U-Boot 在44B0X 开发板上的移植以及代码分析

全局变量来累加的。
void udelay (unsigned long usec)
{
ulong tmo;

tmo = usec / 1000;
tmo *= CFG_HZ;
tmo /= 8;

tmo += get_timer (0);

while (get_timer_masked () < tmo)
/*NOP*/;
}

3) flash 部分（u-boot-1.1.2/board/gold44b.c）
flash 作为内存的一部分，读肯定没有问题，关键是flash 的写部分。
Flash 的写必须先擦除，然后再写。
flash_init 完成初始化部分，这里的主要目的是检验flash 的型号是否正确。

unsigned long flash_init (void)
{
#ifdef __DEBUG_START_FROM_SRAM__
return CFG_DUMMY_FLASH_SIZE;
#else
unsigned long size_b0;
int i;

/* Init: no FLASHes known */
for (i=0; iflash_info[i].flash_id = FLASH_UNKNOWN;
}

/* Static FLASH Bank configuration here - FIXME XXX */

size_b0 = flash_get_size((vu_long *)CFG_FLASH_BASE, &flash_info[0]);

if (flash_info[0].flash_id == FLASH_UNKNOWN) {
printf ("## Unknown FLASH on Bank 0 - Size = 0x%08lx = %ld MB\n",
size_b0, size_b0<20);
}

/* Setup offsets */
flash_get_offsets (0, &flash_info[0]);

/* Monitor protection ON by default */
(void)flash_protect(FLAG_PROTECT_SET,
-CFG_MONITOR_LEN,
0xffffffff,
&flash_info[0]);

flash_info[0].size = size_b0;

return (size_b0);
#endif
}

flash_erase 擦除flash,BlankCheck 则检查该部分内容是否擦除成功。

int flash_erase (flash_info_t *info, int s_first, int s_last)
{
volatile CFG_FLASH_WORD_SIZE *addr = (CFG_FLASH_WORD_SIZE *)(info->start[0]);
volatile CFG_FLASH_WORD_SIZE *addr2;
int flag, prot, sect, l_sect;
ulong start, now, last;
int i;

if ((s_first < 0) || (s_first > s_last)) {
if (info->flash_id == FLASH_UNKNOWN) {
printf ("- missing\n");
} else {
printf ("- no sectors to erase\n");
}
return 1;
}

if (info->flash_id == FLASH_UNKNOWN) {
printf ("Cant erase unknown flash type - aborted\n");
return 1;
}

prot = 0;
for (sect=s_first; sect<=s_last; ++sect) {
if (info->protect[sect]) {
prot++;
}
}

if (prot) {
printf ("- Warning: %d protected sectors will not be erased!\n",
prot);
} else {
printf ("\n");
}

l_sect = -1;

/* Disable interrupts which might cause a timeout here */
flag = disable_interrupts();

/* Start erase on unprotected sectors */
for (sect = s_first; sect<=s_last; sect++) {
if (info->protect[sect] == 0) { /* not protected */
addr2 = (CFG_FLASH_WORD_SIZE *)(info->start[sect]);
if ((info->flash_id & FLASH_VENDMASK) == FLASH_MAN_SST) {
addr[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00AA00AA;
addr[CFG_FLASH_ADDR1] = (CFG_FLASH_WORD_SIZE)0x00550055;
addr[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00800080;
addr[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00AA00AA;
addr[CFG_FLASH_ADDR1] = (CFG_FLASH_WORD_SIZE)0x00550055;
addr2[0] = (CFG_FLASH_WORD_SIZE)0x00500050; /* block erase */
for (i=0; i<50; i++)
udelay(1000); /* wait 1 ms */
} else {
if (sect == s_first) {
addr[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00AA00AA;
addr[CFG_FLASH_ADDR1] = (CFG_FLASH_WORD_SIZE)0x00550055;
addr[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00800080;
addr[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00AA00AA;
addr[CFG_FLASH_ADDR1] = (CFG_FLASH_WORD_SIZE)0x00550055;
}
addr2[0] = (CFG_FLASH_WORD_SIZE)0x00300030; /* sector erase */
}
l_sect = sect;
}
}

/* re-enable interrupts if necessary */
if (flag)
enable_interrupts();

/* wait at least 80us - lets wait 1 ms */
udelay (1000);

/*
* We wait for the last triggered sector
*/
if (l_sect < 0)
goto DONE;

start = get_timer (0);
last = start;
addr = (CFG_FLASH_WORD_SIZE *)(info->start[l_sect]);
while ((addr[0] & (CFG_FLASH_WORD_SIZE)0x00800080) != (CFG_FLASH_WORD_SIZE)0x00800080) {
if ((now = get_timer(start)) > CFG_FLASH_ERASE_TOUT) {
printf ("Timeout\n");
return 1;
}
/* show that were waiting */
if ((now - last) > 50000000) { /* every second */
putc (.);
last = now;
}
}

DONE:
/* reset to read mode */
addr = (CFG_FLASH_WORD_SIZE *)info->start[0];
addr[0] = (CFG_FLASH_WORD_SIZE)0x00F000F0; /* reset bank */

printf (" done\n");
return 0;
}

wirte_word 则想flash 里面写入unsigned long 类型的data，因为flash 一次只能写入16bits，所以这里分两次写入。
/*-----------------------------------------------------------------------
* Write a word to Flash, returns:
* 0 - OK
* 1 - write timeout
* 2 - Flash not erased
*/
static int write_word (flash_info_t *info, ulong dest, ulong data)
{
volatile CFG_FLASH_WORD_SIZE *addr2 = (CFG_FLASH_WORD_SIZE *)(info->start[0]);
volatile CFG_FLASH_WORD_SIZE *dest2 = (CFG_FLASH_WORD_SIZE *)dest;
volatile CFG_FLASH_WORD_SIZE *data2 = (CFG_FLASH_WORD_SIZE *)&data;
ulong start;
int flag;
int i;

/* Check if Flash is (sufficiently) erased */
if ((*((volatile ulong *)dest) & data) != data) {
return (2);
}
/* Disable interrupts which might cause a timeout here */
flag = disable_interrupts();

for (i=0; i<4/sizeof(CFG_FLASH_WORD_SIZE); i++)
{
addr2[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00AA00AA;
addr2[CFG_FLASH_ADDR1] = (CFG_FLASH_WORD_SIZE)0x00550055;
addr2[CFG_FLASH_ADDR0] = (CFG_FLASH_WORD_SIZE)0x00A000A0;

dest2[i] = data2[i];

/* re-enable interrupts if necessary */
if (flag)
enable_interrupts();

/* data polling for D7 */
start = get_timer (0);
while ((dest2[i] & (CFG_FLASH_WORD_SIZE)0x00800080) !=
(data2[i] & (CFG_FLASH_WORD_SIZE)0x00800080)) {
if (get_timer(start) > CFG_FLASH_WRITE_TOUT) {
return (1);
}
}
}

return (0);
}