[PATCH v3 9/9] mtd: rawnand: sunxi: introduce maximize variable user data length

Richard Genoud posted 9 patches 2 weeks, 2 days ago
[PATCH v3 9/9] mtd: rawnand: sunxi: introduce maximize variable user data length
Posted by Richard Genoud 2 weeks, 2 days ago
In Allwinner SoCs, user data can be added in OOB before each ECC data.
For older SoCs like A10, the user data size was the size of a register
(4 bytes) and was mandatory before each ECC step.
So, the A10 OOB Layout is:
[4Bytes USER_DATA_STEP0] [ECC_STEP0 bytes]
[4bytes USER_DATA_STEP1] [ECC_STEP1 bytes]
...
NB: the BBM is stored at the beginning of the USER_DATA_STEP0.

Now, for H6/H616 NAND flash controller, this user data can have a
different size for each step.
So, we are maximizing the user data length to use as many OOB bytes as
possible.

Fixes: 88fd4e4deae8 ("mtd: rawnand: sunxi: Add support for H616 nand controller")
Signed-off-by: Richard Genoud <richard.genoud@bootlin.com>
---
 drivers/mtd/nand/raw/sunxi_nand.c | 321 ++++++++++++++++++++++++------
 1 file changed, 257 insertions(+), 64 deletions(-)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 3d2580d39e70..02647565c8ba 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -209,9 +209,8 @@
 
 /*
  * On A10/A23, this is the size of the NDFC User Data Register, containing the
- * mandatory user data bytes following the ECC for each ECC step.
+ * mandatory user data bytes preceding the ECC for each ECC step.
  * Thus, for each ECC step, we need the ECC bytes + USER_DATA_SZ.
- * Those bits are currently unsused, and kept as default value 0xffffffff.
  *
  * On H6/H616, this size became configurable, from 0 bytes to 32, via the
  * USER_DATA_LEN registers.
@@ -249,6 +248,7 @@ struct sunxi_nand_hw_ecc {
  * @timing_ctl: TIMING_CTL register value for this NAND chip
  * @nsels: number of CS lines required by the NAND chip
  * @sels: array of CS lines descriptions
+ * @user_data_bytes: array of user data lengths for all ECC steps
  */
 struct sunxi_nand_chip {
 	struct list_head node;
@@ -257,6 +257,7 @@ struct sunxi_nand_chip {
 	unsigned long clk_rate;
 	u32 timing_cfg;
 	u32 timing_ctl;
+	u8 *user_data_bytes;
 	int nsels;
 	struct sunxi_nand_chip_sel sels[] __counted_by(nsels);
 };
@@ -823,12 +824,50 @@ static inline u32 sunxi_nfc_buf_to_user_data(const u8 *buf)
 	return buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24);
 }
 
-static void sunxi_nfc_hw_ecc_get_prot_oob_bytes(struct nand_chip *nand, u8 *oob,
-						int step, bool bbm, int page)
+static u8 sunxi_nfc_user_data_sz(struct sunxi_nand_chip *sunxi_nand, int step)
 {
-	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	if (!sunxi_nand->user_data_bytes)
+		return USER_DATA_SZ;
 
-	sunxi_nfc_user_data_to_buf(readl(nfc->regs + NFC_REG_USER_DATA(nfc, step)), oob);
+	return sunxi_nand->user_data_bytes[step];
+}
+
+static void sunxi_nfc_hw_ecc_get_prot_oob_bytes(struct nand_chip *nand, u8 *oob,
+						int step, bool bbm, int page,
+						unsigned int user_data_sz)
+{
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	u32 user_data;
+
+	if (!nfc->caps->reg_user_data_len) {
+		/*
+		 * For A10, the user data for step n is in the nth
+		 * REG_USER_DATA
+		 */
+		user_data = readl(nfc->regs + NFC_REG_USER_DATA(nfc, step));
+		sunxi_nfc_user_data_to_buf(user_data, oob);
+	} else {
+		/*
+		 * For H6 NAND controller, the user data for all steps is
+		 * contained in 32 user data registers, but not at a specific
+		 * offset for each step, they are just concatenated.
+		 */
+		unsigned int user_data_off = 0;
+		unsigned int reg_off;
+		u8 *ptr = oob;
+		unsigned int i;
+
+		for (i = 0; i < step; i++)
+			user_data_off += sunxi_nfc_user_data_sz(sunxi_nand, i);
+
+		user_data_off /= 4;
+		for (i = 0; i < user_data_sz / 4; i++, ptr += 4) {
+			reg_off = NFC_REG_USER_DATA(nfc, user_data_off + i);
+			user_data = readl(nfc->regs + reg_off);
+			sunxi_nfc_user_data_to_buf(user_data, ptr);
+		}
+	}
 
