at91: 9x5: Enable PMECC(Programmable Multibit ECC controller) support

Extract the hwecc initialization code into one function. It is a preparation for adding atmel PMECC support.

Signed-off-by Josh Wu <[email protected]>

---
 drivers/mtd/nand/atmel_nand.c |  108 ++++++++++++++++++++++-------------------
 1 file changed, 57 insertions(+), 51 deletions(-)

drivers/mtd/nand/atmel_nand.c +0 -21

index de66382..113da93 100644
@@ -232,68 +232,19 @@ static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat,
 static void atmel_nand_hwctl(struct mtd_info *mtd, int mode)
 {
 }
-#endif
-
-static void at91_nand_hwcontrol(struct mtd_info *mtd,
-					 int cmd, unsigned int ctrl)
-{
-	struct nand_chip *this = mtd->priv;
-
-	if (ctrl & NAND_CTRL_CHANGE) {
-		ulong IO_ADDR_W = (ulong) this->IO_ADDR_W;
-		IO_ADDR_W &= ~(CONFIG_SYS_NAND_MASK_ALE
-			     | CONFIG_SYS_NAND_MASK_CLE);
-
-		if (ctrl & NAND_CLE)
-			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_CLE;
-		if (ctrl & NAND_ALE)
-			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_ALE;
-
-#ifdef CONFIG_SYS_NAND_ENABLE_PIN
-		at91_set_gpio_value(CONFIG_SYS_NAND_ENABLE_PIN,
-				    !(ctrl & NAND_NCE));
-#endif

drivers/mtd/nand/atmel_nand.c +0 -12

 	struct mtd_info *mtd;
-#endif
-
-	nand->ecc.mode = NAND_ECC_SOFT;
-#ifdef CONFIG_SYS_NAND_DBW_16
-	nand->options = NAND_BUSWIDTH_16;
-#endif
-	nand->cmd_ctrl = at91_nand_hwcontrol;
-#ifdef CONFIG_SYS_NAND_READY_PIN
-	nand->dev_ready = at91_nand_ready;
-#endif
-	nand->chip_delay = 20;
 
-#ifdef CONFIG_ATMEL_NAND_HWECC
 	nand->ecc.mode = NAND_ECC_HW;

drivers/mtd/nand/atmel_nand.c +46 -1

@@ -339,7 +290,62 @@ int board_nand_init(struct nand_chip *nand)
 			break;
 		}
 	}
-#endif
 
 	return 0;
 }
+
+#endif
+
+static void at91_nand_hwcontrol(struct mtd_info *mtd,
+					 int cmd, unsigned int ctrl)
+{
+	struct nand_chip *this = mtd->priv;
+
+	if (ctrl & NAND_CTRL_CHANGE) {
+		ulong IO_ADDR_W = (ulong) this->IO_ADDR_W;
+		IO_ADDR_W &= ~(CONFIG_SYS_NAND_MASK_ALE
+			     | CONFIG_SYS_NAND_MASK_CLE);
+
+		if (ctrl & NAND_CLE)
+			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_CLE;
+		if (ctrl & NAND_ALE)
+			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_ALE;
+
+#ifdef CONFIG_SYS_NAND_ENABLE_PIN
+		at91_set_gpio_value(CONFIG_SYS_NAND_ENABLE_PIN,
+				    !(ctrl & NAND_NCE));
+#endif
+		this->IO_ADDR_W = (void *) IO_ADDR_W;
+	}
+
+	if (cmd != NAND_CMD_NONE)
+		writeb(cmd, this->IO_ADDR_W);
+}
+
+#ifdef CONFIG_SYS_NAND_READY_PIN
+static int at91_nand_ready(struct mtd_info *mtd)
+{
+	return at91_get_gpio_value(CONFIG_SYS_NAND_READY_PIN);
+}
+#endif
+
+int board_nand_init(struct nand_chip *nand)
+{
+	int res = 0;
+
+	nand->ecc.mode = NAND_ECC_SOFT;
+#ifdef CONFIG_SYS_NAND_DBW_16
+	nand->options = NAND_BUSWIDTH_16;
+#endif
+	nand->cmd_ctrl = at91_nand_hwcontrol;
+#ifdef CONFIG_SYS_NAND_READY_PIN

Dear Josh Wu,

Quoted 43 lines · Josh Wu

Extract the hwecc initialization code into one function. It is a preparation for adding atmel PMECC support.

Signed-off-by Josh Wu <[email protected]>

---
  drivers/mtd/nand/atmel_nand.c |  108 ++++++++++++++++++++++-------------------
  1 file changed, 57 insertions(+), 51 deletions(-)

drivers/mtd/nand/atmel_nand.c +0 -27

index de66382..113da93 100644
@@ -232,68 +232,19 @@ static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat,
  static void atmel_nand_hwctl(struct mtd_info *mtd, int mode)
  {
  }
-#endif
-
-static void at91_nand_hwcontrol(struct mtd_info *mtd,
-					 int cmd, unsigned int ctrl)
-{
-	struct nand_chip *this = mtd->priv;
-
-	if (ctrl & NAND_CTRL_CHANGE) {
-		ulong IO_ADDR_W = (ulong) this->IO_ADDR_W;
-		IO_ADDR_W &= ~(CONFIG_SYS_NAND_MASK_ALE
-			     | CONFIG_SYS_NAND_MASK_CLE);
-
-		if (ctrl & NAND_CLE)
-			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_CLE;
-		if (ctrl & NAND_ALE)
-			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_ALE;
-
-#ifdef CONFIG_SYS_NAND_ENABLE_PIN
-		at91_set_gpio_value(CONFIG_SYS_NAND_ENABLE_PIN,
-				    !(ctrl & NAND_NCE));
-#endif
-		this->IO_ADDR_W = (void *) IO_ADDR_W;
-	}
-
-	if (cmd != NAND_CMD_NONE)
-		writeb(cmd, this->IO_ADDR_W);
-}
 

drivers/mtd/nand/atmel_nand.c static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat, · line 236

Quoted 3 lines

drivers/mtd/nand/atmel_nand.c +1 -2

-#ifdef CONFIG_SYS_NAND_READY_PIN
-static int at91_nand_ready(struct mtd_info *mtd)
+int atmel_hw_nand_init_param(struct nand_chip *nand)

Grr ... just realized your kernel patch has the same named function. I would have named it with 'ecc' in ... nevertheless I would accept this.

drivers/mtd/nand/atmel_nand.c static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat, · line 238

Quoted 10 lines

drivers/mtd/nand/atmel_nand.c +0 -7

  {
-	return at91_get_gpio_value(CONFIG_SYS_NAND_READY_PIN);
-}
-#endif
-
-int board_nand_init(struct nand_chip *nand)
-{
-#ifdef CONFIG_ATMEL_NAND_HWECC
  	static int chip_nr = 0;

This seems to be an remnant. It seems this is a mixture between 'SELF_INIT' and older initialization by common nand code. Can you please adopt to the CONFIG_SYS_NAND_SELFINIT? -> please read doc/REDME.nand If I got this correctly you just need to move this static chip_nr plus mtd detection (nand_scan_ident()) into the board_nand_init() and call it _always_. Next step is to define CONFIG_SYS_NAND_SELFINIT in include/nand.h and fix compiler issues (board_nand_init then has no parameter).

I dunno if this is ok to call the nand_scan_ident twice when hwecc is enabled. Scott, can you please comment?

Quoted 22 lines

drivers/mtd/nand/atmel_nand.c +0 -13

  	struct mtd_info *mtd;
-#endif
-
-	nand->ecc.mode = NAND_ECC_SOFT;
-#ifdef CONFIG_SYS_NAND_DBW_16
-	nand->options = NAND_BUSWIDTH_16;
-#endif
-	nand->cmd_ctrl = at91_nand_hwcontrol;
-#ifdef CONFIG_SYS_NAND_READY_PIN
-	nand->dev_ready = at91_nand_ready;
-#endif
-	nand->chip_delay = 20;
 
-#ifdef CONFIG_ATMEL_NAND_HWECC
  	nand->ecc.mode = NAND_ECC_HW;
  	nand->ecc.calculate = atmel_nand_calculate;
  	nand->ecc.correct = atmel_nand_correct;
  	nand->ecc.hwctl = atmel_nand_hwctl;
  	nand->ecc.read_page = atmel_nand_read_page;
  	nand->ecc.bytes = 4;
-#endif
 

drivers/mtd/nand/atmel_nand.c static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat, · line 249

Quoted 3 lines

drivers/mtd/nand/atmel_nand.c +0 -1

-#ifdef CONFIG_ATMEL_NAND_HWECC
  	mtd = &nand_info[chip_nr++];
  	mtd->priv = nand;

I think this is the most problematic part. mtd->priv was setup in nand_init_chip(int) before, so why rewrite it here? I know it was this way before ... I wonder if anybody is using atmel_nand with hwecc.

Quoted 56 lines

drivers/mtd/nand/atmel_nand.c +46 -1

@@ -339,7 +290,62 @@ int board_nand_init(struct nand_chip *nand)
  			break;
  		}
  	}
-#endif
 
  	return 0;
  }
+
+#endif
+
+static void at91_nand_hwcontrol(struct mtd_info *mtd,
+					 int cmd, unsigned int ctrl)
+{
+	struct nand_chip *this = mtd->priv;
+
+	if (ctrl & NAND_CTRL_CHANGE) {
+		ulong IO_ADDR_W = (ulong) this->IO_ADDR_W;
+		IO_ADDR_W &= ~(CONFIG_SYS_NAND_MASK_ALE
+			     | CONFIG_SYS_NAND_MASK_CLE);
+
+		if (ctrl & NAND_CLE)
+			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_CLE;
+		if (ctrl & NAND_ALE)
+			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_ALE;
+
+#ifdef CONFIG_SYS_NAND_ENABLE_PIN
+		at91_set_gpio_value(CONFIG_SYS_NAND_ENABLE_PIN,
+				    !(ctrl & NAND_NCE));
+#endif
+		this->IO_ADDR_W = (void *) IO_ADDR_W;
+	}
+
+	if (cmd != NAND_CMD_NONE)
+		writeb(cmd, this->IO_ADDR_W);
+}
+
+#ifdef CONFIG_SYS_NAND_READY_PIN
+static int at91_nand_ready(struct mtd_info *mtd)
+{
+	return at91_get_gpio_value(CONFIG_SYS_NAND_READY_PIN);
+}
+#endif
+
+int board_nand_init(struct nand_chip *nand)
+{
+	int res = 0;
+
+	nand->ecc.mode = NAND_ECC_SOFT;
+#ifdef CONFIG_SYS_NAND_DBW_16
+	nand->options = NAND_BUSWIDTH_16;
+#endif
+	nand->cmd_ctrl = at91_nand_hwcontrol;
+#ifdef CONFIG_SYS_NAND_READY_PIN

drivers/mtd/nand/atmel_nand.c int board_nand_init(struct nand_chip *nand) · line 351

Quoted 10 lines

drivers/mtd/nand/atmel_nand.c +10 -0

+	nand->dev_ready = at91_nand_ready;
+#endif
+	nand->chip_delay = 20;
+
+#ifdef CONFIG_ATMEL_NAND_HWECC
+	res = atmel_hw_nand_init_param(nand);
+#endif
+
+	return res;
+}

Best regards

Andreas Bie?mann

Dear Josh Wu,

Quoted 36 lines · Josh Wu

Extract the hwecc initialization code into one function. It is a preparation for adding atmel PMECC support.

