From mboxrd@z Thu Jan  1 00:00:00 1970
From: josh.wu@atmel.com (Josh Wu)
Date: Mon, 28 May 2012 16:34:36 +0800
Subject: [PATCH v9 3/3] MTD: at91: atmel_nand: Update driver to support
 Programmable Multibit ECC controller
In-Reply-To: <20120528065822.GL3377@game.jcrosoft.org>
References: <1338038677-6752-1-git-send-email-josh.wu@atmel.com>
 <1338038677-6752-4-git-send-email-josh.wu@atmel.com>
 <20120528065822.GL3377@game.jcrosoft.org>
Message-ID: <4FC3389C.5050303@atmel.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 5/28/2012 2:58 PM, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 21:24 Sat 26 May     , 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 this driver, the user needs to pass in the correction capability and
>> the sector size.
>>
>> This driver has been tested on AT91SAM9X5-EK and AT91SAM9N12-EK with JFFS2,
>> YAFFS2, UBIFS and mtd-utils.
>>
>> Signed-off-by: Hong Xu<hong.xu@atmel.com>
>> Signed-off-by: Josh Wu<josh.wu@atmel.com>
>> ---
>>   drivers/mtd/nand/atmel_nand.c     |  761 ++++++++++++++++++++++++++++++++++++-
>>   drivers/mtd/nand/atmel_nand_ecc.h |  116 ++++++
>>   2 files changed, 876 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
>> index 9a9bfbf..ddcf1ed 100644
>> --- a/drivers/mtd/nand/atmel_nand.c
>> +++ b/drivers/mtd/nand/atmel_nand.c
>> @@ -15,6 +15,8 @@
>>    *     		(u-boot-1.1.5/board/atmel/at91sam9263ek/nand.c)
>>    *     (C) Copyright 2006 ATMEL Rousset, Lacressonniere Nicolas
>>    *
>> + *  Add Programmable Multibit ECC support for various AT91 SoC
>> + *     (C) Copyright 2012 ATMEL, Hong Xu
>>    *
>>    * This program is free software; you can redistribute it and/or modify
>>    * it under the terms of the GNU General Public License version 2 as
>> @@ -77,6 +79,21 @@ static struct nand_ecclayout atmel_oobinfo_small = {
>>   	},
>>   };
>>
>> +/* a structure includes datas for PMECC computation */
>> +struct atmel_pmecc_data {
>> +	int16_t			partial_syn[2 * PMECC_MAX_ERROR_NB + 1];
>> +	int16_t			si[2 * PMECC_MAX_ERROR_NB + 1];
>> +
>> +	/* Sigma table */
>> +	int16_t		smu[PMECC_MAX_ERROR_NB + 2][2 * PMECC_MAX_ERROR_NB + 1];
> you still hardcode the array in the struct
>
> and if the pmecc evolve we will have to touch again
> please allocate them

ok.

