1 files changed, 119 insertions, 20 deletions

diff --git a/drivers/mtd/nand/raw/nand_micron.c b/drivers/mtd/nand/raw/nand_micron.c
index fd3f68e0909f..2cff25f7b48b 100644
--- a/drivers/mtd/nand/raw/nand_micron.c
+++ b/drivers/mtd/nand/raw/nand_micron.c
@@ -16,6 +16,7 @@
  */
 
 #include <linux/mtd/rawnand.h>
+#include <linux/slab.h>
 
 /*
  * Special Micron status bit 3 indicates that the block has been
@@ -63,6 +64,14 @@ struct nand_onfi_vendor_micron {
 	u8 param_revision;
 } __packed;
 
+struct micron_on_die_ecc {
+	void *rawbuf;
+};
+
+struct micron_nand {
+	struct micron_on_die_ecc ecc;
+};
+
 static int micron_nand_setup_read_retry(struct mtd_info *mtd, int retry_mode)
 {
 	struct nand_chip *chip = mtd_to_nand(mtd);
@@ -170,25 +179,71 @@ static int micron_nand_on_die_ecc_setup(struct nand_chip *chip, bool enable)
 	return nand_set_features(chip, ONFI_FEATURE_ON_DIE_ECC, feature);
 }
 
-static int micron_nand_on_die_ecc_status_4(struct nand_chip *chip, u8 status)
+static int micron_nand_on_die_ecc_status_4(struct nand_chip *chip, u8 status,
+					   void *buf, int page,
+					   int oob_required)
 {
+	struct micron_nand *micron = nand_get_manufacturer_data(chip);
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	unsigned int step, max_bitflips = 0;
+	int ret;
+
+	if (!(status & NAND_ECC_STATUS_WRITE_RECOMMENDED)) {
+		if (status & NAND_STATUS_FAIL)
+			mtd->ecc_stats.failed++;
+
+		return 0;
+	}
 
 	/*
-	 * The internal ECC doesn't tell us the number of bitflips
-	 * that have been corrected, but tells us if it recommends to
-	 * rewrite the block. If it's the case, then we pretend we had
-	 * a number of bitflips equal to the ECC strength, which will
-	 * hint the NAND core to rewrite the block.
+	 * The internal ECC doesn't tell us the number of bitflips that have
+	 * been corrected, but tells us if it recommends to rewrite the block.
+	 * If it's the case, we need to read the page in raw mode and compare
+	 * its content to the corrected version to extract the actual number of
+	 * bitflips.
+	 * But before we do that, we must make sure we have all OOB bytes read
+	 * in non-raw mode, even if the user did not request those bytes.
 	 */
-	if (status & NAND_STATUS_FAIL) {
-		mtd->ecc_stats.failed++;
-	} else if (status & NAND_ECC_STATUS_WRITE_RECOMMENDED) {
-		mtd->ecc_stats.corrected += chip->ecc.strength;
-		return chip->ecc.strength;
+	if (!oob_required) {
+		ret = nand_read_data_op(chip, chip->oob_poi, mtd->oobsize,
+					false);
+		if (ret)
+			return ret;
 	}
 
-	return 0;
+	micron_nand_on_die_ecc_setup(chip, false);
+
+	ret = nand_read_page_op(chip, page, 0, micron->ecc.rawbuf,
+				mtd->writesize + mtd->oobsize);
+	if (ret)
+		return ret;
+
+	for (step = 0; step < chip->ecc.steps; step++) {
+		unsigned int offs, i, nbitflips = 0;
+		u8 *rawbuf, *corrbuf;
+
+		offs = step * chip->ecc.size;
+		rawbuf = micron->ecc.rawbuf + offs;
+		corrbuf = buf + offs;
+
+		for (i = 0; i < chip->ecc.size; i++)
+			nbitflips += hweight8(corrbuf[i] ^ rawbuf[i]);
+
+		offs = (step * 16) + 4;
+		rawbuf = micron->ecc.rawbuf + mtd->writesize + offs;
+		corrbuf = chip->oob_poi + offs;
+
+		for (i = 0; i < chip->ecc.bytes + 4; i++)
+			nbitflips += hweight8(corrbuf[i] ^ rawbuf[i]);
+
+		if (WARN_ON(nbitflips > chip->ecc.strength))
+			return -EINVAL;
+
+		max_bitflips = max(nbitflips, max_bitflips);
+		mtd->ecc_stats.corrected += nbitflips;
+	}
+
+	return max_bitflips;
 }
 
 static int micron_nand_on_die_ecc_status_8(struct nand_chip *chip, u8 status)
@@ -243,16 +298,18 @@ micron_nand_read_page_on_die_ecc(struct mtd_info *mtd, struct nand_chip *chip,
 	if (ret)
 		goto out;
 
