[RFC v2 2/2] mkimage: Align fdt images in FIT to 8 bytes

[Bjørn Mork]

"In place" configurations are strongly discouraged, but known to be
used.  This can cause hard to debug alignment problems since the
value of the "data" property only is guaranteed to be 4-byte
aligned.

Unconditionally aligning fdt images to 8 byte boundaries will
prevent these problems, at the maximum price of 4 bytes per fdt.

Signed-off-by: Bjørn Mork <bjorn at mork.no>
---
 tools/fit_image.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/tools/fit_image.c b/tools/fit_image.c
index 923a9755b709..1e060784895d 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -24,6 +24,41 @@
 
 static struct legacy_img_hdr header;
 
+/**
+ * fit_align_fdt_images() - Align all fdt images in the FIT to 8 bytes
+ *
+ * An fdt blob must be placed at an 8 byte aligned offset if it is to
+ * be used "in place". This will not be verified by U-Boot. Simply align
+ * all IH_TYPE_FLATDT images to prevent problems.
+ */
+static int fit_align_fdt_images(void *fit)
+{
+	int images_noffset,  noffset, ret;
+	uint8_t type;
+	size_t size;
+	const void *ptr;
+
+	images_noffset = fdt_path_offset(fit, FIT_IMAGES_PATH);
+	if (images_noffset < 0) {
+		printf("Can't find images parent node '%s' (%s)\n",
+		       FIT_IMAGES_PATH, fdt_strerror(images_noffset));
+		return images_noffset;
+	}
+
+	for (noffset = fdt_first_subnode(fit, images_noffset);
+	     noffset >= 0;
+	     noffset = fdt_next_subnode(fit, noffset)) {
+		fit_image_get_type(fit, noffset, &type);
+		if (type != IH_TYPE_FLATDT)
+			continue;
+
+		ret = fdt_alignprop(fit, noffset, FIT_DATA_PROP, 8);
+		if (ret < 0)
+			return ret;
+	}
+	return 0;
+}
+
 static int fit_add_file_data(struct image_tool_params *params, size_t size_inc,
 			     const char *tmpfile)
 {
@@ -81,6 +116,10 @@ static int fit_add_file_data(struct image_tool_params *params, size_t size_inc,
 						&params->summary);
 	}
 
+	if (!ret) {
+		ret = fit_align_fdt_images(ptr);
+	}
+
 	if (dest_blob) {
 		munmap(dest_blob, destfd_size);
 		close(destfd);
-- 
2.30.2