Signed-off-by Josh Wu <[email protected]>

---
 drivers/mtd/nand/atmel_nand.c |  108 ++++++++++++++++++++++-------------------
 1 file changed, 57 insertions(+), 51 deletions(-)

drivers/mtd/nand/atmel_nand.c +0 -21

index de66382..113da93 100644
@@ -232,68 +232,19 @@ static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat,
 static void atmel_nand_hwctl(struct mtd_info *mtd, int mode)
 {
 }
-#endif
-
-static void at91_nand_hwcontrol(struct mtd_info *mtd,
-					 int cmd, unsigned int ctrl)
-{
-	struct nand_chip *this = mtd->priv;
-
-	if (ctrl & NAND_CTRL_CHANGE) {
-		ulong IO_ADDR_W = (ulong) this->IO_ADDR_W;
-		IO_ADDR_W &= ~(CONFIG_SYS_NAND_MASK_ALE
-			     | CONFIG_SYS_NAND_MASK_CLE);
-
-		if (ctrl & NAND_CLE)
-			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_CLE;
-		if (ctrl & NAND_ALE)
-			IO_ADDR_W |= CONFIG_SYS_NAND_MASK_ALE;
-
-#ifdef CONFIG_SYS_NAND_ENABLE_PIN
-		at91_set_gpio_value(CONFIG_SYS_NAND_ENABLE_PIN,
-				    !(ctrl & NAND_NCE));
-#endif

drivers/mtd/nand/atmel_nand.c static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat, · line 236

Quoted 10 lines

drivers/mtd/nand/atmel_nand.c +1 -8

-		this->IO_ADDR_W = (void *) IO_ADDR_W;
-	}
-
-	if (cmd != NAND_CMD_NONE)
-		writeb(cmd, this->IO_ADDR_W);
-}
 
-#ifdef CONFIG_SYS_NAND_READY_PIN
-static int at91_nand_ready(struct mtd_info *mtd)
+int atmel_hw_nand_init_param(struct nand_chip *nand)

Grr ... just realized your kernel patch has the same named function. I would have named it with 'ecc' in ... nevertheless I would accept this.

drivers/mtd/nand/atmel_nand.c static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat, · line 238

Quoted 9 lines

drivers/mtd/nand/atmel_nand.c +0 -7

 {
-	return at91_get_gpio_value(CONFIG_SYS_NAND_READY_PIN);
-}
-#endif
-
-int board_nand_init(struct nand_chip *nand)
-{
-#ifdef CONFIG_ATMEL_NAND_HWECC
 	static int chip_nr = 0;

This seems to be an remnant. It seems this is a mixture between 'SELF_INIT' and older initialization by common nand code. Can you please adopt to the CONFIG_SYS_NAND_SELFINIT? -> please read doc/REDME.nand If I got this correctly you just need to move this static chip_nr plus mtd detection (nand_scan_ident()) into the board_nand_init() and call it _always_. Next step is to define CONFIG_SYS_NAND_SELFINIT in include/nand.h and fix compiler issues (board_nand_init then has no parameter).

I dunno if this is ok to call the nand_scan_ident twice when hwecc is enabled. Scott, can you please comment?

Signed-off-by Josh Wu <[email protected]>

---
 drivers/mtd/nand/atmel_nand.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

drivers/mtd/nand/atmel_nand.c +0 -1

index 113da93..9dc003e 100644
@@ -79,7 +79,6 @@ static struct nand_ecclayout atmel_oobinfo_small = {
 static int atmel_nand_calculate(struct mtd_info *mtd,
 		const u_char *dat, unsigned char *ecc_code)
 {
-	struct nand_chip *nand_chip = mtd->priv;
 	unsigned int ecc_value;
 
 	/* get the first 2 ECC bytes */

The Programmable Multibit ECC (PMECC) controller is a programmable binary BCH(Bose, Chaudhuri and Hocquenghem) encoder and decoder. This controller can be used to support both SLC and MLC NAND Flash devices. It supports to generate ECC to correct 2, 4, 8, 12 or 24 bits of error per sector of data.

To use PMECC in this driver, the user needs to set the PMECC correction capability, the sector size and ROM lookup table offsets in board config file.

This driver is ported from Linux kernel atmel_nand PMECC patch. The main difference is in this version it uses registers structure access hardware instead of using macros. It is tested in 9x5 serial boards.

Signed-off-by Josh Wu <[email protected]>

---
Changes since v1:
Change 'ecc' array's type from u32 to u8 in structure pmecc_regs (u32 ecc[11] -> u8 ecc[44]). That will make PMECC write correctly. enable 4k-page nand flash pmecc support.
fix coding style errors and warnings.
changed lookup table variable name which sounds correct.

 drivers/mtd/nand/atmel_nand.c     |  654 ++++++++++++++++++++++++++++++++++++-
 drivers/mtd/nand/atmel_nand_ecc.h |  111 +++++++
 2 files changed, 763 insertions(+), 2 deletions(-)

drivers/mtd/nand/atmel_nand.c +23 -0

index 9dc003e..784370c 100644
@@ -5,6 +5,9 @@
  *
  * (C) Copyright 2006 ATMEL Rousset, Lacressonniere Nicolas
  *
+ * Add Programmable Multibit ECC support for various AT91 SoC
+ *     (C) Copyright 2012 ATMEL, Hong Xu
+ *
  * See file CREDITS for list of people who contributed to this
  * project.
  *

@@ -41,6 +44,648 @@
 
 #include "atmel_nand_ecc.h"	/* Hardware ECC registers */
 
+static int chip_nr;
+
+#ifdef CONFIG_ATMEL_NAND_HW_PMECC
+
+struct atmel_nand_host {
+	struct pmecc_regs __iomem *pmecc;
+	struct pmecc_errloc_regs __iomem *pmerrloc;
+	void __iomem		*pmecc_rom_base;
+
+	u8		pmecc_corr_cap;
+	u16		pmecc_sector_size;
+	u32		pmecc_index_table_offset;
+
+	int		pmecc_bytes_per_sector;
+	int		pmecc_sector_number;
+	int		pmecc_degree;	/* Degree of remainders */
+	int		pmecc_cw_len;	/* Length of codeword */
+
+	/* lookup table for alpha_to and index_of */
+	void __iomem	*pmecc_alpha_to;

drivers/mtd/nand/atmel_nand.c +140 -0

+};
+
+static struct atmel_nand_host pmecc_host;
+static struct nand_ecclayout atmel_pmecc_oobinfo;
+
+/*
+ * Return number of ecc bytes per sector according to sector size and
+ * correction capability
+ *
+ * Following table shows what at91 PMECC supported:
+ * Correction Capability	Sector_512_bytes	Sector_1024_bytes
+ * =====================	================	=================
+ *                2-bits                 4-bytes                  4-bytes
+ *                4-bits                 7-bytes                  7-bytes
+ *                8-bits                13-bytes                 14-bytes
+ *               12-bits                20-bytes                 21-bytes
+ *               24-bits                39-bytes                 42-bytes
+ */
+static int pmecc_get_ecc_bytes(int cap, int sector_size)
+{
+	int m = 12 + sector_size / 512;
+	return (m * cap + 7) / 8;
+}
+
+static void pmecc_config_ecc_layout(struct nand_ecclayout *layout,
+	int oobsize, int ecc_len)
+{
+	int i;
+
+	layout->eccbytes = ecc_len;
+
+	/* ECC will occupy the last ecc_len bytes continuously */
+	for (i = 0; i < ecc_len; i++)
+		layout->eccpos[i] = oobsize - ecc_len + i;
+
+	layout->oobfree[0].offset = 2;
+	layout->oobfree[0].length =
+		oobsize - ecc_len - layout->oobfree[0].offset;
+}
+
+static void __iomem *pmecc_get_alpha_to(struct atmel_nand_host *host)
+{
+	int table_size;
+
+	table_size = host->pmecc_sector_size == 512 ?
+		PMECC_INDEX_TABLE_SIZE_512 : PMECC_INDEX_TABLE_SIZE_1024;
+
+	/* the ALPHA lookup table is right behind the INDEX lookup table. */
+	return host->pmecc_rom_base + host->pmecc_index_table_offset +
+			table_size * sizeof(int16_t);
+}
+
+static void pmecc_gen_syndrome(struct mtd_info *mtd, int sector)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int i;
+	uint32_t value;
+
+	/* Fill odd syndromes */
+	for (i = 0; i < host->pmecc_corr_cap; i++) {
+		value = readl(&host->pmecc->rem_port[sector].rem[i / 2]);
+		if (i & 1)
+			value >>= 16;
+		value &= 0xffff;
+		host->pmecc_partial_syn[(2 * i) + 1] = (int16_t)value;
+	}
+}
+
+static void pmecc_substitute(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int16_t __iomem *alpha_to = host->pmecc_alpha_to;
+	int16_t __iomem *index_of = host->pmecc_index_of;
+	int16_t *partial_syn = host->pmecc_partial_syn;
+	const int cap = host->pmecc_corr_cap;
+	int16_t *si;
+	int i, j;
+
+	/* si[] is a table that holds the current syndrome value,
+	 * an element of that table belongs to the field
+	 */
+	si = host->pmecc_si;
+
+	memset(&si[1], 0, sizeof(int16_t) * (2 * cap - 1));
+
+	/* Computation 2t syndromes based on S(x) */
+	/* Odd syndromes */
+	for (i = 1; i < 2 * cap; i += 2) {
+		for (j = 0; j < host->pmecc_degree; j++) {
+			if (partial_syn[i] & ((unsigned short)0x1 << j))
+				si[i] = readw(alpha_to + i * j) ^ si[i];
+		}
+	}
+	/* Even syndrome = (Odd syndrome) ** 2 */
+	for (i = 2, j = 1; j <= cap; i = ++j << 1) {
+		if (si[j] == 0) {
+			si[i] = 0;
+		} else {
+			int16_t tmp;
+
+			tmp = readw(index_of + si[j]);
+			tmp = (tmp * 2) % host->pmecc_cw_len;
+			si[i] = readw(alpha_to + tmp);
+		}
+	}
+
+	return;
+}
+
+static void pmecc_get_sigma(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+
+	int16_t *lmu = host->pmecc_lmu;
+	int16_t *si = host->pmecc_si;
+	int *mu = host->pmecc_mu;
+	int *dmu = host->pmecc_dmu;	/* Discrepancy */
+	int *delta = host->pmecc_delta; /* Delta order */
+	int cw_len = host->pmecc_cw_len;
+	const int16_t cap = host->pmecc_corr_cap;
+	const int num = 2 * cap + 1;
+	int16_t __iomem	*index_of = host->pmecc_index_of;
+	int16_t __iomem	*alpha_to = host->pmecc_alpha_to;
+	int i, j, k;
+	uint32_t dmu_0_count, tmp;
+	int16_t *smu = host->pmecc_smu;
+
+	/* index of largest delta */
+	int ro;
+	int largest;
+	int diff;
+
+	dmu_0_count = 0;
+
+	/* First Row */
+
+	/* Mu */

