scripts/mkits.sh: add support for adding DT overlay blobs to image

Allow adding multiple device tree overlay blobs to an image and
generate configurations for each of them.
This is useful on boards with modern U-Boot which allow e.g. user-
configurable peripherals ("shields") in that way.
Note that currently, each generated configuration adds exactly one
overlay on top of the base image, ie. adding multiple overlays at the
same time is not yet supported.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

scripts/mkits.sh

@@ -32,7 +32,9 @@ usage() {
 	printf "\n\t-d ==> include Device Tree Blob 'dtb'"
 	printf "\n\t-r ==> include RootFS blob 'rootfs'"
 	printf "\n\t-H ==> specify hash algo instead of SHA1"
-	printf "\n\t-o ==> create output file 'its_file'\n"
+	printf "\n\t-o ==> create output file 'its_file'"
+	printf "\n\t-O ==> create config with dt overlay 'name:dtb'"
+	printf "\n\t\t(can be specified more than once)\n"
 	exit 1
 }
 
@@ -41,8 +43,10 @@ ROOTFSNUM=1
 INITRDNUM=1
 HASH=sha1
 LOADABLES=
+DTOVERLAY=
+DTADDR=
 
-while getopts ":A:a:c:C:D:d:e:f:i:k:n:o:v:r:S" OPTION
+while getopts ":A:a:c:C:D:d:e:f:i:k:n:o:O:v:r:S" OPTION
 do
 	case $OPTION in
 		A ) ARCH=$OPTARG;;
@@ -57,6 +61,7 @@ do
 		k ) KERNEL=$OPTARG;;
 		n ) FDTNUM=$OPTARG;;
 		o ) OUTPUT=$OPTARG;;
+		O ) DTOVERLAY="$DTOVERLAY ${OPTARG}";;
 		r ) ROOTFS=$OPTARG;;
 		S ) HASH=$OPTARG;;
 		v ) VERSION=$OPTARG;;
@@ -78,6 +83,11 @@ if [ -n "${COMPATIBLE}" ]; then
 	COMPATIBLE_PROP="compatible = \"${COMPATIBLE}\";"
 fi
 
+[ "$DTOVERLAY" ] && {
+	dtbsize=$(wc -c "$DTB" | cut -d' ' -f1)
+	DTADDR=$(printf "0x%08x" $(($LOAD_ADDR - $dtbsize)) )
+}
+
 # Conditionally create fdt information
 if [ -n "${DTB}" ]; then
 	FDT_NODE="
@@ -86,6 +96,7 @@ if [ -n "${DTB}" ]; then
 			${COMPATIBLE_PROP}
 			data = /incbin/(\"${DTB}\");
 			type = \"flat_dt\";
+			${DTADDR:+load = <${DTADDR}>;}
 			arch = \"${ARCH}\";
 			compression = \"none\";
 			hash@1 {
@@ -141,6 +152,47 @@ if [ -n "${ROOTFS}" ]; then
 	LOADABLES="${LOADABLES:+$LOADABLES, }\"rootfs-${ROOTFSNUM}\""
 fi
 
+# add DT overlay blobs
+FDTOVERLAY_NODE=""
+OVCONFIGS=""
+[ "$DTOVERLAY" ] && for overlay in $DTOVERLAY ; do
+	overlay_blob=${overlay##*:}
+	ovname=${overlay%%:*}
+	ovnode="fdt-$ovname"
+	ovsize=$(wc -c "$overlay_blob" | cut -d' ' -f1)
+	echo "$ovname ($overlay_blob) : $ovsize" >&2
+	DTADDR=$(printf "0x%08x" $(($DTADDR - $ovsize)))
+	FDTOVERLAY_NODE="$FDTOVERLAY_NODE
+
+		$ovnode {
+			description = \"${ARCH_UPPER} OpenWrt ${DEVICE} device tree overlay $ovname\";
+			${COMPATIBLE_PROP}
+			data = /incbin/(\"${overlay_blob}\");
+			type = \"flat_dt\";
+			arch = \"${ARCH}\";
+			load = <${DTADDR}>;
+			compression = \"none\";
+			hash@1 {
+				algo = \"crc32\";
+			};
+			hash@2 {
+				algo = \"${HASH}\";
+			};
+		};
+"
+	OVCONFIGS="$OVCONFIGS
+
+		config-$ovname {
+			description = \"OpenWrt ${DEVICE} with $ovname\";
+			kernel = \"kernel-1\";
+			fdt = \"fdt-$FDTNUM\", \"$ovnode\";
+			${LOADABLES:+loadables = ${LOADABLES};}
+			${COMPATIBLE_PROP}
+			${INITRD_PROP}
+		};
+	"
+done
+
 # Create a default, fully populated DTS file
 DATA="/dts-v1/;
 
@@ -167,6 +219,7 @@ DATA="/dts-v1/;
 		};
 ${INITRD_NODE}
 ${FDT_NODE}
+${FDTOVERLAY_NODE}
 ${ROOTFS_NODE}
 	};
 
@@ -180,6 +233,7 @@ ${ROOTFS_NODE}
 			${COMPATIBLE_PROP}
 			${INITRD_PROP}
 		};
+		${OVCONFIGS}
 	};
 };"