mmc: core: production year for eMMC 4.41 and later

The field containing the production date in the CID register only uses
4 bits to encode the year, starting from 1997 in the original standard.
In 2013, the production year field contains 0, and the kernel reports a
1997 production date.

The eMMC 4.51 specification adds a new interpretation rule. For all
devices implementing the 4.41 specification or later, the production
year field will be interpreted as a value between 2010 and 2025, with
0 corresponding to 2013.
Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/mmc.c

@@ -482,6 +482,10 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
 	}
 
 	if (card->ext_csd.rev >= 5) {
+		/* Adjust production date as per JEDEC JESD84-B451 */
+		if (card->cid.year < 2010)
+			card->cid.year += 16;
+
 		/* check whether the eMMC card supports BKOPS */
 		if (ext_csd[EXT_CSD_BKOPS_SUPPORT] & 0x1) {
 			card->ext_csd.bkops = 1;