drivers/mtd/nand/davinci_nand.c - github/trini/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>
 #include <asm/io.h>
 #include <nand.h>
 #include <asm/arch/nand_defs.h>
 #include <asm/arch/emif_defs.h>

 /* Definitions for 4-bit hardware ECC */
 #define NAND_TIMEOUT			10240
 #define NAND_ECC_BUSY			0xC
 #define NAND_4BITECC_MASK		0x03FF03FF
 #define EMIF_NANDFSR_ECC_STATE_MASK  	0x00000F00
 #define ECC_STATE_NO_ERR		0x0
 #define ECC_STATE_TOO_MANY_ERRS		0x1
 #define ECC_STATE_ERR_CORR_COMP_P	0x2
 #define ECC_STATE_ERR_CORR_COMP_N	0x3

 static emif_registers *const emif_regs = (void *) DAVINCI_ASYNC_EMIF_CNTRL_BASE;

 static void nand_davinci_hwcontrol(struct mtd_info *mtd, int cmd, unsigned int ctrl)
 {
 	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);

 	if (ctrl & NAND_CTRL_CHANGE) {
 		if ( ctrl & NAND_CLE )
 			IO_ADDR_W |= MASK_CLE;
 		if ( ctrl & NAND_ALE )
 			IO_ADDR_W |= MASK_ALE;
 		this->IO_ADDR_W = (void __iomem *) IO_ADDR_W;
 	}

 	if (cmd != NAND_CMD_NONE)
 		writeb(cmd, this->IO_ADDR_W);
 }

 #ifdef CONFIG_SYS_NAND_HW_ECC

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

 	dummy = emif_regs->NANDF1ECC;

 	/* FIXME:  only chipselect 0 is supported for now */
 	emif_regs->NANDFCR |= 1 << 8;
 }

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

 	if (region == 1)
 		ecc = emif_regs->NANDF1ECC;
 	else if (region == 2)
 		ecc = emif_regs->NANDF2ECC;
 	else if (region == 3)
 		ecc = emif_regs->NANDF3ECC;
 	else if (region == 4)
 		ecc = emif_regs->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;
 	const int region = 1;

 	tmp = nand_davinci_readecc(mtd, region);

 	/* Squeeze 4 bytes ECC into 3 bytes by removing RESERVED bits
 	 * and shifting. RESERVED bits are 31 to 28 and 15 to 12. */
 	tmp = (tmp & 0x00000fff) | ((tmp & 0x0fff0000) >> 4);

 	/* Invert so that erased block ECC is correct */
 	tmp = ~tmp;

 	*ecc_code++ = tmp;
 	*ecc_code++ = tmp >>  8;
 	*ecc_code++ = tmp >> 16;

 	/* NOTE:  the above code matches mainline Linux:
 	 *	.PQR.stu ==> ~PQRstu
 	 *
 	 * MontaVista/TI kernels encode those bytes differently, use
 	 * complicated (and allegedly sometimes-wrong) correction code,
 	 * and usually shipped with U-Boot that uses software ECC:
 	 *	.PQR.stu ==> PsQRtu
 	 *
 	 * If you need MV/TI compatible NAND I/O in U-Boot, it should
 	 * be possible to (a) change the mangling above, (b) reverse
 	 * that mangling in nand_davinci_correct_data() below.
 	 */

 	return 0;
 }

 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 = mtd->priv;
 	u_int32_t ecc_nand = read_ecc[0] | (read_ecc[1] << 8) |
 					  (read_ecc[2] << 16);
 	u_int32_t ecc_calc = calc_ecc[0] | (calc_ecc[1] << 8) |
 					  (calc_ecc[2] << 16);
 	u_int32_t diff = ecc_calc ^ ecc_nand;

 	if (diff) {
 		if ((((diff >> 12) ^ diff) & 0xfff) == 0xfff) {
 			/* Correctable error */
 			if ((diff >> (12 + 3)) < this->ecc.size) {
 				uint8_t find_bit = 1 << ((diff >> 12) & 7);
 				uint32_t find_byte = diff >> (12 + 3);

 				dat[find_byte] ^= find_bit;
 				MTDDEBUG(MTD_DEBUG_LEVEL0, "Correcting single "
 					 "bit ECC error at offset: %d, bit: "
 					 "%d\n", find_byte, find_bit);
 				return 1;
 			} else {
 				return -1;
 			}
 		} else if (!(diff & (diff - 1))) {
 			/* Single bit ECC error in the ECC itself,
 			   nothing to fix */
 			MTDDEBUG(MTD_DEBUG_LEVEL0, "Single bit ECC error in "
 				 "ECC.\n");
 			return 1;
 		} else {
 			/* Uncorrectable error */
 			MTDDEBUG(MTD_DEBUG_LEVEL0, "ECC UNCORRECTED_ERROR 1\n");
 			return -1;
 		}
 	}
 	return(0);
 }
 #endif /* CONFIG_SYS_NAND_HW_ECC */