>> +	/* polynomal order */
>> +	int16_t			lmu[PMECC_MAX_ERROR_NB + 1];
>> +
>> +	int			mu[PMECC_MAX_ERROR_NB + 1];
>> +	int			dmu[PMECC_MAX_ERROR_NB + 1];
>> +	int			delta[PMECC_MAX_ERROR_NB + 1];
>> +};
>> +
>>   struct atmel_nand_host {
>>   	struct nand_chip	nand_chip;
>>   	struct mtd_info		mtd;
>> @@ -92,8 +109,25 @@ struct atmel_nand_host {
>>   	bool			has_pmecc;
>>   	u8			pmecc_corr_cap;
>>   	u16			pmecc_sector_size;
>> +
>> +	int			pmecc_bytes_per_sector;
>> +	int			pmecc_sector_number;
>> +	int			pmecc_degree;	/* Degree of remainders */
>> +	int			pmecc_cw_len;	/* Length of codeword */
>> +
>> +	void __iomem		*pmerrloc_base;
>> +	void __iomem		*pmecc_rom_base;
>> +
>> +	/* lookup table for alpha_to and index_of */
>> +	void __iomem		*pmecc_alpha_to;
>> +	void __iomem		*pmecc_index_of;
>> +
>> +	/* data for pmecc computation */
>> +	struct atmel_pmecc_data	*pmecc_data;
>>   };
>>
>> +static struct nand_ecclayout atmel_pmecc_oobinfo;
>> +
>>   static int cpu_has_dma(void)
>>   {
>>   	return cpu_is_at91sam9rl() || cpu_is_at91sam9g45();
>> @@ -287,6 +321,708 @@ static void atmel_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
>>   }
>>
>>   /*
>> + * 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)
>> +{
>> +	void __iomem *p;
>> +
>> +	switch (host->pmecc_sector_size) {
>> +	case 512:
>> +		p = host->pmecc_rom_base + PMECC_LOOKUP_TABLE_OFFSET_512 +
>> +			PMECC_LOOKUP_TABLE_SIZE_512 * sizeof(int16_t);
>> +		break;
>> +	case 1024:
>> +		p = host->pmecc_rom_base + PMECC_LOOKUP_TABLE_OFFSET_1024 +
>> +			PMECC_LOOKUP_TABLE_SIZE_1024 * sizeof(int16_t);
>> +		break;
>> +	default:
>> +		BUG();
>> +	}
>> +
>> +	return p;
>> +}
>> +
>> +static void __iomem *pmecc_get_index_of(struct atmel_nand_host *host)
> this is a __dev_init function plese check the other too
>
> btw you need to use __dev_init and not __init

Here I use pmecc_get_index_of() function to get a lookup table base 
which is in ROM.
I'm not clear about how should I need __dev_init here. Can you give more 
information?

>> +{
>> +	void __iomem *p;
>> +
>> +	switch (host->pmecc_sector_size) {
>> +	case 512:
>> +		p = host->pmecc_rom_base + PMECC_LOOKUP_TABLE_OFFSET_512;
>> +		break;
>> +	case 1024:
>> +		p = host->pmecc_rom_base + PMECC_LOOKUP_TABLE_OFFSET_1024;
>> +		break;
>> +	default:
>> +		BUG();
>> +	}
>> +
>> +	return p;
>> +}
>> +
>> +static void pmecc_gen_syndrome(struct mtd_info *mtd, int sector)
>> +{
>> +	int			i;
>> +	uint32_t		value;
>> +	struct nand_chip	*nand_chip = mtd->priv;
>> +	struct atmel_nand_host	*host = nand_chip->priv;
>> +
>> +	/* Fill odd syndromes */
>> +	for (i = 0; i<  host->pmecc_corr_cap; i++) {
>> +		value = pmecc_readl_rem_relaxed(host->ecc, sector, i / 2);
>> +		value = (i&  1) ? (value&  0xffff0000)>>  16 : value&  0xffff;
> simplify by
> 		if (i&  1)
> 			val>>= 16;
> 		value&= 0xffff;

I'll fix it.

>
>> +		host->pmecc_data->partial_syn[(2 * i) + 1] = (int16_t)value;
>> +	}
>> +}
>> +
>> +static void pmecc_substitute(struct mtd_info *mtd)
>> +{
>> +	int16_t			*si;
>> +	int			i, j;
>> +	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_data->partial_syn;
>> +
>> +	/* si[] is a table that holds the current syndrome value,
>> +	 * an element of that table belongs to the field
>> +	 */
>> +	si = host->pmecc_data->si;
>> +
>> +	for (i = 1; i<  2 * PMECC_MAX_ERROR_NB; i++)
>> +		si[i] = 0;
> please use memset

ok

>> +
>> +	/* Computation 2t syndromes based on S(x) */
>> +	/* Odd syndromes */
>> +	for (i = 1; i<  2 * host->pmecc_corr_cap; i += 2) {
>> +		si[i] = 0;
> shy this you already init the array at 0 before

yes, I'll fix it.

