[PATCH] mtd: nand: Support controllers with custom page accessors

[Marc Gonzalez <marc_gonzalez@sigmadesigns.com>]

If your controller already sends the required NAND commands when
reading or writing a page, then the framework is not supposed to
send READ0 and SEQIN/PAGEPROG respectively.

Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
---
 drivers/mtd/nand/nand_base.c  | 31 ++++++++++++++++++++++++++++---
 drivers/mtd/nand/tango_nand.c | 21 ++++++++++++---------
 include/linux/mtd/nand.h      | 12 ++++++++++++
 3 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 50cdf37cb8e4..b8ea6b397c16 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1970,7 +1970,8 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 						 __func__, buf);
 
 read_retry:
-			chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
+			if (nand_default_page_accessors(&chip->ecc))
+				chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
 
 			/*
 			 * Now read the page into the buffer.  Absent an error,
@@ -2658,7 +2659,8 @@ static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
 	else
 		subpage = 0;
 
-	chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page);
+	if (nand_default_page_accessors(&chip->ecc))
+		chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page);
 
 	if (unlikely(raw))
 		status = chip->ecc.write_page_raw(mtd, chip, buf,
@@ -2681,7 +2683,8 @@ static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
 
 	if (!cached || !NAND_HAS_CACHEPROG(chip)) {
 
-		chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+		if (nand_default_page_accessors(&chip->ecc))
+			chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
 		status = chip->waitfunc(mtd, chip);
 		/*
 		 * See if operation failed and additional status checks are
@@ -4539,6 +4542,25 @@ static bool nand_ecc_strength_good(struct mtd_info *mtd)
 	return corr >= ds_corr && ecc->strength >= chip->ecc_strength_ds;
 }
 
+static bool invalid_ecc_page_accessors(struct nand_chip *chip)
+{
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+
+	if (nand_default_page_accessors(ecc))
+		return false;
+
+	/*
+	 * NAND_ECC_CUSTOM_PAGE_ACCESS flag is set, make sure the NAND
+	 * controller driver implements all the page accessors because
+	 * default helpers are not suitable when the core does not
+	 * send the READ0/PAGEPROG commands.
+	 */
+	return (!ecc->read_page || !ecc->write_page ||
+		!ecc->read_page_raw || !ecc->write_page_raw ||
+		(NAND_HAS_SUBPAGE_READ(chip) && !ecc->read_subpage) ||
+		(NAND_HAS_SUBPAGE_WRITE(chip) && !ecc->write_subpage));
+}
+
 /**
  * nand_scan_tail - [NAND Interface] Scan for the NAND device
  * @mtd: MTD device structure
@@ -4559,6 +4581,9 @@ int nand_scan_tail(struct mtd_info *mtd)
 		   !(chip->bbt_options & NAND_BBT_USE_FLASH)))
 		return -EINVAL;
 
+	if (WARN_ON(invalid_ecc_page_accessors(chip)))
+		return -EINVAL;
+
 	if (!(chip->options & NAND_OWN_BUFFERS)) {
 		nbuf = kzalloc(sizeof(*nbuf) + mtd->writesize
 				+ mtd->oobsize * 3, GFP_KERNEL);
diff --git a/drivers/mtd/nand/tango_nand.c b/drivers/mtd/nand/tango_nand.c
index fd8cf414cb2b..7ed35348993e 100644
--- a/drivers/mtd/nand/tango_nand.c
+++ b/drivers/mtd/nand/tango_nand.c
@@ -343,7 +343,7 @@ static void aux_write(struct nand_chip *chip, const u8 **buf, int len, int *pos)
  * buf = |      PKT_0      | ... |      PKT_N      |
  *       +-----------------+-----+-----------------+
  */
-static int raw_read(struct nand_chip *chip, u8 *buf, u8 *oob)
+static void raw_read(struct nand_chip *chip, u8 *buf, u8 *oob)
 {
 	u8 *oob_orig = oob;
 	const int page_size = chip->mtd.writesize;
@@ -367,11 +367,9 @@ static int raw_read(struct nand_chip *chip, u8 *buf, u8 *oob)
 	aux_read(chip, &oob_orig, BBM_SIZE, &pos);
 	aux_read(chip, &buf, pkt_size - rem, &pos);
 	aux_read(chip, &oob, ecc_size, &pos);
-
-	return 0;
 }
 