 #ifdef CONFIG_SYS_NAND_4BIT_HW_ECC_OOBFIRST
 static struct nand_ecclayout nand_davinci_4bit_layout_oobfirst = {
 /*
  * TI uses a different layout for 4K page deviecs. Since the
  * eccpos filed can hold only a limited number of entries, adding
  * support for 4K page will result in compilation warnings
  * 4K Support will be added later
  */
 #ifdef CONFIG_SYS_NAND_PAGE_2K
 	.eccbytes = 40,
 	.eccpos = {
 		24, 25, 26, 27, 28,
 		29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
 		39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
 		49, 50, 51, 52, 53, 54, 55, 56, 57, 58,
 		59, 60, 61, 62, 63,
 		},
 	.oobfree = {
 		{.offset = 2, .length = 22, },
 	},
 #endif
 };
 #endif

 static void nand_davinci_4bit_enable_hwecc(struct mtd_info *mtd, int mode)
 {
 	u32 val;

 	switch (mode) {
 	case NAND_ECC_WRITE:
 	case NAND_ECC_READ:
 		/*
 		 * Start a new ECC calculation for reading or writing 512 bytes
 		 * of data.
 		 */
 		val = (emif_regs->NANDFCR & ~(3 << 4)) | (1 << 12);
 		emif_regs->NANDFCR = val;
 		break;
 	case NAND_ECC_READSYN:
 		val = emif_regs->NAND4BITECC1;
 		break;
 	default:
 		break;
 	}
 }

 static u32 nand_davinci_4bit_readecc(struct mtd_info *mtd, unsigned int ecc[4])
 {
 	ecc[0] = emif_regs->NAND4BITECC1 & NAND_4BITECC_MASK;
 	ecc[1] = emif_regs->NAND4BITECC2 & NAND_4BITECC_MASK;
 	ecc[2] = emif_regs->NAND4BITECC3 & NAND_4BITECC_MASK;
 	ecc[3] = emif_regs->NAND4BITECC4 & NAND_4BITECC_MASK;

 	return 0;
 }

 static int nand_davinci_4bit_calculate_ecc(struct mtd_info *mtd,
 					   const uint8_t *dat,
 					   uint8_t *ecc_code)
 {
 	unsigned int hw_4ecc[4] = { 0, 0, 0, 0 };
 	unsigned int const1 = 0, const2 = 0;
 	unsigned char count1 = 0;

 	nand_davinci_4bit_readecc(mtd, hw_4ecc);

 	/*Convert 10 bit ecc value to 8 bit */
 	for (count1 = 0; count1 < 2; count1++) {
 		const2 = count1 * 5;
 		const1 = count1 * 2;

 		/* Take first 8 bits from val1 (count1=0) or val5 (count1=1) */
 		ecc_code[const2] = hw_4ecc[const1] & 0xFF;

 		/*
 		 * Take 2 bits as LSB bits from val1 (count1=0) or val5
 		 * (count1=1) and 6 bits from val2 (count1=0) or
 		 * val5 (count1=1)
 		 */
 		ecc_code[const2 + 1] =
 		    ((hw_4ecc[const1] >> 8) & 0x3) | ((hw_4ecc[const1] >> 14) &
 						      0xFC);

 		/*
 		 * Take 4 bits from val2 (count1=0) or val5 (count1=1) and
 		 * 4 bits from val3 (count1=0) or val6 (count1=1)
 		 */
 		ecc_code[const2 + 2] =
 		    ((hw_4ecc[const1] >> 22) & 0xF) |
 		    ((hw_4ecc[const1 + 1] << 4) & 0xF0);

 		/*
 		 * Take 6 bits from val3(count1=0) or val6 (count1=1) and
 		 * 2 bits from val4 (count1=0) or  val7 (count1=1)
 		 */
 		ecc_code[const2 + 3] =
 		    ((hw_4ecc[const1 + 1] >> 4) & 0x3F) |
 		    ((hw_4ecc[const1 + 1] >> 10) & 0xC0);

