spl: nand: support loading legacy image with payload compressed

Add support to load legacy image with payload compressed. This redirects
the boot flow for all legacy images. If the payload is not compressed, the
actual behavior will remain unchanged.

Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/common/spl/spl_nand.c b/common/spl/spl_nand.c
index 82a10ff..7b7579a 100644
--- a/common/spl/spl_nand.c
+++ b/common/spl/spl_nand.c
@@ -56,6 +56,21 @@
 	return size / load->bl_len;
 }
 
+static ulong spl_nand_legacy_read(struct spl_load_info *load, ulong offs,
+				  ulong size, void *dst)
+{
+	int err;
+
+	debug("%s: offs %lx, size %lx, dst %p\n",
+	      __func__, offs, size, dst);
+
+	err = nand_spl_load_image(offs, size, dst);
+	if (err)
+		return 0;
+
+	return size;
+}
+
 struct mtd_info * __weak nand_get_mtd(void)
 {
 	return NULL;
@@ -93,6 +108,18 @@
 		load.bl_len = bl_len;
 		load.read = spl_nand_fit_read;
 		return spl_load_imx_container(spl_image, &load, offset / bl_len);
+	} else if (IS_ENABLED(CONFIG_SPL_LEGACY_IMAGE_FORMAT) &&
+		   image_get_magic(header) == IH_MAGIC) {
+		struct spl_load_info load;
+
+		debug("Found legacy image\n");
+		load.dev = NULL;
+		load.priv = NULL;
+		load.filename = NULL;
+		load.bl_len = 1;
+		load.read = spl_nand_legacy_read;
+
+		return spl_load_legacy_img(spl_image, bootdev, &load, offset);
 	} else {
 		err = spl_parse_image_header(spl_image, bootdev, header);
 		if (err)