build: Optionally build an FIT image with all enabled DTBs

Config.in

@@ -10,3 +10,4 @@ source "$BR2_EXTERNAL_INFIX_PATH/qemu/Config.in"
 
 endmenu
 
+source "$BR2_EXTERNAL_INFIX_PATH/board/common/Config.in"

board/common/Config.in

@@ -0,0 +1,12 @@
+menuconfig FIT_IMAGE
+	bool "Build FIT image"
+
+config FIT_ARCH
+	string
+	depends on FIT_IMAGE
+	default "arm64" if BR2_aarch64
+
+config FIT_KERNEL_LOAD_ADDR
+	string "Kernel load address"
+	depends on FIT_IMAGE
+

board/common/mkfit.sh

@@ -0,0 +1,111 @@
+#!/bin/sh
+
+die()
+{
+    echo "$@" >&2
+    exit 1
+}
+
+load_cfg()
+{
+    local tmp=$(mktemp -p /tmp)
+
+    grep ^FIT_ $BR2_CONFIG >$tmp
+    .  $tmp
+    rm $tmp
+}
+
+load_cfg
+[ "$FIT_IMAGE" = "y" ] || {
+    echo "FIT_IMAGE not set, skipping" >&2
+    exit 0
+}
+
+work=$(pwd)/build/fit-image-local
+dtbs=$(find $BINARIES_DIR -name '*.dtb')
+kernel=$(find $BINARIES_DIR -name '*Image' | head -n1)
+squash=$BINARIES_DIR/rootfs.squashfs
+
+mkdir -p $work
+
+# mkimage will only align images to 4 bytes, but U-Boot will leave
+# both DTB and ramdisk in place when starting the kernel. So we pad
+# all components up to a 4k boundary.
+truncate -s %4k $kernel $dtbs
+
+: >$work/dtbs.itsi
+: >$work/cfgs.itsi
+for dtb in $dtbs; do
+    name=$(basename $dtb .dtb)
+
+    cat <<EOF >>$work/dtbs.itsi
+		$name-dtb {
+			description = "$name";
+			type = "flat_dt";
+			arch = "$FIT_ARCH";
+			compression = "none";
+			data = /incbin/("$dtb");
+		};
+EOF
+    cat <<EOF >>$work/cfgs.itsi
+		$name {
+			description = "$name";
+			kernel = "kernel";
+			ramdisk = "ramdisk";
+			fdt = "$name-dtb";
+		};
+EOF
+done
+
+: >$work/kernel-load.itsi
+if [ "$FIT_KERNEL_LOAD_ADDR" ]; then
+    cat <<EOF >$work/kernel-load.itsi
+			load = <$FIT_KERNEL_LOAD_ADDR>;
+			entry = <$FIT_KERNEL_LOAD_ADDR>;
+EOF
+fi
+
+cat <<EOF >$work/infix.its
+/dts-v1/;
+
+/ {
+	timestamp = <$(date +%s)>;
+	description = "Inf/IX ($FIT_ARCH)";
+	creator = "infix";
+	#address-cells = <0x1>;
+
+	images {
+
+		kernel {
+			description = "Linux";
+			type = "kernel";
+			arch = "$FIT_ARCH";
+			os = "linux";
+$(cat $work/kernel-load.itsi)
+			compression = "none";
+			data = /incbin/("$kernel");
+		};
+
+		ramdisk {
+			description = "Inf/IX";
+			type = "ramdisk";
+			os = "linux";
+			arch = "$FIT_ARCH";
+			compression = "none";
+			data = /incbin/("$squash");
+		};
+
+$(cat $work/dtbs.itsi)
+
+	};
+
+	configurations {
+$(cat $work/cfgs.itsi)
+	};
+};
+EOF
+
+mkimage \
+    -E -p 0x1000 \
+    -f $work/infix.its $BINARIES_DIR/infix.itb \
+    || die "Unable to create FIT image"

board/common/post-image.sh

@@ -1 +1,5 @@
 #!/bin/sh
+
+common=$(dirname $(readlink -f "$0"))
+
+$common/mkfit.sh