start.S源碼：

.globl _start

_start:

// 硬件相關的設置 

    // Peri port setup 

    ldr r0, =0x70000000

    orr r0, r0, #0x13

    mcr p15,0,r0,c15,c2,4       @ 256M(0x70000000-0x7fffffff)

// 關看門狗 

    // 往WTCON(0x7E004000)寫0   

    ldr r0, =0x7E004000

    mov r1, #0

    str r1, [r0]

    // 設置棧 

    ldr sp, =8*1024

    // 設置時鐘 

    bl clock_init

    // 設置DDR 

    bl ddr_init

// 重定位 

    //把片內內存中程序的代碼段、數據段復制到它的鏈接地址去   

    adr r0, _start          // 獲得_start指令當前所在的地址 : 0

    ldr r1, =_start        // _start的鏈接地址 0x51000000 

    ldr r2, =bss_start   // bss段的起始鏈接地址 

    sub r2, r2, r1

    cmp r0,r1

    beq clean_bss

    bl copy2ddr

    cmp r0, #0

    bne halt

// 清BSS 

    // 把BSS段對應的內存清零 

clean_bss:

    ldr r0, =bss_start

    ldr r1, =bss_end

    mov r3, #0

    cmp r0, r1

    beq on_ddr

clean_loop:

    str r3, [r0], #4

    cmp r0, r1    

    bne clean_loop        

on_ddr:

    ldr pc, =main

halt:

    b halt    

==================================================================

clock.S源碼：

.globl clock_init

clock_init:

    // 1.設置LOCK_TIME 

    ldr r0, =0x7E00F000  // APLL_LOCK 

    ldr r1, =0x0000FFFF

    str r1, [r0]

    str r1, [r0, #4]     // MPLL_LOCK 

    str r1, [r0, #8]     // EPLL_LOCK     

#define OTHERS        0x7e00f900

    @ set async mode  // 當CPU時鐘 != HCLK時，要設為異步模式 

    ldr r0, =OTHERS

    ldr r1, [r0]

    bic r1, #0xc0            

    str r1, [r0]

loop1:                        // 等待，直到CPU進入異步模式 

    ldr r0, =OTHERS

    ldr r1, [r0]

    and r1, #0xf00                    

    cmp r1, #0

    bne loop1        

    // SYNC667 

    // MISC_CON[19] = 0 

#define ARM_RATIO    0     // ARMCLK = DOUTAPLL / (ARM_RATIO + 1)    

#define HCLKX2_RATIO 1   // HCLKX2 = HCLKX2IN / (HCLKX2_RATIO + 1) 

#define HCLK_RATIO   1     // HCLK = HCLKX2 / (HCLK_RATIO + 1)       

#define PCLK_RATIO   3      // PCLK   = HCLKX2 / (PCLK_RATIO + 1)     

#define MPLL_RATIO   0     // DOUTMPLL = MOUTMPLL / (MPLL_RATIO + 1)     

    ldr r0, =0x7E00F020         // CLK_DIV0 

    ldr r1, =(ARM_RATIO) | (MPLL_RATIO << 4) | (HCLK_RATIO << 8) | (HCLKX2_RATIO << 9) | (PCLK_RATIO << 12)

    str r1, [r0]

    // 2.配置時鐘 

    // 2.1 配置APLL 

    // 2.1.1 設置APLL

    // 2.1.2 MUXAPLL

    // 2.1.3 SYNC667

    // 2.1.4 DIVAPLL

#define APLL_CON_VAL  ((1<<31) | (266 << 16) | (3 << 8) | (1))

    ldr r0, =0x7E00F00C

    ldr r1, =APLL_CON_VAL

    str r1, [r0]        // APLL_CON, FOUTAPL = MDIV * Fin / (PDIV*2^SDIV) = 266*12/(3*2^1) = 532MHz  

    // 2.2 配置MPLL 

    // 2.2.1 設置MPLL

    // 2.2.2 MUXMPLL

    // 2.2.3 SYNCMUX

    // 2.2.4 SYNC667

    // 2.2.5 HCLKX2_RATIO

    // 2.2.6 PCLK_RATIO

#define MPLL_CON_VAL  ((1<<31) | (266 << 16) | (3 << 8) | (1))

    ldr r0, =0x7E00F010

    ldr r1, =MPLL_CON_VAL

    str r1, [r0]        // MPLL_CON, FOUTMPL = MDIV * Fin / (PDIV*2^SDIV) = 266*12/(3*2^1) = 532MHz  