>> +		for (j = 0; j<  host->pmecc_degree; j++) {
>> +			if (partial_syn[i]&  ((unsigned short)0x1<<  j))
>> +				si[i] = readw_relaxed(alpha_to + i * j) ^ si[i];
>> +		}
>> +	}
>> +	/* Even syndrome = (Odd syndrome) ** 2 */
>> +	for (i = 2; i<= 2 * host->pmecc_corr_cap; i += 2) {
>> +		j = i / 2;
>> +		if (si[j] == 0)
> here if {
> } else {
> }

ok

>> +			si[i] = 0;
>> +		else {
>> +			int16_t tmp;
> missing blank line

ok.

>> +			tmp = readw_relaxed(index_of + si[j]);
>> +			tmp = (tmp * 2) % host->pmecc_cw_len;
>> +			si[i] = readw_relaxed(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;
>> +
>> +	int		i, j, k;
>> +	uint32_t	dmu_0_count, tmp;
>> +	int16_t		(*smu)[2 * PMECC_MAX_ERROR_NB + 1];
>> +	int16_t		*lmu = host->pmecc_data->lmu;
>> +	int16_t		*si = host->pmecc_data->si;
>> +	int		*mu = host->pmecc_data->mu;
>> +	int		*dmu = host->pmecc_data->dmu;	  /* Discrepancy */
>> +	int		*delta = host->pmecc_data->delta; /* Delta order */
>> +	int		cw_len = host->pmecc_cw_len;
>> +	int16_t		cap = host->pmecc_corr_cap;
>> +
>> +	int16_t __iomem	*index_of = host->pmecc_index_of;
>> +	int16_t __iomem	*alpha_to = host->pmecc_alpha_to;
>> +
>> +	/* index of largest delta */
>> +	int ro;
>> +	int largest;
>> +	int diff;
>> +
>> +	dmu_0_count = 0;
>> +	smu = host->pmecc_data->smu;
>> +
>> +	/* First Row */
>> +
>> +	/* Mu */
>> +	mu[0] = -1;
>> +
>> +	memset(&smu[0][0], 0,
>> +		sizeof(int16_t) * (2 * PMECC_MAX_ERROR_NB + 1));
>> +	smu[0][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;
>> +
>> +	/* Second Row */
>> +
>> +	/* Mu */
>> +	mu[1]  = 0;
>> +	/* Sigma(x) set to 1 */
>> +	memset(&smu[1][0], 0,
>> +		sizeof(int16_t) * (2 * PMECC_MAX_ERROR_NB + 1));
>> +	smu[1][0] = 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;
>> +
>> +	/* Init the Sigma(x) last row */
>> +	memset(&smu[cap + 1][0], 0,
>> +		sizeof(int16_t) * (2 * PMECC_MAX_ERROR_NB + 1));
>> +
>> +	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][j] = smu[i][j];
>> +				lmu[cap + 1] = lmu[i];
>> +				return;
>> +			}
>> +
>> +			/* copy polynom */
>> +			for (j = 0; j<= lmu[i]>>  1; j++)
>> +				smu[i + 1][j] = smu[i][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<  (2 * PMECC_MAX_ERROR_NB + 1); k++)
>> +				smu[i+1][k] = 0;
>> +
>> +			/* Compute smu[i+1] */
>> +			for (k = 0; k<= lmu[ro]>>  1; k++) {
>> +				int16_t a, b, c;
>> +
>> +				if (!(smu[ro][k]&&  dmu[i]))
>> +					continue;
>> +				a = readw_relaxed(index_of + dmu[i]);
>> +				b = readw_relaxed(index_of + dmu[ro]);
>> +				c = readw_relaxed(index_of + smu[ro][k]);
>> +				tmp = a + (cw_len - b) + c;
>> +				a = readw_relaxed(alpha_to + tmp % cw_len);
>> +				smu[i + 1][k + diff] = a;
>> +			}
>> +
>> +			for (k = 0; k<= lmu[i]>>  1; k++)
>> +				smu[i + 1][k] ^= smu[i][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][k]&&  si[tmp + 3 - k]) {
>> +				int16_t a, b, c;
>> +				a = readw_relaxed(index_of + smu[i + 1][k]);
>> +				b = si[2 * (i - 1) + 3 - k];
>> +				c = readw_relaxed(index_of + b);
>> +				tmp = a + c;
>> +				tmp %= cw_len;
>> +				dmu[i + 1] = readw_relaxed(alpha_to + tmp) ^
>> +					dmu[i + 1];
>> +			}
>> +		}
>> +	}
>> +
>> +	return;
>> +}
>> +
>> +static int pmecc_err_location(struct mtd_info *mtd)
>> +{
>> +	int			i;
>> +	int			err_nbr;	/* number of error */