-static int raw_write(struct nand_chip *chip, const u8 *buf, const u8 *oob)
+static void raw_write(struct nand_chip *chip, const u8 *buf, const u8 *oob)
 {
 	const u8 *oob_orig = oob;
 	const int page_size = chip->mtd.writesize;
@@ -395,27 +393,31 @@ static int raw_write(struct nand_chip *chip, const u8 *buf, const u8 *oob)
 	aux_write(chip, &oob_orig, BBM_SIZE, &pos);
 	aux_write(chip, &buf, pkt_size - rem, &pos);
 	aux_write(chip, &oob, ecc_size, &pos);
-
-	return 0;
 }
 
 static int tango_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
 			       u8 *buf, int oob_required, int page)
 {
-	return raw_read(chip, buf, chip->oob_poi);
+	chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
+	raw_read(chip, buf, chip->oob_poi);
+	return 0;
 }
 
 static int tango_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
 				const u8 *buf, int oob_required, int page)
 {
-	return raw_write(chip, buf, chip->oob_poi);
+	chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0, page);
+	raw_write(chip, buf, chip->oob_poi);
+	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+	return 0;
 }
 
 static int tango_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
 			  int page)
 {
 	chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
-	return raw_read(chip, NULL, chip->oob_poi);
+	raw_read(chip, NULL, chip->oob_poi);
+	return 0;
 }
 
 static int tango_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
@@ -553,6 +555,7 @@ static int chip_init(struct device *dev, struct device_node *np)
 	ecc->write_page = tango_write_page;
 	ecc->read_oob = tango_read_oob;
 	ecc->write_oob = tango_write_oob;
+	ecc->options = NAND_ECC_CUSTOM_PAGE_ACCESS;
 
 	err = nand_scan_tail(mtd);
 	if (err)
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 06d0c9d740f7..a95a27a30005 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -142,6 +142,12 @@ enum nand_ecc_algo {
  */
 #define NAND_ECC_GENERIC_ERASED_CHECK	BIT(0)
 #define NAND_ECC_MAXIMIZE		BIT(1)
+/*
+ * If your controller already sends the required NAND commands when
+ * reading or writing a page, then the framework is not supposed to
+ * send READ0 and SEQIN/PAGEPROG respectively.
+ */
+#define NAND_ECC_CUSTOM_PAGE_ACCESS	BIT(2)
 
 /* Bit mask for flags passed to do_nand_read_ecc */
 #define NAND_GET_DEVICE		0x80
@@ -186,6 +192,7 @@ enum nand_ecc_algo {
 /* Macros to identify the above */
 #define NAND_HAS_CACHEPROG(chip) ((chip->options & NAND_CACHEPRG))
 #define NAND_HAS_SUBPAGE_READ(chip) ((chip->options & NAND_SUBPAGE_READ))
+#define NAND_HAS_SUBPAGE_WRITE(chip) !(chip->options & NAND_NO_SUBPAGE_WRITE)
 
 /* Non chip related options */
 /* This option skips the bbt scan during initialization. */
@@ -568,6 +575,11 @@ struct nand_ecc_ctrl {
 			int page);
 };
 
+static inline int nand_default_page_accessors(struct nand_ecc_ctrl *ecc)
+{
+	return !(ecc->options & NAND_ECC_CUSTOM_PAGE_ACCESS);
+}
+
 /**
  * struct nand_buffers - buffer structure for read/write
  * @ecccalc:	buffer pointer for calculated ECC, size is oobsize.
-- 
2.9.0