drivers/mtd/nand/mxc_nand_spl.c - github/trini/u-boot - Gitiles

 /*
  * (C) Copyright 2009
  * Magnus Lilja <lilja.magnus@gmail.com>
  *
  * (C) Copyright 2008
  * Maxim Artamonov, <scn1874 at yandex.ru>
  *
  * (C) Copyright 2006-2008
  * Stefan Roese, DENX Software Engineering, sr at denx.de.
  *
  * 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., 59 Temple Place, Suite 330, Boston,
  * MA 02111-1307 USA
  */

 #include <common.h>
 #include <nand.h>
 #include <asm/arch/imx-regs.h>
 #include <asm/io.h>
 #include "mxc_nand.h"

 #if defined(MXC_NFC_V1) || defined(MXC_NFC_V2_1)
 static struct mxc_nand_regs *const nfc = (void *)NFC_BASE_ADDR;
 #elif defined(MXC_NFC_V3_2)
 static struct mxc_nand_regs *const nfc = (void *)NFC_BASE_ADDR_AXI;
 static struct mxc_nand_ip_regs *const nfc_ip = (void *)NFC_BASE_ADDR;
 #endif

 static void nfc_wait_ready(void)
 {
 	uint32_t tmp;

 #if defined(MXC_NFC_V1) || defined(MXC_NFC_V2_1)
 	while (!(readnfc(&nfc->config2) & NFC_V1_V2_CONFIG2_INT))
 		;

 	/* Reset interrupt flag */
 	tmp = readnfc(&nfc->config2);
 	tmp &= ~NFC_V1_V2_CONFIG2_INT;
 	writenfc(tmp, &nfc->config2);
 #elif defined(MXC_NFC_V3_2)
 	while (!(readnfc(&nfc_ip->ipc) & NFC_V3_IPC_INT))
 		;

 	/* Reset interrupt flag */
 	tmp = readnfc(&nfc_ip->ipc);
 	tmp &= ~NFC_V3_IPC_INT;
 	writenfc(tmp, &nfc_ip->ipc);
 #endif
 }

 static void nfc_nand_init(void)
 {
 #if defined(MXC_NFC_V3_2)
 	int ecc_per_page = CONFIG_SYS_NAND_PAGE_SIZE / 512;
 	int tmp;

 	tmp = (readnfc(&nfc_ip->config2) & ~(NFC_V3_CONFIG2_SPAS_MASK |
 			NFC_V3_CONFIG2_EDC_MASK | NFC_V3_CONFIG2_PS_MASK)) |
 		NFC_V3_CONFIG2_SPAS(CONFIG_SYS_NAND_OOBSIZE / 2) |
 		NFC_V3_CONFIG2_INT_MSK | NFC_V3_CONFIG2_ECC_EN |
 		NFC_V3_CONFIG2_ONE_CYCLE;
 	if (CONFIG_SYS_NAND_PAGE_SIZE == 4096)
 		tmp |= NFC_V3_CONFIG2_PS_4096;
 	else if (CONFIG_SYS_NAND_PAGE_SIZE == 2048)
 		tmp |= NFC_V3_CONFIG2_PS_2048;
 	else if (CONFIG_SYS_NAND_PAGE_SIZE == 512)
 		tmp |= NFC_V3_CONFIG2_PS_512;
 	/*
 	 * if spare size is larger that 16 bytes per 512 byte hunk
 	 * then use 8 symbol correction instead of 4
 	 */
 	if (CONFIG_SYS_NAND_OOBSIZE / ecc_per_page > 16)
 		tmp |= NFC_V3_CONFIG2_ECC_MODE_8;
 	else
 		tmp &= ~NFC_V3_CONFIG2_ECC_MODE_8;
 	writenfc(tmp, &nfc_ip->config2);