 	/* De-randomize the Bad Block Marker. */
 	if (bbm && (nand->options & NAND_NEED_SCRAMBLING))
@@ -887,17 +926,46 @@ static void sunxi_nfc_hw_ecc_set_prot_oob_bytes(struct nand_chip *nand,
 						bool bbm, int page)
 {
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
-	u8 user_data[USER_DATA_SZ];
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, step);
+	u8 *user_data = NULL;
 
 	/* Randomize the Bad Block Marker. */
 	if (bbm && (nand->options & NAND_NEED_SCRAMBLING)) {
-		memcpy(user_data, oob, sizeof(user_data));
+		user_data = kmalloc(user_data_sz, GFP_KERNEL);
+		memcpy(user_data, oob, user_data_sz);
 		sunxi_nfc_randomize_bbm(nand, page, user_data);
 		oob = user_data;
 	}
 
-	writel(sunxi_nfc_buf_to_user_data(oob),
-	       nfc->regs + NFC_REG_USER_DATA(nfc, step));
+	if (!nfc->caps->reg_user_data_len) {
+		/*
+		 * For A10, the user data for step n is in the nth
+		 * REG_USER_DATA
+		 */
+		writel(sunxi_nfc_buf_to_user_data(oob),
+		       nfc->regs + NFC_REG_USER_DATA(nfc, step));
+	} else {
+		/*
+		 * For H6 NAND controller, the user data for all steps is
+		 * contained in 32 user data registers, but not at a specific
+		 * offset for each step, they are just concatenated.
+		 */
+		unsigned int user_data_off = 0;
+		const u8 *ptr = oob;
+		unsigned int i;
+
+		for (i = 0; i < step; i++)
+			user_data_off += sunxi_nfc_user_data_sz(sunxi_nand, i);
+
+		user_data_off /= 4;
+		for (i = 0; i < user_data_sz / 4; i++, ptr += 4) {
+			writel(sunxi_nfc_buf_to_user_data(ptr),
+			       nfc->regs + NFC_REG_USER_DATA(nfc, user_data_off + i));
+		}
+	}
+
+	kfree(user_data);
 }
 
 static void sunxi_nfc_hw_ecc_update_stats(struct nand_chip *nand,
@@ -918,6 +986,8 @@ static int sunxi_nfc_hw_ecc_correct(struct nand_chip *nand, u8 *data, u8 *oob,
 				    bool *erased)
 {
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, step);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	u32 tmp;
 
@@ -940,7 +1010,7 @@ static int sunxi_nfc_hw_ecc_correct(struct nand_chip *nand, u8 *data, u8 *oob,
 			memset(data, pattern, ecc->size);
 
 		if (oob)
-			memset(oob, pattern, ecc->bytes + USER_DATA_SZ);
+			memset(oob, pattern, ecc->bytes + user_data_sz);
 
 		return 0;
 	}
@@ -955,12 +1025,15 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 				       u8 *oob, int oob_off,
 				       int *cur_off,
 				       unsigned int *max_bitflips,
-				       bool bbm, bool oob_required, int page)
+				       int step, bool oob_required, int page)
 {
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, step);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	int raw_mode = 0;
 	u32 pattern_found;
+	bool bbm = !step;
 	bool erased;
 	int ret;
 	/* From the controller point of view, we are at step 0 */
@@ -978,8 +1051,7 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 	if (ret)
 		return ret;
 
