SPL: EXYNOS: Prepare for variable size SPL support

When variable size SPL is used, the BL1 expects the SPL to be
encapsulated differently: instead of putting the checksum at a fixed
offset in the SPL blob, prepend the blob with a header including the
size and the checksum.

The enhancements include
	- adding a command line option, '--vs' to indicate the need for the
	variable size encapsulation
	- padding the fixed size encapsulated blob with 0xff instead of random
	memory contents
	- do not silently truncate the input file, report error instead
	- no need to explicitly closing files/freeing memory, this all happens
	on exit; removing cleanups it makes code clearer
	- profuse commenting
	- modify Makefile to allow enabling the new feature per board

Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Signed-off-by: Rajeshwari S Shinde <rajeshwari.s@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

3 files changed, 136 insertions, 44 deletions

diff --git a/include/configs/smdk5420.h b/include/configs/smdk5420.h
index 9eab7d6..447f8e5 100644
--- a/include/configs/smdk5420.h
+++ b/include/configs/smdk5420.h
@@ -19,6 +19,8 @@
 
 #define CONFIG_ARCH_DEVICE_TREE		exynos5420
 
+#define CONFIG_VAR_SIZE_SPL
+
 #define CONFIG_SYS_SDRAM_BASE		0x20000000
 #define CONFIG_SYS_TEXT_BASE		0x23E00000
 
@@ -31,7 +33,11 @@
 /* select serial console configuration */
 #define CONFIG_SERIAL3			/* use SERIAL 3 */
 
+#ifdef CONFIG_VAR_SIZE_SPL
+#define CONFIG_SPL_TEXT_BASE		0x02024410
+#else
 #define CONFIG_SPL_TEXT_BASE	0x02024400
+#endif
 
 #define CONFIG_BOOTCOMMAND	"mmc read 20007000 451 2000; bootm 20007000"
 
diff --git a/spl/Makefile b/spl/Makefile
index 2a787af..0caa982 100644
--- a/spl/Makefile
+++ b/spl/Makefile
@@ -166,8 +166,13 @@ endif
 all:	$(ALL-y)
 
 ifdef CONFIG_SAMSUNG
+ifdef CONFIG_VAR_SIZE_SPL
+VAR_SIZE_PARAM = --vs
+else
+VAR_SIZE_PARAM =
+endif
 $(obj)$(BOARD)-spl.bin: $(obj)u-boot-spl.bin
-	$(OBJTREE)/tools/mk$(BOARD)spl $< $@
+	$(OBJTREE)/tools/mk$(BOARD)spl $(VAR_SIZE_PARAM) $< $@
 endif
 
 $(obj)$(SPL_BIN).bin:	$(obj)$(SPL_BIN)
diff --git a/tools/mkexynosspl.c b/tools/mkexynosspl.c
index ef685b7..32b786c 100644
--- a/tools/mkexynosspl.c
+++ b/tools/mkexynosspl.c
@@ -14,93 +14,174 @@
 #include <compiler.h>
 
 #define CHECKSUM_OFFSET		(14*1024-4)
-#define BUFSIZE			(14*1024)
 #define FILE_PERM		(S_IRUSR | S_IWUSR | S_IRGRP \
 				| S_IWGRP | S_IROTH | S_IWOTH)
 /*
-* Requirement:
-* IROM code reads first 14K bytes from boot device.
-* It then calculates the checksum of 14K-4 bytes and compare with data at
-* 14K-4 offset.
-*
-* This function takes two filenames:
-* IN  "u-boot-spl.bin" and
-* OUT "$(BOARD)-spl.bin as filenames.
-* It reads the "u-boot-spl.bin" in 16K buffer.
-* It calculates checksum of 14K-4 Bytes and stores at 14K-4 offset in buffer.
-* It writes the buffer to "$(BOARD)-spl.bin" file.
-*/
+ * Requirement for the fixed size SPL header:
+ * IROM code reads first (CHECKSUM_OFFSET + 4) bytes from boot device. It then
+ * calculates the checksum of CHECKSUM_OFFSET bytes and compares with data at
+ * CHECKSUM_OFFSET location.
+ *
+ * Requirement for the variable size SPL header:
+
+ * IROM code reads the below header to find out the size of the blob (total
+ * size, header size included) and its checksum. Then it reads the rest of the
+ * blob [i.e size - sizeof(struct var_size_header) bytes], calculates the
+ * checksum and compares it with value read from the header.
+ */
+struct var_size_header {
+	uint32_t spl_size;
+	uint32_t spl_checksum;
+	uint32_t reserved[2];
+};
+
+static const char *prog_name;
+
+static void write_to_file(int ofd, void *buffer, int size)
+{
+	if (write(ofd, buffer, size) == size)
+		return;
+
+	fprintf(stderr, "%s: Failed to write to output file: %s\n",
+		prog_name, strerror(errno));
+	exit(EXIT_FAILURE);
+}
 
