scripts: list_shields: add script for listing the supported shields

Add Python script for listing the supported shields.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>

scripts/list_shields.py

@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2024 Vestas Wind Systems A/S
+# Copyright (c) 2020 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+from dataclasses import dataclass
+from pathlib import Path
+
+#
+# This is shared code between the build system's 'shields' target
+# and the 'west shields' extension command. If you change it, make
+# sure to test both ways it can be used.
+#
+# (It's done this way to keep west optional, making it possible to run
+# 'ninja shields' in a build directory without west installed.)
+#
+
+@dataclass(frozen=True)
+class Shield:
+    name: str
+    dir: Path
+
+def shield_key(shield):
+    return shield.name
+
+def find_shields(args):
+    ret = []
+
+    for root in args.board_roots:
+        for shields in find_shields_in(root):
+            ret.append(shields)
+
+    return sorted(ret, key=shield_key)
+
+def find_shields_in(root):
+    shields = root / 'boards' / 'shields'
+    ret = []
+
+    for maybe_shield in (shields).iterdir():
+        if not maybe_shield.is_dir():
+            continue
+        for maybe_kconfig in maybe_shield.iterdir():
+            if maybe_kconfig.name == 'Kconfig.shield':
+                for maybe_overlay in maybe_shield.iterdir():
+                    file_name = maybe_overlay.name
+                    if file_name.endswith('.overlay'):
+                        shield_name = file_name[:-len('.overlay')]
+                        ret.append(Shield(shield_name, maybe_shield))
+
+    return sorted(ret, key=shield_key)
+
+def parse_args():
+    parser = argparse.ArgumentParser(allow_abbrev=False)
+    add_args(parser)
+    return parser.parse_args()
+
+def add_args(parser):
+    # Remember to update west-completion.bash if you add or remove
+    # flags
+    parser.add_argument("--board-root", dest='board_roots', default=[],
+                        type=Path, action='append',
+                        help='add a board root, may be given more than once')
+
+def dump_shields(shields):
+    for shield in shields:
+        print(f'  {shield.name}')
+
+if __name__ == '__main__':
+    dump_shields(find_shields(parse_args()))