 		/* Take 8 bits from val4 (count1=0) or val7 (count1=1) */
 		ecc_code[const2 + 4] = (hw_4ecc[const1 + 1] >> 18) & 0xFF;
 	}
 	return 0;
 }


 static int nand_davinci_4bit_correct_data(struct mtd_info *mtd, uint8_t *dat,
 					  uint8_t *read_ecc, uint8_t *calc_ecc)
 {
 	struct nand_chip *this = mtd->priv;
 	unsigned short ecc_10bit[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
 	int i;
 	unsigned int hw_4ecc[4] = { 0, 0, 0, 0 }, iserror = 0;
 	unsigned short *pspare = NULL, *pspare1 = NULL;
 	unsigned int numerrors, erroraddress, errorvalue;
 	u32 val;

 	/*
 	 * Check for an ECC where all bytes are 0xFF.  If this is the case, we
 	 * will assume we are looking at an erased page and we should ignore
 	 * the ECC.
 	 */
 	for (i = 0; i < 10; i++) {
 		if (read_ecc[i] != 0xFF)
 			break;
 	}
 	if (i == 10)
 		return 0;

 	/* Convert 8 bit in to 10 bit */
 	pspare = (unsigned short *)&read_ecc[2];
 	pspare1 = (unsigned short *)&read_ecc[0];

 	/* Take 10 bits from 0th and 1st bytes */
 	ecc_10bit[0] = (*pspare1) & 0x3FF;

 	/* Take 6 bits from 1st byte and 4 bits from 2nd byte */
 	ecc_10bit[1] = (((*pspare1) >> 10) & 0x3F)
 	    | (((pspare[0]) << 6) & 0x3C0);

 	/* Take 4 bits form 2nd bytes and 6 bits from 3rd bytes */
 	ecc_10bit[2] = ((pspare[0]) >> 4) & 0x3FF;

 	/*Take 2 bits from 3rd byte and 8 bits from 4th byte */
 	ecc_10bit[3] = (((pspare[0]) >> 14) & 0x3)
 	    | ((((pspare[1])) << 2) & 0x3FC);

 	/* Take 8 bits from 5th byte and 2 bits from 6th byte */
 	ecc_10bit[4] = ((pspare[1]) >> 8)
 	    | ((((pspare[2])) << 8) & 0x300);

 	/* Take 6 bits from 6th byte and 4 bits from 7th byte */
 	ecc_10bit[5] = (pspare[2] >> 2) & 0x3FF;

 	/* Take 4 bits from 7th byte and 6 bits from 8th byte */
 	ecc_10bit[6] = (((pspare[2]) >> 12) & 0xF)
 	    | ((((pspare[3])) << 4) & 0x3F0);

 	/*Take 2 bits from 8th byte and 8 bits from 9th byte */
 	ecc_10bit[7] = ((pspare[3]) >> 6) & 0x3FF;

 	/*
 	 * Write the parity values in the NAND Flash 4-bit ECC Load register.
 	 * Write each parity value one at a time starting from 4bit_ecc_val8
 	 * to 4bit_ecc_val1.
 	 */
 	for (i = 7; i >= 0; i--)
 		emif_regs->NAND4BITECCLOAD = ecc_10bit[i];

 	/*
 	 * Perform a dummy read to the EMIF Revision Code and Status register.
 	 * This is required to ensure time for syndrome calculation after
 	 * writing the ECC values in previous step.
 	 */

 	val = emif_regs->NANDFSR;

 	/*
 	 * Read the syndrome from the NAND Flash 4-Bit ECC 1-4 registers.
 	 * A syndrome value of 0 means no bit errors. If the syndrome is
 	 * non-zero then go further otherwise return.
 	 */
 	nand_davinci_4bit_readecc(mtd, hw_4ecc);

 	if (hw_4ecc[0] == ECC_STATE_NO_ERR && hw_4ecc[1] == ECC_STATE_NO_ERR &&
 	    hw_4ecc[2] == ECC_STATE_NO_ERR && hw_4ecc[3] == ECC_STATE_NO_ERR)
 		return 0;

 	/*
 	 * Clear any previous address calculation by doing a dummy read of an
 	 * error address register.
 	 */
 	val = emif_regs->NANDERRADD1;

 	/*
 	 * Set the addr_calc_st bit(bit no 13) in the NAND Flash Control
 	 * register to 1.
 	 */
 	emif_regs->NANDFCR |= 1 << 13;

