mmu裸机程序

硬件平台：JZ2440

init.c     -->  初始化sdram，创建页表

leds.c   -->  使用init.c初始化的VA地址控制led

start.s  -->  上电初始化汇编程序

start.s 源码：

.text
.global _start
_start:
         ldr sp,=4096
         bl disable_watch_dog
         bl enable_sdram
         bl copy_2th_to_sdram
         bl creat_page_table
         bl enable_mmu
         ldr sp,=0xb4000000
         ldr pc,=0xb0004000
loop1:
     b loop1

init.c  源码：

void disable_watch_dog(void)
{
    (*(unsigned long *)0x53000000)=0;
}


void enable_sdram(void)
{
    unsigned long sdram_conf[]={0x22011110,0x00000700,0x00000700,0x00000700,0x00000700,0x00000700,0x00000700,0x00018005,0x00018005,0x008c07a3,0x000000b1,0x00000030,0x00000030};
    unsigned long* sdram_register=(unsigned long *)0x48000000;
    int i=0;
    for(i=0;i<13;i++)  sdram_register[i]=sdram_conf[i];
}



void copy_2th_to_sdram(void)
{
    unsigned int *sour=(unsigned int *)2048;
    unsigned int *dest=(unsigned int *)0x30004000;
    while(sour<(unsigned int *)4096)
    {
        
        *dest=*sour;
        sour++;
        dest++;
    }    
}



void creat_page_table(void)
{
    #define SET_AP       (3<<10)
    #define SET_DOMINE   (0<<5)
    #define SET_4         (1<<4)
    #define SET_C        (1<<3)
    #define SET_B        (1<<2)
    #define SET_0        (2)
    
    #define mmu_cache  (SET_AP|SET_DOMINE|SET_4|SET_C|SET_B|SET_0)
    #define mmu        (SET_AP|SET_DOMINE|SET_4|SET_0)
    
    unsigned long vir_ad=0,phy_ad=0;
    unsigned long *mmu_base_ad=(unsigned long *)0x30000000;
    
    /*steppingstone*/
    vir_ad=0;
    phy_ad=0;
    *(mmu_base_ad+(vir_ad>>20))=(phy_ad & 0xfff00000)|mmu_cache;

    /*gpio*/
    vir_ad=0xa0000000;
    phy_ad=0x56000000;
    *(mmu_base_ad +( vir_ad>>20))=(phy_ad & 0xfff00000)|mmu;

    /*sdram*/
     vir_ad=0xb0000000;
     phy_ad=0x30000000;
     while(vir_ad<0xb4000000)
     {
         *(mmu_base_ad +(vir_ad>>20))=(phy_ad&0xfff00000)|mmu_cache;
         vir_ad+=0x100000;
         phy_ad+=0x100000;
     }
}


void enable_mmu(void)
{
    unsigned long ttb=0x30000000;
      __asm__
    (
      "mov r0,#0
"                        /**/
      "mcr p15,0,r0,c7,c7,0
"             /*使无效icache dcache*/
      "mcr p15,0,r0,c7,c10,4
"            /*清空*/
      "mcr p15,0,r0,c8,c7,0
"             /*使无效itlb dtlb*/  
      "mov r4,%0
"                        /*页表基地址*/
      "mcr p15,0,r4,c2,c0,0
"             /**/
      "mvn r0,#0
"                        /**/
      "mcr p15,0,r0,c3,c0,0
"             /*域访问控制器为可读写*/
      "mrc p15,0,r0,c1,c0,0
"             /*读控制器的值*/         
      "bic r0,r0,#0x3000
"                /*先清除 再是能*/         
      "bic r0,r0,#0x0300
"                /**/          
      "bic r0,r0,#0x0087
"                /**/      
      "orr r0,r0,#0x0002
"                /*使能对齐检查*/    
      "orr r0,r0,#0x0004
"                /*是能cache_buff*/        
      "orr r0,r0,#0x1000
"                /*使能icache*/               
      "orr r0,r0,#0x0001
"                /*使能mmu*/      
          "mcr p15,0,r0,c1,c0,0
"            
          :                                /**/
      :"r"(ttb)                            /**/
    );
}

leds.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)

static inline delay(unsigned long num)
{
    while(--num);
}

int main(void)
{
    GPFCON=LED1_ON|LED2_ON|LED3_ON;
    while(1)
    {
        GPFDAT=~(1<<4);
        delay(100000);
        GPFDAT=~(1<<5);
        delay(100000);
        GPFDAT=~(1<<6);
        delay(100000);
    }
    
    return 0;
}

链接脚本 mmu.lds ：

SECTIONS
{
    first 0x00000000 :{start.o init.o}
    seconed 0xb0004000:AT(2048){leds.o}
}

编译的Makefile:

objs:=start.o init.o leds.o

mmu.bin:$(objs)
    arm-linux-ld -Tmmu.lds -o mmu_elf $^
    arm-linux-objcopy -O binary -S mmu_elf $@
    arm-linux-objdump -D -m arm mmu_elf > mmu.dis
    
%.o:%.c
    arm-linux-gcc -Wall -O2 -o $@ -c $<
    
%.o:%.s
    arm-linux-gcc -Wall -O2 -o $@ -c $<
    
    
clean:
    rm -f *.bin *.o *.dis mmu_elf