VGV952CJW33: Add bad block table implementation.

This is based of the vendor implementation which uses
a proprietary bad block signature

bbt_pattern[] = {'A', 'R', 'C', 'A' };
mirror_pattern[] = {'a', 'c', 'r', 'a' };

instead of the upstream one:

bbt_pattern[] = {'B', 'b', 't', '0' }
mirror_pattern[] = {'1', 't', 'b', 'B' }

target/linux/lantiq/dts/VGV952CJW33.dts

@@ -172,6 +172,10 @@
 				#size-cells = <1>;
 				lantiq,cs = <1>;			// Seems to be needed (EASY80920NAND.dts)
 
+				nand-on-flash-bbt;
+				nand-ecc-strength = <3>;
+				nand-ecc-step-size = <256>;
+
 				partitions {
 					compatible = "fixed-partitions";
 					#address-cells = <1>;

target/linux/lantiq/patches-4.9/4052-NAND-add-easybox904-bbt.patch

@@ -0,0 +1,70 @@
+diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
+index 7695efe..6dd80a9 100644
+--- a/drivers/mtd/nand/nand_bbt.c
++++ b/drivers/mtd/nand/nand_bbt.c
+@@ -76,6 +76,13 @@
+ #define BBT_ENTRY_MASK		0x03
+ #define BBT_ENTRY_SHIFT		2
+
++#define CUSTOMIZED_BBT 1
++#if CUSTOMIZED_BBT /*ctc*/
++ #define	BAD_BLK_OOB_MARK_START	4
++ #define	BAD_BLK_OOB_MARK_END	5
++ #define	BAD_BLK_OOB_MARK_PATT	0xFF
++#endif
++
+ static int nand_update_bbt(struct mtd_info *mtd, loff_t offs);
+
+ static inline uint8_t bbt_get_entry(struct nand_chip *chip, int block)
+@@ -111,6 +118,10 @@ static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
+  */
+ static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
+ {
++#if CUSTOMIZED_BBT /*ctc*/
++	int i;
++	uint8_t *p = buf;
++#endif
+ 	if (td->options & NAND_BBT_NO_OOB)
+ 		return check_pattern_no_oob(buf, td);
+
+@@ -118,6 +129,13 @@ static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_desc
+ 	if (memcmp(buf + paglen + td->offs, td->pattern, td->len))
+ 		return -1;
+
++#if CUSTOMIZED_BBT /*ctc*/
++	for (i = BAD_BLK_OOB_MARK_START, p=buf+paglen; i <= BAD_BLK_OOB_MARK_END; i++) {
++		if (p[i] != BAD_BLK_OOB_MARK_PATT)
++			return -1;
++	}
++#endif
++
+ 	return 0;
+ }
+
+@@ -1277,8 +1295,13 @@ static int nand_update_bbt(struct mtd_info *mtd, loff_t offs)
+ static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
+
+ /* Generic flash bbt descriptors */
++#if CUSTOMIZED_BBT /*ctc*/
++static uint8_t bbt_pattern[] = {'A', 'R', 'C', 'A' };
++static uint8_t mirror_pattern[] = {'a', 'c', 'r', 'a' };
++#else
+ static uint8_t bbt_pattern[] = {'B', 'b', 't', '0' };
+ static uint8_t mirror_pattern[] = {'1', 't', 'b', 'B' };
++#endif
+
+ static struct nand_bbt_descr bbt_main_descr = {
+ 	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
+@@ -1340,7 +1363,12 @@ static int nand_create_badblock_pattern(struct nand_chip *this)
+ 	bd = kzalloc(sizeof(*bd), GFP_KERNEL);
+ 	if (!bd)
+ 		return -ENOMEM;
++
++#if CUSTOMIZED_BBT /*ctc*/
++	bd->options = 0 & BADBLOCK_SCAN_MASK;
++#else
+ 	bd->options = this->bbt_options & BADBLOCK_SCAN_MASK;
++#endif
+ 	bd->offs = this->badblockpos;
+ 	bd->len = (this->options & NAND_BUSWIDTH_16) ? 2 : 1;
+ 	bd->pattern = scan_ff_pattern;