cmd: gpt: Add command to swap partition order

Adds a command called "gpt transpose" which will swap the order two
partition table entries in the GPT partition table (but leaves them
pointing to the same locations on disk).

This can be useful for swapping bootloaders in systems that use an A/B
partitioning scheme where the bootrom is hard coded to look for the
bootloader in a specific index in the GPT partition table.

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>

1 files changed, 43 insertions, 3 deletions

diff --git a/cmd/gpt.c b/cmd/gpt.c
index d5256035c3a..d4068ee63d1 100644
--- a/cmd/gpt.c
+++ b/cmd/gpt.c
@@ -856,8 +856,9 @@ static int do_rename_gpt_parts(struct blk_desc *dev_desc, char *subcomm,
 	u8 part_count = 0;
 	int partlistlen, ret, numparts = 0, partnum, i = 1, ctr1 = 0, ctr2 = 0;
 
-	if ((subcomm == NULL) || (name1 == NULL) || (name2 == NULL) ||
-	    (strcmp(subcomm, "swap") && (strcmp(subcomm, "rename"))))
+	if (!subcomm || !name1 || !name2 ||
+	    (strcmp(subcomm, "swap") && strcmp(subcomm, "rename") &&
+	     strcmp(subcomm, "transpose")))
 		return -EINVAL;
 
 	ret = get_disk_guid(dev_desc, disk_guid);
@@ -918,6 +919,41 @@ static int do_rename_gpt_parts(struct blk_desc *dev_desc, char *subcomm,
 			ret = -EINVAL;
 			goto out;
 		}
+	} else if (!strcmp(subcomm, "transpose")) {
+		int idx1, idx2;
+		struct disk_partition* first = NULL;
+		struct disk_partition* second= NULL;
+		struct disk_partition tmp_part;
+
+		idx1 = simple_strtoul(name1, NULL, 10);
+		idx2 = simple_strtoul(name2, NULL, 10);
+		if (idx1 == idx2) {
+			printf("Cannot swap partition with itself\n");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		list_for_each(pos, &disk_partitions) {
+			curr = list_entry(pos, struct disk_part, list);
+			if (curr->partnum == idx1)
+				first = &curr->gpt_part_info;
+			else if (curr->partnum == idx2)
+				second = &curr->gpt_part_info;
+		}
+		if (!first) {
+			printf("Illegal partition number %s\n", name1);
+			ret = -EINVAL;
+			goto out;
+		}
+		if (!second) {
+			printf("Illegal partition number %s\n", name2);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		tmp_part = *first;
+		*first = *second;
+		*second = tmp_part;
 	} else { /* rename */
 		if (strlen(name2) > PART_NAME_LEN) {
 			printf("Names longer than %d characters are truncated.\n", PART_NAME_LEN);
@@ -1121,7 +1157,8 @@ static int do_gpt(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 	} else if (strcmp(argv[1], "read") == 0) {
 		ret = do_get_gpt_info(blk_dev_desc, (argc == 5) ? argv[4] : NULL);
 	} else if ((strcmp(argv[1], "swap") == 0) ||
-		   (strcmp(argv[1], "rename") == 0)) {
+		   (strcmp(argv[1], "rename") == 0) ||
+		   (strcmp(argv[1], "transpose") == 0)) {
 		ret = do_rename_gpt_parts(blk_dev_desc, argv[1], argv[4], argv[5]);
 	} else if ((strcmp(argv[1], "set-bootable") == 0)) {
 		ret = gpt_set_bootable(blk_dev_desc, argv[4]);
@@ -1174,6 +1211,8 @@ U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt,
 	" gpt swap <interface> <dev> <name1> <name2>\n"
 	"    - change all partitions named name1 to name2\n"
 	"      and vice-versa\n"
+	" gpt transpose <interface> <dev> <part1> <part2>\n"
+	"    - Swap the order of the entries for part1 and part2 in the partition table\n"
 	" gpt rename <interface> <dev> <part> <name>\n"
 	"    - rename the specified partition\n"
 	" gpt set-bootable <interface> <dev> <list>\n"
@@ -1182,5 +1221,6 @@ U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt,
 	" gpt swap mmc 0 foo bar\n"
 	" gpt rename mmc 0 3 foo\n"
 	" gpt set-bootable mmc 0 boot_a,boot_b\n"
+	" gpt transpose mmc 0 1 2\n"
 #endif
 );