mtd: rawnand: omap_gpmc: Fix BCH6/16 HW based correction

The BCH detection hardware can generate ECC bytes for multiple
sectors in one go. Use that feature.

correct() only corrects one sector at a time so we need to call it
repeatedly for each sector.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/all/20221220102203.52398-2-rogerq@kernel.org

1 files changed, 223 insertions, 102 deletions

diff --git a/drivers/mtd/nand/raw/omap_gpmc.c b/drivers/mtd/nand/raw/omap_gpmc.c
index be3cb3c601..feaa739e78 100644
--- a/drivers/mtd/nand/raw/omap_gpmc.c
+++ b/drivers/mtd/nand/raw/omap_gpmc.c
@@ -27,6 +27,9 @@
 
 #define BADBLOCK_MARKER_LENGTH	2
 #define SECTOR_BYTES		512
+#define ECCSIZE0_SHIFT		12
+#define ECCSIZE1_SHIFT		22
+#define ECC1RESULTSIZE		0x1
 #define ECCCLEAR		(0x1 << 8)
 #define ECCRESULTREG1		(0x1 << 0)
 /* 4 bit padding to make byte aligned, 56 = 52 + 4 */
@@ -186,72 +189,35 @@ static int __maybe_unused omap_correct_data(struct mtd_info *mtd, uint8_t *dat,
 __maybe_unused
 static void omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
 {
-	struct nand_chip	*nand	= mtd_to_nand(mtd);
-	struct omap_nand_info	*info	= nand_get_controller_data(nand);
+	struct nand_chip *nand = mtd_to_nand(mtd);
+	struct omap_nand_info *info = nand_get_controller_data(nand);
 	unsigned int dev_width = (nand->options & NAND_BUSWIDTH_16) ? 1 : 0;
-	unsigned int ecc_algo = 0;
-	unsigned int bch_type = 0;
-	unsigned int eccsize1 = 0x00, eccsize0 = 0x00, bch_wrapmode = 0x00;
-	u32 ecc_size_config_val = 0;
-	u32 ecc_config_val = 0;
-	int cs = info->cs;
+	u32 val;
 
-	/* configure GPMC for specific ecc-scheme */
-	switch (info->ecc_scheme) {
-	case OMAP_ECC_HAM1_CODE_SW:
-		return;
-	case OMAP_ECC_HAM1_CODE_HW:
-		ecc_algo = 0x0;
-		bch_type = 0x0;
-		bch_wrapmode = 0x00;
-		eccsize0 = 0xFF;
-		eccsize1 = 0xFF;
+	/* Clear ecc and enable bits */
+	writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
+
+	/* program ecc and result sizes */
+	val = ((((nand->ecc.size >> 1) - 1) << ECCSIZE1_SHIFT) |
+			ECC1RESULTSIZE);
+	writel(val, &gpmc_cfg->ecc_size_config);
+
+	switch (mode) {
+	case NAND_ECC_READ:
+	case NAND_ECC_WRITE:
+		writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
 		break;
-	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
-	case OMAP_ECC_BCH8_CODE_HW:
-		ecc_algo = 0x1;
-		bch_type = 0x1;
-		if (mode == NAND_ECC_WRITE) {
-			bch_wrapmode = 0x01;
-			eccsize0 = 0;  /* extra bits in nibbles per sector */
-			eccsize1 = 28; /* OOB bits in nibbles per sector */
-		} else {
-			bch_wrapmode = 0x01;
-			eccsize0 = 26; /* ECC bits in nibbles per sector */
-			eccsize1 = 2;  /* non-ECC bits in nibbles per sector */
-		}
-		break;
-	case OMAP_ECC_BCH16_CODE_HW:
-		ecc_algo = 0x1;
-		bch_type = 0x2;
-		if (mode == NAND_ECC_WRITE) {
-			bch_wrapmode = 0x01;
-			eccsize0 = 0;  /* extra bits in nibbles per sector */
-			eccsize1 = 52; /* OOB bits in nibbles per sector */
-		} else {
-			bch_wrapmode = 0x01;
-			eccsize0 = 52; /* ECC bits in nibbles per sector */
-			eccsize1 = 0;  /* non-ECC bits in nibbles per sector */
-		}
+	case NAND_ECC_READSYN:
+		writel(ECCCLEAR, &gpmc_cfg->ecc_control);
 		break;
 	default:
-		return;
+		printf("%s: error: unrecognized Mode[%d]!\n", __func__, mode);
+		break;
 	}
-	/* Clear ecc and enable bits */
-	writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
-	/* Configure ecc size for BCH */
-	ecc_size_config_val = (eccsize1 << 22) | (eccsize0 << 12);
-	writel(ecc_size_config_val, &gpmc_cfg->ecc_size_config);
-
-	/* Configure device details for BCH engine */
-	ecc_config_val = ((ecc_algo << 16)	| /* HAM1 | BCHx */
-			(bch_type << 12)	| /* BCH4/BCH8/BCH16 */
-			(bch_wrapmode << 8)	| /* wrap mode */
-			(dev_width << 7)	| /* bus width */
-			(0x0 << 4)		| /* number of sectors */
-			(cs <<  1)		| /* ECC CS */
-			(0x1));			  /* enable ECC */
-	writel(ecc_config_val, &gpmc_cfg->ecc_config);
+
+	/* (ECC 16 or 8 bit col) | ( CS  )  | ECC Enable */
+	val = (dev_width << 7) | (info->cs << 1) | (0x1);
+	writel(val, &gpmc_cfg->ecc_config);
 }
 