 	/*
 	 * Wait for the corr_state field (bits 8 to 11)in the
 	 * NAND Flash Status register to be equal to 0x0, 0x1, 0x2, or 0x3.
 	 */
 	i = NAND_TIMEOUT;
 	do {
 		val = emif_regs->NANDFSR;
 		val &= 0xc00;
 		i--;
 	} while ((i > 0) && val);

 	iserror = emif_regs->NANDFSR;
 	iserror &= EMIF_NANDFSR_ECC_STATE_MASK;
 	iserror = iserror >> 8;

 	/*
 	 * ECC_STATE_TOO_MANY_ERRS (0x1) means errors cannot be
 	 * corrected (five or more errors).  The number of errors
 	 * calculated (err_num field) differs from the number of errors
 	 * searched.  ECC_STATE_ERR_CORR_COMP_P (0x2) means error
 	 * correction complete (errors on bit 8 or 9).
 	 * ECC_STATE_ERR_CORR_COMP_N (0x3) means error correction
 	 * complete (error exists).
 	 */

 	if (iserror == ECC_STATE_NO_ERR) {
 		val = emif_regs->NANDERRVAL1;
 		return 0;
 	} else if (iserror == ECC_STATE_TOO_MANY_ERRS) {
 		val = emif_regs->NANDERRVAL1;
 		return -1;
 	}

 	numerrors = ((emif_regs->NANDFSR >> 16) & 0x3) + 1;

 	/* Read the error address, error value and correct */
 	for (i = 0; i < numerrors; i++) {
 		if (i > 1) {
 			erroraddress =
 			    ((emif_regs->NANDERRADD2 >>
 			      (16 * (i & 1))) & 0x3FF);
 			erroraddress = ((512 + 7) - erroraddress);
 			errorvalue =
 			    ((emif_regs->NANDERRVAL2 >>
 			      (16 * (i & 1))) & 0xFF);
 		} else {
 			erroraddress =
 			    ((emif_regs->NANDERRADD1 >>
 			      (16 * (i & 1))) & 0x3FF);
 			erroraddress = ((512 + 7) - erroraddress);
 			errorvalue =
 			    ((emif_regs->NANDERRVAL1 >>
 			      (16 * (i & 1))) & 0xFF);
 		}
 		/* xor the corrupt data with error value */
 		if (erroraddress < 512)
 			dat[erroraddress] ^= errorvalue;
 	}

 	return numerrors;
 }

 static int nand_davinci_dev_ready(struct mtd_info *mtd)
 {
 	return emif_regs->NANDFSR & 0x1;
 }

 static void nand_flash_init(void)
 {
 	/* This is for DM6446 EVM and *very* similar.  DO NOT GROW THIS!
 	 * Instead, have your board_init() set EMIF timings, based on its
 	 * knowledge of the clocks and what devices are hooked up ... and
 	 * don't even do that unless no UBL handled it.
 	 */
 #ifdef CONFIG_SOC_DM644X
 	u_int32_t	acfg1 = 0x3ffffffc;

 	/*------------------------------------------------------------------*
 	 *  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->AB1CR = acfg1; /* CS2 */

 	emif_regs->NANDFCR = 0x00000101; /* NAND flash on CS2 */
 #endif
 }

 void davinci_nand_init(struct nand_chip *nand)
 {
 	nand->chip_delay  = 0;
 #ifdef CONFIG_SYS_NAND_USE_FLASH_BBT
 	nand->options	  |= NAND_USE_FLASH_BBT;
 #endif
 #ifdef CONFIG_SYS_NAND_HW_ECC
 	nand->ecc.mode = NAND_ECC_HW;
 	nand->ecc.size = 512;
 	nand->ecc.bytes = 3;
 	nand->ecc.calculate = nand_davinci_calculate_ecc;
 	nand->ecc.correct  = nand_davinci_correct_data;
 	nand->ecc.hwctl  = nand_davinci_enable_hwecc;
 #else
 	nand->ecc.mode = NAND_ECC_SOFT;
 #endif /* CONFIG_SYS_NAND_HW_ECC */
 #ifdef CONFIG_SYS_NAND_4BIT_HW_ECC_OOBFIRST
 	nand->ecc.mode = NAND_ECC_HW_OOB_FIRST;
 	nand->ecc.size = 512;
 	nand->ecc.bytes = 10;
 	nand->ecc.calculate = nand_davinci_4bit_calculate_ecc;
 	nand->ecc.correct = nand_davinci_4bit_correct_data;
 	nand->ecc.hwctl = nand_davinci_4bit_enable_hwecc;
 	nand->ecc.layout = &nand_davinci_4bit_layout_oobfirst;
 #endif
 	/* Set address of hardware control function */
 	nand->cmd_ctrl = nand_davinci_hwcontrol;