-	sunxi_nfc_reset_user_data_len(nfc);
-	sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, nfc_step);
+	sunxi_nfc_set_user_data_len(nfc, user_data_sz, nfc_step);
 	sunxi_nfc_randomizer_config(nand, page, false);
 	sunxi_nfc_randomizer_enable(nand);
 	writel(NFC_DATA_TRANS | NFC_DATA_SWAP_METHOD | NFC_ECC_OP,
@@ -990,7 +1062,7 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 	if (ret)
 		return ret;
 
-	*cur_off = oob_off + ecc->bytes + USER_DATA_SZ;
+	*cur_off = oob_off + ecc->bytes + user_data_sz;
 
 	pattern_found = readl(nfc->regs + nfc->caps->reg_pat_found);
 	pattern_found = field_get(NFC_ECC_PAT_FOUND_MSK(nfc), pattern_found);
@@ -1014,10 +1086,10 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 				      ecc->size);
 
 		nand_change_read_column_op(nand, oob_off, oob,
-					   ecc->bytes + USER_DATA_SZ, false);
+					   ecc->bytes + user_data_sz, false);
 
 		ret = nand_check_erased_ecc_chunk(data,	ecc->size, oob,
-						  ecc->bytes + USER_DATA_SZ,
+						  ecc->bytes + user_data_sz,
 						  NULL, 0, ecc->strength);
 		if (ret >= 0)
 			raw_mode = 1;
@@ -1027,11 +1099,11 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 		if (oob_required) {
 			nand_change_read_column_op(nand, oob_off, NULL, 0,
 						   false);
-			sunxi_nfc_randomizer_read_buf(nand, oob, ecc->bytes + USER_DATA_SZ,
+			sunxi_nfc_randomizer_read_buf(nand, oob, ecc->bytes + user_data_sz,
 						      true, page);
 
 			sunxi_nfc_hw_ecc_get_prot_oob_bytes(nand, oob, nfc_step,
-							    bbm, page);
+							    bbm, page, user_data_sz);
 		}
 	}
 
@@ -1040,13 +1112,42 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 	return raw_mode;
 }
 
+/*
+ * Returns the offset of the OOB for each step.
+ * (it includes the user data before the ECC data.)
+ */
+static int sunxi_get_oob_offset(struct sunxi_nand_chip *sunxi_nand,
+				struct nand_ecc_ctrl *ecc, int step)
+{
+	int ecc_off = step * ecc->bytes;
+	int i;
+
+	for (i = 0; i < step; i++)
+		ecc_off += sunxi_nfc_user_data_sz(sunxi_nand, i);
+
+	return ecc_off;
+}
+
+/*
+ * Returns the offset of the ECC for each step.
+ * So, it's the same as sunxi_get_oob_offset(),
+ * but it skips the next user data.
+ */
+static int sunxi_get_ecc_offset(struct sunxi_nand_chip *sunxi_nand,
+				struct nand_ecc_ctrl *ecc, int step)
+{
+	return sunxi_get_oob_offset(sunxi_nand, ecc, step) +
+		sunxi_nfc_user_data_sz(sunxi_nand, step);
+}
+
 static void sunxi_nfc_hw_ecc_read_extra_oob(struct nand_chip *nand,
 					    u8 *oob, int *cur_off,
 					    bool randomize, int page)
 {
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
-	int offset = ((ecc->bytes + USER_DATA_SZ) * ecc->steps);
+	int offset = sunxi_get_oob_offset(sunxi_nand, ecc, ecc->steps);
 	int len = mtd->oobsize - offset;
 
 	if (len <= 0)
@@ -1071,6 +1172,7 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 					    int nchunks)
 {
 	bool randomized = nand->options & NAND_NEED_SCRAMBLING;
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
@@ -1090,7 +1192,8 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 
 	sunxi_nfc_hw_ecc_enable(nand);
 	sunxi_nfc_reset_user_data_len(nfc);
-	sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, 0);
+	for (i = 0; i < nchunks; i++)
+		sunxi_nfc_set_user_data_len(nfc, sunxi_nfc_user_data_sz(sunxi_nand, i), i);
 	sunxi_nfc_randomizer_config(nand, page, false);
 	sunxi_nfc_randomizer_enable(nand);
 