 /*
@@ -271,6 +237,124 @@ static void omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
 static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
 				uint8_t *ecc_code)
 {
+	u32 val;
+
+	val = readl(&gpmc_cfg->ecc1_result);
+	ecc_code[0] = val & 0xFF;
+	ecc_code[1] = (val >> 16) & 0xFF;
+	ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);
+
+	return 0;
+}
+
+/* GPMC ecc engine settings for read */
+#define BCH_WRAPMODE_1          1       /* BCH wrap mode 1 */
+#define BCH8R_ECC_SIZE0         0x1a    /* ecc_size0 = 26 */
+#define BCH8R_ECC_SIZE1         0x2     /* ecc_size1 = 2 */
+#define BCH4R_ECC_SIZE0         0xd     /* ecc_size0 = 13 */
+#define BCH4R_ECC_SIZE1         0x3     /* ecc_size1 = 3 */
+
+/* GPMC ecc engine settings for write */
+#define BCH_WRAPMODE_6          6       /* BCH wrap mode 6 */
+#define BCH_ECC_SIZE0           0x0     /* ecc_size0 = 0, no oob protection */
+#define BCH_ECC_SIZE1           0x20    /* ecc_size1 = 32 */
+
+/**
+ * omap_enable_hwecc_bch - Program GPMC to perform BCH ECC calculation
+ * @mtd: MTD device structure
+ * @mode: Read/Write mode
+ *
+ * When using BCH with SW correction (i.e. no ELM), sector size is set
+ * to 512 bytes and we use BCH_WRAPMODE_6 wrapping mode
+ * for both reading and writing with:
+ * eccsize0 = 0  (no additional protected byte in spare area)
+ * eccsize1 = 32 (skip 32 nibbles = 16 bytes per sector in spare area)
+ */
+static void __maybe_unused omap_enable_hwecc_bch(struct mtd_info *mtd,
+						 int mode)
+{
+	unsigned int bch_type;
+	unsigned int dev_width, nsectors;
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct omap_nand_info *info = nand_get_controller_data(chip);
+	u32 val, wr_mode;
+	unsigned int ecc_size1, ecc_size0;
+
+	/* GPMC configurations for calculating ECC */
+	switch (info->ecc_scheme) {
+	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
+		bch_type = 1;
+		nsectors = 1;
+		wr_mode   = BCH_WRAPMODE_6;
+		ecc_size0 = BCH_ECC_SIZE0;
+		ecc_size1 = BCH_ECC_SIZE1;
+		break;
+	case OMAP_ECC_BCH8_CODE_HW:
+		bch_type = 1;
+		nsectors = chip->ecc.steps;
+		if (mode == NAND_ECC_READ) {
+			wr_mode   = BCH_WRAPMODE_1;
+			ecc_size0 = BCH8R_ECC_SIZE0;
+			ecc_size1 = BCH8R_ECC_SIZE1;
+		} else {
+			wr_mode   = BCH_WRAPMODE_6;
+			ecc_size0 = BCH_ECC_SIZE0;
+			ecc_size1 = BCH_ECC_SIZE1;
+		}
+		break;
+	case OMAP_ECC_BCH16_CODE_HW:
+		bch_type = 0x2;
+		nsectors = chip->ecc.steps;
+		if (mode == NAND_ECC_READ) {
+			wr_mode   = 0x01;
+			ecc_size0 = 52; /* ECC bits in nibbles per sector */
+			ecc_size1 = 0;  /* non-ECC bits in nibbles per sector */
+		} else {
+			wr_mode   = 0x01;
+			ecc_size0 = 0;  /* extra bits in nibbles per sector */
+			ecc_size1 = 52; /* OOB bits in nibbles per sector */
+		}
+		break;
+	default:
+		return;
+	}
+
+	writel(ECCRESULTREG1, &gpmc_cfg->ecc_control);
+
+	/* Configure ecc size for BCH */
+	val = (ecc_size1 << ECCSIZE1_SHIFT) | (ecc_size0 << ECCSIZE0_SHIFT);
+	writel(val, &gpmc_cfg->ecc_size_config);
+
+	dev_width = (chip->options & NAND_BUSWIDTH_16) ? 1 : 0;
+
+	/* BCH configuration */
+	val = ((1			<< 16) | /* enable BCH */
+	       (bch_type		<< 12) | /* BCH4/BCH8/BCH16 */
+	       (wr_mode			<<  8) | /* wrap mode */
+	       (dev_width		<<  7) | /* bus width */
+	       (((nsectors - 1) & 0x7)	<<  4) | /* number of sectors */
+	       (info->cs		<<  1) | /* ECC CS */
+	       (0x1));				 /* enable ECC */
+
+	writel(val, &gpmc_cfg->ecc_config);
+
+	/* Clear ecc and enable bits */
+	writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
+}
+
+/**
+ * _omap_calculate_ecc_bch - Generate BCH ECC bytes for one sector
+ * @mtd:        MTD device structure
+ * @dat:        The pointer to data on which ecc is computed
+ * @ecc_code:   The ecc_code buffer
+ * @sector:     The sector number (for a multi sector page)
+ *
+ * Support calculating of BCH4/8/16 ECC vectors for one sector
+ * within a page. Sector number is in @sector.
+ */
+static int _omap_calculate_ecc_bch(struct mtd_info *mtd, const u8 *dat,
+				   u8 *ecc_code, int sector)
+{
 	struct nand_chip *chip = mtd_to_nand(mtd);
 	struct omap_nand_info *info = nand_get_controller_data(chip);
 	const uint32_t *ptr;
@@ -278,17 +362,11 @@ static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
 	int8_t i = 0, j;
 
