cpu/arm926ejs/davinci/nand.c - platform/external/u-boot - Gitiles

 /*
  * NAND driver for TI DaVinci based boards.
  *
  * Copyright (C) 2007 Sergey Kubushyn <ksi@koi8.net>
  *
  * Based on Linux DaVinci NAND driver by TI. Original copyright follows:
  */

 /*
  *
  * linux/drivers/mtd/nand/nand_davinci.c
  *
  * NAND Flash Driver
  *
  * Copyright (C) 2006 Texas Instruments.
  *
  * ----------------------------------------------------------------------------
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  * ----------------------------------------------------------------------------
  *
  *  Overview:
  *   This is a device driver for the NAND flash device found on the
  *   DaVinci board which utilizes the Samsung k9k2g08 part.
  *
  Modifications:
  ver. 1.0: Feb 2005, Vinod/Sudhakar
  -
  *
  */

 #include <common.h>

 #ifdef CFG_USE_NAND
 #if !defined(CFG_NAND_LEGACY)

 #include <nand.h>
 #include <asm/arch/nand_defs.h>
 #include <asm/arch/emif_defs.h>

 extern struct nand_chip nand_dev_desc[CFG_MAX_NAND_DEVICE];

 static void nand_davinci_hwcontrol(struct mtd_info *mtd, int cmd)
 {
 	struct		nand_chip *this = mtd->priv;
 	u_int32_t	IO_ADDR_W = (u_int32_t)this->IO_ADDR_W;

 	IO_ADDR_W &= ~(MASK_ALE|MASK_CLE);

 	switch (cmd) {
 		case NAND_CTL_SETCLE:
 			IO_ADDR_W |= MASK_CLE;
 			break;
 		case NAND_CTL_SETALE:
 			IO_ADDR_W |= MASK_ALE;
 			break;
 	}

 	this->IO_ADDR_W = (void *)IO_ADDR_W;
 }

 /* Set WP on deselect, write enable on select */
 static void nand_davinci_select_chip(struct mtd_info *mtd, int chip)
 {
 #define GPIO_SET_DATA01	0x01c67018
 #define GPIO_CLR_DATA01	0x01c6701c
 #define GPIO_NAND_WP	(1 << 4)
 #ifdef SONATA_BOARD_GPIOWP
 	if (chip < 0) {
 		REG(GPIO_CLR_DATA01) |= GPIO_NAND_WP;
 	} else {
 		REG(GPIO_SET_DATA01) |= GPIO_NAND_WP;
 	}
 #endif
 }

 #ifdef CFG_NAND_HW_ECC
 #ifdef CFG_NAND_LARGEPAGE
 static struct nand_oobinfo davinci_nand_oobinfo = {
 	.useecc = MTD_NANDECC_AUTOPLACE,
 	.eccbytes = 12,
 	.eccpos = {8, 9, 10, 24, 25, 26, 40, 41, 42, 56, 57, 58},
 	.oobfree = { {2, 6}, {12, 12}, {28, 12}, {44, 12}, {60, 4} }
 };
 #elif defined(CFG_NAND_SMALLPAGE)
 static struct nand_oobinfo davinci_nand_oobinfo = {
 	.useecc = MTD_NANDECC_AUTOPLACE,
 	.eccbytes = 3,
 	.eccpos = {0, 1, 2},
 	.oobfree = { {6, 2}, {8, 8} }
 };
 #else
 #error "Either CFG_NAND_LARGEPAGE or CFG_NAND_SMALLPAGE must be defined!"
 #endif

 static void nand_davinci_enable_hwecc(struct mtd_info *mtd, int mode)
 {
 	emifregs	emif_addr;
 	int		dummy;

 	emif_addr = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

 	dummy = emif_addr->NANDF1ECC;
 	dummy = emif_addr->NANDF2ECC;
 	dummy = emif_addr->NANDF3ECC;
 	dummy = emif_addr->NANDF4ECC;

 	emif_addr->NANDFCR |= (1 << 8);
 }

 static u_int32_t nand_davinci_readecc(struct mtd_info *mtd, u_int32_t region)
 {
 	u_int32_t	ecc = 0;
 	emifregs	emif_base_addr;

