sam4e8e: Add the SAM4e8e port

This can be flashed to e.g. the duet wifi using bossac. It requires a
later version as is currently included in the klipper repo (1.8
vs. 1.2). Comms are currently via UART0 only, USB serial is still TBD

Signed-off-by: Florian Heilmann <Florian.Heilmann@gmx.net>

src/sam4e8e/Makefile

@@ -0,0 +1,37 @@
+# Additional sam4e8e build rules
+
+# Setup the toolchain
+CROSS_PREFIX=arm-none-eabi-
+dirs-y += src/sam4e8e src/generic
+
+CFLAGS += -mthumb -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=hard
+CFLAGS += -D__SAM4E8E__
+
+CFLAGS_klipper.elf += -L lib/cmsis-sam4e/gcc/gcc
+CFLAGS_klipper.elf += -T lib/cmsis-sam4e/gcc/gcc/sam4e8e_flash.ld
+CFLAGS_klipper.elf += --specs=nano.specs --specs=nosys.specs
+
+dirs-y += lib/cmsis-sam4e/gcc \
+		  lib/cmsis-sam4e/gcc/gcc
+CFLAGS += -Ilib/cmsis-sam4e/include \
+		  -Ilib/cmsis-core
+src-y +=  ../lib/cmsis-sam4e/gcc/system_sam4e.c \
+		  ../lib/cmsis-sam4e/gcc/gcc/startup_sam4e.c
+
+src-$(CONFIG_HAVE_GPIO_SPI) += sam4e8e/spi.c
+src-$(CONFIG_SERIAL) += sam4e8e/serial.c generic/serial_irq.c
+src-$(CONFIG_HAVE_GPIO) += sam4e8e/gpio.c
+src-y += generic/crc16_ccitt.c generic/alloc.c
+src-y += generic/armcm_irq.c generic/timer_irq.c
+src-y += sam4e8e/main.c sam4e8e/timer.c
+
+# Build the additional hex output file
+target-y += $(OUT)klipper.bin
+
+$(OUT)klipper.bin: $(OUT)klipper.elf
+	@echo "  Creating bin file $@"
+	$(Q)$(OBJCOPY) -O binary $< $@
+
+flash: $(OUT)klipper.bin
+	@echo "  Flashing $^ to $(FLASH_DEVICE) via bossac"
+	$(Q)tools/bossa/bin/bossac --port="$(FLASH_DEVICE)" -b -U -e -w -v $(OUT)klipper.bin -R