 	switch (info->ecc_scheme) {
-	case OMAP_ECC_HAM1_CODE_HW:
-		val = readl(&gpmc_cfg->ecc1_result);
-		ecc_code[0] = val & 0xFF;
-		ecc_code[1] = (val >> 16) & 0xFF;
-		ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);
-		break;
 #ifdef CONFIG_BCH
 	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
 #endif
 	case OMAP_ECC_BCH8_CODE_HW:
-		ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[3];
+		ptr = &gpmc_cfg->bch_result_0_3[sector].bch_result_x[3];
 		val = readl(ptr);
 		ecc_code[i++] = (val >>  0) & 0xFF;
 		ptr--;
@@ -300,23 +378,24 @@ static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
 			ecc_code[i++] = (val >>  0) & 0xFF;
 			ptr--;
 		}
+
 		break;
 	case OMAP_ECC_BCH16_CODE_HW:
-		val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[2]);
+		val = readl(&gpmc_cfg->bch_result_4_6[sector].bch_result_x[2]);
 		ecc_code[i++] = (val >>  8) & 0xFF;
 		ecc_code[i++] = (val >>  0) & 0xFF;
-		val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[1]);
+		val = readl(&gpmc_cfg->bch_result_4_6[sector].bch_result_x[1]);
 		ecc_code[i++] = (val >> 24) & 0xFF;
 		ecc_code[i++] = (val >> 16) & 0xFF;
 		ecc_code[i++] = (val >>  8) & 0xFF;
 		ecc_code[i++] = (val >>  0) & 0xFF;
-		val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[0]);
+		val = readl(&gpmc_cfg->bch_result_4_6[sector].bch_result_x[0]);
 		ecc_code[i++] = (val >> 24) & 0xFF;
 		ecc_code[i++] = (val >> 16) & 0xFF;
 		ecc_code[i++] = (val >>  8) & 0xFF;
 		ecc_code[i++] = (val >>  0) & 0xFF;
 		for (j = 3; j >= 0; j--) {
-			val = readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[j]
+			val = readl(&gpmc_cfg->bch_result_0_3[sector].bch_result_x[j]
 									);
 			ecc_code[i++] = (val >> 24) & 0xFF;
 			ecc_code[i++] = (val >> 16) & 0xFF;
@@ -329,18 +408,18 @@ static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
 	}
 	/* ECC scheme specific syndrome customizations */
 	switch (info->ecc_scheme) {
-	case OMAP_ECC_HAM1_CODE_HW:
-		break;
 #ifdef CONFIG_BCH
 	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
-
+		/* Add constant polynomial to remainder, so that
+		 * ECC of blank pages results in 0x0 on reading back
+		 */
 		for (i = 0; i < chip->ecc.bytes; i++)
-			*(ecc_code + i) = *(ecc_code + i) ^
-						bch8_polynomial[i];
+			ecc_code[i] ^= bch8_polynomial[i];
 		break;
 #endif
 	case OMAP_ECC_BCH8_CODE_HW:
-		ecc_code[chip->ecc.bytes - 1] = 0x00;
+		/* Set 14th ECC byte as 0x0 for ROM compatibility */
+		ecc_code[chip->ecc.bytes - 1] = 0x0;
 		break;
 	case OMAP_ECC_BCH16_CODE_HW:
 		break;
@@ -350,6 +429,22 @@ static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
 	return 0;
 }
 