 	emif_base_addr = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

 	if (region == 1)
 		ecc = emif_base_addr->NANDF1ECC;
 	else if (region == 2)
 		ecc = emif_base_addr->NANDF2ECC;
 	else if (region == 3)
 		ecc = emif_base_addr->NANDF3ECC;
 	else if (region == 4)
 		ecc = emif_base_addr->NANDF4ECC;

 	return(ecc);
 }

 static int nand_davinci_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u_char *ecc_code)
 {
 	u_int32_t		tmp;
 	int			region, n;
 	struct nand_chip	*this = mtd->priv;

 	n = (this->eccmode == NAND_ECC_HW12_2048) ? 4 : 1;

 	region = 1;
 	while (n--) {
 		tmp = nand_davinci_readecc(mtd, region);
 		*ecc_code++ = tmp;
 		*ecc_code++ = tmp >> 16;
 		*ecc_code++ = ((tmp >> 8) & 0x0f) | ((tmp >> 20) & 0xf0);
 		region++;
 	}
 	return(0);
 }

 static void nand_davinci_gen_true_ecc(u_int8_t *ecc_buf)
 {
 	u_int32_t	tmp = ecc_buf[0] | (ecc_buf[1] << 16) | ((ecc_buf[2] & 0xf0) << 20) | ((ecc_buf[2] & 0x0f) << 8);

 	ecc_buf[0] = ~(P64o(tmp) | P64e(tmp) | P32o(tmp) | P32e(tmp) | P16o(tmp) | P16e(tmp) | P8o(tmp) | P8e(tmp));
 	ecc_buf[1] = ~(P1024o(tmp) | P1024e(tmp) | P512o(tmp) | P512e(tmp) | P256o(tmp) | P256e(tmp) | P128o(tmp) | P128e(tmp));
 	ecc_buf[2] = ~( P4o(tmp) | P4e(tmp) | P2o(tmp) | P2e(tmp) | P1o(tmp) | P1e(tmp) | P2048o(tmp) | P2048e(tmp));
 }

 static int nand_davinci_compare_ecc(u_int8_t *ecc_nand, u_int8_t *ecc_calc, u_int8_t *page_data)
 {
 	u_int32_t	i;
 	u_int8_t	tmp0_bit[8], tmp1_bit[8], tmp2_bit[8];
 	u_int8_t	comp0_bit[8], comp1_bit[8], comp2_bit[8];
 	u_int8_t	ecc_bit[24];
 	u_int8_t	ecc_sum = 0;
 	u_int8_t	find_bit = 0;
 	u_int32_t	find_byte = 0;
 	int		is_ecc_ff;

 	is_ecc_ff = ((*ecc_nand == 0xff) && (*(ecc_nand + 1) == 0xff) && (*(ecc_nand + 2) == 0xff));

 	nand_davinci_gen_true_ecc(ecc_nand);
 	nand_davinci_gen_true_ecc(ecc_calc);

 	for (i = 0; i <= 2; i++) {
 		*(ecc_nand + i) = ~(*(ecc_nand + i));
 		*(ecc_calc + i) = ~(*(ecc_calc + i));
 	}

 	for (i = 0; i < 8; i++) {
 		tmp0_bit[i] = *ecc_nand % 2;
 		*ecc_nand = *ecc_nand / 2;
 	}

 	for (i = 0; i < 8; i++) {
 		tmp1_bit[i] = *(ecc_nand + 1) % 2;
 		*(ecc_nand + 1) = *(ecc_nand + 1) / 2;
 	}

 	for (i = 0; i < 8; i++) {
 		tmp2_bit[i] = *(ecc_nand + 2) % 2;
 		*(ecc_nand + 2) = *(ecc_nand + 2) / 2;
 	}

 	for (i = 0; i < 8; i++) {
 		comp0_bit[i] = *ecc_calc % 2;
 		*ecc_calc = *ecc_calc / 2;
 	}

 	for (i = 0; i < 8; i++) {
 		comp1_bit[i] = *(ecc_calc + 1) % 2;
 		*(ecc_calc + 1) = *(ecc_calc + 1) / 2;
 	}

 	for (i = 0; i < 8; i++) {
 		comp2_bit[i] = *(ecc_calc + 2) % 2;
 		*(ecc_calc + 2) = *(ecc_calc + 2) / 2;
 	}

 	for (i = 0; i< 6; i++)
 		ecc_bit[i] = tmp2_bit[i + 2] ^ comp2_bit[i + 2];

