mtd: rawnand: omap: Add larger page NAND chips support

There is no reason to be limited to 4kiB page NAND chips just because
this is the maximum length the ELM is able to handle in one go. Just
call the ELM several times and it will process as many data as needed.

Here we introduce the concept of ECC page (which is at most 4kiB). The
ELM will be sought as many times as there are ECC pages.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Ryan Barnett <ryan.barnett@collins.com>
Link: https://lore.kernel.org/linux-mtd/20210610134906.3503303-6-miquel.raynal@bootlin.com

2 files changed, 116 insertions, 69 deletions

diff --git a/drivers/mtd/nand/raw/omap2.c b/drivers/mtd/nand/raw/omap2.c
index 3d5a421a6b5c..b1839eef5b65 100644
--- a/drivers/mtd/nand/raw/omap2.c
+++ b/drivers/mtd/nand/raw/omap2.c
@@ -171,6 +171,10 @@ struct omap_nand_info {
 	struct device			*elm_dev;
 	/* NAND ready gpio */
 	struct gpio_desc		*ready_gpiod;
+	unsigned int			neccpg;
+	unsigned int			nsteps_per_eccpg;
+	unsigned int			eccpg_size;
+	unsigned int			eccpg_bytes;
 };
 
 static inline struct omap_nand_info *mtd_to_omap(struct mtd_info *mtd)
@@ -1355,7 +1359,7 @@ static int omap_elm_correct_data(struct nand_chip *chip, u_char *data,
 {
 	struct omap_nand_info *info = mtd_to_omap(nand_to_mtd(chip));
 	struct nand_ecc_ctrl *ecc = &info->nand.ecc;
-	int eccsteps = info->nand.ecc.steps;
+	int eccsteps = info->nsteps_per_eccpg;
 	int i , j, stat = 0;
 	int eccflag, actual_eccbytes;
 	struct elm_errorvec err_vec[ERROR_VECTOR_MAX];
@@ -1525,28 +1529,37 @@ static int omap_write_page_bch(struct nand_chip *chip, const uint8_t *buf,
 			       int oob_required, int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct omap_nand_info *info = mtd_to_omap(mtd);
 	uint8_t *ecc_calc = chip->ecc.calc_buf;
+	unsigned int eccpg;
 	int ret;
 
 	ret = nand_prog_page_begin_op(chip, page, 0, NULL, 0);
 	if (ret)
 		return ret;
 
-	/* Enable GPMC ecc engine */
-	chip->ecc.hwctl(chip, NAND_ECC_WRITE);
+	for (eccpg = 0; eccpg < info->neccpg; eccpg++) {
+		/* Enable GPMC ecc engine */
+		chip->ecc.hwctl(chip, NAND_ECC_WRITE);
 
-	/* Write data */
-	chip->legacy.write_buf(chip, buf, mtd->writesize);
+		/* Write data */
+		chip->legacy.write_buf(chip, buf + (eccpg * info->eccpg_size),
+				       info->eccpg_size);
 
-	/* Update ecc vector from GPMC result registers */
-	ret = omap_calculate_ecc_bch_multi(mtd, buf, &ecc_calc[0]);
-	if (ret)
-		return ret;
+		/* Update ecc vector from GPMC result registers */
+		ret = omap_calculate_ecc_bch_multi(mtd,
+						   buf + (eccpg * info->eccpg_size),
+						   ecc_calc);
+		if (ret)
+			return ret;
 
-	ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
-					 chip->ecc.total);
-	if (ret)
-		return ret;
+		ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc,
+						 chip->oob_poi,
+						 eccpg * info->eccpg_bytes,
+						 info->eccpg_bytes);
+		if (ret)
+			return ret;
+	}
 