@@ -1125,7 +1228,8 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 
 	for (i = 0; i < nchunks; i++) {
 		int data_off = i * ecc->size;
-		int oob_off = i * (ecc->bytes + USER_DATA_SZ);
+		unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, i);
+		int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
 		u8 *data = buf + data_off;
 		u8 *oob = nand->oob_poi + oob_off;
 		bool erased;
@@ -1143,10 +1247,10 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 			/* TODO: use DMA to retrieve OOB */
 			nand_change_read_column_op(nand,
 						   mtd->writesize + oob_off,
-						   oob, ecc->bytes + USER_DATA_SZ, false);
+						   oob, ecc->bytes + user_data_sz, false);
 
-			sunxi_nfc_hw_ecc_get_prot_oob_bytes(nand, oob, i,
-							    !i, page);
+			sunxi_nfc_hw_ecc_get_prot_oob_bytes(nand, oob, i, !i,
+							    page, user_data_sz);
 		}
 
 		if (erased)
@@ -1158,7 +1262,8 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 	if (status & NFC_ECC_ERR_MSK(nfc)) {
 		for (i = 0; i < nchunks; i++) {
 			int data_off = i * ecc->size;
-			int oob_off = i * (ecc->bytes + USER_DATA_SZ);
+			unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, i);
+			int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
 			u8 *data = buf + data_off;
 			u8 *oob = nand->oob_poi + oob_off;
 
@@ -1178,10 +1283,10 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 			/* TODO: use DMA to retrieve OOB */
 			nand_change_read_column_op(nand,
 						   mtd->writesize + oob_off,
-						   oob, ecc->bytes + USER_DATA_SZ, false);
+						   oob, ecc->bytes + user_data_sz, false);
 
 			ret = nand_check_erased_ecc_chunk(data,	ecc->size, oob,
-							  ecc->bytes + USER_DATA_SZ,
+							  ecc->bytes + user_data_sz,
 							  NULL, 0,
 							  ecc->strength);
 			if (ret >= 0)
@@ -1202,11 +1307,14 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 static int sunxi_nfc_hw_ecc_write_chunk(struct nand_chip *nand,
 					const u8 *data, int data_off,
 					const u8 *oob, int oob_off,
-					int *cur_off, bool bbm,
+					int *cur_off, int step,
 					int page)
 {
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, step);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
+	bool bbm = !step;
 	int ret;
 	/* From the controller point of view, we are at step 0 */
 	const int nfc_step = 0;
@@ -1225,8 +1333,7 @@ static int sunxi_nfc_hw_ecc_write_chunk(struct nand_chip *nand,
 
 	sunxi_nfc_randomizer_config(nand, page, false);
 	sunxi_nfc_randomizer_enable(nand);
-	sunxi_nfc_reset_user_data_len(nfc);
-	sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, nfc_step);
+	sunxi_nfc_set_user_data_len(nfc, user_data_sz, nfc_step);
 	sunxi_nfc_hw_ecc_set_prot_oob_bytes(nand, oob, nfc_step, bbm, page);
 
 	writel(NFC_DATA_TRANS | NFC_DATA_SWAP_METHOD |
@@ -1238,7 +1345,7 @@ static int sunxi_nfc_hw_ecc_write_chunk(struct nand_chip *nand,
 	if (ret)
 		return ret;
 
-	*cur_off = oob_off + ecc->bytes + USER_DATA_SZ;
+	*cur_off = oob_off + ecc->bytes + user_data_sz;
 
 	return 0;
 }
@@ -1248,8 +1355,9 @@ static void sunxi_nfc_hw_ecc_write_extra_oob(struct nand_chip *nand,
 					     int page)
 {
 	struct mtd_info *mtd = nand_to_mtd(nand);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
-	int offset = ((ecc->bytes + USER_DATA_SZ) * ecc->steps);
+	int offset = sunxi_get_oob_offset(sunxi_nand, ecc, ecc->steps);
 	int len = mtd->oobsize - offset;
 
 	if (len <= 0)
@@ -1268,6 +1376,8 @@ static void sunxi_nfc_hw_ecc_write_extra_oob(struct nand_chip *nand,
 static int sunxi_nfc_hw_ecc_read_page(struct nand_chip *nand, uint8_t *buf,
 				      int oob_required, int page)
 {
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	unsigned int max_bitflips = 0;
@@ -1280,16 +1390,17 @@ static int sunxi_nfc_hw_ecc_read_page(struct nand_chip *nand, uint8_t *buf,
 
 	sunxi_nfc_hw_ecc_enable(nand);
 