 	for (i = 0; i < 8; i++)
 		ecc_bit[i + 6] = tmp0_bit[i] ^ comp0_bit[i];

 	for (i = 0; i < 8; i++)
 		ecc_bit[i + 14] = tmp1_bit[i] ^ comp1_bit[i];

 	ecc_bit[22] = tmp2_bit[0] ^ comp2_bit[0];
 	ecc_bit[23] = tmp2_bit[1] ^ comp2_bit[1];

 	for (i = 0; i < 24; i++)
 		ecc_sum += ecc_bit[i];

 	switch (ecc_sum) {
 		case 0:
 			/* Not reached because this function is not called if
 			   ECC values are equal */
 			return 0;
 		case 1:
 			/* Uncorrectable error */
 			DEBUG (MTD_DEBUG_LEVEL0, "ECC UNCORRECTED_ERROR 1\n");
 			return(-1);
 		case 12:
 			/* Correctable error */
 			find_byte = (ecc_bit[23] << 8) +
 				(ecc_bit[21] << 7) +
 				(ecc_bit[19] << 6) +
 				(ecc_bit[17] << 5) +
 				(ecc_bit[15] << 4) +
 				(ecc_bit[13] << 3) +
 				(ecc_bit[11] << 2) +
 				(ecc_bit[9]  << 1) +
 				ecc_bit[7];

 			find_bit = (ecc_bit[5] << 2) + (ecc_bit[3] << 1) + ecc_bit[1];

 			DEBUG (MTD_DEBUG_LEVEL0, "Correcting single bit ECC error at offset: %d, bit: %d\n", find_byte, find_bit);

 			page_data[find_byte] ^= (1 << find_bit);

 			return(0);
 		default:
 			if (is_ecc_ff) {
 				if (ecc_calc[0] == 0 && ecc_calc[1] == 0 && ecc_calc[2] == 0)
 					return(0);
 			}
 			DEBUG (MTD_DEBUG_LEVEL0, "UNCORRECTED_ERROR default\n");
 			return(-1);
 	}
 }

 static int nand_davinci_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc, u_char *calc_ecc)
 {
 	struct nand_chip	*this;
 	int			block_count = 0, i, rc;

 	this = mtd->priv;
 	block_count = (this->eccmode == NAND_ECC_HW12_2048) ? 4 : 1;
 	for (i = 0; i < block_count; i++) {
 		if (memcmp(read_ecc, calc_ecc, 3) != 0) {
 			rc = nand_davinci_compare_ecc(read_ecc, calc_ecc, dat);
 			if (rc < 0) {
 				return(rc);
 			}
 		}
 		read_ecc += 3;
 		calc_ecc += 3;
 		dat += 512;
 	}
 	return(0);
 }
 #endif

 static int nand_davinci_dev_ready(struct mtd_info *mtd)
 {
 	emifregs	emif_addr;

 	emif_addr = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

 	return(emif_addr->NANDFSR & 0x1);
 }

 static int nand_davinci_waitfunc(struct mtd_info *mtd, struct nand_chip *this, int state)
 {
 	while(!nand_davinci_dev_ready(mtd)) {;}
 	*NAND_CE0CLE = NAND_STATUS;
 	return(*NAND_CE0DATA);
 }

 static void nand_flash_init(void)
 {
 	u_int32_t	acfg1 = 0x3ffffffc;
 	u_int32_t	acfg2 = 0x3ffffffc;
 	u_int32_t	acfg3 = 0x3ffffffc;
 	u_int32_t	acfg4 = 0x3ffffffc;
 	emifregs	emif_regs;

 	/*------------------------------------------------------------------*
 	 *  NAND FLASH CHIP TIMEOUT @ 459 MHz                               *
 	 *                                                                  *
 	 *  AEMIF.CLK freq   = PLL1/6 = 459/6 = 76.5 MHz                    *
 	 *  AEMIF.CLK period = 1/76.5 MHz = 13.1 ns                         *
 	 *                                                                  *
 	 *------------------------------------------------------------------*/
 	 acfg1 = 0
 	 	| (0 << 31 )	/* selectStrobe */
 	 	| (0 << 30 )	/* extWait */
 	 	| (1 << 26 )	/* writeSetup	10 ns */
 	 	| (3 << 20 )	/* writeStrobe	40 ns */
 	 	| (1 << 17 )	/* writeHold	10 ns */
 	 	| (1 << 13 )	/* readSetup	10 ns */
 	 	| (5 << 7 )	/* readStrobe	60 ns */
 	 	| (1 << 4 )	/* readHold	10 ns */
 	 	| (3 << 2 )	/* turnAround	?? ns */
 	 	| (0 << 0 )	/* asyncSize	8-bit bus */
 	 	;

