#if defined(CONFIG_S3C2440)   // （2440的主频可达533MHz，但听说设到533MHz时系统

copy_loop:
ldmia    r0!, {r3-r10}        /* copy from source address [r0]    */
stmia    r1!, {r3-r10}        /* copy to   target address [r1]    */
cmp    r0, r2            /* until source end addreee [r2]    */
ble    copy_loop
#endif    /* CONFIG_SKIP_RELOCATE_UBOOT */

    ldr    r2, =( (1<<4)|(0<<1)|(1<<0) ) @ Active low CE Control
str    r2, [r1, #oNFCONT]
ldr    r2, [r1, #oNFCONT]

    ldr    r2, =(0x6)        @ RnB Clear
str    r2, [r1, #oNFSTAT]
ldr    r2, [r1, #oNFSTAT]

    mov    r2, #0xff        @ RESET command
strb    r2, [r1, #oNFCMD]
/*delay一段时间*/
  mov r3, #0                   @ wait
nand1:
add  r3, r3, #0x1
cmp r3, #0xa
blt   nand1
/*等待nand-flash的复位完毕信号*/
nand2:
  ldr   r2, [r1, #oNFSTAT]      @ wait ready
tst    r2, #0x4
beq  nand2

  ldr    r2, [r1, #oNFCONT]
 orr    r2, r2, #0x2        @ Flash Memory Chip Disable  /* 在这里先Display fansh CE先，在C函数中对falsh进行 */

notmatch:
loop3:     b     loop3         @ infinite loop
#endif @ CONFIG_S3C2440_NAND_BOOT  @qljt@@@@@@@@@@@@@@@@@@EEEEEEEEE

/* low level nand read function */

for(i=start_addr; i < (start_addr + size);) {
/* READ0 */
NAND_CLEAR_RB;
         /* 到此应该可以明白s3c2440 nandflash 相关寄存器的确切含义了，就是说s3c2440里面已经集成了对nand flash操

        /* Write Address */

for(j=0; j < NAND_SECTOR_SIZE; j++, i++) {
            *buf = (NFDATA & 0xff); /* 每读一次NANDFLASH就往IO口送下一个byte，直到送

......

static inline void NF_Conf(u16 conf)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    nand->NFCONF = conf;
}

static inline void NF_Cmd(u8 cmd)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    nand->NFCMD = cmd;
}

static inline void NF_CmdW(u8 cmd)
{
    NF_Cmd(cmd);
    udelay(1);
}

static inline void NF_Addr(u8 addr)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    nand->NFADDR = addr;
}

static inline void NF_WaitRB(void)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    while (!(nand->NFSTAT & (1<<0)));
}

static inline void NF_Write(u8 data)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    nand->NFDATA = data;
}

static inline u8 NF_Read(void)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    return(nand->NFDATA);
}

static inline u32 NF_Read_ECC(void)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    return(nand->NFECC);
}

#if defined(CONFIG_S3C2440)
static inline void NF_Cont(u16 cont)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    nand->NFCONT = cont;
}

static inline void NF_SetCE(NFCE_STATE s)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    switch (s) {
    case NFCE_LOW:
        nand->NFCONT &= ~(1<<1);
        break;
    case NFCE_HIGH:
        nand->NFCONT |= (1<<1);
        break;
    }
}

static inline void NF_Init_ECC(void)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    nand->NFCONT |= (1<<4);
}

#else
static inline void NF_SetCE(NFCE_STATE s)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    switch (s) {
    case NFCE_LOW:
        nand->NFCONF &= ~(1<<11);
        break;
    case NFCE_HIGH:
        nand->NFCONF |= (1<<11);
        break;
    }
}

static inline void NF_Init_ECC(void)
{
    S3C2410_NAND * const nand = S3C2410_GetBase_NAND();
    nand->NFCONF |= (1<<12);
}
#endif /*对应#if defined(CONFIG_S3C2440)*/

static inline void NF_Init(void)
{
#if 0
#define TACLS 0
#define TWRPH0 3
#define TWRPH1 0
#else
#define TACLS 0
#define TWRPH0 4
#define TWRPH1 2
#endif

#if defined(CONFIG_S3C2440)
    NF_Conf((TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4));
    NF_Cont((0<<13)|(0<<12)|(0<<10)|(0<<9)|(0<<8)|(0<<6)|(0<<5)|(1<<4)|(0<<1)|(1<<0));
#else
    NF_Conf((1<<15)|(0<<14)|(0<<13)|(1<<12)|(1<<11)|(TACLS<<8)|(TWRPH0<<4)|(TWRPH1<<0));
    /*nand->NFCONF = (1<<15)|(1<<14)|(1<<13)|(1<<12)|(1<<11)|(TACLS<<8)|(TWRPH0<<4)|(TWRPH1<<0); */
    /* 1 1 1 1, 1 xxx, r xxx, r xxx */
    /* En 512B 4step ECCR nFCE=H tACLS tWRPH0 tWRPH1 */
#endif
    NF_Reset();
}

#endif

m = ((r & 0xFF000) >> 12) + 8;
p = ((r & 0x003F0) >> 4) + 2;
s = r & 0x3;
//qljt  /*这两个PLL的算法参见S3C2440datasheet的254页*/
#if defined(CONFIG_S3C2440)
if (pllreg == MPLL)
return((CONFIG_SYS_CLK_FREQ * m * 2) / (p << s)); /* CONFIG_SYS_CLK_FREQ 在qljt2440.h中定义*/
    else if (pllreg == UPLL)
#endif
//qljt
return((CONFIG_SYS_CLK_FREQ * m) / (p << s));
}

int nand_legacy_rw (struct nand_chip* nand, int cmd,
        size_t start, size_t len,
        size_t * retlen, u_char * buf);
extern struct nand_chip nand_dev_desc[CFG_MAX_NAND_DEVICE];
extern int nand_legacy_erase(struct nand_chip *nand, size_t ofs, size_t len, int clean);

/* info for NAND chips, defined in drivers/nand/nand.c */
nand_info_t nand_info[CFG_MAX_NAND_DEVICE];

......

#else /* ! CFG_ENV_OFFSET_REDUND */
int saveenv(void)
{
    size_t total;
    int ret = 0;
    nand_erase_options_t nand_erase_options;

nand_erase_options.length = CFG_ENV_RANGE;
    nand_erase_options.quiet = 0;
    nand_erase_options.jffs2 = 0;
    nand_erase_options.scrub = 0;
    nand_erase_options.offset = CFG_ENV_OFFSET;

if (CFG_ENV_RANGE < CFG_ENV_SIZE)
        return 1;
    puts ("Erasing Nand...\n");

total = CFG_ENV_SIZE;

if (crc32(0, env_ptr->data, ENV_SIZE) != env_ptr->crc)
        return use_default();
#endif /* ! ENV_IS_EMBEDDED */
}

return (0);
}