Add boilerplate method for board configuration at boot time

kmk/bootcfg.py

@@ -0,0 +1,60 @@
+import digitalio
+import microcontroller
+
+
+def bootcfg(
+    sense,
+    source=None,
+    no_cdc=True,
+    no_hid=False,
+    no_midi=True,
+    no_storage=True,
+    usb_id=None,
+):
+
+    if isinstance(sense, microcontroller.Pin):
+        sense = digitalio.DigitalInOut(sense)
+        sense.direction = digitalio.Direction.INPUT
+        sense.pull = digitalio.Pull.UP
+
+        if isinstance(source, microcontroller.Pin):
+            source = digitalio.DigitalInOut(source)
+            source.direction = digitalio.Direction.OUTPUT
+            source.value = False
+    else:
+        return False
+
+    # sense pulled low -> skip boot configuration
+    if not sense.value:
+        return False
+
+    if no_cdc:
+        import usb_cdc
+
+        usb_cdc.disable()
+
+    if no_hid:
+        import usb_hid
+
+        usb_hid.disable()
+
+    if no_midi:
+        import usb_midi
+
+        usb_midi.disable()
+
+    if isinstance(usb_id, tuple):
+        import supervisor
+
+        if hasattr(supervisor, 'set_usb_identification'):
+            supervisor.set_usb_identification(*usb_id)
+
+    # The no_storage entry is intentionally evaluated last to ensure the drive
+    # is mountable and rescueable, in case any of the previous code throws an
+    # exception.
+    if no_storage:
+        import storage
+
+        storage.disable_usb_drive()
+
+    return True