如果沒有Nor FLASH的同學可以跳過這一章節，直接進行下一張節。如果遇到什么問題，一般都是你沒有定義那個宏之類的，這個問題可以很好的額解決。

修改norflash（nor fhash型號：JS28F320）的配置，把include/configs/fl2440.h中關于“Physical?Memory?Map”和“FLASH?and?environment?organization”的配置都刪掉，換成下面的配置：

• /*-----------------------------------------------------------------------
  ?* Physical Memory Map
  ?*/
  #define CONFIG_NR_DRAM_BANKS 1?? /* we have 1 bank of DRAM */
  #define PHYS_SDRAM_1 0x30000000 /* SDRAM Bank #1 */
  #define PHYS_SDRAM_1_SIZE 0x04000000 /* 64 MB */
  
  #define PHYS_FLASH_1 0x00000000 /* Flash Bank #1 */
  #define CONFIG_SYS_FLASH_BASE PHYS_FLASH_1
  #define CONFIG_SYS_MONITOR_BASE ? TEXT_BASE
  #define FLASH_BASE0_PRELIM ? ? ? ?PHYS_FLASH_1
  
  /*-----------------------------------------------------------------------
  ?* FLASH and environment organization
  ?*/
  #if 0
  #define CONFIG_AMD_LV400 1/* uncomment this if you have a LV400 flash */
  #define CONFIG_AMD_LV800 1/* uncomment this if you have a LV800 flash */
  #endif
  
  #define CONFIG_SYS_MAX_FLASH_BANKS 1/* max number of memory banks */
  #define CONFIG_JS2_8F320? 1
  #define CONFIG_SYS_FLASH_PROTECTION ? 1
  #define CONFIG_SYS_FLASH_SIZE ? ?0x00400000 ? ?/*4 MB*/
  #define CONFIG_SYS_MAX_FLASH_SECT ? ?32 ? ? ? ? /*max number of sectors on one chip*/
  
  
• /* timeout values are in ticks */
  #define CONFIG_SYS_FLASH_ERASE_TOUT(2*CONFIG_SYS_HZ) /* Timeout for Flash Erase */
  #define CONFIG_SYS_FLASH_WRITE_TOUT(2*CONFIG_SYS_HZ) /* Timeout for Flash Write */
  
  #defineCONFIG_ENV_IS_IN_FLASH1
  #define CONFIG_ENV_SIZE0x40000/* Total Size of Environment Sector，這是256K的環境變量儲存空間?*/
  #define CONFIG_ENV_OFFSET ?0x100000 ?//在以后的內核分區中環境變量分區的OFFSET值要與此一致
  #endif/* __CONFIG_H */
  

修改board/samsung/fl2440/lowlevel_init.S文件中SDARM刷新參數

? #define?REFCNT???1258

修改flash型號相關文件,用board/cmi/flash.c文件替換board/samsung/ofl2440/flash.c文件，使uboot支持Intel的JS28F320型號nor fhash.

打開board/samsung/fl2440/flash.c文件，修改：

把：
#define FLASH_BLOCK_SIZE??? ??? 0x00010000
改為：
#define FLASH_BLOCK_SIZE??? ????0x00020000

把聲明：
static ?int ? ?write_short? ?(flash_info_t *info, ulong dest, ushort data);//并刪除這個函數體
改為：
static ? ?int ? ? ?write_word ? ? (flash_info_t *info, ulong dest, ushort data);??

刪除write_buff和write_short兩個函數，用下面兩個函數代替：
int write_buff (flash_info_t *info, uchar *src, ulong addr, ulong cnt)
{
? ?ulong cp, wp;
? ?ushort data;
? ?int l;
? ?int i, rc;


? ?wp = (addr & ~1); ? ? ? ?/* get lower word aligned address */


? ?/*
? ? * handle unaligned start bytes
? ? */
? ?if ((l = addr - wp) != 0)
? ?{
? ? ? data = 0;
? ? ? for (i=0, cp=wp; i<l; ++i, ++cp) {
? ? ? ?data = (data >> 8) | (*(uchar *)cp << 8);
? ? ? }
? ? ? for (; i<2 && cnt>0; ++i) {
? ? ?data = (data >> 8) | (*src++ << 8);
? ? ?--cnt;
? ? ?++cp;
? ? ? }
? ? ? for (; cnt==0 && i<2; ++i, ++cp) {
? ? ?data = (data >> 8) | (*(uchar *)cp << 8);
? ? ? }


? ? ? if ((rc = write_word(info, wp, data)) != 0) {
? ? ?return (rc);
? ? ? }
? ? ? wp += 2;
? ?}


? ?/*
? ? * handle word aligned part
? ? */
? ?while (cnt >= 2) {
? ? ? data = *((vu_short*)src);
? ? ? if ((rc = write_word(info, wp, data)) != 0) {
? ? ? return (rc);
? ? ? }
? ? ? src += 2;
? ? ? wp ?+= 2;
? ? ? cnt -= 2;
? ?}


