//void Uart0_Printf(char *fmt,...);


#define __REGb(x)	(*(volatile unsigned char *)(x))
#define __REGi(x)	(*(volatile unsigned int *)(x))
#define NF_BASE		0x4e000000
#define NFCONF		__REGi(NF_BASE + 0x0)
#define NFCONT		__REGi(NF_BASE + 0x4)
#define NFCMD		__REGb(NF_BASE + 0x8)
#define NFADDR		__REGb(NF_BASE + 0xC)
#define NFDATA		__REGb(NF_BASE + 0x10)
#define NFSTAT		__REGb(NF_BASE + 0x20)

#define NAND_CHIP_ENABLE  (NFCONT &= ~(1<<1))
#define NAND_CHIP_DISABLE (NFCONT |=  (1<<1))
#define NAND_CLEAR_RB	  (NFSTAT |=  (1<<2))
#define NAND_DETECT_RB	  { while(! (NFSTAT&(1<<2)) );}

#define NAND_CMD_READ0		0
#define NAND_CMD_READOOB	0x50

#define BUSY 4
static 
void wait_idle(void) {
    int i;

    for(i=0; i<100; i++);
    while(!(NFSTAT & BUSY))
      for(i=0; i<100; i++);

    NFSTAT |= BUSY;
}

#define NAND_SECTOR_SIZE	512
#define NAND_SECTOR_MASK		(NAND_SECTOR_SIZE - 1)
#define NAND_BLOCK_SIZE         (32*NAND_SECTOR_SIZE)
#define NAND_BLOCK_MASK         (NAND_BLOCK_SIZE - 1)

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

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

    /* chip Enable */
    NAND_CHIP_ENABLE;
    for(i=0; i<100; i++);

    for(baddr=start_addr&~NAND_BLOCK_MASK; size>0; baddr+=NAND_BLOCK_SIZE) {

        /* READOOB */
        NAND_CLEAR_RB;
        NFCMD = NAND_CMD_READOOB;
          
        /* Write Address */
		NFADDR = (5) & 0xff;
		NFADDR = (baddr >> 9) & 0xff;
		NFADDR = (baddr >> 17) & 0xff;
		NFADDR = (baddr >> 25) & 0xff;
		
		NAND_DETECT_RB
		if ((NFDATA & 0xff)!= 0xff) {
		    //Uart0_Printf ("bad block at %d\r\n",baddr>>14);
		    continue;   //bad block
		}
          
        for(addr=0; addr<NAND_BLOCK_SIZE && (size>0); size-=NAND_SECTOR_SIZE,addr+=NAND_SECTOR_SIZE) {
          /* READ0 */
          NAND_CLEAR_RB;
          NFCMD = 0;
    
          
          /* Write Address */
    		NFADDR = (baddr+addr) & 0xff;
    		NFADDR = ((baddr+addr) >> 9) & 0xff;
    		NFADDR = ((baddr+addr) >> 17) & 0xff;
    		NFADDR = ((baddr+addr) >> 25) & 0xff;
    
          NAND_DETECT_RB
    
          for(i=0; i < NAND_SECTOR_SIZE; i++) {
    	    *buf = (NFDATA & 0xff);
    	    buf++;
          }
        }
    }

    /* chip Disable */
    NAND_CHIP_DISABLE;

    return 0;
}