+/**
+ * omap_calculate_ecc_bch - ECC generator for 1 sector
+ * @mtd:        MTD device structure
+ * @dat:	The pointer to data on which ecc is computed
+ * @ecc_code:	The ecc_code buffer
+ *
+ * Support calculating of BCH4/8/16 ECC vectors for one sector. This is used
+ * when SW based correction is required as ECC is required for one sector
+ * at a time.
+ */
+static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
+				  const u_char *dat, u_char *ecc_calc)
+{
+	return _omap_calculate_ecc_bch(mtd, dat, ecc_calc, 0);
+}
+
 static inline void omap_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
 {
 	struct nand_chip *chip = mtd_to_nand(mtd);
@@ -474,6 +569,35 @@ static void omap_nand_read_prefetch(struct mtd_info *mtd, uint8_t *buf, int len)
 #endif /* CONFIG_NAND_OMAP_GPMC_PREFETCH */
 
 #ifdef CONFIG_NAND_OMAP_ELM
+
+/**
+ * omap_calculate_ecc_bch_multi - Generate ECC for multiple sectors
+ * @mtd:	MTD device structure
+ * @dat:	The pointer to data on which ecc is computed
+ * @ecc_code:	The ecc_code buffer
+ *
+ * Support calculating of BCH4/8/16 ecc vectors for the entire page in one go.
+ */
+static int omap_calculate_ecc_bch_multi(struct mtd_info *mtd,
+					const u_char *dat, u_char *ecc_calc)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	int eccbytes = chip->ecc.bytes;
+	unsigned long nsectors;
+	int i, ret;
+
+	nsectors = ((readl(&gpmc_cfg->ecc_config) >> 4) & 0x7) + 1;
+	for (i = 0; i < nsectors; i++) {
+		ret = _omap_calculate_ecc_bch(mtd, dat, ecc_calc, i);
+		if (ret)
+			return ret;
+
+		ecc_calc += eccbytes;
+	}
+
+	return 0;
+}
+
 /*
  * omap_reverse_list - re-orders list elements in reverse order [internal]
  * @list:	pointer to start of list
@@ -626,52 +750,49 @@ static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
 {
 	int i, eccsize = chip->ecc.size;
 	int eccbytes = chip->ecc.bytes;
+	int ecctotal = chip->ecc.total;
 	int eccsteps = chip->ecc.steps;
 	uint8_t *p = buf;
 	uint8_t *ecc_calc = chip->buffers->ecccalc;
 	uint8_t *ecc_code = chip->buffers->ecccode;
 	uint32_t *eccpos = chip->ecc.layout->eccpos;
 	uint8_t *oob = chip->oob_poi;
-	uint32_t data_pos;
 	uint32_t oob_pos;
 