 	/* Write ecc vector to OOB area */
 	chip->legacy.write_buf(chip, chip->oob_poi, mtd->oobsize);
@@ -1570,12 +1583,13 @@ static int omap_write_subpage_bch(struct nand_chip *chip, u32 offset,
 				  int oob_required, int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct omap_nand_info *info = mtd_to_omap(mtd);
 	u8 *ecc_calc = chip->ecc.calc_buf;
 	int ecc_size      = chip->ecc.size;
 	int ecc_bytes     = chip->ecc.bytes;
-	int ecc_steps     = chip->ecc.steps;
 	u32 start_step = offset / ecc_size;
 	u32 end_step   = (offset + data_len - 1) / ecc_size;
+	unsigned int eccpg;
 	int step, ret = 0;
 
 	/*
@@ -1588,36 +1602,44 @@ static int omap_write_subpage_bch(struct nand_chip *chip, u32 offset,
 	if (ret)
 		return ret;
 
-	/* Enable GPMC ECC engine */
-	chip->ecc.hwctl(chip, NAND_ECC_WRITE);
-
-	/* Write data */
-	chip->legacy.write_buf(chip, buf, mtd->writesize);
-
-	for (step = 0; step < ecc_steps; step++) {
-		/* Mask ECC of un-touched subpages with 0xFFs */
-		if (step < start_step || step > end_step)
-			memset(ecc_calc, 0xff, ecc_bytes);
-		else
-			ret = _omap_calculate_ecc_bch(mtd, buf, ecc_calc, step);
+	for (eccpg = 0; eccpg < info->neccpg; eccpg++) {
+		/* Enable GPMC ECC engine */
+		chip->ecc.hwctl(chip, NAND_ECC_WRITE);
+
+		/* Write data */
+		chip->legacy.write_buf(chip, buf + (eccpg * info->eccpg_size),
+				       info->eccpg_size);
+
+		for (step = 0; step < info->nsteps_per_eccpg; step++) {
+			unsigned int base_step = eccpg * info->nsteps_per_eccpg;
+			const u8 *bufoffs = buf + (eccpg * info->eccpg_size);
+
+			/* Mask ECC of un-touched subpages with 0xFFs */
+			if ((step + base_step) < start_step ||
+			    (step + base_step) > end_step)
+				memset(ecc_calc + (step * ecc_bytes), 0xff,
+				       ecc_bytes);
+			else
+				ret = _omap_calculate_ecc_bch(mtd,
+							      bufoffs + (step * ecc_size),
+							      ecc_calc + (step * ecc_bytes),
+							      step);
+
+			if (ret)
+				return ret;
+		}
 
+		/*
+		 * Copy the calculated ECC for the whole page including the
+		 * masked values (0xFF) corresponding to unwritten subpages.
+		 */
+		ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi,
+						 eccpg * info->eccpg_bytes,
+						 info->eccpg_bytes);
 		if (ret)
 			return ret;
-
-		buf += ecc_size;
-		ecc_calc += ecc_bytes;
 	}
 
-	/*
-	 * Copy the calculated ECC for the whole page including the
-	 * masked values (0xFF) corresponding to unwritten subpages.
-	 */
-	ecc_calc = chip->ecc.calc_buf;
-	ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
-					 chip->ecc.total);
-	if (ret)
-		return ret;
-
 	/* write OOB buffer to NAND device */
 	chip->legacy.write_buf(chip, chip->oob_poi, mtd->oobsize);
 
@@ -1642,46 +1664,60 @@ static int omap_read_page_bch(struct nand_chip *chip, uint8_t *buf,
 			      int oob_required, int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct omap_nand_info *info = mtd_to_omap(mtd);
 	uint8_t *ecc_calc = chip->ecc.calc_buf;
 	uint8_t *ecc_code = chip->ecc.code_buf;
-	unsigned int max_bitflips = 0;
+	unsigned int max_bitflips = 0, eccpg;
 	int stat, ret;
 
 	ret = nand_read_page_op(chip, page, 0, NULL, 0);
 	if (ret)
 		return ret;
 
-	/* Enable GPMC ecc engine */
-	chip->ecc.hwctl(chip, NAND_ECC_READ);
-
-	/* Read data */
-	chip->legacy.read_buf(chip, buf, mtd->writesize);
+	for (eccpg = 0; eccpg < info->neccpg; eccpg++) {
+		/* Enable GPMC ecc engine */
+		chip->ecc.hwctl(chip, NAND_ECC_READ);
 
