mtd: nand: pxa3xx: Add support for 2048 bytes page size devices

This commit adds support for devices with 2048B page sizes and
4-bit ECC strength requirements. This is achieved by enabling the BCH
ECC engine, which provides a higher strength: 16-bit over 2048 bytes.

Additionally, add a proper ECC layout to model the controller's view
of the device (where 'U' means unused and 'B' is the bad block marker):

 ----------------------------------------------------
 | 2048B data | B | B | 30B spare | 30B ECC | U | U |
 ----------------------------------------------------

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
[Brian: updated with Ezequiel's patch description]
Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
index 31aae53..2a7a0b2 100644 (file)
--- a/drivers/mtd/nand/pxa3xx_nand.c
+++ b/drivers/mtd/nand/pxa3xx_nand.c
@@ -286,6 +286,16 @@ static struct nand_bbt_descr bbt_mirror_descr = {
        .pattern = bbt_mirror_pattern
 };
 
+static struct nand_ecclayout ecc_layout_2KB_bch4bit = {
+       .eccbytes = 32,
+       .eccpos = {
+               32, 33, 34, 35, 36, 37, 38, 39,
+               40, 41, 42, 43, 44, 45, 46, 47,
+               48, 49, 50, 51, 52, 53, 54, 55,
+               56, 57, 58, 59, 60, 61, 62, 63},
+       .oobfree = { {2, 30} }
+};
+
 static struct nand_ecclayout ecc_layout_4KB_bch4bit = {
        .eccbytes = 64,
        .eccpos = {
@@ -1360,6 +1370,17 @@ static int pxa_ecc_init(struct pxa3xx_nand_info *info,
         * Required ECC: 4-bit correction per 512 bytes
         * Select: 16-bit correction per 2048 bytes
         */
+       } else if (strength == 4 && ecc_stepsize == 512 && page_size == 2048) {
+               info->ecc_bch = 1;
+               info->chunk_size = 2048;
+               info->spare_size = 32;
+               info->ecc_size = 32;
+               ecc->mode = NAND_ECC_HW;
+               ecc->size = info->chunk_size;
+               ecc->layout = &ecc_layout_2KB_bch4bit;
+               ecc->strength = 16;
+               return 1;
+
        } else if (strength == 4 && ecc_stepsize == 512 && page_size == 4096) {
                info->ecc_bch = 1;
                info->chunk_size = 2048;