mtd: rawnand: cadence: get meta data size from registers

Add checking size of BCH meta data size in capabilities registers
instead of using fixed value. BCH meta data is used to keep data
from NAND flash OOB area.
Signed-off-by: Piotr Sroka <piotrs@cadence.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1581328530-29966-1-git-send-email-piotrs@cadence.com

drivers/mtd/nand/raw/cadence-nand-controller.c

@@ -30,7 +30,6 @@
  * Generic mode is used for executing rest of commands.
  */
 
-#define MAX_OOB_SIZE_PER_SECTOR	32
 #define MAX_ADDRESS_CYC		6
 #define MAX_ERASE_ADDRESS_CYC	3
 #define MAX_DATA_SIZE		0xFFFC
@@ -190,6 +189,7 @@
 
 /* BCH Engine identification register 3. */
 #define BCH_CFG_3				0x844
+#define		BCH_CFG_3_METADATA_SIZE		GENMASK(23, 16)
 
 /* Ready/Busy# line status. */
 #define RBN_SETINGS				0x1004
@@ -499,6 +499,7 @@ struct cdns_nand_ctrl {
 
 	unsigned long assigned_cs;
 	struct list_head chips;
+	u8 bch_metadata_size;
 };
 
 struct cdns_nand_chip {
@@ -1077,6 +1078,14 @@ static int cadence_nand_read_bch_caps(struct cdns_nand_ctrl *cdns_ctrl)
 	int max_step_size = 0, nstrengths, i;
 	u32 reg;
 
+	reg = readl_relaxed(cdns_ctrl->reg + BCH_CFG_3);
+	cdns_ctrl->bch_metadata_size = FIELD_GET(BCH_CFG_3_METADATA_SIZE, reg);
+	if (cdns_ctrl->bch_metadata_size < 4) {
+		dev_err(cdns_ctrl->dev,
+			"Driver needs at least 4 bytes of BCH meta data\n");
+		return -EIO;
+	}
+
 	reg = readl_relaxed(cdns_ctrl->reg + BCH_CFG_0);
 	cdns_ctrl->ecc_strengths[0] = FIELD_GET(BCH_CFG_0_CORR_CAP_0, reg);
 	cdns_ctrl->ecc_strengths[1] = FIELD_GET(BCH_CFG_0_CORR_CAP_1, reg);
@@ -1170,7 +1179,8 @@ static int cadence_nand_hw_init(struct cdns_nand_ctrl *cdns_ctrl)
 	writel_relaxed(0xFFFFFFFF, cdns_ctrl->reg + INTR_STATUS);
 
 	cadence_nand_get_caps(cdns_ctrl);
-	cadence_nand_read_bch_caps(cdns_ctrl);
+	if (cadence_nand_read_bch_caps(cdns_ctrl))
+		return -EIO;
 
 	/*
 	 * Set IO width access to 8.
@@ -2587,7 +2597,6 @@ int cadence_nand_attach_chip(struct nand_chip *chip)
 	struct cdns_nand_chip *cdns_chip = to_cdns_nand_chip(chip);
 	u32 ecc_size = cdns_chip->sector_count * chip->ecc.bytes;
 	struct mtd_info *mtd = nand_to_mtd(chip);
-	u32 max_oob_data_size;
 	int ret;
 
 	if (chip->options & NAND_BUSWIDTH_16) {
@@ -2628,10 +2637,8 @@ int cadence_nand_attach_chip(struct nand_chip *chip)
 
 	cdns_chip->avail_oob_size = mtd->oobsize - ecc_size;
 
-	max_oob_data_size = MAX_OOB_SIZE_PER_SECTOR;
-
-	if (cdns_chip->avail_oob_size > max_oob_data_size)
-		cdns_chip->avail_oob_size = max_oob_data_size;
+	if (cdns_chip->avail_oob_size > cdns_ctrl->bch_metadata_size)
+		cdns_chip->avail_oob_size = cdns_ctrl->bch_metadata_size;
 
 	if ((cdns_chip->avail_oob_size + cdns_chip->bbm_len + ecc_size)
 	    > mtd->oobsize)