+	sunxi_nfc_reset_user_data_len(nfc);
 	for (i = 0; i < ecc->steps; i++) {
 		int data_off = i * ecc->size;
-		int oob_off = i * (ecc->bytes + USER_DATA_SZ);
+		int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
 		u8 *data = buf + data_off;
 		u8 *oob = nand->oob_poi + oob_off;
 
 		ret = sunxi_nfc_hw_ecc_read_chunk(nand, data, data_off, oob,
 						  oob_off + mtd->writesize,
 						  &cur_off, &max_bitflips,
-						  !i, oob_required, page);
+						  i, oob_required, page);
 		if (ret < 0)
 			return ret;
 		else if (ret)
@@ -1327,6 +1438,8 @@ static int sunxi_nfc_hw_ecc_read_subpage(struct nand_chip *nand,
 					 u32 data_offs, u32 readlen,
 					 u8 *bufpoi, int page)
 {
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	int ret, i, cur_off = 0;
@@ -1338,17 +1451,18 @@ static int sunxi_nfc_hw_ecc_read_subpage(struct nand_chip *nand,
 
 	sunxi_nfc_hw_ecc_enable(nand);
 
+	sunxi_nfc_reset_user_data_len(nfc);
 	for (i = data_offs / ecc->size;
 	     i < DIV_ROUND_UP(data_offs + readlen, ecc->size); i++) {
 		int data_off = i * ecc->size;
-		int oob_off = i * (ecc->bytes + USER_DATA_SZ);
+		int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
 		u8 *data = bufpoi + data_off;
 		u8 *oob = nand->oob_poi + oob_off;
 
 		ret = sunxi_nfc_hw_ecc_read_chunk(nand, data, data_off,
 						  oob,
 						  oob_off + mtd->writesize,
-						  &cur_off, &max_bitflips, !i,
+						  &cur_off, &max_bitflips, i,
 						  false, page);
 		if (ret < 0)
 			return ret;
@@ -1383,6 +1497,8 @@ static int sunxi_nfc_hw_ecc_write_page(struct nand_chip *nand,
 				       const uint8_t *buf, int oob_required,
 				       int page)
 {
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	int ret, i, cur_off = 0;
@@ -1393,15 +1509,16 @@ static int sunxi_nfc_hw_ecc_write_page(struct nand_chip *nand,
 
 	sunxi_nfc_hw_ecc_enable(nand);
 
+	sunxi_nfc_reset_user_data_len(nfc);
 	for (i = 0; i < ecc->steps; i++) {
 		int data_off = i * ecc->size;
-		int oob_off = i * (ecc->bytes + USER_DATA_SZ);
+		int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
 		const u8 *data = buf + data_off;
 		const u8 *oob = nand->oob_poi + oob_off;
 
 		ret = sunxi_nfc_hw_ecc_write_chunk(nand, data, data_off, oob,
 						   oob_off + mtd->writesize,
-						   &cur_off, !i, page);
+						   &cur_off, i, page);
 		if (ret)
 			return ret;
 	}
@@ -1420,6 +1537,8 @@ static int sunxi_nfc_hw_ecc_write_subpage(struct nand_chip *nand,
 					  const u8 *buf, int oob_required,
 					  int page)
 {
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	int ret, i, cur_off = 0;
@@ -1430,16 +1549,17 @@ static int sunxi_nfc_hw_ecc_write_subpage(struct nand_chip *nand,
 
 	sunxi_nfc_hw_ecc_enable(nand);
 
