TQ2440MMU地址映射

下面所说的代码是在linux下面用make编译的，开始都是一样的进行一些初始化，映射原理不懂的话，推荐看看伟山东这本书，这些代码也是这本书里的，而且还有视频教程，这里就不说了。

@*************************************************************************
@ File：head.S
@ 功能：设置SDRAM，将第二部分代码复制到SDRAM，设置页表，启动MMU，
@       然后跳到SDRAM继续执行
@*************************************************************************      

.text
.global _start
_start:
    ldr sp, =4096                       @ 设置栈指针，以下都是C函数，调用前需要设好栈
    bl  disable_watch_dog               @ 关闭WATCHDOG，否则CPU会不断重启
    bl  memsetup                        @ 设置存储控制器以使用SDRAM
    bl  copy_2th_to_sdram               @ 将第二部分代码复制到SDRAM
    bl  create_page_table               @ 设置页表
    bl  mmu_init                        @ 启动MMU
    ldr sp, =0xB4000000                 @ 重设栈指针，指向SDRAM顶端(使用虚拟地址)
    ldr pc, =0xB0004000                 @ 跳到SDRAM中继续执行第二部分代码
halt_loop:
    b   halt_loop

 

 

#define WTCON           (*(volatile unsigned long *)0x53000000)

#define MEM_CTL_BASE    0x48000000

void disable_watch_dog(void)
{
    WTCON = 0;  // 关闭WATCHDOG很简单，往这个寄存器写0即可
}

void memsetup(void)
{
   
    unsigned long  const    mem_cfg_val[]={ 0x22011110,     //BWSCON
                                            0x00000700,     //BANKCON0
                                            0x00000700,     //BANKCON1
                                            0x00000700,     //BANKCON2
                                            0x00000700,     //BANKCON3 
                                            0x00000700,     //BANKCON4
                                            0x00000700,     //BANKCON5
                                            0x00018005,     //BANKCON6
                                            0x00018005,     //BANKCON7
                                            0x008C07A3,     //REFRESH
                                            0x000000B1,     //BANKSIZE
                                            0x00000030,     //MRSRB6
                                            0x00000030,     //MRSRB7
                                    };
    int     i = 0;
    volatile unsigned long *p = (volatile unsigned long *)MEM_CTL_BASE;
    for(; i < 13; i++)
        p[i] = mem_cfg_val[i];
}

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

void create_page_table(void)
{

#define MMU_FULL_ACCESS     (3 << 10)  
#define MMU_DOMAIN          (0 << 5)   
#define MMU_SPECIAL         (1 << 4)   
#define MMU_CACHEABLE       (1 << 3)   
#define MMU_BUFFERABLE      (1 << 2)   
#define MMU_SECTION         (2)        
#define MMU_SECDESC         (MMU_FULL_ACCESS | MMU_DOMAIN | MMU_SPECIAL | \
                             MMU_SECTION)
#define MMU_SECDESC_WB      (MMU_FULL_ACCESS | MMU_DOMAIN | MMU_SPECIAL | \
                             MMU_CACHEABLE | MMU_BUFFERABLE | MMU_SECTION)
#define MMU_SECTION_SIZE    0x00100000

    unsigned long virtuladdr, physicaladdr;
    unsigned long *mmu_tlb_base = (unsigned long *)0x30000000;
   
   
    virtuladdr = 0;
    physicaladdr = 0;
    *(mmu_tlb_base + (virtuladdr >> 20)) = (physicaladdr & 0xFFF00000) | \
                                            MMU_SECDESC_WB;

   
    virtuladdr = 0xA0000000;
    physicaladdr = 0x56000000;
    *(mmu_tlb_base + (virtuladdr >> 20)) = (physicaladdr & 0xFFF00000) | \
                                            MMU_SECDESC;

   
    virtuladdr = 0xB0000000;
    physicaladdr = 0x30000000;
    while (virtuladdr < 0xB4000000)
    {
        *(mmu_tlb_base + (virtuladdr >> 20)) = (physicaladdr & 0xFFF00000) | \
                                                MMU_SECDESC_WB;
        virtuladdr += 0x100000;
        physicaladdr += 0x100000;
    }
}

void mmu_init(void)
{
    unsigned long ttb = 0x30000000;

__asm__(
    "mov    r0, #0\n"
    "mcr    p15, 0, r0, c7, c7, 0\n"   
   
    "mcr    p15, 0, r0, c7, c10, 4\n"  
    "mcr    p15, 0, r0, c8, c7, 0\n"   
   
    "mov    r4, %0\n"                  
    "mcr    p15, 0, r4, c2, c0, 0\n"   
   
    "mvn    r0, #0\n"                  
    "mcr    p15, 0, r0, c3, c0, 0\n"       
   
    "mrc    p15, 0, r0, c1, c0, 0\n"   
   
   
   
   
                                       
    "bic    r0, r0, #0x3000\n"         
    "bic    r0, r0, #0x0300\n"         
    "bic    r0, r0, #0x0087\n"         

   
    "orr    r0, r0, #0x0002\n"         
    "orr    r0, r0, #0x0004\n"         
    "orr    r0, r0, #0x1000\n"         
    "orr    r0, r0, #0x0001\n"         
   
    "mcr    p15, 0, r0, c1, c0, 0\n"   
    :
    : "r" (ttb) );
}

 

 

#define GPBCON      (*(volatile unsigned long *)0xA0000010)     // 物理地址0x56000010
#define GPBDAT      (*(volatile unsigned long *)0xA0000014)     // 物理地址0x56000014

#define GPB5_out    (1<<(5*2))
#define GPB6_out    (1<<(6*2))
#define GPB7_out    (1<<(7*2))
#define GPB8_out    (1<<(8*2))

static inline void wait(unsigned long dly)
{
    for(; dly > 0; dly--);
}

int main(void)
{
    unsigned long i = 0;
   
    // 将LED1-4对应的GPB5/6/7/8四个引脚设为输出
    GPBCON = GPB5_out|GPB6_out|GPB7_out|GPB8_out;      

    while(1){
        wait(30000);
        GPBDAT = (~(i<<5));     // 根据i的值，点亮LED1-4
        if(++i == 16)
            i = 0;
    }

    return 0;
}