    // 3.選擇PLL的輸出作為時鐘源 

    ldr r0, =0x7E00F01C

    ldr r1, =0x03

    str r1, [r0]

    mov pc, lr

===================================================================

sdram.c源碼：

#include "common.h"

#define MEMCCMD        0x7e001004

#define P1REFRESH        0x7e001010

#define P1CASLAT          0x7e001014

#define MEM_SYS_CFG   0x7e00f120

#define P1MEMCFG        0x7e00100c

#define P1T_DQSS          0x7e001018

#define P1T_MRD           0x7e00101c

#define P1T_RAS             0x7e001020

#define P1T_RC               0x7e001024

#define P1T_RCD            0x7e001028

#define P1T_RFC             0x7e00102c

#define P1T_RP               0x7e001030

#define P1T_RRD            0x7e001034

#define P1T_WR              0x7e001038

#define P1T_WTR            0x7e00103c

#define P1T_XP               0x7e001040

#define P1T_XSR             0x7e001044

#define P1T_ESR              0x7e001048

#define P1MEMCFG2      0X7e00104c

#define P1_chip_0_cfg     0x7e001200

#define P1MEMSTAT      0x7e001000

#define P1MEMCCMD    0x7e001004

#define P1DIRECTCMD   0x7e001008

#define HCLK    133000000

#define nstoclk(ns)    (ns/( 1000000000/HCLK)+1)

int ddr_init( void )

{

    // tell dramc to configure                

    set_val( MEMCCMD, 0x4 );

    // set refresh period    

    set_val( P1REFRESH, nstoclk(7800) );

    // set timing para        

    set_val( P1CASLAT, ( 3 << 1 ) );  

    set_val( P1T_DQSS, 0x1 );    // 0.75 - 1.25

    set_val( P1T_MRD, 0x2 );

    set_val( P1T_RAS, nstoclk(45) );

    set_val( P1T_RC, nstoclk(68) );        

    u32 trcd = nstoclk( 23 );

    set_val( P1T_RCD, trcd | (( trcd - 3 ) << 3 ) );

    u32 trfc = nstoclk( 80 );

    set_val( P1T_RFC, trfc | ( ( trfc-3 ) << 5 ) );   

    u32 trp = nstoclk( 23 );

    set_val( P1T_RP, trp | ( ( trp - 3 ) << 3 ) ); 

    set_val( P1T_RRD, nstoclk(15) );

    set_val( P1T_WR, nstoclk(15) );

    set_val( P1T_WTR, 0x7 );

    set_val( P1T_XP, 0x2 );

    set_val( P1T_XSR, nstoclk(120) );

    set_val( P1T_ESR, nstoclk(120) );

    // set mem cfg 

    set_nbit( P1MEMCFG, 0, 3, 0x2 );  // 10 column address 

    // set_nbit: 把從第bit位開始的一共len位消零，然后把這幾位設為val 

    set_nbit( P1MEMCFG, 3, 3, 0x2 );  // 13 row address 

    set_zero( P1MEMCFG, 6 );              // A10/AP 

    set_nbit( P1MEMCFG, 15, 3, 0x2 ); // Burst 4 

    set_nbit( P1MEMCFG2, 0, 4, 0x5 );

    set_2bit( P1MEMCFG2, 6, 0x1 );     // 32 bit 

    set_nbit( P1MEMCFG2, 8, 3, 0x3 ); // Mobile DDR SDRAM 

    set_2bit( P1MEMCFG2, 11, 0x1 );

    set_one( P1_chip_0_cfg, 16 );         // Bank-Row-Column organization 

    // memory init

    set_val( P1DIRECTCMD, 0xc0000 );  // NOP

    set_val( P1DIRECTCMD, 0x000 );      // precharge

    set_val( P1DIRECTCMD, 0x40000 );  // auto refresh

    set_val( P1DIRECTCMD, 0x40000 );  // auto refresh

    set_val( P1DIRECTCMD, 0xa0000 );  // EMRS

    set_val( P1DIRECTCMD, 0x80032 );  // MRS

    set_val( MEM_SYS_CFG, 0x0 );

    // set dramc to "go" status    

    set_val( P1MEMCCMD, 0x000 );

    // wait ready

    while( !(( read_val( P1MEMSTAT ) & 0x3 ) == 0x1));