-	if (chip->ecc.strength == 4)
-		max_bitflips = micron_nand_on_die_ecc_status_4(chip, status);
-	else
-		max_bitflips = micron_nand_on_die_ecc_status_8(chip, status);
-
 	ret = nand_read_data_op(chip, buf, mtd->writesize, false);
 	if (!ret && oob_required)
 		ret = nand_read_data_op(chip, chip->oob_poi, mtd->oobsize,
 					false);
 
+	if (chip->ecc.strength == 4)
+		max_bitflips = micron_nand_on_die_ecc_status_4(chip, status,
+							       buf, page,
+							       oob_required);
+	else
+		max_bitflips = micron_nand_on_die_ecc_status_8(chip, status);
+
 out:
 	micron_nand_on_die_ecc_setup(chip, false);
 
@@ -362,12 +419,19 @@ static int micron_supports_on_die_ecc(struct nand_chip *chip)
 static int micron_nand_init(struct nand_chip *chip)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
+	struct micron_nand *micron;
 	int ondie;
 	int ret;
 
+	micron = kzalloc(sizeof(*micron), GFP_KERNEL);
+	if (!micron)
+		return -ENOMEM;
+
+	nand_set_manufacturer_data(chip, micron);
+
 	ret = micron_nand_onfi_init(chip);
 	if (ret)
-		return ret;
+		goto err_free_manuf_data;
 
 	if (mtd->writesize == 2048)
 		chip->bbt_options |= NAND_BBT_SCAN2NDPAGE;
@@ -377,13 +441,33 @@ static int micron_nand_init(struct nand_chip *chip)
 	if (ondie == MICRON_ON_DIE_MANDATORY &&
 	    chip->ecc.mode != NAND_ECC_ON_DIE) {
 		pr_err("On-die ECC forcefully enabled, not supported\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto err_free_manuf_data;
 	}
 
 	if (chip->ecc.mode == NAND_ECC_ON_DIE) {
 		if (ondie == MICRON_ON_DIE_UNSUPPORTED) {
 			pr_err("On-die ECC selected but not supported\n");
-			return -EINVAL;
+			ret = -EINVAL;
+			goto err_free_manuf_data;
+		}
+
+		/*
+		 * In case of 4bit on-die ECC, we need a buffer to store a
+		 * page dumped in raw mode so that we can compare its content
+		 * to the same page after ECC correction happened and extract
+		 * the real number of bitflips from this comparison.
+		 * That's not needed for 8-bit ECC, because the status expose
+		 * a better approximation of the number of bitflips in a page.
+		 */
+		if (chip->ecc_strength_ds == 4) {
+			micron->ecc.rawbuf = kmalloc(mtd->writesize +
+						     mtd->oobsize,
+						     GFP_KERNEL);
+			if (!micron->ecc.rawbuf) {
+				ret = -ENOMEM;
+				goto err_free_manuf_data;
+			}
 		}
 
 		if (chip->ecc_strength_ds == 4)
@@ -410,6 +494,20 @@ static int micron_nand_init(struct nand_chip *chip)
 	}
 
 	return 0;
+
+err_free_manuf_data:
+	kfree(micron->ecc.rawbuf);
+	kfree(micron);
+
+	return ret;
+}
+
+static void micron_nand_cleanup(struct nand_chip *chip)
+{
+	struct micron_nand *micron = nand_get_manufacturer_data(chip);
+
+	kfree(micron->ecc.rawbuf);
+	kfree(micron);
 }
 
 static void micron_fixup_onfi_param_page(struct nand_chip *chip,
@@ -426,5 +524,6 @@ static void micron_fixup_onfi_param_page(struct nand_chip *chip,
 
 const struct nand_manufacturer_ops micron_nand_manuf_ops = {
 	.init = micron_nand_init,
+	.cleanup = micron_nand_cleanup,
 	.fixup_onfi_param_page = micron_fixup_onfi_param_page,
 };