 	tmp = NFC_V3_CONFIG3_NUM_OF_DEVS(0) |
 			NFC_V3_CONFIG3_NO_SDMA |
 			NFC_V3_CONFIG3_RBB_MODE |
 			NFC_V3_CONFIG3_SBB(6) | /* Reset default */
 			NFC_V3_CONFIG3_ADD_OP(0);
 #ifndef CONFIG_SYS_NAND_BUSWIDTH_16
 	tmp |= NFC_V3_CONFIG3_FW8;
 #endif
 	writenfc(tmp, &nfc_ip->config3);

 	writenfc(0, &nfc_ip->delay_line);
 #elif defined(MXC_NFC_V2_1)
 	int ecc_per_page = CONFIG_SYS_NAND_PAGE_SIZE / 512;
 	int config1;

 	writenfc(CONFIG_SYS_NAND_OOBSIZE / 2, &nfc->spare_area_size);

 	/* unlocking RAM Buff */
 	writenfc(0x2, &nfc->config);

 	/* hardware ECC checking and correct */
 	config1 = readnfc(&nfc->config1) | NFC_V1_V2_CONFIG1_ECC_EN |
 			NFC_V1_V2_CONFIG1_INT_MSK | NFC_V2_CONFIG1_ONE_CYCLE |
 			NFC_V2_CONFIG1_FP_INT;
 	/*
 	 * if spare size is larger that 16 bytes per 512 byte hunk
 	 * then use 8 symbol correction instead of 4
 	 */
 	if (CONFIG_SYS_NAND_OOBSIZE / ecc_per_page > 16)
 		config1 &= ~NFC_V2_CONFIG1_ECC_MODE_4;
 	else
 		config1 |= NFC_V2_CONFIG1_ECC_MODE_4;
 	writenfc(config1, &nfc->config1);
 #elif defined(MXC_NFC_V1)
 	/* unlocking RAM Buff */
 	writenfc(0x2, &nfc->config);

 	/* hardware ECC checking and correct */
 	writenfc(NFC_V1_V2_CONFIG1_ECC_EN | NFC_V1_V2_CONFIG1_INT_MSK,
 			&nfc->config1);
 #endif
 }

 static void nfc_nand_command(unsigned short command)
 {
 	writenfc(command, &nfc->flash_cmd);
 	writenfc(NFC_CMD, &nfc->operation);
 	nfc_wait_ready();
 }

 static void nfc_nand_address(unsigned short address)
 {
 	writenfc(address, &nfc->flash_addr);
 	writenfc(NFC_ADDR, &nfc->operation);
 	nfc_wait_ready();
 }

 static void nfc_nand_page_address(unsigned int page_address)
 {
 	unsigned int page_count;

 	nfc_nand_address(0x00);

 	/* code only for large page flash */
 	if (CONFIG_SYS_NAND_PAGE_SIZE > 512)
 		nfc_nand_address(0x00);

 	page_count = CONFIG_SYS_NAND_SIZE / CONFIG_SYS_NAND_PAGE_SIZE;

 	if (page_address <= page_count) {
 		page_count--; /* transform 0x01000000 to 0x00ffffff */
 		do {
 			nfc_nand_address(page_address & 0xff);
 			page_address = page_address >> 8;
 			page_count = page_count >> 8;
 		} while (page_count);
 	}

 	nfc_nand_address(0x00);
 }

 static void nfc_nand_data_output(void)
 {
 #ifdef NAND_MXC_2K_MULTI_CYCLE
 	int i;
 #endif

