mkimage: fit: spl: Add an optional static offset for external data

When building a FIT with external data (-E), U-Boot proper may require
absolute positioning for executing the external firmware. To acheive this
use the (-p) switch, which will replace the amended 'data-offset' with
'data-position' indicating the absolute position of external data.

It is considered an error if the requested absolute position overlaps with the
initial data required for the compact FIT.

Signed-off-by: Teddy Reed <teddy.reed@gmail.com>

doc/mkimage.1

@@ -151,6 +151,12 @@ the corresponding public key is written into this file for for run-time
 verification. Typically the file here is the device tree binary used by
 CONFIG_OF_CONTROL in U-Boot.
 
+.TP
+.BI "\-p [" "external position" "]"
+Place external data at a static external position. See \-E. Instead of writing
+a 'data-offset' property defining the offset from the end of the FIT, \-p will
+use 'data-position' as the absolute position from the base of the FIT.
+
 .TP
 .BI "\-r
 Specifies that keys used to sign the FIT are required. This means that they

doc/uImage.FIT/source_file_format.txt

@@ -282,6 +282,9 @@ In this case the 'data' property is omitted. Instead you can use:
     aligned to a 4-byte boundary.
   - data-size : size of the data in bytes
 
+The 'data-offset' property can be substituted with 'data-position', which
+defines an absolute position or address as the offset. This is helpful when
+booting U-Boot proper before performing relocation.
 
 9) Examples
 -----------

tools/fit_image.c

@@ -416,7 +416,13 @@ static int fit_extract_data(struct image_tool_params *params, const char *fname)
 			ret = -EPERM;
 			goto err_munmap;
 		}
-		fdt_setprop_u32(fdt, node, "data-offset", buf_ptr);
+		if (params->external_offset > 0) {
+			/* An external offset positions the data absolutely. */
+			fdt_setprop_u32(fdt, node, "data-position",
+					params->external_offset + buf_ptr);
+		} else {
+			fdt_setprop_u32(fdt, node, "data-offset", buf_ptr);
+		}
 		fdt_setprop_u32(fdt, node, "data-size", len);
 
 		buf_ptr += (len + 3) & ~3;
@@ -437,6 +443,17 @@ static int fit_extract_data(struct image_tool_params *params, const char *fname)
 		ret = -EIO;
 		goto err;
 	}
+
+	/* Check if an offset for the external data was set. */
+	if (params->external_offset > 0) {
+		if (params->external_offset < new_size) {
+			debug("External offset %x overlaps FIT length %x",
+			      params->external_offset, new_size);
+			ret = -EINVAL;
+			goto err;
+		}
+		new_size = params->external_offset;
+	}
 	if (lseek(fd, new_size, SEEK_SET) < 0) {
 		debug("%s: Failed to seek to end of file: %s\n", __func__,
 		      strerror(errno));

tools/imagetool.h

@@ -74,6 +74,7 @@ struct image_tool_params {
 	struct content_info *content_tail;
 	bool external_data;	/* Store data outside the FIT */
 	bool quiet;		/* Don't output text in normal operation */
+	unsigned int external_offset;	/* Add padding to external data */
 };
 
 /*

tools/mkimage.c

@@ -93,11 +93,13 @@ static void usage(const char *msg)
 		"          -f => input filename for FIT source\n");
 #ifdef CONFIG_FIT_SIGNATURE
 	fprintf(stderr,
-		"Signing / verified boot options: [-k keydir] [-K dtb] [ -c <comment>] [-r]\n"
+		"Signing / verified boot options: [-E] [-k keydir] [-K dtb] [ -c <comment>] [-p addr] [-r]\n"
+		"          -E => place data outside of the FIT structure\n"
 		"          -k => set directory containing private keys\n"
 		"          -K => write public keys to this .dtb file\n"
 		"          -c => add comment in signature node\n"
 		"          -F => re-sign existing FIT image\n"
+		"          -p => place external data at a static position\n"
 		"          -r => mark keys used as 'required' in dtb\n");
 #else
 	fprintf(stderr,
@@ -136,7 +138,7 @@ static void process_args(int argc, char **argv)
 	int opt;
 
 	while ((opt = getopt(argc, argv,
-			     "a:A:b:cC:d:D:e:Ef:Fk:K:ln:O:rR:qsT:vVx")) != -1) {
+			     "a:A:b:cC:d:D:e:Ef:Fk:K:ln:p:O:rR:qsT:vVx")) != -1) {
 		switch (opt) {
 		case 'a':
 			params.addr = strtoull(optarg, &ptr, 16);
@@ -216,6 +218,13 @@ static void process_args(int argc, char **argv)
 			if (params.os < 0)
 				usage("Invalid operating system");
 			break;
+		case 'p':
+			params.external_offset = strtoull(optarg, &ptr, 16);
+			if (*ptr) {
+				fprintf(stderr, "%s: invalid offset size %s\n",
+					params.cmdname, optarg);
+				exit(EXIT_FAILURE);
+			}
 		case 'q':
 			params.quiet = 1;
 			break;