tuple[str, str, str]]) -> None:
+    writer = csv.writer(sys.stdout)
+    writer.writerow(["Binding", "Buses", "On Bus"])
+    for row in rows:
+        writer.writerow(row)
+
+
+def emit_table(rows: Sequence[Tuple[str, str, str]]) -> None:
+    headers = ("Binding", "Buses", "On Bus")
+    if not rows:
+        print("No bus-related bindings found.")
+        return
+
+    widths = [len(header) for header in headers]
+    for row in rows:
+        for idx, value in enumerate(row):
+            widths[idx] = max(widths[idx], len(value))
+
+    header_line = "  ".join(header.ljust(widths[idx]) for idx, header in enumerate(headers))
+    separator = "  ".join("-" * widths[idx] for idx in range(len(headers)))
+    print(header_line)
+    print(separator)
+    for row in rows:
+        print("  ".join(value.ljust(widths[idx]) for idx, value in enumerate(row)))
+
+
+def main() -> None:
+    args = parse_args()
+    bindings_root = args.bindings_root.resolve()
+    binding_files = [str(path) for path in find_binding_files(bindings_root)]
+
+    bindings = bindings_from_paths(binding_files)
+
+    rows: List[Tuple[str, str, str]] = []
+    for binding in bindings:
+        rows.extend(collect_binding_rows(binding, bindings_root))
+
+    rows = sort_rows(rows)
+
+    if args.csv:
+        emit_csv(rows)
+    else:
+        emit_table(rows)
+
+
+if __name__ == "__main__":
+    main()