mtd: rawnand: fix ecc parameters for mt7622

According to the datasheet, mt7622 only has 5 ECC capabilities instead
of 7, and the decoding error register is arranged  as follows:
+------+---------+---------+---------+---------+
| Bits |  19:15  |  14:10  |   9:5   |   4:0   |
+------+---------+---------+---------+---------+
| Name | ERRNUM3 | ERRNUM2 | ERRNUM1 | ERRNUM0 |
+------+---------+---------+---------+---------+
This means err_mask should be 0x1f instead of 0x3f and the number of
bits shifted in mtk_ecc_get_stats should be 5 instead of 8.

This commit introduces err_shift for the difference in this register
and fix other existing parameters.

Public MT7622 reference manual can be found on [0] and the info this
commit is based on is from page 656 and page 660.

[0]: https://wiki.banana-pi.org/Banana_Pi_BPI-R64#Documents

Fixes: 98dea8d ("mtd: nand: mtk: Support MT7622 NAND flash controller.")
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220402160315.919094-1-gch981213@gmail.com

Author: 981213

drivers/mtd/nand/raw/mtk_ecc.c

@@ -43,6 +43,7 @@
 
 struct mtk_ecc_caps {
 	u32 err_mask;
+	u32 err_shift;
 	const u8 *ecc_strength;
 	const u32 *ecc_regs;
 	u8 num_ecc_strength;
@@ -76,7 +77,7 @@ static const u8 ecc_strength_mt2712[] = {
 };
 
 static const u8 ecc_strength_mt7622[] = {
-	4, 6, 8, 10, 12, 14, 16
+	4, 6, 8, 10, 12
 };
 
 enum mtk_ecc_regs {
@@ -221,7 +222,7 @@ void mtk_ecc_get_stats(struct mtk_ecc *ecc, struct mtk_ecc_stats *stats,
 	for (i = 0; i < sectors; i++) {
 		offset = (i >> 2) << 2;
 		err = readl(ecc->regs + ECC_DECENUM0 + offset);
-		err = err >> ((i % 4) * 8);
+		err = err >> ((i % 4) * ecc->caps->err_shift);
 		err &= ecc->caps->err_mask;
 		if (err == ecc->caps->err_mask) {
 			/* uncorrectable errors */
@@ -449,6 +450,7 @@ EXPORT_SYMBOL(mtk_ecc_get_parity_bits);
 
 static const struct mtk_ecc_caps mtk_ecc_caps_mt2701 = {
 	.err_mask = 0x3f,
+	.err_shift = 8,
 	.ecc_strength = ecc_strength_mt2701,
 	.ecc_regs = mt2701_ecc_regs,
 	.num_ecc_strength = 20,
@@ -459,6 +461,7 @@ static const struct mtk_ecc_caps mtk_ecc_caps_mt2701 = {
 
 static const struct mtk_ecc_caps mtk_ecc_caps_mt2712 = {
 	.err_mask = 0x7f,
+	.err_shift = 8,
 	.ecc_strength = ecc_strength_mt2712,
 	.ecc_regs = mt2712_ecc_regs,
 	.num_ecc_strength = 23,
@@ -468,10 +471,11 @@ static const struct mtk_ecc_caps mtk_ecc_caps_mt2712 = {
 };
 
 static const struct mtk_ecc_caps mtk_ecc_caps_mt7622 = {
-	.err_mask = 0x3f,
+	.err_mask = 0x1f,
+	.err_shift = 5,
 	.ecc_strength = ecc_strength_mt7622,
 	.ecc_regs = mt7622_ecc_regs,
-	.num_ecc_strength = 7,
+	.num_ecc_strength = 5,
 	.ecc_mode_shift = 4,
 	.parity_bits = 13,
 	.pg_irq_sel = 0,