stm32f4: Add initial support for STM32F446 chip

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/stm32f4/Makefile

@@ -0,0 +1,46 @@
+# Additional STM32F4 build rules
+
+# Setup the toolchain
+CROSS_PREFIX=arm-none-eabi-
+
+dirs-y += src/stm32f4 src/generic
+dirs-y += lib/stm32f4 lib/stm32f4/gcc
+
+CFLAGS += -mthumb -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=hard
+CFLAGS += -Ilib/cmsis-core -Ilib/stm32f4/include
+CFLAGS += -DSTM32F446xx
+
+# Add source files
+src-y += stm32f4/main.c stm32f4/clock.c stm32f4/gpio.c
+src-y += generic/crc16_ccitt.c generic/alloc.c
+src-y += generic/armcm_irq.c generic/armcm_timer.c
+src-y += ../lib/stm32f4/system_stm32f4xx.c
+src-$(CONFIG_SERIAL) += stm32f4/serial.c generic/serial_irq.c
+
+# Add assembler build rules
+$(OUT)%.o: %.s $(OUT)autoconf.h $(OUT)board-link
+	@echo "  Assembling $@"
+	$(Q)$(AS) $< -o $@
+
+asmsrc-y = ../lib/stm32f4/gcc/startup_stm32f446xx.s
+OBJS_klipper.elf += $(patsubst %.s, $(OUT)src/%.o,$(asmsrc-y))
+
+# Build the linker script
+$(OUT)stm32f4.ld: src/stm32f4/stm32f4.ld $(OUT)board-link
+	@echo "  Preprocessing $@"
+	$(Q)$(CPP) -P -MD -MT $@ -DFLASH_START=0 $< -o $@
+
+CFLAGS_klipper.elf += -T $(OUT)stm32f4.ld
+CFLAGS_klipper.elf += --specs=nano.specs --specs=nosys.specs
+$(OUT)klipper.elf : $(OUT)stm32f4.ld
+
+# Binary output file rules
+target-y += $(OUT)klipper.bin
+
+$(OUT)klipper.bin: $(OUT)klipper.elf
+	@echo "  Creating hex file $@"
+	$(Q)$(OBJCOPY) -O binary $< $@
+
+flash: $(OUT)klipper.bin
+	@echo "  Flashing $< to $(FLASH_DEVICE) via stm32flash"
+	$(Q)stm32flash -w $< -v -g 0 $(FLASH_DEVICE)