 #if defined(MXC_NFC_V1) || defined(MXC_NFC_V2_1)
 	writenfc(0, &nfc->buf_addr);
 #elif defined(MXC_NFC_V3_2)
 	int config1 = readnfc(&nfc->config1);
 	config1 &= ~NFC_V3_CONFIG1_RBA_MASK;
 	writenfc(config1, &nfc->config1);
 #endif
 	writenfc(NFC_OUTPUT, &nfc->operation);
 	nfc_wait_ready();
 #ifdef NAND_MXC_2K_MULTI_CYCLE
 	/*
 	 * This NAND controller requires multiple input commands
 	 * for pages larger than 512 bytes.
 	 */
 	for (i = 1; i < CONFIG_SYS_NAND_PAGE_SIZE / 512; i++) {
 		writenfc(i, &nfc->buf_addr);
 		writenfc(NFC_OUTPUT, &nfc->operation);
 		nfc_wait_ready();
 	}
 #endif
 }

 static int nfc_nand_check_ecc(void)
 {
 #if defined(MXC_NFC_V1)
 	u16 ecc_status = readw(&nfc->ecc_status_result);
 	return (ecc_status & 0x3) == 2 || (ecc_status >> 2) == 2;
 #elif defined(MXC_NFC_V2_1) || defined(MXC_NFC_V3_2)
 	u32 ecc_status = readl(&nfc->ecc_status_result);
 	int ecc_per_page = CONFIG_SYS_NAND_PAGE_SIZE / 512;
 	int err_limit = CONFIG_SYS_NAND_OOBSIZE / ecc_per_page > 16 ? 8 : 4;
 	int subpages = CONFIG_SYS_NAND_PAGE_SIZE / 512;

 	do {
 		if ((ecc_status & 0xf) > err_limit)
 			return 1;
 		ecc_status >>= 4;
 	} while (--subpages);

 	return 0;
 #endif
 }

 static void nfc_nand_read_page(unsigned int page_address)
 {
 	/* read in first 0 buffer */
 #if defined(MXC_NFC_V1) || defined(MXC_NFC_V2_1)
 	writenfc(0, &nfc->buf_addr);
 #elif defined(MXC_NFC_V3_2)
 	int config1 = readnfc(&nfc->config1);
 	config1 &= ~NFC_V3_CONFIG1_RBA_MASK;
 	writenfc(config1, &nfc->config1);
 #endif
 	nfc_nand_command(NAND_CMD_READ0);
 	nfc_nand_page_address(page_address);

 	if (CONFIG_SYS_NAND_PAGE_SIZE > 512)
 		nfc_nand_command(NAND_CMD_READSTART);

 	nfc_nand_data_output(); /* fill the main buffer 0 */
 }

 static int nfc_read_page(unsigned int page_address, unsigned char *buf)
 {
 	int i;
 	u32 *src;
 	u32 *dst;

 	nfc_nand_read_page(page_address);

 	if (nfc_nand_check_ecc())
 		return -1;

 	src = (u32 *)&nfc->main_area[0][0];
 	dst = (u32 *)buf;

 	/* main copy loop from NAND-buffer to SDRAM memory */
 	for (i = 0; i < CONFIG_SYS_NAND_PAGE_SIZE / 4; i++) {
 		writel(readl(src), dst);
 		src++;
 		dst++;
 	}

 	return 0;
 }

 static int is_badblock(int pagenumber)
 {
 	int page = pagenumber;
 	u32 badblock;
 	u32 *src;

 	/* Check the first two pages for bad block markers */
 	for (page = pagenumber; page < pagenumber + 2; page++) {
 		nfc_nand_read_page(page);

 		src = (u32 *)&nfc->spare_area[0][0];

 		/*
 		 * IMPORTANT NOTE: The nand flash controller uses a non-
 		 * standard layout for large page devices. This can
 		 * affect the position of the bad block marker.
 		 */
 		/* Get the bad block marker */
 		badblock = readl(&src[CONFIG_SYS_NAND_BAD_BLOCK_POS / 4]);
 		badblock >>= 8 * (CONFIG_SYS_NAND_BAD_BLOCK_POS % 4);
 		badblock &= 0xff;