 	emif_regs = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

 	emif_regs->AWCCR |= 0x10000000;
 	emif_regs->AB1CR = acfg1;	/* 0x08244128 */;
 	emif_regs->AB2CR = acfg2;
 	emif_regs->AB3CR = acfg3;
 	emif_regs->AB4CR = acfg4;
 	emif_regs->NANDFCR = 0x00000101;
 }

 int board_nand_init(struct nand_chip *nand)
 {
 	nand->IO_ADDR_R   = (void  __iomem *)NAND_CE0DATA;
 	nand->IO_ADDR_W   = (void  __iomem *)NAND_CE0DATA;
 	nand->chip_delay  = 0;
 	nand->select_chip = nand_davinci_select_chip;
 #ifdef CFG_NAND_USE_FLASH_BBT
 	nand->options	  = NAND_USE_FLASH_BBT;
 #endif
 #ifdef CFG_NAND_HW_ECC
 #ifdef CFG_NAND_LARGEPAGE
 	nand->eccmode     = NAND_ECC_HW12_2048;
 #elif defined(CFG_NAND_SMALLPAGE)
 	nand->eccmode     = NAND_ECC_HW3_512;
 #else
 #error "Either CFG_NAND_LARGEPAGE or CFG_NAND_SMALLPAGE must be defined!"
 #endif
 	nand->autooob	  = &davinci_nand_oobinfo;
 	nand->calculate_ecc = nand_davinci_calculate_ecc;
 	nand->correct_data  = nand_davinci_correct_data;
 	nand->enable_hwecc  = nand_davinci_enable_hwecc;
 #else
 	nand->eccmode     = NAND_ECC_SOFT;
 #endif

 	/* Set address of hardware control function */
 	nand->hwcontrol = nand_davinci_hwcontrol;

 	nand->dev_ready = nand_davinci_dev_ready;
 	nand->waitfunc = nand_davinci_waitfunc;

 	nand_flash_init();

 	return(0);
 }

 #else
 #error "U-Boot legacy NAND support not available for DaVinci chips"
 #endif
 #endif	/* CFG_USE_NAND */
	/*
	* NAND driver for TI DaVinci based boards.
	*
	* Copyright (C) 2007 Sergey Kubushyn <ksi@koi8.net>
	*
	* Based on Linux DaVinci NAND driver by TI. Original copyright follows:
	*/

	/*
	*
	* linux/drivers/mtd/nand/nand_davinci.c
	*
	* NAND Flash Driver
	*
	* Copyright (C) 2006 Texas Instruments.
	*
	* ----------------------------------------------------------------------------
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	* ----------------------------------------------------------------------------
	*
	* Overview:
	* This is a device driver for the NAND flash device found on the
	* DaVinci board which utilizes the Samsung k9k2g08 part.
	*
	Modifications:
	ver. 1.0: Feb 2005, Vinod/Sudhakar
	-
	*
	*/

	#include <common.h>

	#ifdef CFG_USE_NAND
	#if !defined(CFG_NAND_LEGACY)

	#include <nand.h>
	#include <asm/arch/nand_defs.h>
	#include <asm/arch/emif_defs.h>

	extern struct nand_chip nand_dev_desc[CFG_MAX_NAND_DEVICE];

	static void nand_davinci_hwcontrol(struct mtd_info *mtd, int cmd)
	{
	struct nand_chip *this = mtd->priv;
	u_int32_t IO_ADDR_W = (u_int32_t)this->IO_ADDR_W;