>> +	int			roots_nbr;	/* number of roots */
>> +	int			sector_size;
>> +	uint32_t		val;
>> +	struct nand_chip	*nand_chip = mtd->priv;
>> +	struct atmel_nand_host	*host = nand_chip->priv;
>> +	int			timeout_count = 0;
>> +	int			cap = host->pmecc_corr_cap;
>> +
>> +	err_nbr = 0;
>> +	sector_size = host->pmecc_sector_size;
>> +
>> +	pmerrloc_writel(host->pmerrloc_base, ELDIS, PMERRLOC_DISABLE);
>> +
>> +	for (i = 0; i<= host->pmecc_data->lmu[cap + 1]>>  1; i++) {
>> +		pmerrloc_writel_sigma_relaxed(host->pmerrloc_base, i,
>> +				      host->pmecc_data->smu[cap + 1][i]);
>> +		err_nbr++;
>> +	}
>> +
>> +	val = (err_nbr - 1)<<  16;
>> +	if (sector_size == 1024)
>> +		val |= 1;
>> +
>> +	pmerrloc_writel(host->pmerrloc_base, ELCFG, val);
>> +	pmerrloc_writel(host->pmerrloc_base, ELEN,
>> +			sector_size * 8 + host->pmecc_degree * cap);
>> +
>> +	while (!(pmerrloc_readl_relaxed(host->pmerrloc_base, ELISR)
>> +		&  PMERRLOC_CALC_DONE)) {
>> +		if (unlikely(timeout_count++>  PMECC_MAX_TIMEOUT_COUNT))
>> +			return -1;	/* Time out */
>> +		cpu_relax();
>> +	}
>> +
>> +	roots_nbr = (pmerrloc_readl_relaxed(host->pmerrloc_base, ELISR)
>> +		&  PMERRLOC_ERR_NUM_MASK)>>  8;
>> +	/* Number of roots == degree of smu hence<= cap */
>> +	if (roots_nbr == host->pmecc_data->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,
>> +		int extra_bytes, int err_nbr)
>> +{
>> +	int			i = 0;
>> +	int			byte_pos, bit_pos;
>> +	int			sector_size, ecc_size;
>> +	uint32_t		tmp;
>> +	struct nand_chip	*nand_chip = mtd->priv;
>> +	struct atmel_nand_host	*host = nand_chip->priv;
>> +
>> +	sector_size = host->pmecc_sector_size;
>> +	ecc_size = nand_chip->ecc.bytes;
>> +
>> +	while (err_nbr) {
>> +		tmp = pmerrloc_readl_el_relaxed(host->pmerrloc_base, i) - 1;
>> +		byte_pos = tmp / 8;
>> +		bit_pos  = tmp % 8;
>> +		dev_info(host->dev, "PMECC correction, byte_pos: %d bit_pos: %d\n",
>> +					byte_pos, bit_pos);
>> +
>> +		if (byte_pos<  (sector_size + extra_bytes)) {
>> +			tmp = sector_size +
>> +				pmecc_readl_relaxed(host->ecc, SADDR);
>> +
>> +			if (byte_pos<  tmp)
>> +				*(buf + byte_pos) ^= (1<<  bit_pos);
>> +			else
>> +				*(buf + byte_pos + ecc_size) ^= (1<<  bit_pos);
>> +		}
>> +
>> +		i++;
>> +		err_nbr--;
>> +	}
>> +
>> +	return;
>> +}
>> +
>> +static int pmecc_correction(struct mtd_info *mtd, u32 pmecc_stat, uint8_t *buf,
>> +	u8 *ecc)
>> +{
>> +	int			i, err_nbr;
>> +	uint8_t			*buf_pos;
>> +	int			eccbytes;
>> +	struct nand_chip	*nand_chip = mtd->priv;
>> +	struct atmel_nand_host	*host = nand_chip->priv;
>> +
>> +	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) {
>> +				dev_err(host->dev, "PMECC: Too many errors\n");
>> +				mtd->ecc_stats.failed++;
>> +				return -EIO;
>> +			} else {
>> +				pmecc_correct_data(mtd, buf_pos, 0, 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)
>> +{
>> +	uint32_t		stat;
>> +	int			timeout_count = 0;
>> +	int			eccsize = chip->ecc.size;
>> +	uint8_t			*oob = chip->oob_poi;
>> +	struct atmel_nand_host	*host = chip->priv;
>> +	uint32_t		*eccpos = chip->ecc.layout->eccpos;
>> +
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_RST);
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DISABLE);
>> +	pmecc_writel(host->ecc, CFG, (pmecc_readl_relaxed(host->ecc, CFG)