 		/* bad block marker verify */
 		if (badblock != 0xff)
 			return 1; /* potential bad block */
 	}

 	return 0;
 }

 static int nand_load(unsigned int from, unsigned int size, unsigned char *buf)
 {
 	int i;
 	unsigned int page;
 	unsigned int maxpages = CONFIG_SYS_NAND_SIZE /
 				CONFIG_SYS_NAND_PAGE_SIZE;

 	nfc_nand_init();

 	/* Convert to page number */
 	page = from / CONFIG_SYS_NAND_PAGE_SIZE;
 	i = 0;

 	while (i < size / CONFIG_SYS_NAND_PAGE_SIZE) {
 		if (nfc_read_page(page, buf) < 0)
 			return -1;

 		page++;
 		i++;
 		buf = buf + CONFIG_SYS_NAND_PAGE_SIZE;

 		/*
 		 * Check if we have crossed a block boundary, and if so
 		 * check for bad block.
 		 */
 		if (!(page % CONFIG_SYS_NAND_PAGE_COUNT)) {
 			/*
 			 * Yes, new block. See if this block is good. If not,
 			 * loop until we find a good block.
 			 */
 			while (is_badblock(page)) {
 				page = page + CONFIG_SYS_NAND_PAGE_COUNT;
 				/* Check i we've reached the end of flash. */
 				if (page >= maxpages)
 					return -1;
 			}
 		}
 	}

 	return 0;
 }

 /*
  * The main entry for NAND booting. It's necessary that SDRAM is already
  * configured and available since this code loads the main U-Boot image
  * from NAND into SDRAM and starts it from there.
  */
 void nand_boot(void)
 {
 	__attribute__((noreturn)) void (*uboot)(void);

 	/*
 	 * CONFIG_SYS_NAND_U_BOOT_OFFS and CONFIG_SYS_NAND_U_BOOT_SIZE must
 	 * be aligned to full pages
 	 */
 	if (!nand_load(CONFIG_SYS_NAND_U_BOOT_OFFS, CONFIG_SYS_NAND_U_BOOT_SIZE,
 		       (uchar *)CONFIG_SYS_NAND_U_BOOT_DST)) {
 		/* Copy from NAND successful, start U-boot */
 		uboot = (void *)CONFIG_SYS_NAND_U_BOOT_START;
 		uboot();
 	} else {
 		/* Unrecoverable error when copying from NAND */
 		hang();
 	}
 }
	/*
	* (C) Copyright 2009
	* Magnus Lilja <lilja.magnus@gmail.com>
	*
	* (C) Copyright 2008
	* Maxim Artamonov, <scn1874 at yandex.ru>
	*
	* (C) Copyright 2006-2008
	* Stefan Roese, DENX Software Engineering, sr at denx.de.
	*
	* 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., 59 Temple Place, Suite 330, Boston,
	* MA 02111-1307 USA
	*/

	#include <common.h>
	#include <nand.h>
	#include <asm/arch/imx-regs.h>
	#include <asm/io.h>
	#include "mxc_nand.h"

	#if defined(MXC_NFC_V1) \|\| defined(MXC_NFC_V2_1)
	static struct mxc_nand_regs const nfc = (void )NFC_BASE_ADDR;
	#elif defined(MXC_NFC_V3_2)
	static struct mxc_nand_regs const nfc = (void )NFC_BASE_ADDR_AXI;
	static struct mxc_nand_ip_regs const nfc_ip = (void )NFC_BASE_ADDR;
	#endif

	static void nfc_wait_ready(void)
	{
	uint32_t tmp;

	#if defined(MXC_NFC_V1) \|\| defined(MXC_NFC_V2_1)
	while (!(readnfc(&nfc->config2) & NFC_V1_V2_CONFIG2_INT))
	;

	/* Reset interrupt flag */
	tmp = readnfc(&nfc->config2);
	tmp &= ~NFC_V1_V2_CONFIG2_INT;
	writenfc(tmp, &nfc->config2);
	#elif defined(MXC_NFC_V3_2)
	while (!(readnfc(&nfc_ip->ipc) & NFC_V3_IPC_INT))
	;

