add stm32 dev template

templates/dev/stm32-blink/Makefile

@@ -0,0 +1,67 @@
+PREFIX   ?= arm-none-eabi-
+CC        = $(PREFIX)gcc
+OBJCOPY   = $(PREFIX)objcopy
+SIZE      = $(PREFIX)size
+
+PNAME    := blink
+BUILD    := build
+
+# libopencm3 is provided by the Nix shell
+OPENCM3_DIR ?= ""
+
+SRCS     := src/main.c
+OBJS     := $(addprefix $(BUILD)/, $(SRCS:.c=.o))
+
+# STM32G4
+CPU_FLAGS := -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16
+
+CFLAGS   := $(CPU_FLAGS) \
+            -DSTM32G4 \
+            -Os -Wall -Wextra \
+            -ffunction-sections -fdata-sections \
+            -I$(OPENCM3_DIR)/include
+
+LDFLAGS  := $(CPU_FLAGS) \
+            -nostartfiles \
+            -Wl,--gc-sections \
+            -L$(OPENCM3_DIR)/lib \
+            -lopencm3_stm32g4
+
+ELF := $(BUILD)/$(PNAME).elf
+BIN := $(BUILD)/$(PNAME).bin
+HEX := $(BUILD)/$(PNAME).hex
+
+.PHONY: all clean flash size
+
+all: $(BIN) $(HEX) size
+
+$(BUILD)/%.o: %.c
+	@mkdir -p $(@D)
+	$(CC) $(CFLAGS) -c $< -o $@
+
+LDSCRIPT := $(BUILD)/stm32g474xe.ld
+
+$(LDSCRIPT):
+	@mkdir -p $(@D)
+	$(CC) -I$(OPENCM3_DIR)/include $(shell python3 $(OPENCM3_DIR)/scripts/genlink.py $(OPENCM3_DIR)/ld/devices.data stm32g474xe DEFS) -P -E $(OPENCM3_DIR)/ld/linker.ld.S -o $@
+
+$(ELF): $(OBJS) $(LDSCRIPT)
+	$(CC) $(OBJS) $(LDFLAGS) -T$(LDSCRIPT) -o $@
+
+$(BIN): $(ELF)
+	$(OBJCOPY) -O binary $< $@
+
+$(HEX): $(ELF)
+	$(OBJCOPY) -O ihex $< $@
+
+size: $(ELF)
+	$(SIZE) $<
+
+flash: $(BIN)
+	openocd \
+	  -f interface/stlink.cfg \
+	  -f target/stm32g4x.cfg \
+	  -c "program $(BIN) verify reset exit 0x08000000"
+
+clean:
+	rm -rf $(BUILD)