drivers/mtd/nand/atmel_nand.c +6 -0

+
+	/* Second Row */
+
+	/* Mu */
+	mu[1] = 0;
+	/* Sigma(x) set to 1 */

drivers/mtd/nand/atmel_nand.c +19 -0

+
+	for (i = 1; i <= cap; i++) {
+		mu[i + 1] = i << 1;
+		/* Begin Computing Sigma (Mu+1) and L(mu) */
+		/* check if discrepancy is set to 0 */
+		if (dmu[i] == 0) {
+			dmu_0_count++;
+
+			tmp = ((cap - (lmu[i] >> 1) - 1) / 2);
+			if ((cap - (lmu[i] >> 1) - 1) & 0x1)
+				tmp += 2;
+			else
+				tmp += 1;
+
+			if (dmu_0_count == tmp) {
+				for (j = 0; j <= (lmu[i] >> 1) + 1; j++)
+					smu[(cap + 1) * num + j] =
+							smu[i * num + j];
+

drivers/mtd/nand/atmel_nand.c +91 -0

+		} else {
+			ro = 0;
+			largest = -1;
+			/* find largest delta with dmu != 0 */
+			for (j = 0; j < i; j++) {
+				if ((dmu[j]) && (delta[j] > largest)) {
+					largest = delta[j];
+					ro = j;
+				}
+			}
+
+			/* compute difference */
+			diff = (mu[i] - mu[ro]);
+
+			/* Compute degree of the new smu polynomial */
+			if ((lmu[i] >> 1) > ((lmu[ro] >> 1) + diff))
+				lmu[i + 1] = lmu[i];
+			else
+				lmu[i + 1] = ((lmu[ro] >> 1) + diff) * 2;
+
+			/* Init smu[i+1] with 0 */
+			for (k = 0; k < num; k++)
+				smu[(i + 1) * num + k] = 0;
+
+			/* Compute smu[i+1] */
+			for (k = 0; k <= lmu[ro] >> 1; k++) {
+				int16_t a, b, c;
+
+				if (!(smu[ro * num + k] && dmu[i]))
+					continue;
+				a = readw(index_of + dmu[i]);
+				b = readw(index_of + dmu[ro]);
+				c = readw(index_of + smu[ro * num + k]);
+				tmp = a + (cw_len - b) + c;
+				a = readw(alpha_to + tmp % cw_len);
+				smu[(i + 1) * num + (k + diff)] = a;
+			}
+
+			for (k = 0; k <= lmu[i] >> 1; k++)
+				smu[(i + 1) * num + k] ^= smu[i * num + k];
+		}
+
+		/* End Computing Sigma (Mu+1) and L(mu) */
+		/* In either case compute delta */
+		delta[i + 1] = (mu[i + 1] * 2 - lmu[i + 1]) >> 1;
+
+		/* Do not compute discrepancy for the last iteration */
+		if (i >= cap)
+			continue;
+
+		for (k = 0; k <= (lmu[i + 1] >> 1); k++) {
+			tmp = 2 * (i - 1);
+			if (k == 0) {
+				dmu[i + 1] = si[tmp + 3];
+			} else if (smu[(i + 1) * num + k] && si[tmp + 3 - k]) {
+				int16_t a, b, c;
+				a = readw(index_of +
+						smu[(i + 1) * num + k]);
+				b = si[2 * (i - 1) + 3 - k];
+				c = readw(index_of + b);
+				tmp = a + c;
+				tmp %= cw_len;
+				dmu[i + 1] = readw(alpha_to + tmp) ^
+					dmu[i + 1];
+			}
+		}
+	}
+
+	return;
+}
+
+static int pmecc_err_location(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	const int cap = host->pmecc_corr_cap;
+	const int num = 2 * cap + 1;
+	int sector_size = host->pmecc_sector_size;
+	int err_nbr = 0;	/* number of error */
+	int roots_nbr;		/* number of roots */
+	int i;
+	uint32_t val;
+	int16_t *smu = host->pmecc_smu;
+
+	writel(PMERRLOC_DISABLE, &host->pmerrloc->eldis);
+
+	for (i = 0; i <= host->pmecc_lmu[cap + 1] >> 1; i++) {
+		writel(smu[(cap + 1) * num + i], &host->pmerrloc->sigma[i]);
+		err_nbr++;
+	}
+

drivers/mtd/nand/atmel_nand.c +224 -0

+
+	roots_nbr = (readl(&host->pmerrloc->elisr) & PMERRLOC_ERR_NUM_MASK)
+			>> 8;
+	/* Number of roots == degree of smu hence <= cap */
+	if (roots_nbr == host->pmecc_lmu[cap + 1] >> 1)
+		return err_nbr - 1;
+
+	/* Number of roots does not match the degree of smu
+	 * unable to correct error */
+	return -1;
+}
+
+static void pmecc_correct_data(struct mtd_info *mtd, uint8_t *buf, uint8_t *ecc,
+		int sector_num, int extra_bytes, int err_nbr)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int i = 0;
+	int byte_pos, bit_pos, sector_size, pos;
+	uint32_t tmp;
+	uint8_t err_byte;
+
+	sector_size = host->pmecc_sector_size;
+
+	while (err_nbr) {
+		tmp = readl(&host->pmerrloc->el[i]) - 1;
+		byte_pos = tmp / 8;
+		bit_pos  = tmp % 8;
+
+		if (byte_pos >= (sector_size + extra_bytes))
+			BUG();	/* should never happen */
+
+		if (byte_pos < sector_size) {
+			err_byte = *(buf + byte_pos);
+			*(buf + byte_pos) ^= (1 << bit_pos);
+
+			pos = sector_num * host->pmecc_sector_size + byte_pos;
+			printk(KERN_INFO "Bit flip in data area, byte_pos: %d, bit_pos: %d, 0x%02x -> 0x%02x\n",
+				pos, bit_pos, err_byte, *(buf + byte_pos));
+		} else {
+			/* Bit flip in OOB area */
+			tmp = sector_num * host->pmecc_bytes_per_sector
+					+ (byte_pos - sector_size);
+			err_byte = ecc[tmp];
+			ecc[tmp] ^= (1 << bit_pos);
+
+			pos = tmp + nand_chip->ecc.layout->eccpos[0];
+			printk(KERN_INFO "Bit flip in OOB, oob_byte_pos: %d, bit_pos: %d, 0x%02x -> 0x%02x\n",
+				pos, bit_pos, err_byte, ecc[tmp]);
+		}
+
+		i++;
+		err_nbr--;
+	}
+
+	return;
+}
+
+static int pmecc_correction(struct mtd_info *mtd, u32 pmecc_stat, uint8_t *buf,
+	u8 *ecc)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int i, err_nbr, eccbytes;
+	uint8_t *buf_pos;
+
+	eccbytes = nand_chip->ecc.bytes;
+	for (i = 0; i < eccbytes; i++)
+		if (ecc[i] != 0xff)
+			goto normal_check;
+	/* Erased page, return OK */
+	return 0;
+
+normal_check:
+	for (i = 0; i < host->pmecc_sector_number; i++) {
+		err_nbr = 0;
+		if (pmecc_stat & 0x1) {
+			buf_pos = buf + i * host->pmecc_sector_size;
+
+			pmecc_gen_syndrome(mtd, i);
+			pmecc_substitute(mtd);
+			pmecc_get_sigma(mtd);
+
+			err_nbr = pmecc_err_location(mtd);
+			if (err_nbr == -1) {
+				printk(KERN_ERR "PMECC: Too many errors\n");
+				mtd->ecc_stats.failed++;
+				return -EIO;
+			} else {
+				pmecc_correct_data(mtd, buf_pos, ecc, i,
+					host->pmecc_bytes_per_sector, err_nbr);
+				mtd->ecc_stats.corrected += err_nbr;
+			}
+		}
+		pmecc_stat >>= 1;
+	}
+
+	return 0;
+}
+
+static int atmel_nand_pmecc_read_page(struct mtd_info *mtd,
+	struct nand_chip *chip, uint8_t *buf, int page)
+{
+	struct atmel_nand_host *host = chip->priv;
+	int eccsize = chip->ecc.size;
+	uint8_t *oob = chip->oob_poi;
+	uint32_t *eccpos = chip->ecc.layout->eccpos;
+	uint32_t stat;
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_RST);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DISABLE);
+	pmecc_writel(host->pmecc, cfg, ((pmecc_readl(host->pmecc, cfg))
+		& ~PMECC_CFG_WRITE_OP) | PMECC_CFG_AUTO_ENABLE);
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_ENABLE);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DATA);
+
+	chip->read_buf(mtd, buf, eccsize);
+	chip->read_buf(mtd, oob, mtd->oobsize);
+
+	while ((pmecc_readl(host->pmecc, sr) & PMECC_SR_BUSY))
+		udelay(1);
+
+	stat = pmecc_readl(host->pmecc, isr);
+	if (stat != 0)
+		if (pmecc_correction(mtd, stat, buf, &oob[eccpos[0]]) != 0)
+			return -EIO;
+
+	return 0;
+}
+
+static void atmel_nand_pmecc_write_page(struct mtd_info *mtd,
+		struct nand_chip *chip, const uint8_t *buf)
+{
+	struct atmel_nand_host *host = chip->priv;
+	uint32_t *eccpos = chip->ecc.layout->eccpos;
+	int i, j;
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_RST);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DISABLE);
+
+	pmecc_writel(host->pmecc, cfg, (pmecc_readl(host->pmecc, cfg) |
+		PMECC_CFG_WRITE_OP) & ~PMECC_CFG_AUTO_ENABLE);
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_ENABLE);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DATA);
+
+	chip->write_buf(mtd, (u8 *)buf, mtd->writesize);
+
+	while ((pmecc_readl(host->pmecc, sr) & PMECC_SR_BUSY))
+		udelay(1);
+
+	for (i = 0; i < host->pmecc_sector_number; i++) {
+		for (j = 0; j < host->pmecc_bytes_per_sector; j++) {
+			int pos;
+
+			pos = i * host->pmecc_bytes_per_sector + j;
+			chip->oob_poi[eccpos[pos]] =
+				readb(&host->pmecc->ecc_port[i].ecc[j]);
+		}
+	}
+	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
+}
+
+static void atmel_pmecc_core_init(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	uint32_t val = 0;
+	struct nand_ecclayout *ecc_layout;
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_RST);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DISABLE);
+
+	switch (host->pmecc_corr_cap) {
+	case 2:
+		val = PMECC_CFG_BCH_ERR2;
+		break;
+	case 4:
+		val = PMECC_CFG_BCH_ERR4;
+		break;
+	case 8:
+		val = PMECC_CFG_BCH_ERR8;
+		break;
+	case 12:
+		val = PMECC_CFG_BCH_ERR12;
+		break;
+	case 24:
+		val = PMECC_CFG_BCH_ERR24;
+		break;
+	}
+
+	if (host->pmecc_sector_size == 512)
+		val |= PMECC_CFG_SECTOR512;
+	else if (host->pmecc_sector_size == 1024)
+		val |= PMECC_CFG_SECTOR1024;
+
+	switch (host->pmecc_sector_number) {
+	case 1:
+		val |= PMECC_CFG_PAGE_1SECTOR;
+		break;
+	case 2:
+		val |= PMECC_CFG_PAGE_2SECTORS;
+		break;
+	case 4:
+		val |= PMECC_CFG_PAGE_4SECTORS;
+		break;
+	case 8:
+		val |= PMECC_CFG_PAGE_8SECTORS;
+		break;
+	}
+
+	val |= (PMECC_CFG_READ_OP | PMECC_CFG_SPARE_DISABLE
+		| PMECC_CFG_AUTO_DISABLE);
+	pmecc_writel(host->pmecc, cfg, val);
+
+	ecc_layout = nand_chip->ecc.layout;
+	pmecc_writel(host->pmecc, sarea, mtd->oobsize - 1);
+	pmecc_writel(host->pmecc, saddr, ecc_layout->eccpos[0]);
+	pmecc_writel(host->pmecc, eaddr,
+			ecc_layout->eccpos[ecc_layout->eccbytes - 1]);
+	/* See datasheet about PMECC Clock Control Register */
+	pmecc_writel(host->pmecc, clk, PMECC_CLK_133MHZ);
+	pmecc_writel(host->pmecc, idr, 0xff);

