From 32c17dd886a5b506781b86c6227bb059ce33420b Mon Sep 17 00:00:00 2001
From: Tung Nguyen <tung.nguyen@amperecomputing.com>
Date: Sun, 5 Sep 2021 09:22:08 +0000
Subject: [PATCH] flashcp support offset option

The flashcp command from mtd-utils just support to flash from offset 0.
Add offset option to specify the start offset so that firmware can be
flashed correctly

Signed-off-by: Tung Nguyen <tung.nguyen@amperecomputing.com>
---
 misc-utils/flashcp.c | 50 +++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/misc-utils/flashcp.c b/misc-utils/flashcp.c
index 341c210..0a0e75b 100644
--- a/misc-utils/flashcp.c
+++ b/misc-utils/flashcp.c
@@ -91,7 +91,7 @@ static NORETURN void showusage(bool error)
 			"\n"
 			"Flash Copy - Written by Abraham van der Merwe <abraham@2d3d.co.za>\n"
 			"\n"
-			"usage: %1$s [ -v | --verbose | -A | --erase-all ] <filename> <device>\n"
+			"usage: %1$s [ -v | --verbose | -A | --erase-all ] <filename> <device> <offset>\n"
 			"       %1$s -h | --help\n"
 			"       %1$s -V | --version\n"
 			"\n"
@@ -102,6 +102,7 @@ static NORETURN void showusage(bool error)
 			"   -V | --version   Show version information and exit\n"
 			"   <filename>       File which you want to copy to flash\n"
 			"   <device>         Flash device to write to (e.g. /dev/mtd0, /dev/mtd1, etc.)\n"
+			"   <offset>         The start offset. Optional, default: 0\n"
 			"\n",
 			PROGRAM_NAME);
 
@@ -156,6 +157,16 @@ static void safe_rewind (int fd,const char *filename)
 	}
 }
 
+static int safe_rewind_offset(int fd, const char *filename, off_t offset)
+{
+	if (lseek(fd, offset, SEEK_SET) < 0) {
+		log_printf(LOG_ERROR, "While seeking to start of %s: %m\n", filename);
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}
+
 /******************************************************************************/
 
 static int dev_fd = -1,fil_fd = -1;
@@ -169,6 +180,8 @@ static void cleanup (void)
 int main (int argc,char *argv[])
 {
 	const char *filename = NULL,*device = NULL;
+	off_t offset;
+
 	int i,flags = FLAG_NONE;
 	ssize_t result;
 	size_t size,written;
@@ -225,6 +238,20 @@ int main (int argc,char *argv[])
 				showusage(true);
 		}
 	}
+
+	if (optind + 3 == argc) {
+		flags |= FLAG_FILENAME;
+		filename = argv[optind];
+		DEBUG("Got filename: %s\n", filename);
+
+		flags |= FLAG_DEVICE;
+		device = argv[optind + 1];
+		DEBUG("Got device: %s\n", device);
+
+		offset = strtoul(argv[optind + 2], NULL, 16);
+		DEBUG("Got offset: 0x%x\n", offset);
+	}
+
 	if (optind+2 == argc) {
 		flags |= FLAG_FILENAME;
 		filename = argv[optind];
@@ -233,6 +260,8 @@ int main (int argc,char *argv[])
 		flags |= FLAG_DEVICE;
 		device = argv[optind+1];
 		DEBUG("Got device: %s\n",device);
+
+		offset = 0;
 	}
 
 	if (flags & FLAG_HELP || device == NULL)
@@ -264,6 +293,12 @@ int main (int argc,char *argv[])
 		exit (EXIT_FAILURE);
 	}
 
+	/* does offset is out of the mtd */
+	if (offset > mtd.size) {
+		log_printf(LOG_ERROR, "%s offset won't fit into %s!\n", offset, device);
+		exit(EXIT_FAILURE);
+	}
+
 	/* diff block flashcp */
 	if (flags & FLAG_PARTITION)
 	{
@@ -284,6 +319,8 @@ int main (int argc,char *argv[])
 	}
 	else
 	{
+		/* Erase from the offset */
+		erase.start = offset;
 		erase.length = (filestat.st_size + mtd.erasesize - 1) / mtd.erasesize;
 		erase.length *= mtd.erasesize;
 	}
@@ -330,6 +367,12 @@ int main (int argc,char *argv[])
 	size = filestat.st_size;
 	i = BUFSIZE;
 	written = 0;
+
+	/* if offset is greater than 0 */
+	if (offset)
+		if (safe_rewind_offset(dev_fd, device, offset) != EXIT_SUCCESS)
+			return EXIT_FAILURE;
+
 	while (size)
 	{
 		if (size < BUFSIZE) i = size;
@@ -374,8 +417,9 @@ int main (int argc,char *argv[])
 	 * verify that flash == file data *
 	 **********************************/
 
-	safe_rewind (fil_fd,filename);
-	safe_rewind (dev_fd,device);
+	safe_rewind(fil_fd, filename);
+	safe_rewind_offset(dev_fd, device, offset);
+
 	size = filestat.st_size;
 	i = BUFSIZE;
 	written = 0;
-- 
2.25.1