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研发客服按照前面sdram的代码，启动代码里面关看门狗、初始化存储控制器（主要是BANK0的Norflash和BANK6的SDRAM）、设置栈到SDRAM的最高地址，text段的数据直接从Norflash里面取。
代码如下：
head.S
@*************************************************************************
@ File：head.S
@ 功能：设置SDRAM，将栈设置到SDRAM，然后继续执行
@*************************************************************************
.equMEM_CTL_BASE, 0x48000000
.equSDRAM_BASE, 0x30000000
.text
.global _start
_start:
b reset
reset:
bl disable_watch_dog @ 关闭WATCHDOG，否则CPU会不断重启
bl memsetup@ 设置存储控制器
ldr sp, =0x34000000 @ 设置栈
bl main
halt_loop:
b halt_loop
disable_watch_dog:
@ 往WATCHDOG寄存器写0即可
mov r1, #0x53000000
mov r2, #0x0
str r2, [r1]
mov pc, lr @ 返回
memsetup:
@ 设置存储控制器以便使用SDRAM等外设
mov r1, #MEM_CTL_BASE @ 存储控制器的13个寄存器的开始地址
adrlr2, mem_cfg_val @ 这13个值的起始存储地址
add r3, r1, #52 @ 13*4 = 54
@ 依次将内存控制单元对SDRAM初始化的参数写入至寄存器
str_loop:
ldr r4, [r2], #4@ 读取设置值，并让r2加4
str r4, [r1], #4@ 将此值写入寄存器，并让r1加4
cmp r1, r3 @ 判断是否设置完所有13个寄存器
bne str_loop@ 若没有写成，继续
mov pc, lr @ 返回
.align 4
mem_cfg_val:
@ 存储控制器13个寄存器的设置值
.long 0x22011110 @ BWSCON
.long 0x00000700 @ BANKCON0
.long 0x00000700 @ BANKCON1
.long 0x00000700 @ BANKCON2
.long 0x00000700 @ BANKCON3
.long 0x00000700 @ BANKCON4
.long 0x00000700 @ BANKCON5
.long 0x00018005 @ BANKCON6
.long 0x00018005 @ BANKCON7
.long 0x008C07A3 @ REFRESH
.long 0x000000B1 @ BANKSIZE
.long 0x00000030 @ MRSRB6
.long 0x00000030 @ MRSRB7
nand.c
#define LARGER_NAND_PAGE
#define GSTATUS1 (*(volatile unsigned int *)0x560000B0)
#define BUSY 1
#define NAND_SECTOR_SIZE 512
#define NAND_BLOCK_MASK (NAND_SECTOR_SIZE - 1)
#define NAND_SECTOR_SIZE_LP 2048
#define NAND_BLOCK_MASK_LP (NAND_SECTOR_SIZE_LP - 1)
typedef unsigned int S3C24X0_REG32;
/* NAND FLASH (see S3C2410 manual chapter 6) */
typedef struct {
S3C24X0_REG32 NFCONF;
S3C24X0_REG32 NFCMD;
S3C24X0_REG32 NFADDR;
S3C24X0_REG32 NFDATA;
S3C24X0_REG32 NFSTAT;
S3C24X0_REG32 NFECC;
} S3C2410_NAND;
/* NAND FLASH (see S3C2440 manual chapter 6, www.100ask.net) */
typedef struct {
S3C24X0_REG32 NFCONF;
S3C24X0_REG32 NFCONT;
S3C24X0_REG32 NFCMD;
S3C24X0_REG32 NFADDR;
S3C24X0_REG32 NFDATA;
S3C24X0_REG32 NFMECCD0;
S3C24X0_REG32 NFMECCD1;
S3C24X0_REG32 NFSECCD;
S3C24X0_REG32 NFSTAT;
S3C24X0_REG32 NFESTAT0;
S3C24X0_REG32 NFESTAT1;
S3C24X0_REG32 NFMECC0;
S3C24X0_REG32 NFMECC1;
S3C24X0_REG32 NFSECC;
S3C24X0_REG32 NFSBLK;
S3C24X0_REG32 NFEBLK;
} S3C2440_NAND;
typedef struct {
void (*nand_reset)(void);
void (*wait_idle)(void);
void (*nand_select_chip)(void);
void (*nand_deselect_chip)(void);
void (*write_cmd)(int cmd);
void (*write_addr)(unsigned int addr);
unsigned char (*read_data)(void);
}t_nand_chip;
static S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;
static t_nand_chip nand_chip;
/* 供外部调用的函数 */
void nand_init(void);
void nand_read(unsigned char *buf, unsigned long start_addr, int size);
/* NAND Flash操作的总入口, 它们将调用S3C2440的相应函数 */
static void nand_reset(void);
static void wait_idle(void);
static void nand_select_chip(void);
static void nand_deselect_chip(void);
static void write_cmd(int cmd);
static void write_addr(unsigned int addr);
static unsigned char read_data(void);
/* S3C2440的NAND Flash处理函数 */
static void s3c2440_nand_reset(void);
static void s3c2440_wait_idle(void);
static void s3c2440_nand_select_chip(void);
static void s3c2440_nand_deselect_chip(void);
static void s3c2440_write_cmd(int cmd);
static void s3c2440_write_addr(unsigned int addr);
static unsigned char s3c2440_read_data(void);
/* S3C2440的NAND Flash操作函数 */
/* 复位 */
static void s3c2440_nand_reset(void)
{
s3c2440_nand_select_chip();