drivers/mtd/nand/atmel_nand.c +70 -2

+	host->pmecc_index_table_offset = CONFIG_PMECC_INDEX_TABLE_OFFSET;
+
+	printk(KERN_INFO "Initialize PMECC params, cap: %d, sector: %d\n",
+		 cap, sector_size);
+
+	host->pmecc = (struct pmecc_regs __iomem *) ATMEL_BASE_PMECC;
+	host->pmerrloc = (struct pmecc_errloc_regs __iomem *)
+			ATMEL_BASE_PMERRLOC;
+	host->pmecc_rom_base = (void __iomem *) ATMEL_BASE_ROM;
+
+	/* ECC is calculated for the whole page (1 step) */
+	nand->ecc.size = mtd->writesize;
+
+	/* set ECC page size and oob layout */
+	switch (mtd->writesize) {
+	case 2048:
+	case 4096:
+		host->pmecc_degree = PMECC_GF_DIMENSION_13;
+		host->pmecc_cw_len = (1 << host->pmecc_degree) - 1;
+		host->pmecc_sector_number = mtd->writesize / sector_size;
+		host->pmecc_bytes_per_sector = pmecc_get_ecc_bytes(
+			cap, sector_size);
+		host->pmecc_alpha_to = pmecc_get_alpha_to(host);
+		host->pmecc_index_of = host->pmecc_rom_base +
+			host->pmecc_index_table_offset;
+
+		nand->ecc.steps = 1;
+		nand->ecc.bytes = host->pmecc_bytes_per_sector *
+				       host->pmecc_sector_number;
+		if (nand->ecc.bytes > mtd->oobsize - 2) {
+			printk(KERN_ERR "No room for ECC bytes\n");
+			return -EINVAL;
+		}
+		pmecc_config_ecc_layout(&atmel_pmecc_oobinfo,
+					mtd->oobsize,
+					nand->ecc.bytes);
+		nand->ecc.layout = &atmel_pmecc_oobinfo;
+		break;
+	case 512:
+	case 1024:
+		/* TODO */
+		printk(KERN_ERR "Unsupported page size for PMECC, use Software ECC\n");
+	default:
+		/* page size not handled by HW ECC */
+		/* switching back to soft ECC */
+		nand->ecc.mode = NAND_ECC_SOFT;
+		nand->ecc.read_page = NULL;
+		nand->ecc.postpad = 0;
+		nand->ecc.prepad = 0;
+		nand->ecc.bytes = 0;
+		return 0;
+	}
+
+	nand->ecc.read_page = atmel_nand_pmecc_read_page;
+	nand->ecc.write_page = atmel_nand_pmecc_write_page;
+
+	atmel_pmecc_core_init(mtd);
+
+	return 0;
+}
+
+#else
+
 /* oob layout for large page size
  * bad block info is on bytes 0 and 1
  * the bytes have to be consecutives to avoid

@@ -234,7 +879,6 @@ static void atmel_nand_hwctl(struct mtd_info *mtd, int mode)
 
 int atmel_hw_nand_init_param(struct nand_chip *nand)
 {
-	static int chip_nr = 0;
 	struct mtd_info *mtd;
 
 	nand->ecc.mode = NAND_ECC_HW;

@@ -293,7 +937,9 @@ int atmel_hw_nand_init_param(struct nand_chip *nand)
 	return 0;
 }
 
-#endif
+#endif /* CONFIG_ATMEL_NAND_HW_PMECC */
+
+#endif /* CONFIG_ATMEL_NAND_HWECC */
 
 static void at91_nand_hwcontrol(struct mtd_info *mtd,
 					 int cmd, unsigned int ctrl)

@@ -343,8 +989,12 @@ int board_nand_init(struct nand_chip *nand)
 	nand->chip_delay = 20;
 
 #ifdef CONFIG_ATMEL_NAND_HWECC
+#ifdef CONFIG_ATMEL_NAND_HW_PMECC
+	res = atmel_pmecc_nand_init_params(nand);
+#else
 	res = atmel_hw_nand_init_param(nand);
 #endif
+#endif
 
 	return res;
 }

drivers/mtd/nand/atmel_nand_ecc.h +102 -0

index 1ee7f99..8f06b14 100644
@@ -33,4 +33,115 @@
 #define ATMEL_ECC_NPR		0x10			/* NParity register */
 #define		ATMEL_ECC_NPARITY	(0xffff << 0)		/* NParity */
 
+/* Register access macros for PMECC */
+#define pmecc_readl(addr, reg) \
+	readl(&addr->reg)
+
+#define pmecc_writel(addr, reg, value) \
+	writel((value), &addr->reg)
+
+/* PMECC Register Definitions */
+#define PMECC_MAX_SECTOR_NUM			8
+struct pmecc_regs {
+	u32 cfg;		/* 0x00 PMECC Configuration Register */
+	u32 sarea;		/* 0x04 PMECC Spare Area Size Register */
+	u32 saddr;		/* 0x08 PMECC Start Address Register */
+	u32 eaddr;		/* 0x0C PMECC End Address Register */
+	u32 clk;		/* 0x10 PMECC Clock Control Register */
+	u32 ctrl;		/* 0x14 PMECC Control Register */
+	u32 sr;			/* 0x18 PMECC Status Register */
+	u32 ier;		/* 0x1C PMECC Interrupt Enable Register */
+	u32 idr;		/* 0x20 PMECC Interrupt Disable Register */
+	u32 imr;		/* 0x24 PMECC Interrupt Mask Register */
+	u32 isr;		/* 0x28 PMECC Interrupt Status Register */
+	u32 reserved0[5];	/* 0x2C-0x3C Reserved */
+
+	/* 0x40 + sector_num * (0x40), Redundancy Registers */
+	struct {
+		u8 ecc[44];	/* PMECC Generated Redundancy Byte Per Sector */
+		u32 reserved1[5];
+	} ecc_port[PMECC_MAX_SECTOR_NUM];
+
+	/* 0x240 + sector_num * (0x40) Remainder Registers */
+	struct {
+		u32 rem[12];
+		u32 reserved2[4];
+	} rem_port[PMECC_MAX_SECTOR_NUM];
+	u32 reserved3[16];	/* 0x440-0x47C Reserved */
+};
+
+/* For PMECC Configuration Register */
+#define		PMECC_CFG_BCH_ERR2		(0 << 0)
+#define		PMECC_CFG_BCH_ERR4		(1 << 0)
+#define		PMECC_CFG_BCH_ERR8		(2 << 0)
+#define		PMECC_CFG_BCH_ERR12		(3 << 0)
+#define		PMECC_CFG_BCH_ERR24		(4 << 0)
+
+#define		PMECC_CFG_SECTOR512		(0 << 4)
+#define		PMECC_CFG_SECTOR1024		(1 << 4)
+
+#define		PMECC_CFG_PAGE_1SECTOR		(0 << 8)
+#define		PMECC_CFG_PAGE_2SECTORS		(1 << 8)
+#define		PMECC_CFG_PAGE_4SECTORS		(2 << 8)
+#define		PMECC_CFG_PAGE_8SECTORS		(3 << 8)
+
+#define		PMECC_CFG_READ_OP		(0 << 12)
+#define		PMECC_CFG_WRITE_OP		(1 << 12)
+
+#define		PMECC_CFG_SPARE_ENABLE		(1 << 16)
+#define		PMECC_CFG_SPARE_DISABLE		(0 << 16)
+
+#define		PMECC_CFG_AUTO_ENABLE		(1 << 20)
+#define		PMECC_CFG_AUTO_DISABLE		(0 << 20)
+
+/* For PMECC Clock Control Register */
+#define		PMECC_CLK_133MHZ		(2 << 0)
+
+/* For PMECC Control Register */
+#define		PMECC_CTRL_RST			(1 << 0)
+#define		PMECC_CTRL_DATA			(1 << 1)
+#define		PMECC_CTRL_USER			(1 << 2)
+#define		PMECC_CTRL_ENABLE		(1 << 4)
+#define		PMECC_CTRL_DISABLE		(1 << 5)
+
+/* For PMECC Status Register */
+#define		PMECC_SR_BUSY			(1 << 0)
+#define		PMECC_SR_ENABLE			(1 << 4)
+
+/* PMERRLOC Register Definitions */
+struct pmecc_errloc_regs {
+	u32 elcfg;	/* 0x00 Error Location Configuration Register */
+	u32 elprim;	/* 0x04 Error Location Primitive Register */
+	u32 elen;	/* 0x08 Error Location Enable Register */
+	u32 eldis;	/* 0x0C Error Location Disable Register */
+	u32 elsr;	/* 0x10 Error Location Status Register */
+	u32 elier;	/* 0x14 Error Location Interrupt Enable Register */
+	u32 elidr;	/* 0x08 Error Location Interrupt Disable Register */
+	u32 elimr;	/* 0x0C Error Location Interrupt Mask Register */
+	u32 elisr;	/* 0x20 Error Location Interrupt Status Register */
+	u32 reserved0;	/* 0x24 Reserved */
+	u32 sigma[25];	/* 0x28-0x88 Error Location Sigma Registers */
+	u32 el[24];	/* 0x8C-0xE8 Error Location Registers */
+	u32 reserved1[5];	/* 0xEC-0xFC Reserved */
+};
+
+/* For Error Location Configuration Register */
+#define		PMERRLOC_ELCFG_SECTOR_512	(0 << 0)
+#define		PMERRLOC_ELCFG_SECTOR_1024	(1 << 0)
+#define		PMERRLOC_ELCFG_NUM_ERRORS(n)	((n) << 16)
+
+/* For Error Location Disable Register */
+#define		PMERRLOC_DISABLE		(1 << 0)
+
+/* For Error Location Interrupt Status Register */
+#define		PMERRLOC_ERR_NUM_MASK		(0x1f << 8)

Dear Josh Wu,

Quoted 68 lines · Josh Wu

The Programmable Multibit ECC (PMECC) controller is a programmable binary BCH(Bose, Chaudhuri and Hocquenghem) encoder and decoder. This controller can be used to support both SLC and MLC NAND Flash devices. It supports to generate ECC to correct 2, 4, 8, 12 or 24 bits of error per sector of data.