-	data_pos = 0;
 	/* oob area start */
 	oob_pos = (eccsize * eccsteps) + chip->ecc.layout->eccpos[0];
 	oob += chip->ecc.layout->eccpos[0];
 
-	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize,
-				oob += eccbytes) {
-		chip->ecc.hwctl(mtd, NAND_ECC_READ);
-		/* read data */
-		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, data_pos, -1);
-		chip->read_buf(mtd, p, eccsize);
-
-		/* read respective ecc from oob area */
-		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, oob_pos, -1);
-		chip->read_buf(mtd, oob, eccbytes);
-		/* read syndrome */
-		chip->ecc.calculate(mtd, p, &ecc_calc[i]);
-
-		data_pos += eccsize;
-		oob_pos += eccbytes;
-	}
+	/* Enable ECC engine */
+	chip->ecc.hwctl(mtd, NAND_ECC_READ);
+
+	/* read entire page */
+	chip->cmdfunc(mtd, NAND_CMD_RNDOUT, 0, -1);
+	chip->read_buf(mtd, buf, mtd->writesize);
+
+	/* read all ecc bytes from oob area */
+	chip->cmdfunc(mtd, NAND_CMD_RNDOUT, oob_pos, -1);
+	chip->read_buf(mtd, oob, ecctotal);
+
+	/* Calculate ecc bytes */
+	omap_calculate_ecc_bch_multi(mtd, buf, ecc_calc);
 
 	for (i = 0; i < chip->ecc.total; i++)
 		ecc_code[i] = chip->oob_poi[eccpos[i]];
 
+	/* error detect & correct */
 	eccsteps = chip->ecc.steps;
 	p = buf;
 
 	for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
 		int stat;
-
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
 		if (stat < 0)
 			mtd->ecc_stats.failed++;
 		else
 			mtd->ecc_stats.corrected += stat;
 	}
+
 	return 0;
 }
 #endif /* CONFIG_NAND_OMAP_ELM */
@@ -819,9 +940,9 @@ static int omap_select_ecc_scheme(struct nand_chip *nand,
 		nand->ecc.strength	= 8;
 		nand->ecc.size		= SECTOR_BYTES;
 		nand->ecc.bytes		= 13;
-		nand->ecc.hwctl		= omap_enable_hwecc;
+		nand->ecc.hwctl		= omap_enable_hwecc_bch;
 		nand->ecc.correct	= omap_correct_data_bch_sw;
-		nand->ecc.calculate	= omap_calculate_ecc;
+		nand->ecc.calculate	= omap_calculate_ecc_bch;
 		/* define ecc-layout */
 		ecclayout->eccbytes	= nand->ecc.bytes * eccsteps;
 		ecclayout->eccpos[0]	= BADBLOCK_MARKER_LENGTH;
@@ -860,9 +981,9 @@ static int omap_select_ecc_scheme(struct nand_chip *nand,
 		nand->ecc.strength	= 8;
 		nand->ecc.size		= SECTOR_BYTES;
 		nand->ecc.bytes		= 14;
-		nand->ecc.hwctl		= omap_enable_hwecc;
+		nand->ecc.hwctl		= omap_enable_hwecc_bch;
 		nand->ecc.correct	= omap_correct_data_bch;
-		nand->ecc.calculate	= omap_calculate_ecc;
+		nand->ecc.calculate	= omap_calculate_ecc_bch;
 		nand->ecc.read_page	= omap_read_page_bch;
 		/* define ecc-layout */
 		ecclayout->eccbytes	= nand->ecc.bytes * eccsteps;
@@ -893,9 +1014,9 @@ static int omap_select_ecc_scheme(struct nand_chip *nand,
 		nand->ecc.size		= SECTOR_BYTES;
 		nand->ecc.bytes		= 26;
 		nand->ecc.strength	= 16;
-		nand->ecc.hwctl		= omap_enable_hwecc;
+		nand->ecc.hwctl		= omap_enable_hwecc_bch;
 		nand->ecc.correct	= omap_correct_data_bch;
-		nand->ecc.calculate	= omap_calculate_ecc;
+		nand->ecc.calculate	= omap_calculate_ecc_bch;
 		nand->ecc.read_page	= omap_read_page_bch;
 		/* define ecc-layout */
 		ecclayout->eccbytes	= nand->ecc.bytes * eccsteps;