+	sunxi_nfc_reset_user_data_len(nfc);
 	for (i = data_offs / ecc->size;
 	     i < DIV_ROUND_UP(data_offs + data_len, ecc->size); i++) {
 		int data_off = i * ecc->size;
-		int oob_off = i * (ecc->bytes + USER_DATA_SZ);
+		int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
 		const u8 *data = buf + data_off;
 		const u8 *oob = nand->oob_poi + oob_off;
 
 		ret = sunxi_nfc_hw_ecc_write_chunk(nand, data, data_off, oob,
 						   oob_off + mtd->writesize,
-						   &cur_off, !i, page);
+						   &cur_off, i, page);
 		if (ret)
 			return ret;
 	}
@@ -1455,6 +1575,7 @@ static int sunxi_nfc_hw_ecc_write_page_dma(struct nand_chip *nand,
 					   int page)
 {
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	struct scatterlist sg;
 	u32 wait;
@@ -1473,10 +1594,12 @@ static int sunxi_nfc_hw_ecc_write_page_dma(struct nand_chip *nand,
 
 	sunxi_nfc_reset_user_data_len(nfc);
 	for (i = 0; i < ecc->steps; i++) {
-		const u8 *oob = nand->oob_poi + (i * (ecc->bytes + USER_DATA_SZ));
+		unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, i);
+		int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
+		const u8 *oob = nand->oob_poi + oob_off;
 
 		sunxi_nfc_hw_ecc_set_prot_oob_bytes(nand, oob, i, !i, page);
-		sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, i);
+		sunxi_nfc_set_user_data_len(nfc, user_data_sz, i);
 	}
 
 	nand_prog_page_begin_op(nand, page, 0, NULL, 0);
@@ -1740,11 +1863,12 @@ static int sunxi_nand_ooblayout_ecc(struct mtd_info *mtd, int section,
 {
 	struct nand_chip *nand = mtd_to_nand(mtd);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 
 	if (section >= ecc->steps)
 		return -ERANGE;
 
-	oobregion->offset = section * (ecc->bytes + USER_DATA_SZ) + USER_DATA_SZ;
+	oobregion->offset = sunxi_get_ecc_offset(sunxi_nand, ecc, section);
 	oobregion->length = ecc->bytes;
 
 	return 0;
@@ -1755,6 +1879,8 @@ static int sunxi_nand_ooblayout_free(struct mtd_info *mtd, int section,
 {
 	struct nand_chip *nand = mtd_to_nand(mtd);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, section);
 
 	/*
 	 * The controller does not provide access to OOB bytes
@@ -1765,18 +1891,18 @@ static int sunxi_nand_ooblayout_free(struct mtd_info *mtd, int section,
 
 	/*
 	 * The first 2 bytes are used for BB markers, hence we
-	 * only have USER_DATA_SZ - 2 bytes available in the first user data
+	 * only have user_data_sz - 2 bytes available in the first user data
 	 * section.
 	 */
 	if (section == 0) {
 		oobregion->offset = 2;
-		oobregion->length = USER_DATA_SZ - 2;
+		oobregion->length = user_data_sz - 2;
 
 		return 0;
 	}
 
-	oobregion->offset = section * (ecc->bytes + USER_DATA_SZ);
-	oobregion->length = USER_DATA_SZ;
+	oobregion->offset = sunxi_get_ecc_offset(sunxi_nand, ecc, section);
+	oobregion->length = user_data_sz;
 
 	return 0;
 }
@@ -1786,6 +1912,43 @@ static const struct mtd_ooblayout_ops sunxi_nand_ooblayout_ops = {
 	.free = sunxi_nand_ooblayout_free,
 };
 
+static void sunxi_nand_detach_chip(struct nand_chip *nand)
+{
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+
+	devm_kfree(nfc->dev, sunxi_nand->user_data_bytes);
+	sunxi_nand->user_data_bytes = NULL;
+}
+
+static int sunxi_nfc_maximize_user_data(struct nand_chip *nand, uint32_t oobsize,
+					int ecc_bytes, int nsectors)
+{
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	const struct sunxi_nfc_caps *c = nfc->caps;
+	int remaining_bytes = oobsize - (ecc_bytes * nsectors);
+	int i, step;
+
+	sunxi_nand->user_data_bytes = devm_kzalloc(nfc->dev, nsectors,
+						   GFP_KERNEL);
+	if (!sunxi_nand->user_data_bytes)
+		return -ENOMEM;
+
+	for (step = 0; (step < nsectors) && (remaining_bytes > 0); step++) {
+		for (i = 0; i < c->nuser_data_tab; i++) {
+			if (c->user_data_len_tab[i] > remaining_bytes)
+				break;
+			sunxi_nand->user_data_bytes[step] = c->user_data_len_tab[i];
+		}
+		remaining_bytes -= sunxi_nand->user_data_bytes[step];
+		if (sunxi_nand->user_data_bytes[step] == 0)
+			break;
+	}
+
+	return 0;
+}
+
 static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 				       struct nand_ecc_ctrl *ecc,
 				       struct device_node *np)
@@ -1795,33 +1958,50 @@ static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 	const u8 *strengths = nfc->caps->ecc_strengths;
 	struct mtd_info *mtd = nand_to_mtd(nand);
 	struct nand_device *nanddev = mtd_to_nanddev(mtd);
+	int total_user_data_sz = 0;
 	int nsectors;
 	int ecc_mode;
 	int i;
 