	IO_ADDR_W &= ~(MASK_ALE\|MASK_CLE);

	switch (cmd) {
	case NAND_CTL_SETCLE:
	IO_ADDR_W \|= MASK_CLE;
	break;
	case NAND_CTL_SETALE:
	IO_ADDR_W \|= MASK_ALE;
	break;
	}

	this->IO_ADDR_W = (void *)IO_ADDR_W;
	}

	/* Set WP on deselect, write enable on select */
	static void nand_davinci_select_chip(struct mtd_info *mtd, int chip)
	{
	#define GPIO_SET_DATA01 0x01c67018
	#define GPIO_CLR_DATA01 0x01c6701c
	#define GPIO_NAND_WP (1 << 4)
	#ifdef SONATA_BOARD_GPIOWP
	if (chip < 0) {
	REG(GPIO_CLR_DATA01) \|= GPIO_NAND_WP;
	} else {
	REG(GPIO_SET_DATA01) \|= GPIO_NAND_WP;
	}
	#endif
	}

	#ifdef CFG_NAND_HW_ECC
	#ifdef CFG_NAND_LARGEPAGE
	static struct nand_oobinfo davinci_nand_oobinfo = {
	.useecc = MTD_NANDECC_AUTOPLACE,
	.eccbytes = 12,
	.eccpos = {8, 9, 10, 24, 25, 26, 40, 41, 42, 56, 57, 58},
	.oobfree = { {2, 6}, {12, 12}, {28, 12}, {44, 12}, {60, 4} }
	};
	#elif defined(CFG_NAND_SMALLPAGE)
	static struct nand_oobinfo davinci_nand_oobinfo = {
	.useecc = MTD_NANDECC_AUTOPLACE,
	.eccbytes = 3,
	.eccpos = {0, 1, 2},
	.oobfree = { {6, 2}, {8, 8} }
	};
	#else
	#error "Either CFG_NAND_LARGEPAGE or CFG_NAND_SMALLPAGE must be defined!"
	#endif

	static void nand_davinci_enable_hwecc(struct mtd_info *mtd, int mode)
	{
	emifregs emif_addr;
	int dummy;

	emif_addr = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

	dummy = emif_addr->NANDF1ECC;
	dummy = emif_addr->NANDF2ECC;
	dummy = emif_addr->NANDF3ECC;
	dummy = emif_addr->NANDF4ECC;

	emif_addr->NANDFCR \|= (1 << 8);
	}

	static u_int32_t nand_davinci_readecc(struct mtd_info *mtd, u_int32_t region)
	{
	u_int32_t ecc = 0;
	emifregs emif_base_addr;

	emif_base_addr = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

	if (region == 1)
	ecc = emif_base_addr->NANDF1ECC;
	else if (region == 2)
	ecc = emif_base_addr->NANDF2ECC;
	else if (region == 3)
	ecc = emif_base_addr->NANDF3ECC;
	else if (region == 4)
	ecc = emif_base_addr->NANDF4ECC;

	return(ecc);
	}

	static int nand_davinci_calculate_ecc(struct mtd_info mtd, const u_char dat, u_char *ecc_code)
	{
	u_int32_t tmp;
	int region, n;
	struct nand_chip *this = mtd->priv;

	n = (this->eccmode == NAND_ECC_HW12_2048) ? 4 : 1;

	region = 1;
	while (n--) {
	tmp = nand_davinci_readecc(mtd, region);
	*ecc_code++ = tmp;
	*ecc_code++ = tmp >> 16;
	*ecc_code++ = ((tmp >> 8) & 0x0f) \| ((tmp >> 20) & 0xf0);
	region++;
	}
	return(0);
	}

	static void nand_davinci_gen_true_ecc(u_int8_t *ecc_buf)
	{
	u_int32_t tmp = ecc_buf[0] \| (ecc_buf[1] << 16) \| ((ecc_buf[2] & 0xf0) << 20) \| ((ecc_buf[2] & 0x0f) << 8);

	ecc_buf[0] = ~(P64o(tmp) \| P64e(tmp) \| P32o(tmp) \| P32e(tmp) \| P16o(tmp) \| P16e(tmp) \| P8o(tmp) \| P8e(tmp));
	ecc_buf[1] = ~(P1024o(tmp) \| P1024e(tmp) \| P512o(tmp) \| P512e(tmp) \| P256o(tmp) \| P256e(tmp) \| P128o(tmp) \| P128e(tmp));
	ecc_buf[2] = ~( P4o(tmp) \| P4e(tmp) \| P2o(tmp) \| P2e(tmp) \| P1o(tmp) \| P1e(tmp) \| P2048o(tmp) \| P2048e(tmp));
	}