To use PMECC in this driver, the user needs to set the PMECC correction capability, the sector size and ROM lookup table offsets in board config file.

This driver is ported from Linux kernel atmel_nand PMECC patch. The main difference is in this version it uses registers structure access hardware instead of using macros. It is tested in 9x5 serial boards.

Signed-off-by Josh Wu <[email protected]>

---
Changes since v1:
Change 'ecc' array's type from u32 to u8 in structure pmecc_regs (u32 ecc[11] -> u8 ecc[44]). That will make PMECC write correctly. enable 4k-page nand flash pmecc support.
fix coding style errors and warnings.
changed lookup table variable name which sounds correct.

  drivers/mtd/nand/atmel_nand.c     |  654 ++++++++++++++++++++++++++++++++++++-
  drivers/mtd/nand/atmel_nand_ecc.h |  111 +++++++
  2 files changed, 763 insertions(+), 2 deletions(-)

drivers/mtd/nand/atmel_nand.c +29 -0

index 9dc003e..784370c 100644
@@ -5,6 +5,9 @@
   *
   * (C) Copyright 2006 ATMEL Rousset, Lacressonniere Nicolas
   *
+ * Add Programmable Multibit ECC support for various AT91 SoC
+ *     (C) Copyright 2012 ATMEL, Hong Xu
+ *
   * See file CREDITS for list of people who contributed to this
   * project.
   *

@@ -41,6 +44,648 @@
 
  #include "atmel_nand_ecc.h"	/* Hardware ECC registers */
 
+static int chip_nr;
+
+#ifdef CONFIG_ATMEL_NAND_HW_PMECC
+
+struct atmel_nand_host {
+	struct pmecc_regs __iomem *pmecc;
+	struct pmecc_errloc_regs __iomem *pmerrloc;
+	void __iomem		*pmecc_rom_base;
+
+	u8		pmecc_corr_cap;
+	u16		pmecc_sector_size;
+	u32		pmecc_index_table_offset;
+
+	int		pmecc_bytes_per_sector;
+	int		pmecc_sector_number;
+	int		pmecc_degree;	/* Degree of remainders */
+	int		pmecc_cw_len;	/* Length of codeword */
+
+	/* lookup table for alpha_to and index_of */
+	void __iomem	*pmecc_alpha_to;
+	void __iomem	*pmecc_index_of;
+
+	/* data for pmecc computation */
+	int16_t	pmecc_smu[(CONFIG_PMECC_CAP + 2) * (2 * CONFIG_PMECC_CAP + 1)];
+	int16_t	pmecc_partial_syn[2 * CONFIG_PMECC_CAP + 1];
+	int16_t	pmecc_si[2 * CONFIG_PMECC_CAP + 1];

drivers/mtd/nand/atmel_nand.c line 76

Quoted 4 lines

drivers/mtd/nand/atmel_nand.c +4 -0

+	int16_t	pmecc_lmu[CONFIG_PMECC_CAP + 1]; /* polynomal order */
+	int	pmecc_mu[CONFIG_PMECC_CAP + 1];
+	int	pmecc_dmu[CONFIG_PMECC_CAP + 1];
+	int	pmecc_delta[CONFIG_PMECC_CAP + 1];

can you please add some README entry describing these new config parameters? Namely CONFIG_ATMEL_NAND_HW_PMECC, CONFIG_PMECC_CAP, CONFIG_PMECC_SECTOR_SIZE (can't this be derived from some already available NAND information?) and CONFIG_PMECC_INDEX_TABLE_OFFSET.

Quoted 145 lines

drivers/mtd/nand/atmel_nand.c +144 -0

+};
+
+static struct atmel_nand_host pmecc_host;
+static struct nand_ecclayout atmel_pmecc_oobinfo;
+
+/*
+ * Return number of ecc bytes per sector according to sector size and
+ * correction capability
+ *
+ * Following table shows what at91 PMECC supported:
+ * Correction Capability	Sector_512_bytes	Sector_1024_bytes
+ * =====================	================	=================
+ *                2-bits                 4-bytes                  4-bytes
+ *                4-bits                 7-bytes                  7-bytes
+ *                8-bits                13-bytes                 14-bytes
+ *               12-bits                20-bytes                 21-bytes
+ *               24-bits                39-bytes                 42-bytes
+ */
+static int pmecc_get_ecc_bytes(int cap, int sector_size)
+{
+	int m = 12 + sector_size / 512;
+	return (m * cap + 7) / 8;
+}
+
+static void pmecc_config_ecc_layout(struct nand_ecclayout *layout,
+	int oobsize, int ecc_len)
+{
+	int i;
+
+	layout->eccbytes = ecc_len;
+
+	/* ECC will occupy the last ecc_len bytes continuously */
+	for (i = 0; i < ecc_len; i++)
+		layout->eccpos[i] = oobsize - ecc_len + i;
+
+	layout->oobfree[0].offset = 2;
+	layout->oobfree[0].length =
+		oobsize - ecc_len - layout->oobfree[0].offset;
+}
+
+static void __iomem *pmecc_get_alpha_to(struct atmel_nand_host *host)
+{
+	int table_size;
+
+	table_size = host->pmecc_sector_size == 512 ?
+		PMECC_INDEX_TABLE_SIZE_512 : PMECC_INDEX_TABLE_SIZE_1024;
+
+	/* the ALPHA lookup table is right behind the INDEX lookup table. */
+	return host->pmecc_rom_base + host->pmecc_index_table_offset +
+			table_size * sizeof(int16_t);
+}
+
+static void pmecc_gen_syndrome(struct mtd_info *mtd, int sector)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int i;
+	uint32_t value;
+
+	/* Fill odd syndromes */
+	for (i = 0; i < host->pmecc_corr_cap; i++) {
+		value = readl(&host->pmecc->rem_port[sector].rem[i / 2]);
+		if (i & 1)
+			value >>= 16;
+		value &= 0xffff;
+		host->pmecc_partial_syn[(2 * i) + 1] = (int16_t)value;
+	}
+}
+
+static void pmecc_substitute(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int16_t __iomem *alpha_to = host->pmecc_alpha_to;
+	int16_t __iomem *index_of = host->pmecc_index_of;
+	int16_t *partial_syn = host->pmecc_partial_syn;
+	const int cap = host->pmecc_corr_cap;
+	int16_t *si;
+	int i, j;
+
+	/* si[] is a table that holds the current syndrome value,
+	 * an element of that table belongs to the field
+	 */
+	si = host->pmecc_si;
+
+	memset(&si[1], 0, sizeof(int16_t) * (2 * cap - 1));
+
+	/* Computation 2t syndromes based on S(x) */
+	/* Odd syndromes */
+	for (i = 1; i < 2 * cap; i += 2) {
+		for (j = 0; j < host->pmecc_degree; j++) {
+			if (partial_syn[i] & ((unsigned short)0x1 << j))
+				si[i] = readw(alpha_to + i * j) ^ si[i];
+		}
+	}
+	/* Even syndrome = (Odd syndrome) ** 2 */
+	for (i = 2, j = 1; j <= cap; i = ++j << 1) {
+		if (si[j] == 0) {
+			si[i] = 0;
+		} else {
+			int16_t tmp;
+
+			tmp = readw(index_of + si[j]);
+			tmp = (tmp * 2) % host->pmecc_cw_len;
+			si[i] = readw(alpha_to + tmp);
+		}
+	}
+
+	return;
+}
+
+static void pmecc_get_sigma(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+
+	int16_t *lmu = host->pmecc_lmu;
+	int16_t *si = host->pmecc_si;
+	int *mu = host->pmecc_mu;
+	int *dmu = host->pmecc_dmu;	/* Discrepancy */
+	int *delta = host->pmecc_delta; /* Delta order */
+	int cw_len = host->pmecc_cw_len;
+	const int16_t cap = host->pmecc_corr_cap;
+	const int num = 2 * cap + 1;
+	int16_t __iomem	*index_of = host->pmecc_index_of;
+	int16_t __iomem	*alpha_to = host->pmecc_alpha_to;
+	int i, j, k;
+	uint32_t dmu_0_count, tmp;
+	int16_t *smu = host->pmecc_smu;
+
+	/* index of largest delta */
+	int ro;
+	int largest;
+	int diff;
+
+	dmu_0_count = 0;
+
+	/* First Row */
+
+	/* Mu */
+	mu[0] = -1;
+
+	memset(smu, 0, sizeof(int16_t) * num);
+	smu[0] = 1;

drivers/mtd/nand/atmel_nand.c line 226

Quoted 6 lines

drivers/mtd/nand/atmel_nand.c +6 -0

+
+	/* discrepancy set to 1 */
+	dmu[0] = 1;
+	/* polynom order set to 0 */
+	lmu[0] = 0;
+	delta[0] = (mu[0] * 2 - lmu[0]) >> 1;

---------------------^
isn't mu[0] -1 here

Quoted 6 lines

drivers/mtd/nand/atmel_nand.c +6 -0

+
+	/* Second Row */
+
+	/* Mu */
+	mu[1] = 0;
+	/* Sigma(x) set to 1 */

drivers/mtd/nand/atmel_nand.c line 242

Quoted 10 lines

drivers/mtd/nand/atmel_nand.c +10 -0

+	memset(&smu[num], 0, sizeof(int16_t) * num);
+	smu[num] = 1;
+
+	/* discrepancy set to S1 */
+	dmu[1] = si[1];
+
+	/* polynom order set to 0 */
+	lmu[1] = 0;
+
+	delta[1] = (mu[1] * 2 - lmu[1]) >> 1;

----------------------^
isn't mu[1] 0 here?

I see, this algorithm is just copied from the processors datasheet.

drivers/mtd/nand/atmel_nand.c line 245

Quoted 4 lines

drivers/mtd/nand/atmel_nand.c +3 -0

+
+	/* Init the Sigma(x) last row */
+	memset(&smu[(cap + 1) * num], 0, sizeof(int16_t) * num);

Isn't the whole smu zeroed here at this stage? why not just call memset(smu, 0, sizeof(int16) * ARRAY_SIZE(smu))?

