Allow mpconfigboard.mk to set board extensions

Looking at the PR to add Beetle esp32 c3 (adafruit#6615) I noticed that any
microcontroller of this type would require modifying build_board_info,
which in turn causes a build of all boards. The same would be true of
esp32 boards, of which we hope a large number will be submitted soon.

Instead, create two different ways for an mpconfigboard.mk file to
override the default setting by port: For espressif, use the existing
IDF_TARGET variable. For the general case, allow the EXTENSIONS variable
to be specified.

Note that the value cannot come from mpconfigport.mk and cannot be
conditional. This condition could be lifted in the future if it is
useful. Additionally, if IDF_TARGET and EXTENSIONS both exist, the one
that appears FIRST in the mpconfigboard.mk file is used, which is
a bit tricky.

I ran "DEBUG=x RELEASE_TAG=x build_board_info.py > foo.json" before and
after to generate a copy of the release info. When diffing them, there
is no difference (as expected).

I also used a new quick debug facility just for checking extensions,
"build_board_info.py espressif:adafruit_feather_esp32s2", to spot check
that the code was working as expected, since running the full
"build_board_info" process is time consuming.

The remaining special cases in "extension_by_board" should be moved to
the correct mpconfigport.mk files and the whole facility of "extension by
board" should be removed from build_board_info.py.

Author: jepler

ports/nrf/boards/microbit_v2/mpconfigboard.mk

@@ -7,3 +7,5 @@ INTERNAL_FLASH_FILESYSTEM = 1
 
 # USB pins aren't used.
 CIRCUITPY_USB = 0
+
+EXTENSIONS = combined.hex

tools/build_board_info.py

@@ -6,6 +6,8 @@
 
 import json
 import os
+import pathlib
+import re
 import subprocess
 import sys
 import sh
@@ -66,27 +68,38 @@
     "pca10056": BIN_UF2,
     "pca10059": BIN_UF2,
     "electronut_labs_blip": HEX,
-    "microbit_v2": COMBINED_HEX,
     # stm32
     "meowbit_v121": UF2,
     "sparkfun_stm32_thing_plus": BIN_UF2,
     "swan_r5": BIN_UF2,
-    # esp32
-    "adafruit_feather_esp32_v2": BIN,
-    # esp32c3
-    "adafruit_qtpy_esp32c3": BIN,
-    "ai_thinker_esp32-c3s": BIN,
-    "ai_thinker_esp32-c3s-2m": BIN,
-    "espressif_esp32c3_devkitm_1_n4": BIN,
-    "lilygo_ttgo_t-01c3": BIN,
-    "lolin_c3_mini": BIN,
-    "microdev_micro_c3": BIN,
-    "lilygo_ttgo_t-oi-plus": BIN,
     # broadcom
     "raspberrypi_zero": KERNEL_IMG,
     "raspberrypi_zero_w": KERNEL_IMG,
 }
 
+# Per board overrides
+extension_by_idftarget = {
+    "esp32": BIN,
+    "esp32c3": BIN,
+}
+
+
+def extension_by_mpconfigboard(board_path, default):
+
+    with open(board_path / "mpconfigboard.mk") as mpconfig:
+        for line in mpconfig:
+            # Handle both = and := definitions.
+            if not (m := re.match(r"^([A-Z][A-Z0-9_]*)\s*:?=\s*(.*)$", line)):
+                continue
+            key = m.group(1)
+            value = m.group(2)
+            if key == "IDF_TARGET" and value in extension_by_idftarget:
+                return extension_by_idftarget[value]
+            if key == "EXTENSIONS":
+                return tuple(value.split())
+    return default
+
+
 language_allow_list = set(
     [
         "ID",
@@ -120,6 +133,14 @@ def get_languages(list_all=False):
     return sorted(list(languages), key=str.casefold)
 
 
+def get_board_extension(port, board):
+    board_path = pathlib.Path(os.path.join("../ports", port, "boards", board))
+    extensions = extension_by_port[port]
+    extensions = extension_by_mpconfigboard(board_path, extensions)
+    extensions = extension_by_board.get(board_path.name, extensions)
+    return extensions
+
+
 def get_board_mapping():
     boards = {}
     for port in SUPPORTED_PORTS:
@@ -128,8 +149,7 @@ def get_board_mapping():
             if board_path.is_dir():
                 board_files = os.listdir(board_path.path)
                 board_id = board_path.name
-                extensions = extension_by_port[port]
-                extensions = extension_by_board.get(board_path.name, extensions)
+                extensions = get_board_extension(port, board_id)
                 aliases = aliases_by_board.get(board_path.name, [])
                 boards[board_id] = {
                     "port": port,
@@ -341,4 +361,10 @@ def generate_download_info():
     if "RELEASE_TAG" in os.environ and os.environ["RELEASE_TAG"]:
         generate_download_info()
     else:
-        print("skipping website update because this isn't a tag")
+        if len(sys.argv) == 1:
+            print("skipping website update because this isn't a tag")
+        else:
+            for arg in sys.argv[1:]:
+                port, board = arg.split(":", 1)
+                extensions = get_board_extension(port, board)
+                print(f"{port:<12} {board:30} {' '.join(extensions)}")