[PATCH 15/19] drivers: mtd: nand: base: Add support for Hardware ECC for check bad block

[dinesh.maniyam@intel.com]

From: Dinesh Maniyam <dinesh.maniyam@intel.com>

This patch is to leverage linux code to support hardware ECC interface
in verify nand bad block.

Signed-off-by: Dinesh Maniyam <dinesh.maniyam@intel.com>
---
 drivers/mtd/nand/raw/nand_base.c | 71 +++++++++++++++++++++-----------
 include/linux/mtd/rawnand.h      | 13 ++++++
 2 files changed, 60 insertions(+), 24 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 4401bdcdb9..9b1b2d1f85 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -9,6 +9,8 @@
  *  Copyright (C) 2000 Steven J. Hill (sjhill@realitydiluted.com)
  *		  2002-2006 Thomas Gleixner (tglx@linutronix.de)
  *
+ *  Copyright (C) 2024 Intel Corporation <www.intel.com>
+ *
  *  Credits:
  *	David Woodhouse for adding multichip support
  *
@@ -306,6 +308,35 @@ void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
 	ioread16_rep(chip->IO_ADDR_R, p, len >> 1);
 }
 
+/*
+ * nand_bbm_get_next_page - Get the next page for bad block markers
+ * @chip: The NAND chip
+ * @page: First page to start checking for bad block marker usage
+ *
+ * Returns an integer that corresponds to the page offset within a block, for
+ * a page that is used to store bad block markers. If no more pages are
+ * available, -EINVAL is returned.
+ */
+int nand_bbm_get_next_page(struct nand_chip *chip, int page)
+{
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	int last_page = ((mtd->erasesize - mtd->writesize) >>
+			 chip->page_shift) & chip->pagemask;
+	unsigned int bbm_flags = NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE
+		| NAND_BBM_LASTPAGE;
+
+	if (page == 0 && !(chip->options & bbm_flags))
+		return 0;
+	if (page == 0 && chip->options & NAND_BBM_FIRSTPAGE)
+		return 0;
+	if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
+		return 1;
+	if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
+		return last_page;
+
+	return -EINVAL;
+}
+
 /**
  * nand_block_bad - [DEFAULT] Read bad block marker from the chip
  * @mtd: MTD device structure
@@ -315,40 +346,32 @@ void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
  */
 static int nand_block_bad(struct mtd_info *mtd, loff_t ofs)
 {
-	int page, res = 0, i = 0;
 	struct nand_chip *chip = mtd_to_nand(mtd);
-	u16 bad;
+	int first_page, page_offset;
+	int res;
+	u8 bad;
 
-	if (chip->bbt_options & NAND_BBT_SCANLASTPAGE)
-		ofs += mtd->erasesize - mtd->writesize;
+	first_page = (int)(ofs >> chip->page_shift) & chip->pagemask;
+	page_offset = nand_bbm_get_next_page(chip, 0);
 
-	page = (int)(ofs >> chip->page_shift) & chip->pagemask;
+	while (page_offset >= 0) {
+		res = chip->ecc.read_oob(mtd, chip, first_page + page_offset);
+		if (res < 0)
+			return res;
 
-	do {
-		if (chip->options & NAND_BUSWIDTH_16) {
-			chip->cmdfunc(mtd, NAND_CMD_READOOB,
-					chip->badblockpos & 0xFE, page);
-			bad = cpu_to_le16(chip->read_word(mtd));
-			if (chip->badblockpos & 0x1)
-				bad >>= 8;
-			else
-				bad &= 0xFF;
-		} else {
-			chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos,
-					page);
-			bad = chip->read_byte(mtd);
-		}
+		bad = chip->oob_poi[chip->badblockpos];
 
 		if (likely(chip->badblockbits == 8))
 			res = bad != 0xFF;
 		else
 			res = hweight8(bad) < chip->badblockbits;
-		ofs += mtd->writesize;
-		page = (int)(ofs >> chip->page_shift) & chip->pagemask;
-		i++;
-	} while (!res && i < 2 && (chip->bbt_options & NAND_BBT_SCAN2NDPAGE));
+		if (res)
+			return res;
 
-	return res;
+		page_offset = nand_bbm_get_next_page(chip, page_offset + 1);
+	}
+
+	return 0;
 }
 
 /**
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index 537c62424a..49444e9353 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -4,6 +4,8 @@
  *                        Steven J. Hill <sjhill@realitydiluted.com>
  *		          Thomas Gleixner <tglx@linutronix.de>
  *
+ *  Copyright (C) 2024 Intel Corporation <www.intel.com>
+ *
  * Info:
  *	Contains standard defines and IDs for NAND flash devices
  *
@@ -131,6 +133,17 @@ void nand_wait_ready(struct mtd_info *mtd);
 
 #define NAND_DATA_IFACE_CHECK_ONLY	-1
 
+/*
+ * There are different places where the manufacturer stores the factory bad
+ * block markers.
+ *
+ * Position within the block: Each of these pages needs to be checked for a
+ * bad block marking pattern.
+ */
+#define NAND_BBM_FIRSTPAGE	BIT(24)
+#define NAND_BBM_SECONDPAGE	BIT(25)
+#define NAND_BBM_LASTPAGE	BIT(26)
+
 /*
  * Constants for ECC_MODES
  */
-- 
2.26.2