Quoted 26 lines

drivers/mtd/nand/atmel_nand.c +25 -0

+
+	for (i = 1; i <= cap; i++) {
+		mu[i + 1] = i << 1;
+		/* Begin Computing Sigma (Mu+1) and L(mu) */
+		/* check if discrepancy is set to 0 */
+		if (dmu[i] == 0) {
+			dmu_0_count++;
+
+			tmp = ((cap - (lmu[i] >> 1) - 1) / 2);
+			if ((cap - (lmu[i] >> 1) - 1) & 0x1)
+				tmp += 2;
+			else
+				tmp += 1;
+
+			if (dmu_0_count == tmp) {
+				for (j = 0; j <= (lmu[i] >> 1) + 1; j++)
+					smu[(cap + 1) * num + j] =
+							smu[i * num + j];
+
+				lmu[cap + 1] = lmu[i];
+				return;
+			}
+
+			/* copy polynom */
+			for (j = 0; j <= lmu[i] >> 1; j++)

drivers/mtd/nand/atmel_nand.c line 274

Quoted 4 lines

drivers/mtd/nand/atmel_nand.c +4 -0

+				smu[(i + 1) * num + j] = smu[i * num + j];
+
+			/* copy previous polynom order to the next */
+			lmu[i + 1] = lmu[i];

Horrible to read, this was written first by an electrical engineer (insider joke)? Can you please add a comment at top of pmecc_get_sigma and add a warning about extremely complicated to read algorithm ;) But it must be right cause it is written down in the datasheet ...

Quoted 96 lines

drivers/mtd/nand/atmel_nand.c +95 -0

+		} else {
+			ro = 0;
+			largest = -1;
+			/* find largest delta with dmu != 0 */
+			for (j = 0; j < i; j++) {
+				if ((dmu[j]) && (delta[j] > largest)) {
+					largest = delta[j];
+					ro = j;
+				}
+			}
+
+			/* compute difference */
+			diff = (mu[i] - mu[ro]);
+
+			/* Compute degree of the new smu polynomial */
+			if ((lmu[i] >> 1) > ((lmu[ro] >> 1) + diff))
+				lmu[i + 1] = lmu[i];
+			else
+				lmu[i + 1] = ((lmu[ro] >> 1) + diff) * 2;
+
+			/* Init smu[i+1] with 0 */
+			for (k = 0; k < num; k++)
+				smu[(i + 1) * num + k] = 0;
+
+			/* Compute smu[i+1] */
+			for (k = 0; k <= lmu[ro] >> 1; k++) {
+				int16_t a, b, c;
+
+				if (!(smu[ro * num + k] && dmu[i]))
+					continue;
+				a = readw(index_of + dmu[i]);
+				b = readw(index_of + dmu[ro]);
+				c = readw(index_of + smu[ro * num + k]);
+				tmp = a + (cw_len - b) + c;
+				a = readw(alpha_to + tmp % cw_len);
+				smu[(i + 1) * num + (k + diff)] = a;
+			}
+
+			for (k = 0; k <= lmu[i] >> 1; k++)
+				smu[(i + 1) * num + k] ^= smu[i * num + k];
+		}
+
+		/* End Computing Sigma (Mu+1) and L(mu) */
+		/* In either case compute delta */
+		delta[i + 1] = (mu[i + 1] * 2 - lmu[i + 1]) >> 1;
+
+		/* Do not compute discrepancy for the last iteration */
+		if (i >= cap)
+			continue;
+
+		for (k = 0; k <= (lmu[i + 1] >> 1); k++) {
+			tmp = 2 * (i - 1);
+			if (k == 0) {
+				dmu[i + 1] = si[tmp + 3];
+			} else if (smu[(i + 1) * num + k] && si[tmp + 3 - k]) {
+				int16_t a, b, c;
+				a = readw(index_of +
+						smu[(i + 1) * num + k]);
+				b = si[2 * (i - 1) + 3 - k];
+				c = readw(index_of + b);
+				tmp = a + c;
+				tmp %= cw_len;
+				dmu[i + 1] = readw(alpha_to + tmp) ^
+					dmu[i + 1];
+			}
+		}
+	}
+
+	return;
+}
+
+static int pmecc_err_location(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	const int cap = host->pmecc_corr_cap;
+	const int num = 2 * cap + 1;
+	int sector_size = host->pmecc_sector_size;
+	int err_nbr = 0;	/* number of error */
+	int roots_nbr;		/* number of roots */
+	int i;
+	uint32_t val;
+	int16_t *smu = host->pmecc_smu;
+
+	writel(PMERRLOC_DISABLE, &host->pmerrloc->eldis);
+
+	for (i = 0; i <= host->pmecc_lmu[cap + 1] >> 1; i++) {
+		writel(smu[(cap + 1) * num + i], &host->pmerrloc->sigma[i]);
+		err_nbr++;
+	}
+
+	val = PMERRLOC_ELCFG_NUM_ERRORS(err_nbr - 1);
+	if (sector_size == 1024)
+		val |= PMERRLOC_ELCFG_SECTOR_1024;
+

drivers/mtd/nand/atmel_nand.c line 375

Quoted 6 lines

drivers/mtd/nand/atmel_nand.c +6 -0

+	writel(val, &host->pmerrloc->elcfg);
+	writel(sector_size * 8 + host->pmecc_degree * cap,
+			&host->pmerrloc->elen);
+
+	while (!(readl(&host->pmerrloc->elisr) & PMERRLOC_CALC_DONE))
+		udelay(10);

Can you please add some timeout here. Maybe a WATCHDOG_RESET is also required?

Quoted 228 lines

drivers/mtd/nand/atmel_nand.c +227 -0

+
+	roots_nbr = (readl(&host->pmerrloc->elisr) & PMERRLOC_ERR_NUM_MASK)
+			>> 8;
+	/* Number of roots == degree of smu hence <= cap */
+	if (roots_nbr == host->pmecc_lmu[cap + 1] >> 1)
+		return err_nbr - 1;
+
+	/* Number of roots does not match the degree of smu
+	 * unable to correct error */
+	return -1;
+}
+
+static void pmecc_correct_data(struct mtd_info *mtd, uint8_t *buf, uint8_t *ecc,
+		int sector_num, int extra_bytes, int err_nbr)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int i = 0;
+	int byte_pos, bit_pos, sector_size, pos;
+	uint32_t tmp;
+	uint8_t err_byte;
+
+	sector_size = host->pmecc_sector_size;
+
+	while (err_nbr) {
+		tmp = readl(&host->pmerrloc->el[i]) - 1;
+		byte_pos = tmp / 8;
+		bit_pos  = tmp % 8;
+
+		if (byte_pos >= (sector_size + extra_bytes))
+			BUG();	/* should never happen */
+
+		if (byte_pos < sector_size) {
+			err_byte = *(buf + byte_pos);
+			*(buf + byte_pos) ^= (1 << bit_pos);
+
+			pos = sector_num * host->pmecc_sector_size + byte_pos;
+			printk(KERN_INFO "Bit flip in data area, byte_pos: %d, bit_pos: %d, 0x%02x -> 0x%02x\n",
+				pos, bit_pos, err_byte, *(buf + byte_pos));
+		} else {
+			/* Bit flip in OOB area */
+			tmp = sector_num * host->pmecc_bytes_per_sector
+					+ (byte_pos - sector_size);
+			err_byte = ecc[tmp];
+			ecc[tmp] ^= (1 << bit_pos);
+
+			pos = tmp + nand_chip->ecc.layout->eccpos[0];
+			printk(KERN_INFO "Bit flip in OOB, oob_byte_pos: %d, bit_pos: %d, 0x%02x -> 0x%02x\n",
+				pos, bit_pos, err_byte, ecc[tmp]);
+		}
+
+		i++;
+		err_nbr--;
+	}
+
+	return;
+}
+
+static int pmecc_correction(struct mtd_info *mtd, u32 pmecc_stat, uint8_t *buf,
+	u8 *ecc)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	int i, err_nbr, eccbytes;
+	uint8_t *buf_pos;
+
+	eccbytes = nand_chip->ecc.bytes;
+	for (i = 0; i < eccbytes; i++)
+		if (ecc[i] != 0xff)
+			goto normal_check;
+	/* Erased page, return OK */
+	return 0;
+
+normal_check:
+	for (i = 0; i < host->pmecc_sector_number; i++) {
+		err_nbr = 0;
+		if (pmecc_stat & 0x1) {
+			buf_pos = buf + i * host->pmecc_sector_size;
+
+			pmecc_gen_syndrome(mtd, i);
+			pmecc_substitute(mtd);
+			pmecc_get_sigma(mtd);
+
+			err_nbr = pmecc_err_location(mtd);
+			if (err_nbr == -1) {
+				printk(KERN_ERR "PMECC: Too many errors\n");
+				mtd->ecc_stats.failed++;
+				return -EIO;
+			} else {
+				pmecc_correct_data(mtd, buf_pos, ecc, i,
+					host->pmecc_bytes_per_sector, err_nbr);
+				mtd->ecc_stats.corrected += err_nbr;
+			}
+		}
+		pmecc_stat >>= 1;
+	}
+
+	return 0;
+}
+
+static int atmel_nand_pmecc_read_page(struct mtd_info *mtd,
+	struct nand_chip *chip, uint8_t *buf, int page)
+{
+	struct atmel_nand_host *host = chip->priv;
+	int eccsize = chip->ecc.size;
+	uint8_t *oob = chip->oob_poi;
+	uint32_t *eccpos = chip->ecc.layout->eccpos;
+	uint32_t stat;
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_RST);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DISABLE);
+	pmecc_writel(host->pmecc, cfg, ((pmecc_readl(host->pmecc, cfg))
+		& ~PMECC_CFG_WRITE_OP) | PMECC_CFG_AUTO_ENABLE);
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_ENABLE);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DATA);
+
+	chip->read_buf(mtd, buf, eccsize);
+	chip->read_buf(mtd, oob, mtd->oobsize);
+
+	while ((pmecc_readl(host->pmecc, sr) & PMECC_SR_BUSY))
+		udelay(1);
+
+	stat = pmecc_readl(host->pmecc, isr);
+	if (stat != 0)
+		if (pmecc_correction(mtd, stat, buf, &oob[eccpos[0]]) != 0)
+			return -EIO;
+
+	return 0;
+}
+
+static void atmel_nand_pmecc_write_page(struct mtd_info *mtd,
+		struct nand_chip *chip, const uint8_t *buf)
+{
+	struct atmel_nand_host *host = chip->priv;
+	uint32_t *eccpos = chip->ecc.layout->eccpos;
+	int i, j;
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_RST);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DISABLE);
+
+	pmecc_writel(host->pmecc, cfg, (pmecc_readl(host->pmecc, cfg) |
+		PMECC_CFG_WRITE_OP) & ~PMECC_CFG_AUTO_ENABLE);
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_ENABLE);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DATA);
+
+	chip->write_buf(mtd, (u8 *)buf, mtd->writesize);
+
+	while ((pmecc_readl(host->pmecc, sr) & PMECC_SR_BUSY))
+		udelay(1);
+
+	for (i = 0; i < host->pmecc_sector_number; i++) {
+		for (j = 0; j < host->pmecc_bytes_per_sector; j++) {
+			int pos;
+
+			pos = i * host->pmecc_bytes_per_sector + j;
+			chip->oob_poi[eccpos[pos]] =
+				readb(&host->pmecc->ecc_port[i].ecc[j]);
+		}
+	}
+	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
+}
+
+static void atmel_pmecc_core_init(struct mtd_info *mtd)
+{
+	struct nand_chip *nand_chip = mtd->priv;
+	struct atmel_nand_host *host = nand_chip->priv;
+	uint32_t val = 0;
+	struct nand_ecclayout *ecc_layout;
+
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_RST);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_DISABLE);
+
+	switch (host->pmecc_corr_cap) {
+	case 2:
+		val = PMECC_CFG_BCH_ERR2;
+		break;
+	case 4:
+		val = PMECC_CFG_BCH_ERR4;
+		break;
+	case 8:
+		val = PMECC_CFG_BCH_ERR8;
+		break;
+	case 12:
+		val = PMECC_CFG_BCH_ERR12;
+		break;
+	case 24:
+		val = PMECC_CFG_BCH_ERR24;
+		break;
+	}
+
+	if (host->pmecc_sector_size == 512)
+		val |= PMECC_CFG_SECTOR512;
+	else if (host->pmecc_sector_size == 1024)
+		val |= PMECC_CFG_SECTOR1024;
+
+	switch (host->pmecc_sector_number) {
+	case 1:
+		val |= PMECC_CFG_PAGE_1SECTOR;
+		break;
+	case 2:
+		val |= PMECC_CFG_PAGE_2SECTORS;
+		break;
+	case 4:
+		val |= PMECC_CFG_PAGE_4SECTORS;
+		break;
+	case 8:
+		val |= PMECC_CFG_PAGE_8SECTORS;
+		break;
+	}
+
+	val |= (PMECC_CFG_READ_OP | PMECC_CFG_SPARE_DISABLE
+		| PMECC_CFG_AUTO_DISABLE);
+	pmecc_writel(host->pmecc, cfg, val);
+
+	ecc_layout = nand_chip->ecc.layout;
+	pmecc_writel(host->pmecc, sarea, mtd->oobsize - 1);
+	pmecc_writel(host->pmecc, saddr, ecc_layout->eccpos[0]);
+	pmecc_writel(host->pmecc, eaddr,
+			ecc_layout->eccpos[ecc_layout->eccbytes - 1]);
+	/* See datasheet about PMECC Clock Control Register */
+	pmecc_writel(host->pmecc, clk, PMECC_CLK_133MHZ);
+	pmecc_writel(host->pmecc, idr, 0xff);
+	pmecc_writel(host->pmecc, ctrl, PMECC_CTRL_ENABLE);
+}
+

