nand_read.c

基于s3c2410、2440的从SD卡引导Linux内核程序

#include "nand_read.h"

#define __REGb(x)	(*(volatile unsigned char *)(x))
#define __REGi(x)	(*(volatile unsigned int *)(x))
#define NF_BASE		0x4e000000
#define NFCONF		__REGi(NF_BASE + 0x00)
#define NFCMD		__REGb(NF_BASE + 0x04)
#define NFADDR		__REGb(NF_BASE + 0x08)
#define NFDATA		__REGb(NF_BASE + 0x0c)
#define NFSTAT		__REGb(NF_BASE + 0x10)

#define BUSY 1
void wait_idle(void)
{
	int i;

	while(!(NFSTAT & BUSY))
		for(i=0; i<10; i++);
}

#define NAND_SECTOR_SIZE	512
#define NAND_BLOCK_MASK		(NAND_SECTOR_SIZE - 1)

/* low level nand read function */
int nand_read_ll(unsigned char *buf, unsigned long start_addr, int size)
{
	int i, j;

	if ((start_addr & NAND_BLOCK_MASK) || (size & NAND_BLOCK_MASK))
	{
		return -1;	/* invalid alignment */
	}

    
    NFCONF &= ~0x800;	/* chip Enable */
    for(i=0; i<10; i++);

    for(i=start_addr; i < (start_addr + size);)
    {
		/* READ0 */
		NFCMD = 0;

		/* Write Address */
		NFADDR = i & 0xff;
		NFADDR = (i >> 9) & 0xff;
		NFADDR = (i >> 17) & 0xff;
		NFADDR = (i >> 25) & 0xff;

		wait_idle();

		for(j=0; j < NAND_SECTOR_SIZE; j++, i++)
		{
			*buf = (NFDATA & 0xff);
			buf++;
		}
    }

	NFCONF |= 0x800;	/* chip disable */

	return 0;
}