sdram 裸机程序

硬件平台 ：JZ2440

实现功能：将led闪烁代码从2440的2k sram中拷贝到sdram

start.s      -->   上电初始化，拷贝代码

sdram.c   -->   led代码

start.s 源码：

.equ MENRI_BASE, 0x48000000
.equ SDRAM_BASE, 0x30000000

.text
.global _start
_start:
        bl close_watchdog
        bl sdram_set
        bl copy_sram_to_sdram
        ldr pc,=on_sdram
on_sdram:
        ldr sp,=0x34000000
        bl main
loop1:
       b loop1

close_watchdog:
        ldr r0,=0x53000000
        mov r1,#0x0
        str r1,[r0]
        mov pc,lr

copy_sram_to_sdram:
        ldr r0,=SDRAM_BASE
        mov r1,#0x0
        mov r3,#*
l:
        ldr r4,[r1], #
        str r4,[r0],#
        cmp r1, r3
        bne l

         mov pc,lr 

sdram_set:
        mov r1,#MENRI_BASE
        adrl r2,mem_reg_set
        add r3,r1,#
m:
        ldr r4,[r2],#
        str r4,[r1],#
        cmp r1,r3
        bne m

        mov pc,lr

.align
mem_reg_set:
.long  0x22011110
.long  0x00000700
.long  0x00000700
.long  0x00000700
.long  0x00000700
.long  0x00000700
.long  0x00000700
.long  0x00018005
.long  0x00018005
.long  0x008c07a3
.long  0x000000b1
.long  0x00000030
.long  0x00000030

sdram.c 源码：

#define GPFCON (*(unsigned long *)0x56000050)
#define GPFDAT (*(unsigned long *)0x56000054)
#define LED1_ON   (1<<8)
#define LED2_ON   (1<<10)
#define LED3_ON   (1<<12)

void delay(unsigned long num)
{
    while(--num);
}

int main(void)
{
    GPFCON=LED1_ON|LED2_ON|LED3_ON;
    while()
    {
        GPFDAT=(<<);
        delay();
        GPFDAT=(<<);
        delay();
        GPFDAT=(<<);
        delay();
    }

    return ;
}

编译的Makefile：

sdram.bin:start.s sdram.c
    arm-linux-gcc -o start.o -c start.s
    arm-linux-gcc -o sdram.o -c sdram.c
    arm-linux-ld -Ttext 0x3000000 -o sdram_elf start.o sdram.o
    arm-linux-objcopy  -O binary -S sdram_elf sdram.bin
    arm-linux-objdump -D -m arm sdram_elf > sdram.dis
clean:
    rm *.o *.dis *.bin sdram_elf