 	nand->dev_ready = nand_davinci_dev_ready;

 	nand_flash_init();
 }

 int board_nand_init(struct nand_chip *chip) __attribute__((weak));

 int board_nand_init(struct nand_chip *chip)
 {
 	davinci_nand_init(chip);
 	return 0;
 }
	/*
	* 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>
	#include <asm/io.h>
	#include <nand.h>
	#include <asm/arch/nand_defs.h>
	#include <asm/arch/emif_defs.h>

	/* Definitions for 4-bit hardware ECC */
	#define NAND_TIMEOUT 10240
	#define NAND_ECC_BUSY 0xC
	#define NAND_4BITECC_MASK 0x03FF03FF
	#define EMIF_NANDFSR_ECC_STATE_MASK 0x00000F00
	#define ECC_STATE_NO_ERR 0x0
	#define ECC_STATE_TOO_MANY_ERRS 0x1
	#define ECC_STATE_ERR_CORR_COMP_P 0x2
	#define ECC_STATE_ERR_CORR_COMP_N 0x3

	static emif_registers const emif_regs = (void ) DAVINCI_ASYNC_EMIF_CNTRL_BASE;

	static void nand_davinci_hwcontrol(struct mtd_info *mtd, int cmd, unsigned int ctrl)
	{
	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);

	if (ctrl & NAND_CTRL_CHANGE) {
	if ( ctrl & NAND_CLE )
	IO_ADDR_W \|= MASK_CLE;
	if ( ctrl & NAND_ALE )
	IO_ADDR_W \|= MASK_ALE;
	this->IO_ADDR_W = (void __iomem *) IO_ADDR_W;
	}

	if (cmd != NAND_CMD_NONE)
	writeb(cmd, this->IO_ADDR_W);
	}

	#ifdef CONFIG_SYS_NAND_HW_ECC

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

	dummy = emif_regs->NANDF1ECC;

	/* FIXME: only chipselect 0 is supported for now */
	emif_regs->NANDFCR \|= 1 << 8;
	}

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

	if (region == 1)
	ecc = emif_regs->NANDF1ECC;
	else if (region == 2)
	ecc = emif_regs->NANDF2ECC;
	else if (region == 3)
	ecc = emif_regs->NANDF3ECC;
	else if (region == 4)
	ecc = emif_regs->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;
	const int region = 1;

	tmp = nand_davinci_readecc(mtd, region);

	/* Squeeze 4 bytes ECC into 3 bytes by removing RESERVED bits
	* and shifting. RESERVED bits are 31 to 28 and 15 to 12. */
	tmp = (tmp & 0x00000fff) \| ((tmp & 0x0fff0000) >> 4);

	/* Invert so that erased block ECC is correct */
	tmp = ~tmp;

	*ecc_code++ = tmp;
	*ecc_code++ = tmp >> 8;
	*ecc_code++ = tmp >> 16;

	/* NOTE: the above code matches mainline Linux:
	* .PQR.stu ==> ~PQRstu
	*
	* MontaVista/TI kernels encode those bytes differently, use
	* complicated (and allegedly sometimes-wrong) correction code,
	* and usually shipped with U-Boot that uses software ECC:
	* .PQR.stu ==> PsQRtu
	*
	* If you need MV/TI compatible NAND I/O in U-Boot, it should
	* be possible to (a) change the mangling above, (b) reverse
	* that mangling in nand_davinci_correct_data() below.
	*/

	return 0;
	}

	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 = mtd->priv;
	u_int32_t ecc_nand = read_ecc[0] \| (read_ecc[1] << 8) \|
	(read_ecc[2] << 16);
	u_int32_t ecc_calc = calc_ecc[0] \| (calc_ecc[1] << 8) \|
	(calc_ecc[2] << 16);
	u_int32_t diff = ecc_calc ^ ecc_nand;

	if (diff) {
	if ((((diff >> 12) ^ diff) & 0xfff) == 0xfff) {
	/* Correctable error */
	if ((diff >> (12 + 3)) < this->ecc.size) {
	uint8_t find_bit = 1 << ((diff >> 12) & 7);
	uint32_t find_byte = diff >> (12 + 3);

