De-duplicate platform detection (#19603)

builddefs/build_keyboard.mk

@@ -184,6 +184,12 @@ include $(BUILDDEFS_PATH)/converters.mk
 
 include $(BUILDDEFS_PATH)/mcu_selection.mk
 
+# 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:]')
+
 # Find all the C source files to be compiled in subfolders.
 KEYBOARD_SRC :=
 
@@ -257,24 +263,6 @@ 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)","")

builddefs/converters.mk

@@ -19,6 +19,7 @@ ifneq ($(CONVERT_TO),)
 
     -include $(CONVERTER)/pre_converter.mk
 
+    PLATFORM_KEY = $(shell echo $(CONVERTER) | rev | cut -d "/" -f4 | rev)
     TARGET := $(TARGET)_$(CONVERT_TO)
 
     # Configure any defaults