spl: Add option to enable SPL Legacy image support

Add a Kconfig option that enables Legacy image support, this allows
boards to explicitly disable this, for instance when needed for
security reasons.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
[trini: Move to common/spl/Kconfig]
Signed-off-by: Tom Rini <trini@konsulko.com>

common/spl/Kconfig

@@ -23,6 +23,14 @@ config SPL_RAW_IMAGE_SUPPORT
 	  is y. If this is not set, SPL will move on to other available
 	  boot media to find a suitable image.
 
+config SPL_LEGACY_IMAGE_SUPPORT
+	bool "Support SPL loading and booting of Legacy images"
+	default y
+	help
+	  SPL will support loading and booting Legacy images when this option
+	  is y. If this is not set, SPL will move on to other available
+	  boot media to find a suitable image.
+
 config SPL_SYS_MALLOC_SIMPLE
 	bool
 	depends on SPL

common/spl/spl.c

@@ -93,9 +93,10 @@ void spl_set_header_raw_uboot(struct spl_image_info *spl_image)
 int spl_parse_image_header(struct spl_image_info *spl_image,
 			   const struct image_header *header)
 {
-	u32 header_size = sizeof(struct image_header);
-
 	if (image_get_magic(header) == IH_MAGIC) {
+#ifdef CONFIG_SPL_LEGACY_IMAGE_SUPPORT
+		u32 header_size = sizeof(struct image_header);
+
 		if (spl_image->flags & SPL_COPY_PAYLOAD_ONLY) {
 			/*
 			 * On some system (e.g. powerpc), the load-address and
@@ -118,6 +119,11 @@ int spl_parse_image_header(struct spl_image_info *spl_image,
 		debug("spl: payload image: %.*s load addr: 0x%lx size: %d\n",
 			(int)sizeof(spl_image->name), spl_image->name,
 			spl_image->load_addr, spl_image->size);
+#else
+		/* LEGACY image not supported */
+		debug("Legacy boot image support not enabled, proceeding to other boot methods");
+		return -EINVAL;
+#endif
 	} else {
 #ifdef CONFIG_SPL_PANIC_ON_RAW_IMAGE
 		/*