	dat[find_byte] ^= find_bit;
	MTDDEBUG(MTD_DEBUG_LEVEL0, "Correcting single "
	"bit ECC error at offset: %d, bit: "
	"%d\n", find_byte, find_bit);
	return 1;
	} else {
	return -1;
	}
	} else if (!(diff & (diff - 1))) {
	/* Single bit ECC error in the ECC itself,
	nothing to fix */
	MTDDEBUG(MTD_DEBUG_LEVEL0, "Single bit ECC error in "
	"ECC.\n");
	return 1;
	} else {
	/* Uncorrectable error */
	MTDDEBUG(MTD_DEBUG_LEVEL0, "ECC UNCORRECTED_ERROR 1\n");
	return -1;
	}
	}
	return(0);
	}
	#endif /* CONFIG_SYS_NAND_HW_ECC */

	#ifdef CONFIG_SYS_NAND_4BIT_HW_ECC_OOBFIRST
	static struct nand_ecclayout nand_davinci_4bit_layout_oobfirst = {
	/*
	* TI uses a different layout for 4K page deviecs. Since the
	* eccpos filed can hold only a limited number of entries, adding
	* support for 4K page will result in compilation warnings
	* 4K Support will be added later
	*/
	#ifdef CONFIG_SYS_NAND_PAGE_2K
	.eccbytes = 40,
	.eccpos = {
	24, 25, 26, 27, 28,
	29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
	39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
	49, 50, 51, 52, 53, 54, 55, 56, 57, 58,
	59, 60, 61, 62, 63,
	},
	.oobfree = {
	{.offset = 2, .length = 22, },
	},
	#endif
	};
	#endif

	static void nand_davinci_4bit_enable_hwecc(struct mtd_info *mtd, int mode)
	{
	u32 val;

	switch (mode) {
	case NAND_ECC_WRITE:
	case NAND_ECC_READ:
	/*
	* Start a new ECC calculation for reading or writing 512 bytes
	* of data.
	*/
	val = (emif_regs->NANDFCR & ~(3 << 4)) \| (1 << 12);
	emif_regs->NANDFCR = val;
	break;
	case NAND_ECC_READSYN:
	val = emif_regs->NAND4BITECC1;
	break;
	default:
	break;
	}
	}

	static u32 nand_davinci_4bit_readecc(struct mtd_info *mtd, unsigned int ecc[4])
	{
	ecc[0] = emif_regs->NAND4BITECC1 & NAND_4BITECC_MASK;
	ecc[1] = emif_regs->NAND4BITECC2 & NAND_4BITECC_MASK;
	ecc[2] = emif_regs->NAND4BITECC3 & NAND_4BITECC_MASK;
	ecc[3] = emif_regs->NAND4BITECC4 & NAND_4BITECC_MASK;

	return 0;
	}

	static int nand_davinci_4bit_calculate_ecc(struct mtd_info *mtd,
	const uint8_t *dat,
	uint8_t *ecc_code)
	{
	unsigned int hw_4ecc[4] = { 0, 0, 0, 0 };
	unsigned int const1 = 0, const2 = 0;
	unsigned char count1 = 0;

	nand_davinci_4bit_readecc(mtd, hw_4ecc);

	/Convert 10 bit ecc value to 8 bit /
	for (count1 = 0; count1 < 2; count1++) {
	const2 = count1 * 5;
	const1 = count1 * 2;

	/* Take first 8 bits from val1 (count1=0) or val5 (count1=1) */
	ecc_code[const2] = hw_4ecc[const1] & 0xFF;

	/*
	* Take 2 bits as LSB bits from val1 (count1=0) or val5
	* (count1=1) and 6 bits from val2 (count1=0) or
	* val5 (count1=1)
	*/
	ecc_code[const2 + 1] =
	((hw_4ecc[const1] >> 8) & 0x3) \| ((hw_4ecc[const1] >> 14) &
	0xFC);

	/*
	* Take 4 bits from val2 (count1=0) or val5 (count1=1) and
	* 4 bits from val3 (count1=0) or val6 (count1=1)
	*/
	ecc_code[const2 + 2] =
	((hw_4ecc[const1] >> 22) & 0xF) \|
	((hw_4ecc[const1 + 1] << 4) & 0xF0);

	/*
	* Take 6 bits from val3(count1=0) or val6 (count1=1) and
	* 2 bits from val4 (count1=0) or val7 (count1=1)
	*/
	ecc_code[const2 + 3] =
	((hw_4ecc[const1 + 1] >> 4) & 0x3F) \|
	((hw_4ecc[const1 + 1] >> 10) & 0xC0);