drivers/mtd/nand/atmel_nand.c line 609

Quoted 7 lines

drivers/mtd/nand/atmel_nand.c +7 -0

+static int atmel_pmecc_nand_init_params(struct nand_chip *nand)
+{
+	struct mtd_info *mtd;
+	struct atmel_nand_host *host;
+	int cap, sector_size;
+
+	mtd = &nand_info[chip_nr++];

NAK

drivers/mtd/nand/atmel_nand.c line 614

Quoted 6 lines

drivers/mtd/nand/atmel_nand.c +5 -0

+	mtd->priv = nand;
+	host = nand->priv = &pmecc_host;
+
+	/* Detect NAND chips */
+	if (nand_scan_ident(mtd, 1, NULL)) {

please change that, read later on.

drivers/mtd/nand/atmel_nand.c line 625

Quoted 12 lines

drivers/mtd/nand/atmel_nand.c +11 -0

+		printk(KERN_WARNING "NAND Flash not found !\n");
+		return -ENXIO;
+	}
+
+	nand->ecc.mode = NAND_ECC_HW;
+	nand->ecc.calculate = NULL;
+	nand->ecc.correct = NULL;
+	nand->ecc.hwctl = NULL;
+
+	cap = host->pmecc_corr_cap = CONFIG_PMECC_CAP;
+	sector_size = host->pmecc_sector_size = CONFIG_PMECC_SECTOR_SIZE;

Can't we use some information from the nand chip here? Do we need to hard code this paramater?

Quoted 210 lines

drivers/mtd/nand/atmel_nand.c +70 -2

+	host->pmecc_index_table_offset = CONFIG_PMECC_INDEX_TABLE_OFFSET;
+
+	printk(KERN_INFO "Initialize PMECC params, cap: %d, sector: %d\n",
+		 cap, sector_size);
+
+	host->pmecc = (struct pmecc_regs __iomem *) ATMEL_BASE_PMECC;
+	host->pmerrloc = (struct pmecc_errloc_regs __iomem *)
+			ATMEL_BASE_PMERRLOC;
+	host->pmecc_rom_base = (void __iomem *) ATMEL_BASE_ROM;
+
+	/* ECC is calculated for the whole page (1 step) */
+	nand->ecc.size = mtd->writesize;
+
+	/* set ECC page size and oob layout */
+	switch (mtd->writesize) {
+	case 2048:
+	case 4096:
+		host->pmecc_degree = PMECC_GF_DIMENSION_13;
+		host->pmecc_cw_len = (1 << host->pmecc_degree) - 1;
+		host->pmecc_sector_number = mtd->writesize / sector_size;
+		host->pmecc_bytes_per_sector = pmecc_get_ecc_bytes(
+			cap, sector_size);
+		host->pmecc_alpha_to = pmecc_get_alpha_to(host);
+		host->pmecc_index_of = host->pmecc_rom_base +
+			host->pmecc_index_table_offset;
+
+		nand->ecc.steps = 1;
+		nand->ecc.bytes = host->pmecc_bytes_per_sector *
+				       host->pmecc_sector_number;
+		if (nand->ecc.bytes > mtd->oobsize - 2) {
+			printk(KERN_ERR "No room for ECC bytes\n");
+			return -EINVAL;
+		}
+		pmecc_config_ecc_layout(&atmel_pmecc_oobinfo,
+					mtd->oobsize,
+					nand->ecc.bytes);
+		nand->ecc.layout = &atmel_pmecc_oobinfo;
+		break;
+	case 512:
+	case 1024:
+		/* TODO */
+		printk(KERN_ERR "Unsupported page size for PMECC, use Software ECC\n");
+	default:
+		/* page size not handled by HW ECC */
+		/* switching back to soft ECC */
+		nand->ecc.mode = NAND_ECC_SOFT;
+		nand->ecc.read_page = NULL;
+		nand->ecc.postpad = 0;
+		nand->ecc.prepad = 0;
+		nand->ecc.bytes = 0;
+		return 0;
+	}
+
+	nand->ecc.read_page = atmel_nand_pmecc_read_page;
+	nand->ecc.write_page = atmel_nand_pmecc_write_page;
+
+	atmel_pmecc_core_init(mtd);
+
+	return 0;
+}
+
+#else
+
  /* oob layout for large page size
   * bad block info is on bytes 0 and 1
   * the bytes have to be consecutives to avoid

@@ -234,7 +879,6 @@ static void atmel_nand_hwctl(struct mtd_info *mtd, int mode)
 
  int atmel_hw_nand_init_param(struct nand_chip *nand)
  {
-	static int chip_nr = 0;
  	struct mtd_info *mtd;
 
  	nand->ecc.mode = NAND_ECC_HW;

@@ -293,7 +937,9 @@ int atmel_hw_nand_init_param(struct nand_chip *nand)
  	return 0;
  }
 
-#endif
+#endif /* CONFIG_ATMEL_NAND_HW_PMECC */
+
+#endif /* CONFIG_ATMEL_NAND_HWECC */
 
  static void at91_nand_hwcontrol(struct mtd_info *mtd,
  					 int cmd, unsigned int ctrl)

@@ -343,8 +989,12 @@ int board_nand_init(struct nand_chip *nand)
  	nand->chip_delay = 20;
 
  #ifdef CONFIG_ATMEL_NAND_HWECC
+#ifdef CONFIG_ATMEL_NAND_HW_PMECC
+	res = atmel_pmecc_nand_init_params(nand);
+#else
  	res = atmel_hw_nand_init_param(nand);
  #endif
+#endif
 
  	return res;
  }

drivers/mtd/nand/atmel_nand_ecc.h +102 -0

index 1ee7f99..8f06b14 100644
@@ -33,4 +33,115 @@
  #define ATMEL_ECC_NPR		0x10			/* NParity register */
  #define		ATMEL_ECC_NPARITY	(0xffff << 0)		/* NParity */
 
