[PATCH u-boot 2/4] cmd: mvebu/bubt: Validate EXT_CSD[179] eMMC register in mmc_burn_image()

["Pali Rohár" <pali@kernel.org>]

When determining eMMC boot partition for a bootloader, validate that
EXT_CSD[179] eMMC register is set to recognized value.

This prevent situation that EXT_CSD[179] Boot Enable value is improperly
parsed and passed into EXT_CSD[179] Partition Access.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 cmd/mvebu/bubt.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/cmd/mvebu/bubt.c b/cmd/mvebu/bubt.c
index ca24a5c1c4ba..b8fe7c7a1461 100644
--- a/cmd/mvebu/bubt.c
+++ b/cmd/mvebu/bubt.c
@@ -223,9 +223,29 @@ static int mmc_burn_image(size_t image_size)
 	orig_part = mmc->block_dev.hwpart;
 #endif
 
-	part = EXT_CSD_EXTRACT_BOOT_PART(mmc->part_config);
-	if (part == 7)
+	if (mmc->part_config == MMCPART_NOAVAILABLE) {
 		part = 0;
+	} else {
+		switch (EXT_CSD_EXTRACT_BOOT_PART(mmc->part_config)) {
+		case 0: /* Booting from this eMMC device is disabled */
+			printf("Error - Booting from this eMMC device is disabled\n");
+			printf("Hint: Use 'mmc partconf' command to choose boot partition\n");
+			return -ENODEV;
+		case 1: /* Boot partition 1 is used for booting */
+			part = 1;
+			break;
+		case 2: /* Boot partition 2 is used for booting */
+			part = 2;
+			break;
+		case 7: /* User area is used for booting */
+			part = 0;
+			break;
+		default: /* Other values are reserved / unsupported */
+			printf("Error - This eMMC device has configured Reserved boot option\n");
+			printf("Hint: Use 'mmc partconf' command to choose boot partition\n");
+			return -ENODEV;
+		}
+	}
 
 #ifdef CONFIG_BLK
 	err = blk_dselect_hwpart(blk_desc, part);
-- 
2.20.1