	/* Reset interrupt flag */
	tmp = readnfc(&nfc_ip->ipc);
	tmp &= ~NFC_V3_IPC_INT;
	writenfc(tmp, &nfc_ip->ipc);
	#endif
	}

	static void nfc_nand_init(void)
	{
	#if defined(MXC_NFC_V3_2)
	int ecc_per_page = CONFIG_SYS_NAND_PAGE_SIZE / 512;
	int tmp;

	tmp = (readnfc(&nfc_ip->config2) & ~(NFC_V3_CONFIG2_SPAS_MASK \|
	NFC_V3_CONFIG2_EDC_MASK \| NFC_V3_CONFIG2_PS_MASK)) \|
	NFC_V3_CONFIG2_SPAS(CONFIG_SYS_NAND_OOBSIZE / 2) \|
	NFC_V3_CONFIG2_INT_MSK \| NFC_V3_CONFIG2_ECC_EN \|
	NFC_V3_CONFIG2_ONE_CYCLE;
	if (CONFIG_SYS_NAND_PAGE_SIZE == 4096)
	tmp \|= NFC_V3_CONFIG2_PS_4096;
	else if (CONFIG_SYS_NAND_PAGE_SIZE == 2048)
	tmp \|= NFC_V3_CONFIG2_PS_2048;
	else if (CONFIG_SYS_NAND_PAGE_SIZE == 512)
	tmp \|= NFC_V3_CONFIG2_PS_512;
	/*
	* if spare size is larger that 16 bytes per 512 byte hunk
	* then use 8 symbol correction instead of 4
	*/
	if (CONFIG_SYS_NAND_OOBSIZE / ecc_per_page > 16)
	tmp \|= NFC_V3_CONFIG2_ECC_MODE_8;
	else
	tmp &= ~NFC_V3_CONFIG2_ECC_MODE_8;
	writenfc(tmp, &nfc_ip->config2);

	tmp = NFC_V3_CONFIG3_NUM_OF_DEVS(0) \|
	NFC_V3_CONFIG3_NO_SDMA \|
	NFC_V3_CONFIG3_RBB_MODE \|
	NFC_V3_CONFIG3_SBB(6) \| /* Reset default */
	NFC_V3_CONFIG3_ADD_OP(0);
	#ifndef CONFIG_SYS_NAND_BUSWIDTH_16
	tmp \|= NFC_V3_CONFIG3_FW8;
	#endif
	writenfc(tmp, &nfc_ip->config3);

	writenfc(0, &nfc_ip->delay_line);
	#elif defined(MXC_NFC_V2_1)
	int ecc_per_page = CONFIG_SYS_NAND_PAGE_SIZE / 512;
	int config1;

	writenfc(CONFIG_SYS_NAND_OOBSIZE / 2, &nfc->spare_area_size);

	/* unlocking RAM Buff */
	writenfc(0x2, &nfc->config);

	/* hardware ECC checking and correct */
	config1 = readnfc(&nfc->config1) \| NFC_V1_V2_CONFIG1_ECC_EN \|
	NFC_V1_V2_CONFIG1_INT_MSK \| NFC_V2_CONFIG1_ONE_CYCLE \|
	NFC_V2_CONFIG1_FP_INT;
	/*
	* if spare size is larger that 16 bytes per 512 byte hunk
	* then use 8 symbol correction instead of 4
	*/
	if (CONFIG_SYS_NAND_OOBSIZE / ecc_per_page > 16)
	config1 &= ~NFC_V2_CONFIG1_ECC_MODE_4;
	else
	config1 \|= NFC_V2_CONFIG1_ECC_MODE_4;
	writenfc(config1, &nfc->config1);
	#elif defined(MXC_NFC_V1)
	/* unlocking RAM Buff */
	writenfc(0x2, &nfc->config);

