Add u-boot build targets

Author: gsingh93

Makefile

@@ -344,6 +344,46 @@ rootfs_clean:
 	$(SUDO) rm -f $(CPIO_FILE)
 	$(SUDO) rm -f $(ROOTFS)
 
+##
+## U-Boot
+##
+
+# Note: We're reusing the TARGET variable from the Linux build section
+
+UBOOT_SRC := $(ROOT_DIR)/u-boot
+UBOOT_OUT := $(OUT_DIR)/uboot/$(ARCH)
+UBOOT_CONFIG := $(UBOOT_OUT)/.config
+UBOOT_BIN := $(UBOOT_OUT)/u-boot.bin
+
+ifeq ($(ARCH),x86_64)
+  UBOOT_DEFCONFIG=qemu-x86_64_defconfig
+else ifeq ($(ARCH),i386)
+  UBOOT_DEFCONFIG=qemu-x86_defconfig
+else ifeq ($(ARCH),arm64)
+  UBOOT_DEFCONFIG=qemu_arm64_defconfig
+endif
+
+UBOOT_MAKE := \
+	PATH=$(CLANG_DIR)/bin:$(PATH) \
+	$(MAKE) \
+	-C $(UBOOT_SRC) \
+	HOSTCC=clang \
+	O=$(UBOOT_OUT) \
+	-j `nproc`
+
+.PHONY: uboot_defconfig
+uboot_defconfig $(UBOOT_CONFIG): | $(CLANG_DIR)
+	+ $(UBOOT_MAKE) $(UBOOT_DEFCONFIG)
+
+.PHONY: uboot
+uboot $(UBOOT_BIN): $(UBOOT_CONFIG) | $(CLANG_DIR)
+	+ $(UBOOT_MAKE) CROSS_COMPILE=$(TARGET)- CC=clang
+	cd $(UBOOT_SRC) && ./scripts/gen_compile_commands.py -d $(UBOOT_OUT)
+
+.PHONY: uboot_clean
+uboot_clean:
+	+ $(UBOOT_MAKE) mrproper
+
 ##
 ## Run QEMU
 ##