	/* Take 8 bits from val4 (count1=0) or val7 (count1=1) */
	ecc_code[const2 + 4] = (hw_4ecc[const1 + 1] >> 18) & 0xFF;
	}
	return 0;
	}


	static int nand_davinci_4bit_correct_data(struct mtd_info mtd, uint8_t dat,
	uint8_t read_ecc, uint8_t calc_ecc)
	{
	struct nand_chip *this = mtd->priv;
	unsigned short ecc_10bit[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
	int i;
	unsigned int hw_4ecc[4] = { 0, 0, 0, 0 }, iserror = 0;
	unsigned short pspare = NULL, pspare1 = NULL;
	unsigned int numerrors, erroraddress, errorvalue;
	u32 val;

	/*
	* Check for an ECC where all bytes are 0xFF. If this is the case, we
	* will assume we are looking at an erased page and we should ignore
	* the ECC.
	*/
	for (i = 0; i < 10; i++) {
	if (read_ecc[i] != 0xFF)
	break;
	}
	if (i == 10)
	return 0;

	/* Convert 8 bit in to 10 bit */
	pspare = (unsigned short *)&read_ecc[2];
	pspare1 = (unsigned short *)&read_ecc[0];

	/* Take 10 bits from 0th and 1st bytes */
	ecc_10bit[0] = (*pspare1) & 0x3FF;

	/* Take 6 bits from 1st byte and 4 bits from 2nd byte */
	ecc_10bit[1] = (((*pspare1) >> 10) & 0x3F)
	\| (((pspare[0]) << 6) & 0x3C0);

	/* Take 4 bits form 2nd bytes and 6 bits from 3rd bytes */
	ecc_10bit[2] = ((pspare[0]) >> 4) & 0x3FF;

	/Take 2 bits from 3rd byte and 8 bits from 4th byte /
	ecc_10bit[3] = (((pspare[0]) >> 14) & 0x3)
	\| ((((pspare[1])) << 2) & 0x3FC);

	/* Take 8 bits from 5th byte and 2 bits from 6th byte */
	ecc_10bit[4] = ((pspare[1]) >> 8)
	\| ((((pspare[2])) << 8) & 0x300);

	/* Take 6 bits from 6th byte and 4 bits from 7th byte */
	ecc_10bit[5] = (pspare[2] >> 2) & 0x3FF;

	/* Take 4 bits from 7th byte and 6 bits from 8th byte */
	ecc_10bit[6] = (((pspare[2]) >> 12) & 0xF)
	\| ((((pspare[3])) << 4) & 0x3F0);

	/Take 2 bits from 8th byte and 8 bits from 9th byte /
	ecc_10bit[7] = ((pspare[3]) >> 6) & 0x3FF;

	/*
	* Write the parity values in the NAND Flash 4-bit ECC Load register.
	* Write each parity value one at a time starting from 4bit_ecc_val8
	* to 4bit_ecc_val1.
	*/
	for (i = 7; i >= 0; i--)
	emif_regs->NAND4BITECCLOAD = ecc_10bit[i];

	/*
	* Perform a dummy read to the EMIF Revision Code and Status register.
	* This is required to ensure time for syndrome calculation after
	* writing the ECC values in previous step.
	*/

	val = emif_regs->NANDFSR;

	/*
	* Read the syndrome from the NAND Flash 4-Bit ECC 1-4 registers.
	* A syndrome value of 0 means no bit errors. If the syndrome is
	* non-zero then go further otherwise return.
	*/
	nand_davinci_4bit_readecc(mtd, hw_4ecc);

	if (hw_4ecc[0] == ECC_STATE_NO_ERR && hw_4ecc[1] == ECC_STATE_NO_ERR &&
	hw_4ecc[2] == ECC_STATE_NO_ERR && hw_4ecc[3] == ECC_STATE_NO_ERR)
	return 0;

	/*
	* Clear any previous address calculation by doing a dummy read of an
	* error address register.
	*/
	val = emif_regs->NANDERRADD1;

	/*
	* Set the addr_calc_st bit(bit no 13) in the NAND Flash Control
	* register to 1.
	*/
	emif_regs->NANDFCR \|= 1 << 13;

	/*
	* Wait for the corr_state field (bits 8 to 11)in the
	* NAND Flash Status register to be equal to 0x0, 0x1, 0x2, or 0x3.
	*/
	i = NAND_TIMEOUT;
	do {
	val = emif_regs->NANDFSR;
	val &= 0xc00;
	i--;
	} while ((i > 0) && val);

	iserror = emif_regs->NANDFSR;
	iserror &= EMIF_NANDFSR_ECC_STATE_MASK;
	iserror = iserror >> 8;