-	/* Read oob bytes */
-	ret = nand_change_read_column_op(chip,
-					 mtd->writesize + BBM_LEN,
-					 chip->oob_poi + BBM_LEN,
-					 chip->ecc.total, false);
-	if (ret)
-		return ret;
+		/* Read data */
+		ret = nand_change_read_column_op(chip, eccpg * info->eccpg_size,
+						 buf + (eccpg * info->eccpg_size),
+						 info->eccpg_size, false);
+		if (ret)
+			return ret;
 
-	/* Calculate ecc bytes */
-	ret = omap_calculate_ecc_bch_multi(mtd, buf, ecc_calc);
-	if (ret)
-		return ret;
+		/* Read oob bytes */
+		ret = nand_change_read_column_op(chip,
+						 mtd->writesize + BBM_LEN +
+						 (eccpg * info->eccpg_bytes),
+						 chip->oob_poi + BBM_LEN +
+						 (eccpg * info->eccpg_bytes),
+						 info->eccpg_bytes, false);
+		if (ret)
+			return ret;
 
-	ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
-					 chip->ecc.total);
-	if (ret)
-		return ret;
+		/* Calculate ecc bytes */
+		ret = omap_calculate_ecc_bch_multi(mtd,
+						   buf + (eccpg * info->eccpg_size),
+						   ecc_calc);
+		if (ret)
+			return ret;
 
-	stat = chip->ecc.correct(chip, buf, ecc_code, ecc_calc);
+		ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code,
+						 chip->oob_poi,
+						 eccpg * info->eccpg_bytes,
+						 info->eccpg_bytes);
+		if (ret)
+			return ret;
 
-	if (stat < 0) {
-		mtd->ecc_stats.failed++;
-	} else {
-		mtd->ecc_stats.corrected += stat;
-		max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		stat = chip->ecc.correct(chip,
+					 buf + (eccpg * info->eccpg_size),
+					 ecc_code, ecc_calc);
+		if (stat < 0) {
+			mtd->ecc_stats.failed++;
+		} else {
+			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 	}
 
 	return max_bitflips;
@@ -2150,9 +2186,20 @@ static int omap_nand_attach_chip(struct nand_chip *chip)
 	}
 
 	if (elm_bch_strength >= 0) {
+		chip->ecc.steps = mtd->writesize / chip->ecc.size;
+		info->neccpg = chip->ecc.steps / ERROR_VECTOR_MAX;
+		if (info->neccpg) {
+			info->nsteps_per_eccpg = ERROR_VECTOR_MAX;
+		} else {
+			info->neccpg = 1;
+			info->nsteps_per_eccpg = chip->ecc.steps;
+		}
+		info->eccpg_size = info->nsteps_per_eccpg * chip->ecc.size;
+		info->eccpg_bytes = info->nsteps_per_eccpg * chip->ecc.bytes;
+
 		err = elm_config(info->elm_dev, elm_bch_strength,
-				 mtd->writesize / chip->ecc.size,
-				 chip->ecc.size, chip->ecc.bytes);
+				 info->nsteps_per_eccpg, chip->ecc.size,
+				 chip->ecc.bytes);
 		if (err < 0)
 			return err;
 	}
diff --git a/drivers/mtd/nand/raw/omap_elm.c b/drivers/mtd/nand/raw/omap_elm.c
index 550695a4c1ab..2b21ce04b3ec 100644
--- a/drivers/mtd/nand/raw/omap_elm.c
+++ b/drivers/mtd/nand/raw/omap_elm.c
@@ -116,7 +116,7 @@ int elm_config(struct device *dev, enum bch_ecc bch_type,
 		return -EINVAL;
 	}
 	/* ELM support 8 error syndrome process */
-	if (ecc_steps > ERROR_VECTOR_MAX) {
+	if (ecc_steps > ERROR_VECTOR_MAX && ecc_steps % ERROR_VECTOR_MAX) {
 		dev_err(dev, "unsupported config ecc-step=%d\n", ecc_steps);
 		return -EINVAL;
 	}