image: improve UBI image sizing on NAND devices

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>

include/image-commands.mk

@@ -133,6 +133,8 @@ define Build/append-md5sum-ascii-salted
 	rm $@.salted
 endef
 
+UBI_NAND_SIZE_LIMIT= ($(IMAGE_SIZE) - ($(NAND_SIZE) * 20 / 1024))
+
 define Build/append-ubi
 	sh $(TOPDIR)/scripts/ubinize-image.sh \
 		$(if $(UBOOTENV_IN_UBI),--uboot-env) \
@@ -146,6 +148,8 @@ define Build/append-ubi
 		$(UBINIZE_OPTS)
 	cat $@.tmp >> $@
 	rm $@.tmp
+	$(if $(and $(IMAGE_SIZE),$(NAND_SIZE)),\
+		$(call Build/check-size,$(UBI_NAND_SIZE_LIMIT)))
 endef
 
 define Build/ubinize-kernel

include/image.mk

@@ -386,6 +386,7 @@ define Device/Init
   DEVICE_IMG_NAME = $$(DEVICE_IMG_PREFIX)-$$(1)-$$(2)
   FACTORY_IMG_NAME :=
   IMAGE_SIZE :=
+  NAND_SIZE :=
   KERNEL_PREFIX = $$(DEVICE_IMG_PREFIX)
   KERNEL_SUFFIX := -kernel.bin
   KERNEL_INITRAMFS_SUFFIX = $$(KERNEL_SUFFIX)
@@ -446,7 +447,7 @@ DEFAULT_DEVICE_VARS := \
   DEVICE_DTS_DIR DEVICE_DTS_OVERLAY DEVICE_DTS_LOADADDR \
   DEVICE_FDT_NUM DEVICE_IMG_PREFIX SOC BOARD_NAME UIMAGE_MAGIC UIMAGE_NAME \
   UIMAGE_TIME SUPPORTED_DEVICES IMAGE_METADATA KERNEL_ENTRY KERNEL_LOADADDR \
-  UBOOT_PATH IMAGE_SIZE \
+  UBOOT_PATH IMAGE_SIZE NAND_SIZE \
   FACTORY_IMG_NAME FACTORY_SIZE \
   DEVICE_PACKAGES DEVICE_COMPAT_VERSION DEVICE_COMPAT_MESSAGE \
   DEVICE_VENDOR DEVICE_MODEL DEVICE_VARIANT \