+/*
+ * The argv is expected to include one optional parameter and two filenames:
+ * [--vs] IN OUT
+ *
+ * --vs - turns on the variable size SPL mode
+ * IN  - the u-boot SPL binary, usually u-boot-spl.bin
+ * OUT - the prepared SPL blob, usually ${BOARD}-spl.bin
+ *
+ * This utility first reads the "u-boot-spl.bin" into a buffer. In case of
+ * fixed size SPL the buffer size is exactly CHECKSUM_OFFSET (such that
+ * smaller u-boot-spl.bin gets padded with 0xff bytes, the larger than limit
+ * u-boot-spl.bin causes an error). For variable size SPL the buffer size is
+ * eqaul to size of the IN file.
+ *
+ * Then it calculates checksum of the buffer by just summing up all bytes.
+ * Then
+ *
+ * - for fixed size SPL the buffer is written into the output file and the
+ *   checksum is appended to the file in little endian format, which results
+ *   in checksum added exactly at CHECKSUM_OFFSET.
+ *
+ * - for variable size SPL the checksum and file size are stored in the
+ *   var_size_header structure (again, in little endian format) and the
+ *   structure is written into the output file. Then the buffer is written
+ *   into the output file.
+ */
 int main(int argc, char **argv)
 {
-	unsigned char buffer[BUFSIZE];
+	unsigned char *buffer;
 	int i, ifd, ofd;
 	uint32_t checksum = 0;
 	off_t	len;
-	ssize_t count;
+	int	var_size_flag, read_size, count;
 	struct stat stat;
-
-	if (argc != 3) {
-		fprintf(stderr, "Usage: %s <infile> <outfile>\n", argv[0]);
+	const int if_index = argc - 2; /* Input file name index in argv. */
+	const int of_index = argc - 1; /* Output file name index in argv. */
+
+	/* Strip path off the program name. */
+	prog_name = strrchr(argv[0], '/');
+	if (prog_name)
+		prog_name++;
+	else
+		prog_name = argv[0];
+
+	if ((argc < 3) ||
+	    (argc > 4) ||
+	    ((argc == 4) && strcmp(argv[1], "--vs"))) {
+		fprintf(stderr, "Usage: %s [--vs] <infile> <outfile>\n",
+			prog_name);
 		exit(EXIT_FAILURE);
 	}
 
-	ifd = open(argv[1], O_RDONLY);
+	/* four args mean variable size SPL wrapper is required */
+	var_size_flag = (argc == 4);
+
+	ifd = open(argv[if_index], O_RDONLY);
 	if (ifd < 0) {
 		fprintf(stderr, "%s: Can't open %s: %s\n",
-			argv[0], argv[1], strerror(errno));
+			prog_name, argv[if_index], strerror(errno));
 		exit(EXIT_FAILURE);
 	}
 
-	ofd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, FILE_PERM);
+	ofd = open(argv[of_index], O_WRONLY | O_CREAT | O_TRUNC, FILE_PERM);
 	if (ifd < 0) {
 		fprintf(stderr, "%s: Can't open %s: %s\n",
-			argv[0], argv[2], strerror(errno));
-		close(ifd);
+			prog_name, argv[of_index], strerror(errno));
 		exit(EXIT_FAILURE);
 	}
 
 	if (fstat(ifd, &stat)) {
 		fprintf(stderr, "%s: Unable to get size of %s: %s\n",
-			argv[0], argv[1], strerror(errno));
-		close(ifd);
-		close(ofd);
+			prog_name, argv[if_index], strerror(errno));
 		exit(EXIT_FAILURE);
 	}
 
 	len = stat.st_size;
 
-	count = (len < CHECKSUM_OFFSET) ? len : CHECKSUM_OFFSET;
-
-	if (read(ifd, buffer, count) != count) {
-		fprintf(stderr, "%s: Can't read %s: %s\n",
-			argv[0], argv[1], strerror(errno));
+	if (var_size_flag) {
+		read_size = len;
+		count = len;
+	} else {
+		if (len > CHECKSUM_OFFSET) {
+			fprintf(stderr,
+				"%s: %s is too big (exceeds %d bytes)\n",
+				prog_name, argv[if_index], CHECKSUM_OFFSET);
+			exit(EXIT_FAILURE);
+		}
+		count = CHECKSUM_OFFSET;
+		read_size = len;
+	}
 
-		close(ifd);
-		close(ofd);
+	buffer = malloc(count);
+	if (!buffer) {
+		fprintf(stderr,
+			"%s: Failed to allocate %d bytes to store %s\n",
+			prog_name, count, argv[if_index]);
+		exit(EXIT_FAILURE);
+	}
 
+	if (read(ifd, buffer, read_size) != read_size) {
+		fprintf(stderr, "%s: Can't read %s: %s\n",
+			prog_name, argv[if_index], strerror(errno));
 		exit(EXIT_FAILURE);
 	}
 
-	for (i = 0, checksum = 0; i < CHECKSUM_OFFSET; i++)
-		checksum += buffer[i];
+	/* Pad if needed with 0xff to make flashing faster. */
+	if (read_size < count)
+		memset((char *)buffer + read_size, 0xff, count - read_size);
 
+	for (i = 0, checksum = 0; i < count; i++)
+		checksum += buffer[i];
 	checksum = cpu_to_le32(checksum);
 
-	memcpy(&buffer[CHECKSUM_OFFSET], &checksum, sizeof(checksum));
-
-	if (write(ofd, buffer, BUFSIZE) != BUFSIZE) {
-		fprintf(stderr, "%s: Can't write %s: %s\n",
-			argv[0], argv[2], strerror(errno));
+	if (var_size_flag) {
+		/* Prepare and write out the variable size SPL header. */
+		struct var_size_header vsh;
+		uint32_t spl_size;
 
-		close(ifd);
-		close(ofd);
+		memset(&vsh, 0, sizeof(vsh));
+		memcpy(&vsh.spl_checksum, &checksum, sizeof(checksum));
 
-		exit(EXIT_FAILURE);
+		spl_size = cpu_to_le32(count + sizeof(struct var_size_header));
+		memcpy(&vsh.spl_size, &spl_size, sizeof(spl_size));
+		write_to_file(ofd, &vsh, sizeof(vsh));
 	}
 
+	write_to_file(ofd, buffer, count);
+
+	/* For fixed size SPL checksum is appended in the end. */
+	if (!var_size_flag)
+		write_to_file(ofd, &checksum, sizeof(checksum));
+
 	close(ifd);
 	close(ofd);
+	free(buffer);
 
 	return EXIT_SUCCESS;
 }