 	if (nanddev->ecc.user_conf.flags & NAND_ECC_MAXIMIZE_STRENGTH) {
-		int bytes;
+		int bytes = mtd->oobsize;
 
 		ecc->size = 1024;
 		nsectors = mtd->writesize / ecc->size;
 
-		/*
-		 * The 2 BBM bytes should not be removed from the grand total,
-		 * because they are part of the USER_DATA_SZ.
-		 * But we can't modify that for older platform since it may
-		 * result in a stronger ECC at the end, and break the
-		 * compatibility.
-		 */
-		if (nfc->caps->legacy_max_strength)
-			bytes = (mtd->oobsize - 2) / nsectors;
-		else
-			bytes = mtd->oobsize / nsectors;
+		if (!nfc->caps->reg_user_data_len) {
+			/*
+			 * If there's a fixed user data length, subtract it before
+			 * computing the max ECC strength
+			 */
+
+			for (i = 0; i < nsectors; i++)
+				total_user_data_sz += sunxi_nfc_user_data_sz(sunxi_nand, i);
+
+			/*
+			 * The 2 BBM bytes should not be removed from the grand total,
+			 * because they are part of the USER_DATA_SZ.
+			 * But we can't modify that for older platform since it may
+			 * result in a stronger ECC at the end, and break the
+			 * compatibility.
+			 */
+			if (nfc->caps->legacy_max_strength)
+				bytes -= 2;
+
+			bytes -= total_user_data_sz;
+		} else {
+			/*
+			 * remove at least the BBM size before computing the
+			 * max ECC
+			 */
+			bytes -= 2;
+		}
 
 		/*
-		 * USER_DATA_SZ non-ECC bytes are added before each ECC bytes
-		 * section, they contain the 2 BBM bytes
+		 * Once all user data has been subtracted, the rest can be used
+		 * for ECC bytes
 		 */
-		bytes -= USER_DATA_SZ;
+		bytes /= nsectors;
 
 		/* and bytes has to be even. */
 		if (bytes % 2)
@@ -1874,7 +2054,19 @@ static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 
 	nsectors = mtd->writesize / ecc->size;
 
-	if (mtd->oobsize < ((ecc->bytes + USER_DATA_SZ) * nsectors))
+	/*
+	 * The rationale for variable data length is to prioritize maximum ECC
+	 * strength, and then use the remaining space for user data.
+	 */
+	if (nfc->caps->reg_user_data_len)
+		sunxi_nfc_maximize_user_data(nand, mtd->oobsize, ecc->bytes,
+					     nsectors);
+
+	if (total_user_data_sz == 0)
+		for (i = 0; i < nsectors; i++)
+			total_user_data_sz += sunxi_nfc_user_data_sz(sunxi_nand, i);
+
+	if (mtd->oobsize < (ecc->bytes * nsectors + total_user_data_sz))
 		return -EINVAL;
 
 	ecc->read_oob = sunxi_nfc_hw_ecc_read_oob;
@@ -2104,6 +2296,7 @@ static int sunxi_nfc_exec_op(struct nand_chip *nand,
 
 static const struct nand_controller_ops sunxi_nand_controller_ops = {
 	.attach_chip = sunxi_nand_attach_chip,
+	.detach_chip = sunxi_nand_detach_chip,
 	.setup_interface = sunxi_nfc_setup_interface,
 	.exec_op = sunxi_nfc_exec_op,
 };