Patchwork [U-Boot,v3,3/5] at91: atmel_nand: Update driver to support Programmable Multibit ECC controller

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Submitter Wu, Josh
Date Aug. 23, 2012, 10:05 a.m.
Message ID <1345716338-11217-4-git-send-email-josh.wu@atmel.com>
Download mbox | patch
Permalink /patch/179589/
State Accepted
Delegated to: Andreas Bießmann
Headers show

Comments

Wu, Josh - Aug. 23, 2012, 10:05 a.m.
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 <josh.wu@atmel.com>
---
Changes since v2:
   add timeout when read hardware register.
   add README document for atmel pmecc.
   according to Scott and Andreas' suggestion, refined the pmecc_get_sigma() 
     function and add more comments for the function.

 doc/README.atmel_pmecc            |   44 +++
 drivers/mtd/nand/atmel_nand.c     |  680 ++++++++++++++++++++++++++++++++++++-
 drivers/mtd/nand/atmel_nand_ecc.h |  113 ++++++
 3 files changed, 836 insertions(+), 1 deletion(-)
 create mode 100644 doc/README.atmel_pmecc
Andreas Bießmann - Sept. 1, 2012, 2:25 p.m.
Dear Josh Wu,

On 23.08.2012 12:05, Josh Wu wrote:
> 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 <josh.wu@atmel.com>
> ---

applied to u-boot-atmel/master (slightly modified due to required rebase 
cause of change in 1/5), thanks!

Best regards

Andreas Bießmann

Patch

diff --git a/doc/README.atmel_pmecc b/doc/README.atmel_pmecc
new file mode 100644
index 0000000..b483744
--- /dev/null
+++ b/doc/README.atmel_pmecc
@@ -0,0 +1,44 @@ 
+How to enable PMECC(Programmable Multibit ECC) for nand on Atmel SoCs
+-----------------------------------------------------------
+2012-08-22 Josh Wu <josh.wu@atmel.com>
+
+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 (512 or
+1024 bytes) of data.
+
+Following Atmel AT91 products support PMECC.
+- AT91SAM9X25, X35, G25, G15, G35 (tested)
+- AT91SAM9N12 (not tested, Should work)
+
+As soon as your nand flash software ECC works, you can enable PMECC.
+
+To use PMECC in this driver, the user needs to set:
+	1. the PMECC correction error bits capability: CONFIG_PMECC_CAP.
+	   It can be 2, 4, 8, 12 or 24.
+	2. The PMECC sector size: CONFIG_PMECC_SECTOR_SIZE.
+	   It only can be 512 or 1024.
+	3. The PMECC index lookup table's offsets in ROM code: CONFIG_PMECC_INDEX_TABLE_OFFSET.
+	   In the chip datasheet section "Boot Stragegies", you can find
+	   two Galois Field Table in the ROM code. One table is for 512-bytes
+	   sector. Another is for 1024-byte sector. Each Galois Field includes
+	   two sub-table: indext table & alpha table.
+	   In the beginning of each Galois Field Table is the index table,
+	   Alpha table is in the following.
+	   So the index table's offset is same as the Galois Field Table.
+
+	   Please set CONFIG_PMECC_INDEX_TABLE_OFFSET correctly according the
+	   Galois Field Table's offset base on the sector size you used.
+
+Take AT91SAM9X5EK as an example, the board definition file likes:
+
+/* PMECC & PMERRLOC */
+#define CONFIG_ATMEL_NAND_HWECC		1
+#define CONFIG_ATMEL_NAND_HW_PMECC	1
+#define CONFIG_PMECC_CAP		2
+#define CONFIG_PMECC_SECTOR_SIZE	512
+#define CONFIG_PMECC_INDEX_TABLE_OFFSET	0x8000
+
+NOTE: If you use 1024 as the sector size, then need set 0x10000 as the
+ CONFIG_PMECC_INDEX_TABLE_OFFSET
diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index 05a6317..70b3ce4 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -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.
  *
@@ -30,6 +33,7 @@ 
 #include <asm/arch/at91_pio.h>
 