	/* hardware ECC checking and correct */
	writenfc(NFC_V1_V2_CONFIG1_ECC_EN \| NFC_V1_V2_CONFIG1_INT_MSK,
	&nfc->config1);
	#endif
	}

	static void nfc_nand_command(unsigned short command)
	{
	writenfc(command, &nfc->flash_cmd);
	writenfc(NFC_CMD, &nfc->operation);
	nfc_wait_ready();
	}

	static void nfc_nand_address(unsigned short address)
	{
	writenfc(address, &nfc->flash_addr);
	writenfc(NFC_ADDR, &nfc->operation);
	nfc_wait_ready();
	}

	static void nfc_nand_page_address(unsigned int page_address)
	{
	unsigned int page_count;

	nfc_nand_address(0x00);

	/* code only for large page flash */
	if (CONFIG_SYS_NAND_PAGE_SIZE > 512)
	nfc_nand_address(0x00);

	page_count = CONFIG_SYS_NAND_SIZE / CONFIG_SYS_NAND_PAGE_SIZE;

	if (page_address <= page_count) {
	page_count--; /* transform 0x01000000 to 0x00ffffff */
	do {
	nfc_nand_address(page_address & 0xff);
	page_address = page_address >> 8;
	page_count = page_count >> 8;
	} while (page_count);
	}

	nfc_nand_address(0x00);
	}

	static void nfc_nand_data_output(void)
	{
	#ifdef NAND_MXC_2K_MULTI_CYCLE
	int i;
	#endif

	#if defined(MXC_NFC_V1) \|\| defined(MXC_NFC_V2_1)
	writenfc(0, &nfc->buf_addr);
	#elif defined(MXC_NFC_V3_2)
	int config1 = readnfc(&nfc->config1);
	config1 &= ~NFC_V3_CONFIG1_RBA_MASK;
	writenfc(config1, &nfc->config1);
	#endif
	writenfc(NFC_OUTPUT, &nfc->operation);
	nfc_wait_ready();
	#ifdef NAND_MXC_2K_MULTI_CYCLE
	/*
	* This NAND controller requires multiple input commands
	* for pages larger than 512 bytes.
	*/
	for (i = 1; i < CONFIG_SYS_NAND_PAGE_SIZE / 512; i++) {
	writenfc(i, &nfc->buf_addr);
	writenfc(NFC_OUTPUT, &nfc->operation);
	nfc_wait_ready();
	}
	#endif
	}

	static int nfc_nand_check_ecc(void)
	{
	#if defined(MXC_NFC_V1)
	u16 ecc_status = readw(&nfc->ecc_status_result);
	return (ecc_status & 0x3) == 2 \|\| (ecc_status >> 2) == 2;
	#elif defined(MXC_NFC_V2_1) \|\| defined(MXC_NFC_V3_2)
	u32 ecc_status = readl(&nfc->ecc_status_result);
	int ecc_per_page = CONFIG_SYS_NAND_PAGE_SIZE / 512;
	int err_limit = CONFIG_SYS_NAND_OOBSIZE / ecc_per_page > 16 ? 8 : 4;
	int subpages = CONFIG_SYS_NAND_PAGE_SIZE / 512;

	do {
	if ((ecc_status & 0xf) > err_limit)
	return 1;
	ecc_status >>= 4;
	} while (--subpages);

	return 0;
	#endif
	}

	static void nfc_nand_read_page(unsigned int page_address)
	{
	/* read in first 0 buffer */
	#if defined(MXC_NFC_V1) \|\| defined(MXC_NFC_V2_1)
	writenfc(0, &nfc->buf_addr);
	#elif defined(MXC_NFC_V3_2)
	int config1 = readnfc(&nfc->config1);
	config1 &= ~NFC_V3_CONFIG1_RBA_MASK;
	writenfc(config1, &nfc->config1);
	#endif
	nfc_nand_command(NAND_CMD_READ0);
	nfc_nand_page_address(page_address);

	if (CONFIG_SYS_NAND_PAGE_SIZE > 512)
	nfc_nand_command(NAND_CMD_READSTART);

	nfc_nand_data_output(); /* fill the main buffer 0 */
	}

	static int nfc_read_page(unsigned int page_address, unsigned char *buf)
	{
	int i;
	u32 *src;
	u32 *dst;

	nfc_nand_read_page(page_address);

	if (nfc_nand_check_ecc())
	return -1;

	src = (u32 *)&nfc->main_area[0][0];
	dst = (u32 *)buf;

