Fix compiler settings for MCUs with floating point

tmk_core/chibios.mk

@@ -168,6 +168,22 @@ OPT_DEFS += -DPROTOCOL_CHIBIOS
 
 MCUFLAGS = -mcpu=$(MCU)
 
+# FPU options default (Cortex-M4 and Cortex-M7 single precision).
+ifeq ($(USE_FPU_OPT),)
+  USE_FPU_OPT = -mfloat-abi=$(USE_FPU) -mfpu=fpv4-sp-d16 -fsingle-precision-constant
+endif
+
+# FPU-related options
+ifeq ($(USE_FPU),)
+  USE_FPU = no
+endif
+ifneq ($(USE_FPU),no)
+  OPT    += $(USE_FPU_OPT)
+  OPT_DEFS  += -DCORTEX_USE_FPU=TRUE
+else
+  OPT_DEFS  += -DCORTEX_USE_FPU=FALSE
+endif
+
 DEBUG = gdb
 
 DFU_ARGS ?=