	static int nand_davinci_compare_ecc(u_int8_t ecc_nand, u_int8_t ecc_calc, u_int8_t *page_data)
	{
	u_int32_t i;
	u_int8_t tmp0_bit[8], tmp1_bit[8], tmp2_bit[8];
	u_int8_t comp0_bit[8], comp1_bit[8], comp2_bit[8];
	u_int8_t ecc_bit[24];
	u_int8_t ecc_sum = 0;
	u_int8_t find_bit = 0;
	u_int32_t find_byte = 0;
	int is_ecc_ff;

	is_ecc_ff = ((ecc_nand == 0xff) && ((ecc_nand + 1) == 0xff) && (*(ecc_nand + 2) == 0xff));

	nand_davinci_gen_true_ecc(ecc_nand);
	nand_davinci_gen_true_ecc(ecc_calc);

	for (i = 0; i <= 2; i++) {
	(ecc_nand + i) = ~((ecc_nand + i));
	(ecc_calc + i) = ~((ecc_calc + i));
	}

	for (i = 0; i < 8; i++) {
	tmp0_bit[i] = *ecc_nand % 2;
	ecc_nand = ecc_nand / 2;
	}

	for (i = 0; i < 8; i++) {
	tmp1_bit[i] = *(ecc_nand + 1) % 2;
	(ecc_nand + 1) = (ecc_nand + 1) / 2;
	}

	for (i = 0; i < 8; i++) {
	tmp2_bit[i] = *(ecc_nand + 2) % 2;
	(ecc_nand + 2) = (ecc_nand + 2) / 2;
	}

	for (i = 0; i < 8; i++) {
	comp0_bit[i] = *ecc_calc % 2;
	ecc_calc = ecc_calc / 2;
	}

	for (i = 0; i < 8; i++) {
	comp1_bit[i] = *(ecc_calc + 1) % 2;
	(ecc_calc + 1) = (ecc_calc + 1) / 2;
	}

	for (i = 0; i < 8; i++) {
	comp2_bit[i] = *(ecc_calc + 2) % 2;
	(ecc_calc + 2) = (ecc_calc + 2) / 2;
	}

	for (i = 0; i< 6; i++)
	ecc_bit[i] = tmp2_bit[i + 2] ^ comp2_bit[i + 2];

	for (i = 0; i < 8; i++)
	ecc_bit[i + 6] = tmp0_bit[i] ^ comp0_bit[i];

	for (i = 0; i < 8; i++)
	ecc_bit[i + 14] = tmp1_bit[i] ^ comp1_bit[i];

	ecc_bit[22] = tmp2_bit[0] ^ comp2_bit[0];
	ecc_bit[23] = tmp2_bit[1] ^ comp2_bit[1];

	for (i = 0; i < 24; i++)
	ecc_sum += ecc_bit[i];

	switch (ecc_sum) {
	case 0:
	/* Not reached because this function is not called if
	ECC values are equal */
	return 0;
	case 1:
	/* Uncorrectable error */
	DEBUG (MTD_DEBUG_LEVEL0, "ECC UNCORRECTED_ERROR 1\n");
	return(-1);
	case 12:
	/* Correctable error */
	find_byte = (ecc_bit[23] << 8) +
	(ecc_bit[21] << 7) +
	(ecc_bit[19] << 6) +
	(ecc_bit[17] << 5) +
	(ecc_bit[15] << 4) +
	(ecc_bit[13] << 3) +
	(ecc_bit[11] << 2) +
	(ecc_bit[9] << 1) +
	ecc_bit[7];

	find_bit = (ecc_bit[5] << 2) + (ecc_bit[3] << 1) + ecc_bit[1];

	DEBUG (MTD_DEBUG_LEVEL0, "Correcting single bit ECC error at offset: %d, bit: %d\n", find_byte, find_bit);

	page_data[find_byte] ^= (1 << find_bit);

	return(0);
	default:
	if (is_ecc_ff) {
	if (ecc_calc[0] == 0 && ecc_calc[1] == 0 && ecc_calc[2] == 0)
	return(0);
	}
	DEBUG (MTD_DEBUG_LEVEL0, "UNCORRECTED_ERROR default\n");
	return(-1);
	}
	}

	static int nand_davinci_correct_data(struct mtd_info mtd, u_char dat, u_char read_ecc, u_char calc_ecc)
	{
	struct nand_chip *this;
	int block_count = 0, i, rc;