? ?if (cnt == 0) {
? ? ? return ERR_OK;
? ?}


? ?/*
? ? * handle unaligned tail bytes
? ? */
? ?data = 0;
? ?for (i=0, cp=wp; i<2 && cnt>0; ++i, ++cp) {
? ? ? data = (data >> 8) | (*src++ << 8);
? ? ? --cnt;
? ?}
? ?for (; i<2; ++i, ++cp) {
? ? ? data = (data >> 8) | (*(uchar *)cp << 8);
? ?}


? ?return write_word(info, wp, data);
}

/*
?* Write 16 bit (short) to flash
?*/

static int write_word (flash_info_t *info, ulong dest, ushort data)
{
? ?vu_short *addr = (vu_short *)dest, val;
? ?int rc = ERR_OK;
? ?int flag;


? ?/* Check if Flash is (sufficiently) erased , fix by kavin*/
? ?if ((*addr & data) != data)
? ? ? return ERR_NOT_ERASED;


? ?/*
? ? * Disable interrupts which might cause a timeout
? ? * here. Remember that our exception vectors are
? ? * at address 0 in the flash, and we don't want a
? ? * (ticker) exception to happen while the flash
? ? * chip is in programming mode.
? ? */
? ?flag = disable_interrupts();


? ?/* clear status register command */
? ?*addr = 0x50;


? ?/* program set-up command */
? ?*addr = 0x40;


? ?/* latch address/data */
? ?*addr = data;


? ?/* arm simple, non interrupt dependent timer */
? ?reset_timer_masked();


? ?/* wait while polling the status register */
? ?while(((val = *addr) & 0x80) != 0x80)
? ?{
? ? ? if (get_timer_masked() > CONFIG_SYS_FLASH_WRITE_TOUT) {
? ? ? rc = ERR_TIMOUT;
? ? ? /* suspend program command */
? ? ? *addr = 0xB0;
? ? ? goto outahere;
? ? ? }
? ?}


? ?if(val & 0x1A) { ? ? ? ?/* check for error */
? ? ? printf("\nFlash write error %02x at address %08lx\n",
? ? ? ? ? ?(int)val, (unsigned long)dest);
? ? ? if(val & (1<<3)) {
? ? ?printf("Voltage range error.\n");
? ? ?rc = ERR_PROG_ERROR;
? ? ?goto outahere;
? ? ? }
? ? ? if(val & (1<<1)) {
? ? ?printf("Device protect error.\n");
? ? ?rc = ERR_PROTECTED;
? ? ?goto outahere;
? ? ? }
? ? ? if(val & (1<<4)) {
? ? ?printf("Programming error.\n");
? ? ?rc = ERR_PROG_ERROR;
? ? ?goto outahere;
? ? ? }
? ? ? rc = ERR_PROG_ERROR;
? ? ? goto outahere;
? ?}


outahere:
? ?/* read array command */
? ?*addr = 0xFF;


? ?if (flag)
? ? ? enable_interrupts();


? ?return rc;
}

到目前為止我們還不能用tftp來下載文件，因為我們還沒有移植DM9000網卡。

至此，uboot就能完會支持從nor flash啟動，編譯生成新的u-boot.bin并通過DNW的USB線下載到SDRAM中運行，便可看到u-boot檢測到了我們的flash。用flinfo命令可以看 到具體的塊信息，還可以用flash的各種命令對flash進行操作，從而實現這塊nor flash驅動的完全支持。燒寫當然也是沒問題的了，把需要燒寫的文件下載到SDRAM中后，用cp.b命令就可以了。

下面大該分析一下這個驅動文件的函數調用，此flash.c文件中有如下幾個函數：

static ulong? flash_get_size ??? ??? (vu_short *addr, flash_info_t *info);
static void ??? flash_get_offsets ??? (ulong base, flash_info_t *info);
static int??????? write_word (flash_info_t *info, ulong dest, ushort data)

unsigned long flash_init (void)
void flash_print_info? (flash_info_t *info)
int flash_erase (flash_info_t *info, int s_first, int s_last)
int flash_real_protect(flash_info_t *info, long sector, int prot)
int write_buff (flash_info_t *info, uchar *src, ulong addr, ulong cnt)

????? 1.u-boot啟動只會用到flash.c文件中的flash_init函數，正如上面所述；
????? 2.以static修飾的3個函數只在flash.c文件中被調用；
????? 3.最后面的4個函數會被/common/cmd_flash.c文件中的函數調用，以實現u-boot下的各種命令操作。

?附：若用JLINK下載u-boot.bin到nor flash 中，需要把/include/configs/fl2440.h 中定義的以下這個宏注釋掉:

? ? ? ?/*?#define CONFIG_SKIP_RELOCATE_UBOOT??? 1 ?*/ ??注釋掉u-boo才能初始化CPU

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