>> +		&  ~PMECC_CFG_WRITE_OP) | PMECC_CFG_AUTO_ENABLE);
>> +
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_ENABLE);
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DATA);
>> +
>> +	chip->read_buf(mtd, buf, eccsize);
>> +	chip->read_buf(mtd, oob, mtd->oobsize);
>> +
>> +	while ((pmecc_readl_relaxed(host->ecc, SR)&  PMECC_SR_BUSY)) {
>> +		if (unlikely(timeout_count++>  PMECC_MAX_TIMEOUT_COUNT))
>> +			return -EIO;	/* Time out */
>> +		cpu_relax();
>> +	}
>> +
>> +	stat = pmecc_readl_relaxed(host->ecc, 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)
>> +{
>> +	int			i, j;
>> +	int			timeout_count = 0;
>> +	struct atmel_nand_host	*host = chip->priv;
>> +	uint32_t		*eccpos = chip->ecc.layout->eccpos;
>> +
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_RST);
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DISABLE);
>> +
>> +	pmecc_writel(host->ecc, CFG, (pmecc_readl_relaxed(host->ecc, CFG) |
>> +		PMECC_CFG_WRITE_OP)&  ~PMECC_CFG_AUTO_ENABLE);
>> +
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_ENABLE);
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DATA);
>> +
>> +	chip->write_buf(mtd, (u8 *)buf, mtd->writesize);
>> +
>> +	while ((pmecc_readl_relaxed(host->ecc, SR)&  PMECC_SR_BUSY)) {
>> +		if (unlikely(timeout_count++>  PMECC_MAX_TIMEOUT_COUNT)) {
>> +			dev_err(host->dev, "PMECC: Timeout to get ECC value.\n");
>> +			return;	/* Time out */
>> +		}
>> +		cpu_relax();
>> +	}
>> +
>> +	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]] =
>> +				pmecc_readb_ecc_relaxed(host->ecc, i, j);
>> +		}
>> +	}
>> +	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
>> +
>> +	return;
>> +}
>> +
>> +static void atmel_pmecc_core_init(struct mtd_info *mtd)
>> +{
>> +	uint32_t		val = 0;
>> +	struct nand_chip	*nand_chip = mtd->priv;
>> +	struct atmel_nand_host	*host = nand_chip->priv;
>> +	struct nand_ecclayout	*ecc_layout;
>> +
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_RST);
>> +	pmecc_writel(host->ecc, 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->ecc, CFG, val);
>> +
>> +	ecc_layout = nand_chip->ecc.layout;
>> +	pmecc_writel(host->ecc, SAREA, mtd->oobsize - 1);
>> +	pmecc_writel(host->ecc, SADDR, ecc_layout->eccpos[0]);
>> +	pmecc_writel(host->ecc, EADDR,
>> +			ecc_layout->eccpos[ecc_layout->eccbytes - 1]);
>> +	/* See datasheet about PMECC Clock Control Register */
>> +	pmecc_writel(host->ecc, CLK, 2);
>> +	pmecc_writel(host->ecc, IDR, 0xff);
>> +	pmecc_writel(host->ecc, CTRL, PMECC_CTRL_ENABLE);
>> +}
>> +
>> +static int __init atmel_pmecc_nand_init_params(struct platform_device *pdev,
>> +					 struct atmel_nand_host *host)
>> +{
>> +	int			cap, sector_size, err_no;
>> +	struct mtd_info		*mtd;
>> +	struct nand_chip	*nand_chip;
>> +	struct resource		*regs;
>> +	struct resource		*regs_pmerr, *regs_rom;
>> +
>> +	cap = host->pmecc_corr_cap;
>> +	sector_size = host->pmecc_sector_size;
>> +	dev_info(host->dev, "Initialize PMECC params, cap: %d, sector: %d\n",
>> +		 cap, sector_size);
>> +
>> +	/* Sanity check */
>> +	if ((sector_size != 512)&&  (sector_size != 1024)) {
>> +		dev_err(host->dev,
>> +			"Unsupported PMECC sector size: %d; should be 512 or 1024 bytes\n",
>> +			sector_size);
>> +		return -EINVAL;
>> +	}
>> +	if ((cap != 2)&&  (cap != 4)&&  (cap != 8)&&  (cap != 12)&&