s3c2440_write_cmd(0xff); // 复位命令
s3c2440_wait_idle();
s3c2440_nand_deselect_chip();
}
/* 等待NAND Flash就绪 */
static void s3c2440_wait_idle(void)
{
int i;
volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFSTAT;
while(!(*p & BUSY))
for(i=0; i<10; i++);
}
/* 发出片选信号 */
static void s3c2440_nand_select_chip(void)
{
int i;
s3c2440nand->NFCONT &= ~(1<<1);
for(i=0; i<10; i++);
}
/* 取消片选信号 */
static void s3c2440_nand_deselect_chip(void)
{
s3c2440nand->NFCONT |= (1<<1);
}
/* 发出命令 */
static void s3c2440_write_cmd(int cmd)
{
volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFCMD;
*p = cmd;
}
/* 发出地址 */
static void s3c2440_write_addr(unsigned int addr)
{
int i;
volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFADDR;
*p = addr & 0xff;
for(i=0; i<10; i++);
*p = (addr >> 9) & 0xff;
for(i=0; i<10; i++);
*p = (addr >> 17) & 0xff;
for(i=0; i<10; i++);
*p = (addr >> 25) & 0xff;
for(i=0; i<10; i++);
}
static void s3c2440_write_addr_lp(unsigned int addr)
{
int i;
volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFADDR;
int col, page;
col = addr & NAND_BLOCK_MASK_LP;
page = addr / NAND_SECTOR_SIZE_LP;
*p = col & 0xff; /* Column Address A0~A7 */
for(i=0; i<10; i++);
*p = (col >> 8) & 0x0f; /* Column Address A8~A11 */
for(i=0; i<10; i++);
*p = page & 0xff; /* Row Address A12~A19 */
for(i=0; i<10; i++);
*p = (page >> 8) & 0xff; /* Row Address A20~A27 */
for(i=0; i<10; i++);
*p = (page >> 16) & 0x03; /* Row Address A28~A29 */
for(i=0; i<10; i++);
}
/* 读取数据 */
static unsigned char s3c2440_read_data(void)
{
volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFDATA;
return *p;
}
/* 在第一次使用NAND Flash前，复位一下NAND Flash */
static void nand_reset(void)
{
nand_chip.nand_reset();
}
static void wait_idle(void)
{
nand_chip.wait_idle();
}
static void nand_select_chip(void)
{
int i;
nand_chip.nand_select_chip();
for(i=0; i<10; i++);
}
static void nand_deselect_chip(void)
{
nand_chip.nand_deselect_chip();
}
static void write_cmd(int cmd)
{
nand_chip.write_cmd(cmd);
}
static void write_addr(unsigned int addr)
{
nand_chip.write_addr(addr);
}
static unsigned char read_data(void)
{
return nand_chip.read_data();
}
/* 初始化NAND Flash */
void nand_init(void)
{
#define TACLS 0
#define TWRPH0 3
#define TWRPH1 0
nand_chip.nand_reset = s3c2440_nand_reset;
nand_chip.wait_idle = s3c2440_wait_idle;
nand_chip.nand_select_chip = s3c2440_nand_select_chip;
nand_chip.nand_deselect_chip = s3c2440_nand_deselect_chip;
nand_chip.write_cmd = s3c2440_write_cmd;
#ifdef LARGER_NAND_PAGE
nand_chip.write_addr = s3c2440_write_addr_lp;
#else
nand_chip.write_addr = s3c2440_write_addr;
#endif
nand_chip.read_data = s3c2440_read_data;
/* 设置时序 */
s3c2440nand->NFCONF = (TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4);
/* 使能NAND Flash控制器, 初始化ECC, 禁止片选 */
s3c2440nand->NFCONT = (1<<4)|(1<<1)|(1<<0);
/* 复位NAND Flash */
nand_reset();
}
/* 读函数 */
void nand_read(unsigned char *buf, unsigned long start_addr, int size)
{
int i, j;
#ifdef LARGER_NAND_PAGE
if ((start_addr & NAND_BLOCK_MASK_LP) || (size & NAND_BLOCK_MASK_LP)) {
return ; /* 地址或长度不对齐 */
}
#else
if ((start_addr & NAND_BLOCK_MASK) || (size & NAND_BLOCK_MASK)) {
return ; /* 地址或长度不对齐 */
}
#endif
/* 选中芯片 */
nand_select_chip();
for(i=start_addr; i < (start_addr + size);) {
/* 发出READ0命令 */
write_cmd(0);
/* Write Address */
write_addr(i);
#ifdef LARGER_NAND_PAGE
write_cmd(0x30);
#endif
wait_idle();
#ifdef LARGER_NAND_PAGE
for(j=0; j < NAND_SECTOR_SIZE_LP; j++, i++) {
#else
for(j=0; j < NAND_SECTOR_SIZE; j++, i++) {
#endif
*buf = read_data();
buf++;
}
}
/* 取消片选信号 */
nand_deselect_chip();
return ;