	/* main copy loop from NAND-buffer to SDRAM memory */
	for (i = 0; i < CONFIG_SYS_NAND_PAGE_SIZE / 4; i++) {
	writel(readl(src), dst);
	src++;
	dst++;
	}

	return 0;
	}

	static int is_badblock(int pagenumber)
	{
	int page = pagenumber;
	u32 badblock;
	u32 *src;

	/* Check the first two pages for bad block markers */
	for (page = pagenumber; page < pagenumber + 2; page++) {
	nfc_nand_read_page(page);

	src = (u32 *)&nfc->spare_area[0][0];

	/*
	* IMPORTANT NOTE: The nand flash controller uses a non-
	* standard layout for large page devices. This can
	* affect the position of the bad block marker.
	*/
	/* Get the bad block marker */
	badblock = readl(&src[CONFIG_SYS_NAND_BAD_BLOCK_POS / 4]);
	badblock >>= 8 * (CONFIG_SYS_NAND_BAD_BLOCK_POS % 4);
	badblock &= 0xff;

	/* bad block marker verify */
	if (badblock != 0xff)
	return 1; /* potential bad block */
	}

	return 0;
	}

	static int nand_load(unsigned int from, unsigned int size, unsigned char *buf)
	{
	int i;
	unsigned int page;
	unsigned int maxpages = CONFIG_SYS_NAND_SIZE /
	CONFIG_SYS_NAND_PAGE_SIZE;

	nfc_nand_init();

	/* Convert to page number */
	page = from / CONFIG_SYS_NAND_PAGE_SIZE;
	i = 0;

	while (i < size / CONFIG_SYS_NAND_PAGE_SIZE) {
	if (nfc_read_page(page, buf) < 0)
	return -1;

	page++;
	i++;
	buf = buf + CONFIG_SYS_NAND_PAGE_SIZE;

	/*
	* Check if we have crossed a block boundary, and if so
	* check for bad block.
	*/
	if (!(page % CONFIG_SYS_NAND_PAGE_COUNT)) {
	/*
	* Yes, new block. See if this block is good. If not,
	* loop until we find a good block.
	*/
	while (is_badblock(page)) {
	page = page + CONFIG_SYS_NAND_PAGE_COUNT;
	/* Check i we've reached the end of flash. */
	if (page >= maxpages)
	return -1;
	}
	}
	}

	return 0;
	}

	/*
	* The main entry for NAND booting. It's necessary that SDRAM is already
	* configured and available since this code loads the main U-Boot image
	* from NAND into SDRAM and starts it from there.
	*/
	void nand_boot(void)
	{
	__attribute__((noreturn)) void (*uboot)(void);

	/*
	* CONFIG_SYS_NAND_U_BOOT_OFFS and CONFIG_SYS_NAND_U_BOOT_SIZE must
	* be aligned to full pages
	*/
	if (!nand_load(CONFIG_SYS_NAND_U_BOOT_OFFS, CONFIG_SYS_NAND_U_BOOT_SIZE,
	(uchar *)CONFIG_SYS_NAND_U_BOOT_DST)) {
	/* Copy from NAND successful, start U-boot */
	uboot = (void *)CONFIG_SYS_NAND_U_BOOT_START;
	uboot();
	} else {
	/* Unrecoverable error when copying from NAND */
	hang();
	}
	}