De-duplicate platform detection (#19545)

builddefs/build_keyboard.mk

@@ -180,6 +180,13 @@ generated-files: $(KEYMAP_OUTPUT)/src/config.h $(KEYMAP_OUTPUT)/src/keymap.c
 
 endif
 
+# PLATFORM_KEY should be detected in info.json via key 'processor' (or rules.mk 'MCU')
+ifeq ($(PLATFORM_KEY),)
+    $(call CATASTROPHIC_ERROR,Platform not defined)
+endif
+PLATFORM=$(shell echo $(PLATFORM_KEY) | tr '[:lower:]' '[:upper:]')
+
+
 include $(BUILDDEFS_PATH)/converters.mk
 
 include $(BUILDDEFS_PATH)/mcu_selection.mk
@@ -257,24 +264,6 @@ ifneq ("$(wildcard $(KEYBOARD_PATH_5)/$(KEYBOARD_FOLDER_5).h)","")
     FOUND_KEYBOARD_H = $(KEYBOARD_FOLDER_5).h
 endif
 
-# Determine and set parameters based on the keyboard's processor family.
-# We can assume a ChibiOS target When MCU_FAMILY is defined since it's
-# not used for LUFA
-ifdef MCU_FAMILY
-    PLATFORM=CHIBIOS
-    PLATFORM_KEY=chibios
-    FIRMWARE_FORMAT?=bin
-    OPT_DEFS += -DMCU_$(MCU_FAMILY)
-else ifdef ARM_ATSAM
-    PLATFORM=ARM_ATSAM
-    PLATFORM_KEY=arm_atsam
-    FIRMWARE_FORMAT=bin
-else
-    PLATFORM=AVR
-    PLATFORM_KEY=avr
-    FIRMWARE_FORMAT?=hex
-endif
-
 # Find all of the config.h files and add them to our CONFIG_H define.
 CONFIG_H :=
 ifneq ("$(wildcard $(KEYBOARD_PATH_5)/config.h)","")