	/*
	* ECC_STATE_TOO_MANY_ERRS (0x1) means errors cannot be
	* corrected (five or more errors). The number of errors
	* calculated (err_num field) differs from the number of errors
	* searched. ECC_STATE_ERR_CORR_COMP_P (0x2) means error
	* correction complete (errors on bit 8 or 9).
	* ECC_STATE_ERR_CORR_COMP_N (0x3) means error correction
	* complete (error exists).
	*/

	if (iserror == ECC_STATE_NO_ERR) {
	val = emif_regs->NANDERRVAL1;
	return 0;
	} else if (iserror == ECC_STATE_TOO_MANY_ERRS) {
	val = emif_regs->NANDERRVAL1;
	return -1;
	}

	numerrors = ((emif_regs->NANDFSR >> 16) & 0x3) + 1;

	/* Read the error address, error value and correct */
	for (i = 0; i < numerrors; i++) {
	if (i > 1) {
	erroraddress =
	((emif_regs->NANDERRADD2 >>
	(16 * (i & 1))) & 0x3FF);
	erroraddress = ((512 + 7) - erroraddress);
	errorvalue =
	((emif_regs->NANDERRVAL2 >>
	(16 * (i & 1))) & 0xFF);
	} else {
	erroraddress =
	((emif_regs->NANDERRADD1 >>
	(16 * (i & 1))) & 0x3FF);
	erroraddress = ((512 + 7) - erroraddress);
	errorvalue =
	((emif_regs->NANDERRVAL1 >>
	(16 * (i & 1))) & 0xFF);
	}
	/* xor the corrupt data with error value */
	if (erroraddress < 512)
	dat[erroraddress] ^= errorvalue;
	}

	return numerrors;
	}

	static int nand_davinci_dev_ready(struct mtd_info *mtd)
	{
	return emif_regs->NANDFSR & 0x1;
	}

	static void nand_flash_init(void)
	{
	/* This is for DM6446 EVM and very similar. DO NOT GROW THIS!
	* Instead, have your board_init() set EMIF timings, based on its
	* knowledge of the clocks and what devices are hooked up ... and
	* don't even do that unless no UBL handled it.
	*/
	#ifdef CONFIG_SOC_DM644X
	u_int32_t acfg1 = 0x3ffffffc;

	/------------------------------------------------------------------
	* 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->AB1CR = acfg1; /* CS2 */

	emif_regs->NANDFCR = 0x00000101; /* NAND flash on CS2 */
	#endif
	}

	void davinci_nand_init(struct nand_chip *nand)
	{
	nand->chip_delay = 0;
	#ifdef CONFIG_SYS_NAND_USE_FLASH_BBT
	nand->options \|= NAND_USE_FLASH_BBT;
	#endif
	#ifdef CONFIG_SYS_NAND_HW_ECC
	nand->ecc.mode = NAND_ECC_HW;
	nand->ecc.size = 512;
	nand->ecc.bytes = 3;
	nand->ecc.calculate = nand_davinci_calculate_ecc;
	nand->ecc.correct = nand_davinci_correct_data;
	nand->ecc.hwctl = nand_davinci_enable_hwecc;
	#else
	nand->ecc.mode = NAND_ECC_SOFT;
	#endif /* CONFIG_SYS_NAND_HW_ECC */
	#ifdef CONFIG_SYS_NAND_4BIT_HW_ECC_OOBFIRST
	nand->ecc.mode = NAND_ECC_HW_OOB_FIRST;
	nand->ecc.size = 512;
	nand->ecc.bytes = 10;
	nand->ecc.calculate = nand_davinci_4bit_calculate_ecc;
	nand->ecc.correct = nand_davinci_4bit_correct_data;
	nand->ecc.hwctl = nand_davinci_4bit_enable_hwecc;
	nand->ecc.layout = &nand_davinci_4bit_layout_oobfirst;
	#endif
	/* Set address of hardware control function */
	nand->cmd_ctrl = nand_davinci_hwcontrol;

	nand->dev_ready = nand_davinci_dev_ready;

	nand_flash_init();
	}

	int board_nand_init(struct nand_chip *chip) __attribute__((weak));

	int board_nand_init(struct nand_chip *chip)
	{
	davinci_nand_init(chip);
	return 0;
	}