>> +	    (cap != 24)) {
>> +		dev_err(host->dev,
>> +			"Unsupported PMECC correction capability, should be 2, 4, 8, 12 or 24\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	nand_chip =&host->nand_chip;
>> +	mtd =&host->mtd;
>> +
>> +	nand_chip->ecc.mode = NAND_ECC_SOFT;	/* By default */
>> +
>> +	regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
>> +	if (!regs) {
>> +		dev_warn(host->dev,
>> +			"Can't get I/O resource regs, rolling back on software ECC\n");
>> +		return 0;
>> +	}
>> +
>> +	host->ecc = ioremap(regs->start, resource_size(regs));
>> +	if (host->ecc == NULL) {
>> +		dev_err(host->dev, "ioremap failed\n");
>> +		err_no = -EIO;
>> +		goto err_pmecc_ioremap;
>> +	}
>> +
>> +	regs_pmerr = platform_get_resource(pdev, IORESOURCE_MEM, 2);
>> +	regs_rom = platform_get_resource(pdev, IORESOURCE_MEM, 3);
>> +	if (regs_pmerr&&  regs_rom) {
>> +		host->pmerrloc_base = ioremap(regs_pmerr->start,
>> +			resource_size(regs_pmerr));
>> +		host->pmecc_rom_base = ioremap(regs_rom->start,
>> +			resource_size(regs_rom));
>> +
>> +		if (host->pmerrloc_base&&  host->pmecc_rom_base) {
>> +			nand_chip->ecc.mode = NAND_ECC_HW;
>> +			nand_chip->ecc.read_page =
>> +				atmel_nand_pmecc_read_page;
>> +			nand_chip->ecc.write_page =
>> +				atmel_nand_pmecc_write_page;
>> +		} else {
>> +			dev_err(host->dev,
>> +				"Can not get I/O resource for PMECC controller!\n");
>> +			err_no = -EIO;
>> +			goto err_pmloc_ioremap;
>> +		}
>> +	}
>> +
>> +	/* ECC is calculated for the whole page (1 step) */
>> +	nand_chip->ecc.size = mtd->writesize;
>> +
>> +	/* set ECC page size and oob layout */
>> +	switch (mtd->writesize) {
>> +	case 2048:
>> +		host->pmecc_degree = PMECC_GF_DIMENSION_13;
>> +		host->pmecc_cw_len = (1<<  host->pmecc_degree) - 1;
>> +		host->pmecc_corr_cap = cap;
>> +		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 = pmecc_get_index_of(host);
>> +
>> +		nand_chip->ecc.steps = 1;
>> +		nand_chip->ecc.strength = cap;
>> +		nand_chip->ecc.bytes = host->pmecc_bytes_per_sector *
>> +				       host->pmecc_sector_number;
>> +		if (nand_chip->ecc.bytes>  mtd->oobsize - 2) {
>> +			dev_err(host->dev, "No room for ECC bytes\n");
>> +			err_no = -EINVAL;
>> +			goto err;
>> +		}
>> +		pmecc_config_ecc_layout(&atmel_pmecc_oobinfo,
>> +					mtd->oobsize,
>> +					nand_chip->ecc.bytes);
>> +		nand_chip->ecc.layout =&atmel_pmecc_oobinfo;
>> +		break;
>> +	case 512:
>> +	case 1024:
>> +	case 4096:
>> +		/* TODO */
>> +		dev_warn(host->dev,
>> +			"Unsupported page size for PMECC, use Software ECC\n");
>> +	default:
>> +		/* page size not handled by HW ECC */
>> +		/* switching back to soft ECC */
>> +		nand_chip->ecc.mode = NAND_ECC_SOFT;
>> +		nand_chip->ecc.calculate = NULL;
>> +		nand_chip->ecc.correct = NULL;
>> +		nand_chip->ecc.hwctl = NULL;
>> +		nand_chip->ecc.read_page = NULL;
>> +		nand_chip->ecc.write_page = NULL;
>> +		nand_chip->ecc.postpad = 0;
>> +		nand_chip->ecc.prepad = 0;
>> +		nand_chip->ecc.bytes = 0;
>> +		err_no = 0;
>> +		goto err;
>> +	}
>> +
>> +	/* Allocate data for PMECC computation */
>> +	host->pmecc_data = kzalloc(sizeof(struct atmel_pmecc_data), GFP_KERNEL);
> why do you always allocate the pmecc_data?
>
> you need to allocate it only if you use it

