ARM+LINUX移植攻略（四）U-boot-2009.08移植TE2440II开发板--支持Norflash

哈尔滨理工大学软件工程专业08-7李万鹏原创作品，转载请标明出处
http://blog.csdn.net/woshixingaaa/archive/2011/02/10/6177621.aspx
TE2440II开发板使用的Norflash是INTEL的JS28F320J3D75，4M，32个block,每个128KB。本文添加对Norflash的支持，使Uboot可以烧录到Norflash，从Norflash启动，并执行Norflash下的命令。
这样需要注释掉 /include/configs/TE2440II.h中的
#define CONFIG_SKIP_LOWLEVEL_INIT 1
//#define CONFIG_SKIP_RELOCATE_UBOOT 1
把include/configs/TE2440II.h的Physical Memory Map和FLASH and environment organization修改为，这里添加了/board/cmi/flash.c中部份变量的宏定义。FLASH and environment organization这里的sector指的是手册中的bank，所以大小是128KB，为32块。#define CONFIG_ENV_ADDR (CONFIG_SYS_FLASH_BASE + 0x40000)，这个偏移是自己定的，是放环境变量的，只要不在uboot的代码区就可以。
CONFIG_SYS_FLASH_ERASE_TOUT和CONFIG_SYS_FLASH_WRITE_TOUT是超时的时间，如果小了，自己改大些。cpu/arm920t/s3c24x0/timer.c中讲述了怎么获得时间的。
/*-----------------------------------------------------------------------
* 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 FLASH_BASE0_PRELIM PHYS_FLASH_1
#define CONFIG_SYS_MONITOR_BASE TEXT_BASE

/*-----------------------------------------------------------------------
* FLASH and environment organization
*/
#define CONFIG_SYS_MAX_FLASH_BANKS 1 /* max number of memory banks */
#define CONFIG_INTEL_JS28F320 1
#define PHYS_FLASH_SIZE 0x400000 /* 4M */
#define CONFIG_SYS_MAX_FLASH_SECT 32
#define CONFIG_ENV_ADDR (CONFIG_SYS_FLASH_BASE + 0x40000)

/* 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 */

#define CONFIG_ENV_IS_IN_FLASH 1
#define CONFIG_ENV_SIZE 0x20000 /* Total Size of Environment Sector */

#endif /* __CONFIG_H */
用board/cmi/下的flash.c文件替换board/samsung/TE2440II/下的flash.c，因为cmi目录下的正好是JS28F320J3D75的驱动文件。删除这个write_short函数的申明和定 义、删除write_buff函数。替换成下面的两个函数：
/******************************************************************************************************
* Copy memory to flash.
*/

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);
}

/******************************************************************************************************
* Copy memory 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;
}
修改flash.c文件中的一个宏定义：
把：
#define FLASH_BLOCK_SIZE 0x00010000
改为：
#define FLASH_BLOCK_SIZE 0x00020000
修改开发板目录下的lowlevel_init.S文件中SDARM刷新参数为：
#define REFCNT 1258 /* period=7.8125us, HCLK=405/4 Mhz, (2048+1-7.8125*405/4) */
Lowlevel_init.S中对SDRAM进行了初始化，因为我们要把第二阶段的代码搬运到SDRAM中，REFCNT是刷新计数器，这个在移植的时候是一定要修改的。手册上有公式：Refresh period = (2^11-refresh_count+1)/HCLK，我使用的这款芯片在datasheet写着8192Refresh cycle/64ms，所以一个刷新周期为64ms/8192=7.8125us。目前公认的标准是，存储体中电容中数据有效保存期上限是64ms,也就是说每一行刷新的循环周期是64ms，这样刷新的速度就是：行数量/64ms。我的理解是CPU并不知道你用的SDRAM的刷新速度是多少，特殊功能寄存器也没有直接传递刷新速度的位，但是有一个刷新计数器，可以通过刷新计数器间接获得刷新速度，所以要设定刷新计数器。
然后就可以烧录Norflash了。