+/* Register access macros for PMECC */
+#define pmecc_readl(addr, reg) \
+	readl(&addr->reg)
+
+#define pmecc_writel(addr, reg, value) \
+	writel((value), &addr->reg)
+
+/* PMECC Register Definitions */
+#define PMECC_MAX_SECTOR_NUM			8
+struct pmecc_regs {
+	u32 cfg;		/* 0x00 PMECC Configuration Register */
+	u32 sarea;		/* 0x04 PMECC Spare Area Size Register */
+	u32 saddr;		/* 0x08 PMECC Start Address Register */
+	u32 eaddr;		/* 0x0C PMECC End Address Register */
+	u32 clk;		/* 0x10 PMECC Clock Control Register */
+	u32 ctrl;		/* 0x14 PMECC Control Register */
+	u32 sr;			/* 0x18 PMECC Status Register */
+	u32 ier;		/* 0x1C PMECC Interrupt Enable Register */
+	u32 idr;		/* 0x20 PMECC Interrupt Disable Register */
+	u32 imr;		/* 0x24 PMECC Interrupt Mask Register */
+	u32 isr;		/* 0x28 PMECC Interrupt Status Register */
+	u32 reserved0[5];	/* 0x2C-0x3C Reserved */
+
+	/* 0x40 + sector_num * (0x40), Redundancy Registers */
+	struct {
+		u8 ecc[44];	/* PMECC Generated Redundancy Byte Per Sector */
+		u32 reserved1[5];
+	} ecc_port[PMECC_MAX_SECTOR_NUM];
+
+	/* 0x240 + sector_num * (0x40) Remainder Registers */
+	struct {
+		u32 rem[12];
+		u32 reserved2[4];
+	} rem_port[PMECC_MAX_SECTOR_NUM];
+	u32 reserved3[16];	/* 0x440-0x47C Reserved */
+};
+
+/* For PMECC Configuration Register */
+#define		PMECC_CFG_BCH_ERR2		(0 << 0)
+#define		PMECC_CFG_BCH_ERR4		(1 << 0)
+#define		PMECC_CFG_BCH_ERR8		(2 << 0)
+#define		PMECC_CFG_BCH_ERR12		(3 << 0)
+#define		PMECC_CFG_BCH_ERR24		(4 << 0)
+
+#define		PMECC_CFG_SECTOR512		(0 << 4)
+#define		PMECC_CFG_SECTOR1024		(1 << 4)
+
+#define		PMECC_CFG_PAGE_1SECTOR		(0 << 8)
+#define		PMECC_CFG_PAGE_2SECTORS		(1 << 8)
+#define		PMECC_CFG_PAGE_4SECTORS		(2 << 8)
+#define		PMECC_CFG_PAGE_8SECTORS		(3 << 8)
+
+#define		PMECC_CFG_READ_OP		(0 << 12)
+#define		PMECC_CFG_WRITE_OP		(1 << 12)
+
+#define		PMECC_CFG_SPARE_ENABLE		(1 << 16)
+#define		PMECC_CFG_SPARE_DISABLE		(0 << 16)
+
+#define		PMECC_CFG_AUTO_ENABLE		(1 << 20)
+#define		PMECC_CFG_AUTO_DISABLE		(0 << 20)
+
+/* For PMECC Clock Control Register */
+#define		PMECC_CLK_133MHZ		(2 << 0)
+
+/* For PMECC Control Register */
+#define		PMECC_CTRL_RST			(1 << 0)
+#define		PMECC_CTRL_DATA			(1 << 1)
+#define		PMECC_CTRL_USER			(1 << 2)
+#define		PMECC_CTRL_ENABLE		(1 << 4)
+#define		PMECC_CTRL_DISABLE		(1 << 5)
+
+/* For PMECC Status Register */
+#define		PMECC_SR_BUSY			(1 << 0)
+#define		PMECC_SR_ENABLE			(1 << 4)
+
+/* PMERRLOC Register Definitions */
+struct pmecc_errloc_regs {
+	u32 elcfg;	/* 0x00 Error Location Configuration Register */
+	u32 elprim;	/* 0x04 Error Location Primitive Register */
+	u32 elen;	/* 0x08 Error Location Enable Register */
+	u32 eldis;	/* 0x0C Error Location Disable Register */
+	u32 elsr;	/* 0x10 Error Location Status Register */
+	u32 elier;	/* 0x14 Error Location Interrupt Enable Register */
+	u32 elidr;	/* 0x08 Error Location Interrupt Disable Register */
+	u32 elimr;	/* 0x0C Error Location Interrupt Mask Register */
+	u32 elisr;	/* 0x20 Error Location Interrupt Status Register */
+	u32 reserved0;	/* 0x24 Reserved */
+	u32 sigma[25];	/* 0x28-0x88 Error Location Sigma Registers */
+	u32 el[24];	/* 0x8C-0xE8 Error Location Registers */
+	u32 reserved1[5];	/* 0xEC-0xFC Reserved */
+};
+
+/* For Error Location Configuration Register */
+#define		PMERRLOC_ELCFG_SECTOR_512	(0 << 0)
+#define		PMERRLOC_ELCFG_SECTOR_1024	(1 << 0)
+#define		PMERRLOC_ELCFG_NUM_ERRORS(n)	((n) << 16)
+
+/* For Error Location Disable Register */
+#define		PMERRLOC_DISABLE		(1 << 0)
+
+/* For Error Location Interrupt Status Register */
+#define		PMERRLOC_ERR_NUM_MASK		(0x1f << 8)

drivers/mtd/nand/atmel_nand_ecc.h line 147

Quoted 10 lines

drivers/mtd/nand/atmel_nand_ecc.h +9 -0

+#define		PMERRLOC_CALC_DONE		(1 << 0)
+
+/* Galois field dimension */
+#define PMECC_GF_DIMENSION_13			13
+#define PMECC_GF_DIMENSION_14			14
+
+#define PMECC_INDEX_TABLE_SIZE_512		0x2000
+#define PMECC_INDEX_TABLE_SIZE_1024		0x4000
+
  #endif

Not really nice code but it seems the kernel guys accepted it the same way. So I will _not_ NAK it. But please add at least a README entry describing the new config parameters, think about the sector size (ore explain me why you need another config) and please change the driver

initialization to the SELF_INIT as mentioned in another mail. You use again the nand_scan_indent() inside your xx_nand_init_params(). Please rewrite the board_nand_init() as shown in doc/README.nand, maybe copy the stub from mtd/nand.c's nand_init() and nand_init_chip(). Call in your own atmel_nand_init_chip() nand_scan_ident() and after that setup the parameters for eighter ECC or PMECC. Always hand over the struct nand_chip and do not work with the nand_chip array in the xx_init_param() functions.

Best regards

Andreas Bie?mann

Hi, Andreas

Quoted 5 lines · Andreas Bie?mann

can you please add some README entry describing these new config parameters?
Namely CONFIG_ATMEL_NAND_HW_PMECC, CONFIG_PMECC_CAP, CONFIG_PMECC_SECTOR_SIZE (can't this be derived from some already available NAND information?) and CONFIG_PMECC_INDEX_TABLE_OFFSET.

OK, I will add a README file to explain all the parameters. this CONFIG_PMECC_SECTOR_SIZE means how many bytes to generate out PMECC code. It only can be 512 and 1024.
So for a nand chip whose page size is 2048, if CONFIG_PMECC_SECTOR_SIZE is set as 512, then PMECC will generate PMECC code for each 512 bytes.

I think it cannot be derived from nand information.

Quoted 8 lines · Josh Wu

Hi, Andreas

Quoted 5 lines · Andreas Bie?mann

can you please add some README entry describing these new config parameters?
Namely CONFIG_ATMEL_NAND_HW_PMECC, CONFIG_PMECC_CAP, CONFIG_PMECC_SECTOR_SIZE (can't this be derived from some already available NAND information?) and CONFIG_PMECC_INDEX_TABLE_OFFSET.

Quoted 7 lines

OK, I will add a README file to explain all the parameters. this CONFIG_PMECC_SECTOR_SIZE means how many bytes to generate out PMECC code. It only can be 512 and 1024.
So for a nand chip whose page size is 2048, if CONFIG_PMECC_SECTOR_SIZE is set as 512, then PMECC will generate PMECC code for each 512 bytes.

I think it cannot be derived from nand information.

So this is basically nand->ecc.size?

While this can't be directly read
from the chip, usually there's a convention for a given type of NAND chip on a given controller. Do you really need to support both 512 and 1024 for any single chip?

Why do you set nand->ecc.size to mtd->writesize if that isn't the actual ECC chunk size?

-Scott

The Programmable Multibit ECC (PMECC) controller is a programmable binary BCH(Bose, Chaudhuri and Hocquenghem) encoder and decoder. This controller can be used to support both SLC and MLC NAND Flash devices. It supports to generate ECC to correct 2, 4, 8, 12 or 24 bits of error per sector of data.

To use PMECC in this driver, the user needs to set the PMECC correction capability, the sector size and ROM lookup table offsets in board config file.

This driver is ported from Linux kernel atmel_nand PMECC patch. The main difference is in this version it uses registers structure access hardware instead of using macros.

Signed-off-by Josh Wu <[email protected]>

---
 board/atmel/at91sam9x5ek/at91sam9x5ek.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

board/atmel/at91sam9x5ek/at91sam9x5ek.c +5 -5

index 17db0fd..8dc24ab 100644
@@ -63,13 +63,13 @@ static void at91sam9x5ek_nand_hw_init(void)
 	writel(csa, &matrix->ebicsa);
 
 	/* Configure SMC CS3 for NAND/SmartMedia */
-	writel(AT91_SMC_SETUP_NWE(2) | AT91_SMC_SETUP_NCS_WR(0) |
-		AT91_SMC_SETUP_NRD(2) | AT91_SMC_SETUP_NCS_RD(0),
+	writel(AT91_SMC_SETUP_NWE(1) | AT91_SMC_SETUP_NCS_WR(0) |
+		AT91_SMC_SETUP_NRD(1) | AT91_SMC_SETUP_NCS_RD(0),
 		&smc->cs[3].setup);
-	writel(AT91_SMC_PULSE_NWE(4) | AT91_SMC_PULSE_NCS_WR(4) |
-		AT91_SMC_PULSE_NRD(4) | AT91_SMC_PULSE_NCS_RD(4),
+	writel(AT91_SMC_PULSE_NWE(3) | AT91_SMC_PULSE_NCS_WR(5) |
+		AT91_SMC_PULSE_NRD(4) | AT91_SMC_PULSE_NCS_RD(6),
 		&smc->cs[3].pulse);
-	writel(AT91_SMC_CYCLE_NWE(7) | AT91_SMC_CYCLE_NRD(7),
+	writel(AT91_SMC_CYCLE_NWE(5) | AT91_SMC_CYCLE_NRD(6),
 		&smc->cs[3].cycle);
 	writel(AT91_SMC_MODE_RM_NRD | AT91_SMC_MODE_WM_NWE |
 		AT91_SMC_MODE_EXNW_DISABLE |

Dear Josh Wu,

Quoted 36 lines · Josh Wu

Signed-off-by Josh Wu <[email protected]>

---
  board/atmel/at91sam9x5ek/at91sam9x5ek.c |   12 ++++++------
  1 file changed, 6 insertions(+), 6 deletions(-)

board/atmel/at91sam9x5ek/at91sam9x5ek.c +6 -6

index 17db0fd..8dc24ab 100644
@@ -63,13 +63,13 @@ static void at91sam9x5ek_nand_hw_init(void)
  	writel(csa, &matrix->ebicsa);
 
  	/* Configure SMC CS3 for NAND/SmartMedia */
-	writel(AT91_SMC_SETUP_NWE(2) | AT91_SMC_SETUP_NCS_WR(0) |
-		AT91_SMC_SETUP_NRD(2) | AT91_SMC_SETUP_NCS_RD(0),
+	writel(AT91_SMC_SETUP_NWE(1) | AT91_SMC_SETUP_NCS_WR(0) |
+		AT91_SMC_SETUP_NRD(1) | AT91_SMC_SETUP_NCS_RD(0),
  		&smc->cs[3].setup);
-	writel(AT91_SMC_PULSE_NWE(4) | AT91_SMC_PULSE_NCS_WR(4) |
-		AT91_SMC_PULSE_NRD(4) | AT91_SMC_PULSE_NCS_RD(4),
+	writel(AT91_SMC_PULSE_NWE(3) | AT91_SMC_PULSE_NCS_WR(5) |
+		AT91_SMC_PULSE_NRD(4) | AT91_SMC_PULSE_NCS_RD(6),
  		&smc->cs[3].pulse);
-	writel(AT91_SMC_CYCLE_NWE(7) | AT91_SMC_CYCLE_NRD(7),
+	writel(AT91_SMC_CYCLE_NWE(5) | AT91_SMC_CYCLE_NRD(6),
  		&smc->cs[3].cycle);
  	writel(AT91_SMC_MODE_RM_NRD | AT91_SMC_MODE_WM_NWE |
  		AT91_SMC_MODE_EXNW_DISABLE |

@@ -78,7 +78,7 @@ static void at91sam9x5ek_nand_hw_init(void)
  #else /* CONFIG_SYS_NAND_DBW_8 */
  		AT91_SMC_MODE_DBW_8 |
  #endif
-		AT91_SMC_MODE_TDF_CYCLE(3),
+		AT91_SMC_MODE_TDF_CYCLE(1),
  		&smc->cs[3].mode);