 #include <nand.h>
+#include <watchdog.h>
 
 #ifdef CONFIG_ATMEL_NAND_HWECC
 
@@ -41,6 +45,674 @@ 
 
 #include "atmel_nand_ecc.h"	/* Hardware ECC registers */
 
+#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];
+	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];
+};
+
+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] & (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);
+		}
+	}
+}
+
+/*
+ * This function defines a Berlekamp iterative procedure for
+ * finding the value of the error location polynomial.
+ * The input is si[], initialize by pmecc_substitute().
+ * The output is smu[][].
+ *
+ * This function is written according to chip datasheet Chapter:
+ * Find the Error Location Polynomial Sigma(x) of Section:
+ * Programmable Multibit ECC Control (PMECC).
+ */
+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;
+
+	/* Init the Sigma(x) */
+	memset(smu, 0, sizeof(int16_t) * ARRAY_SIZE(smu));
+
+	dmu_0_count = 0;
+
+	/* First Row */
+
+	/* Mu */
+	mu[0] = -1;
+
+	smu[0] = 1;
+
+	/* discrepancy set to 1 */
+	dmu[0] = 1;
+	/* polynom order set to 0 */
+	lmu[0] = 0;
+	/* delta[0] = (mu[0] * 2 - lmu[0]) >> 1; */
+	delta[0] = -1;
+
+	/* Second Row */
+
+	/* Mu */
+	mu[1] = 0;
+	/* Sigma(x) set to 1 */
+	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; */
+	delta[1] = 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++)
+				smu[(i + 1) * num + j] = smu[i * num + j];
+
+			/* copy previous polynom order to the next */
+			lmu[i + 1] = lmu[i];
+		} 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];
+			}
+		}
+	}
+}
+
+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;
+	int timeout = PMECC_MAX_TIMEOUT_US;
+
+	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;
+
+	writel(val, &host->pmerrloc->elcfg);
+	writel(sector_size * 8 + host->pmecc_degree * cap,
+			&host->pmerrloc->elen);
+
+	while (--timeout) {
+		if (readl(&host->pmerrloc->elisr) & PMERRLOC_CALC_DONE)
+			break;
+		WATCHDOG_RESET();
+		udelay(1);
+	}
+
+	if (!timeout) {
+		printk(KERN_ERR "atmel_nand : Timeout to calculate PMECC error location\n");
+		return -1;
+	}
+
+	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;
+	int timeout = PMECC_MAX_TIMEOUT_US;
+
+	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 (--timeout) {
+		if (!(pmecc_readl(host->pmecc, sr) & PMECC_SR_BUSY))
+			break;
+		WATCHDOG_RESET();
+		udelay(1);
+	}
+
+	if (!timeout) {
+		printk(KERN_ERR "atmel_nand : Timeout to read PMECC page\n");
+		return -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;
+	int timeout = PMECC_MAX_TIMEOUT_US;
+
+	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 (--timeout) {
+		if (!(pmecc_readl(host->pmecc, sr) & PMECC_SR_BUSY))
+			break;
+		WATCHDOG_RESET();
+		udelay(1);
+	}
+
+	if (!timeout) {
+		printk(KERN_ERR "atmel_nand : Timeout to read PMECC status, fail to write PMECC in oob\n");
+		return;
+	}
+
+	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);
+}
+
+static int atmel_pmecc_nand_init_params(struct nand_chip *nand,
+		struct mtd_info *mtd)
+{
+	struct atmel_nand_host *host;
+	int cap, sector_size;
+
+	host = nand->priv = &pmecc_host;
+
+	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;
+	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
@@ -285,7 +957,9 @@  int atmel_hwecc_nand_init_param(struct nand_chip *nand, struct mtd_info *mtd)
 	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)
@@ -350,8 +1024,12 @@  int atmel_nand_chip_init(int devnum, ulong base_addr)
 		return ret;
 
 #ifdef CONFIG_ATMEL_NAND_HWECC
+#ifdef CONFIG_ATMEL_NAND_HW_PMECC
+	ret = atmel_pmecc_nand_init_params(nand, mtd);
+#else
 	ret = atmel_hwecc_nand_init_param(nand, mtd);
 #endif
+#endif
 	if (ret)
 		return ret;
 
diff --git a/drivers/mtd/nand/atmel_nand_ecc.h b/drivers/mtd/nand/atmel_nand_ecc.h
index 1ee7f99..4732582 100644
--- a/drivers/mtd/nand/atmel_nand_ecc.h
+++ b/drivers/mtd/nand/atmel_nand_ecc.h
@@ -33,4 +33,117 @@ 
 #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)
+#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
+
+#define PMECC_MAX_TIMEOUT_US		(100 * 1000)
+
 #endif