include variables and .h files as pp directives

build_keyboard.mk

@@ -157,7 +157,10 @@ endif
 
 OUTPUTS := $(KEYMAP_OUTPUT) $(KEYBOARD_OUTPUT)
 $(KEYMAP_OUTPUT)_SRC := $(SRC)
-$(KEYMAP_OUTPUT)_DEFS := $(OPT_DEFS) $(GFXDEFS) -DQMK_KEYBOARD=\"$(KEYBOARD)\" -DQMK_KEYMAP=\"$(KEYMAP)\"
+$(KEYMAP_OUTPUT)_DEFS := $(OPT_DEFS) $(GFXDEFS) \
+-DQMK_KEYBOARD=\"$(KEYBOARD)\" -DQMK_KEYBOARD_H=\"$(KEYBOARD).h\" \
+-DQMK_KEYMAP=\"$(KEYMAP)\" -DQMK_KEYMAP_H=\"$(KEYMAP).h\" \
+-DQMK_SUBPROJECT=\"$(SUBPROJECT)\" -DQMK_SUBPROJECT_H=\"$(SUBPROJECT).h\"
 $(KEYMAP_OUTPUT)_INC :=  $(VPATH) $(EXTRAINCDIRS)
 $(KEYMAP_OUTPUT)_CONFIG := $(CONFIG_H)
 $(KEYBOARD_OUTPUT)_SRC := $(CHIBISRC) $(GFXSRC)

keyboards/planck/planck.c

@@ -1,4 +1,4 @@
-#include "planck.h"
+#include QMK_KEYBOARD_H
 
 #ifdef ONEHAND_ENABLE
 __attribute__ ((weak))