	this = mtd->priv;
	block_count = (this->eccmode == NAND_ECC_HW12_2048) ? 4 : 1;
	for (i = 0; i < block_count; i++) {
	if (memcmp(read_ecc, calc_ecc, 3) != 0) {
	rc = nand_davinci_compare_ecc(read_ecc, calc_ecc, dat);
	if (rc < 0) {
	return(rc);
	}
	}
	read_ecc += 3;
	calc_ecc += 3;
	dat += 512;
	}
	return(0);
	}
	#endif

	static int nand_davinci_dev_ready(struct mtd_info *mtd)
	{
	emifregs emif_addr;

	emif_addr = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

	return(emif_addr->NANDFSR & 0x1);
	}

	static int nand_davinci_waitfunc(struct mtd_info mtd, struct nand_chip this, int state)
	{
	while(!nand_davinci_dev_ready(mtd)) {;}
	*NAND_CE0CLE = NAND_STATUS;
	return(*NAND_CE0DATA);
	}

	static void nand_flash_init(void)
	{
	u_int32_t acfg1 = 0x3ffffffc;
	u_int32_t acfg2 = 0x3ffffffc;
	u_int32_t acfg3 = 0x3ffffffc;
	u_int32_t acfg4 = 0x3ffffffc;
	emifregs emif_regs;

	/------------------------------------------------------------------
	* NAND FLASH CHIP TIMEOUT @ 459 MHz *
	* *
	* AEMIF.CLK freq = PLL1/6 = 459/6 = 76.5 MHz *
	* AEMIF.CLK period = 1/76.5 MHz = 13.1 ns *
	* *
	------------------------------------------------------------------/
	acfg1 = 0
	\| (0 << 31 ) /* selectStrobe */
	\| (0 << 30 ) /* extWait */
	\| (1 << 26 ) /* writeSetup 10 ns */
	\| (3 << 20 ) /* writeStrobe 40 ns */
	\| (1 << 17 ) /* writeHold 10 ns */
	\| (1 << 13 ) /* readSetup 10 ns */
	\| (5 << 7 ) /* readStrobe 60 ns */
	\| (1 << 4 ) /* readHold 10 ns */
	\| (3 << 2 ) /* turnAround ?? ns */
	\| (0 << 0 ) /* asyncSize 8-bit bus */
	;

	emif_regs = (emifregs)DAVINCI_ASYNC_EMIF_CNTRL_BASE;

	emif_regs->AWCCR \|= 0x10000000;
	emif_regs->AB1CR = acfg1; /* 0x08244128 */;
	emif_regs->AB2CR = acfg2;
	emif_regs->AB3CR = acfg3;
	emif_regs->AB4CR = acfg4;
	emif_regs->NANDFCR = 0x00000101;
	}

	int board_nand_init(struct nand_chip *nand)
	{
	nand->IO_ADDR_R = (void __iomem *)NAND_CE0DATA;
	nand->IO_ADDR_W = (void __iomem *)NAND_CE0DATA;
	nand->chip_delay = 0;
	nand->select_chip = nand_davinci_select_chip;
	#ifdef CFG_NAND_USE_FLASH_BBT
	nand->options = NAND_USE_FLASH_BBT;
	#endif
	#ifdef CFG_NAND_HW_ECC
	#ifdef CFG_NAND_LARGEPAGE
	nand->eccmode = NAND_ECC_HW12_2048;
	#elif defined(CFG_NAND_SMALLPAGE)
	nand->eccmode = NAND_ECC_HW3_512;
	#else
	#error "Either CFG_NAND_LARGEPAGE or CFG_NAND_SMALLPAGE must be defined!"
	#endif
	nand->autooob = &davinci_nand_oobinfo;
	nand->calculate_ecc = nand_davinci_calculate_ecc;
	nand->correct_data = nand_davinci_correct_data;
	nand->enable_hwecc = nand_davinci_enable_hwecc;
	#else
	nand->eccmode = NAND_ECC_SOFT;
	#endif

	/* Set address of hardware control function */
	nand->hwcontrol = nand_davinci_hwcontrol;

	nand->dev_ready = nand_davinci_dev_ready;
	nand->waitfunc = nand_davinci_waitfunc;

	nand_flash_init();

	return(0);
	}

	#else
	#error "U-Boot legacy NAND support not available for DaVinci chips"
	#endif
	#endif /* CFG_USE_NAND */