nios2: Build infrastructure

This patch adds Makefile and Kconfig files required for building a
nios2 kernel.

Signed-off-by: Ley Foon Tan <lftan@altera.com>
diff --git a/arch/nios2/boot/Makefile b/arch/nios2/boot/Makefile
new file mode 100644
index 0000000..59392dc
--- /dev/null
+++ b/arch/nios2/boot/Makefile
@@ -0,0 +1,52 @@
+#
+# arch/nios2/boot/Makefile
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+
+UIMAGE_LOADADDR = $(shell $(NM) vmlinux | awk '$$NF == "_stext" {print $$1}')
+UIMAGE_ENTRYADDR = $(shell $(NM) vmlinux | awk '$$NF == "_start" {print $$1}')
+UIMAGE_COMPRESSION = gzip
+
+OBJCOPYFLAGS_vmlinux.bin := -O binary
+
+targets += vmlinux.bin vmlinux.gz vmImage
+
+$(obj)/vmlinux.bin: vmlinux FORCE
+	$(call if_changed,objcopy)
+
+$(obj)/vmlinux.gz: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,gzip)
+
+$(obj)/vmImage: $(obj)/vmlinux.gz
+	$(call if_changed,uimage)
+	@$(kecho) 'Kernel: $@ is ready'
+
+# Rule to build device tree blobs
+DTB_SRC := $(patsubst "%",%,$(CONFIG_NIOS2_DTB_SOURCE))
+
+# Make sure the generated dtb gets removed during clean
+extra-$(CONFIG_NIOS2_DTB_SOURCE_BOOL) += system.dtb
+
+$(obj)/system.dtb: $(DTB_SRC) FORCE
+	$(call cmd,dtc)
+
+# Ensure system.dtb exists
+$(obj)/linked_dtb.o: $(obj)/system.dtb
+
+obj-$(CONFIG_NIOS2_DTB_SOURCE_BOOL) += linked_dtb.o
+
+targets += $(dtb-y)
+
+# Rule to build device tree blobs with make command
+$(obj)/%.dtb: $(src)/dts/%.dts FORCE
+	$(call if_changed_dep,dtc)
+
+$(obj)/dtbs: $(addprefix $(obj)/, $(dtb-y))
+
+clean-files := *.dtb
+
+install:
+	sh $(srctree)/$(src)/install.sh $(KERNELRELEASE) $(BOOTIMAGE) System.map "$(INSTALL_PATH)"