If not using PMECC, the code will never come to here. So I think it's 
right time to allocate all the computation data here.

>
> Best Regards,
> J.
>> +	if (!host->pmecc_data) {
>> +		dev_err(host->dev,
>> +				"Cannot allocate memory for PMECC computation!\n");
>> +		err_no = -ENOMEM;
>> +		goto err;
>> +	}
>> +
>> +	atmel_pmecc_core_init(mtd);
>> +
>> +	return 0;
>> +
>> +err:
>> +err_pmloc_ioremap:
>> +	iounmap(host->ecc);
>> +	if (host->pmerrloc_base)
>> +		iounmap(host->pmerrloc_base);
>> +	if (host->pmecc_rom_base)
>> +		iounmap(host->pmecc_rom_base);
>> +err_pmecc_ioremap:
>> +	return err_no;
>> +}
>> +
>> +/*
>>    * Calculate HW ECC
>>    *
>>    * function called after a write
>> @@ -720,7 +1456,11 @@ static int __init atmel_nand_probe(struct platform_device *pdev)
>>   	}
>>
>>   	if (nand_chip->ecc.mode == NAND_ECC_HW) {
>> -		res = atmel_hw_nand_init_params(pdev, host);
>> +		if (host->has_pmecc)
>> +			res = atmel_pmecc_nand_init_params(pdev, host);
>> +		else
>> +			res = atmel_hw_nand_init_params(pdev, host);
>> +
>>   		if (res != 0)
>>   			goto err_hw_ecc;
>>   	}
>> @@ -741,6 +1481,12 @@ static int __init atmel_nand_probe(struct platform_device *pdev)
>>   err_scan_tail:
>>   	if (host->ecc)
>>   		iounmap(host->ecc);
>> +	if (host->has_pmecc) {
> no need to check if you have teh pmecc
>
> if it's no the case pmerrloc_base will be NULLo
>
> don't you need to disable it in the error path?

right, I should disable the hardware in this error path.

>
> Best Regards,
> J.

Best Regards,
Josh Wu