tools: kwbimage: Align SPI and NAND images to 256 bytes

Writing into SPI NOR and NAND memory can be done only in 256 bytes long
blocks. Align final image size so that when it is burned into SPI NOR or
NAND memory via U-Boot's commands (sf or mtd), we can use the $filesize
variable directly as the length argument.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Chris Packham <judge.packham@gmail.com>
Tested-by: Chris Packham <judge.packham@gmail.com>

tools/kwbimage.c

@@ -1510,6 +1510,17 @@ static int image_get_version(void)
 	return e->version;
 }
 
+static int image_get_bootfrom(void)
+{
+	struct image_cfg_element *e;
+
+	e = image_find_option(IMAGE_CFG_BOOT_FROM);
+	if (!e)
+		return -1;
+
+	return e->bootfrom;
+}
+
 static void kwbimage_set_header(void *ptr, struct stat *sbuf, int ifd,
 				struct image_tool_params *params)
 {
@@ -1642,6 +1653,7 @@ static int kwbimage_generate(struct image_tool_params *params,
 	FILE *fcfg;
 	struct stat s;
 	int alloc_len;
+	int bootfrom;
 	int version;
 	void *hdr;
 	int ret;
@@ -1678,6 +1690,7 @@ static int kwbimage_generate(struct image_tool_params *params,
 		exit(EXIT_FAILURE);
 	}
 
+	bootfrom = image_get_bootfrom();
 	version = image_get_version();
 	switch (version) {
 		/*
@@ -1717,8 +1730,12 @@ static int kwbimage_generate(struct image_tool_params *params,
 	 * The resulting image needs to be 4-byte aligned. At least
 	 * the Marvell hdrparser tool complains if its unaligned.
 	 * After the image data is stored 4-byte checksum.
+	 * Final SPI and NAND images must be aligned to 256 bytes.
 	 */
-	return 4 + (4 - s.st_size % 4) % 4;
+	if (bootfrom == IBR_HDR_SPI_ID || bootfrom == IBR_HDR_NAND_ID)
+		return 4 + (256 - (alloc_len + s.st_size + 4) % 256) % 256;
+	else
+		return 4 + (4 - s.st_size % 4) % 4;
 }
 
 /*