}

===================================================================

nand.c源碼：

#define MEM_SYS_CFG     (*((volatile unsigned long *)0x7E00F120))

#define NFCONF               (*((volatile unsigned long *)0x70200000))

#define NFCONT               (*((volatile unsigned long *)0x70200004))

#define NFCMMD            (*((volatile unsigned long *)0x70200008))

#define NFADDR             (*((volatile unsigned long *)0x7020000C))

#define NFDATA             (*((volatile unsigned char *)0x70200010))

#define NFSTAT              (*((volatile unsigned long *)0x70200028))

void nand_select(void)

{

    NFCONT &= ~(1<<1);

}

void nand_deselect(void)

{

    NFCONT |= (1<<1);

}

void nand_cmd(unsigned char cmd)

{

    NFCMMD = cmd;

}

void nand_addr(unsigned char addr)

{

    NFADDR = addr;

}

unsigned char nand_get_data(void)

{

    return NFDATA;

}

void nand_send_data(unsigned char data)

{

    NFDATA = data;

}

void wait_ready(void)

{

    while ((NFSTAT & 0x1) == 0);

}

void nand_reset(void)

{

    // 選中 

    nand_select();

    // 發出0xff命令 

    nand_cmd(0xff);

    // 等待就緒 

    wait_ready();

    // 取消選中 

    nand_deselect();

}

void nand_init(void)

{

#if 1                         //經測試可以用

#define TACLS        7

#define TWRPH0    7

#define TWRPH1    7

    NFCONF &= ~((7<<4) | (7<<8) | (7<<12) | (1<<30));

    NFCONF |= ((TACLS<<12) | (TWRPH0<<8) | (TWRPH1<<4));

    // 使能nand flash controller 

    NFCONT |= 1;

    NFCONT &= ~(1<<16);

    nand_reset();

#else

    // 讓xm0csn2用作nand flash cs0 片選引腳 

    MEM_SYS_CFG &= ~(1<<1);

    // 設置時間參數 

#define TACLS     0

#define TWRPH0    1

#define TWRPH1    0

    NFCONF &= ~((1<<30) | (7<<12) | (7<<8) | (7<<4));

    NFCONF |= ((TACLS<<12) | (TWRPH0<<8) | (TWRPH1<<4));

    // 使能nand flash controller 

    NFCONT |= 1;

    NFCONT &= ~(1<<16); // 森止soft lock 

    nand_reset();

#endif

}

void nand_send_addr(unsigned int addr)

{

#if 0    

    unsigned int page = addr / 2048;

    // 這兩個地址表示從頁內哪里開始 

    nand_addr(addr & 0xff);

    nand_addr((addr >> 8) & 0xff);

    // 下面三個地址表示哪一頁 

    nand_addr(page & 0xff);

    nand_addr((page >> 8) & 0xff);

    nand_addr((page >> 16) & 0xff);

#elif 0

    nand_addr(addr & 0xff);              // a0~a7 

    nand_addr((addr >> 8) & 0x7);   // 程序的角度: a8~a10 

    nand_addr((addr >> 11) & 0xff); // 程序的角度: a11~a18 

    nand_addr((addr >> 19) & 0xff); // 程序的角度: a19~a26 

    nand_addr((addr >> 27) & 0xff); // 程序的角度: a27~    

#elif 1                   //經測試可以用

    nand_addr(addr & 0xff);               // a0~a7 

    nand_addr((addr >> 8) & 0x7);    // 程序的角度: a8~a11 

    nand_addr((addr >> 12) & 0xff);  // 程序的角度: a12~a19 

    nand_addr((addr >> 20) & 0xff);  // 程序的角度: a20~a27 

    nand_addr((addr >> 28) & 0x01); // 程序的角度: a28~    

#endif

}

//單板的nand flash Page Size : (4K + 218(OOB))Byte

int nand_read(unsigned int nand_start, unsigned int ddr_start, unsigned int len)

{

    unsigned int addr = nand_start;

    int i = nand_start % 4096;

    int count = 0;

    unsigned char *dest = (unsigned char *)ddr_start;

    // 選中芯片 

    nand_select();

    while (count < len)

    {

        // 發出命令0x00 

        nand_cmd(0x00);

        // 發出地址 

        nand_send_addr(addr);

        // 發出命令0x30 

        nand_cmd(0x30);

        // 等待就緒 

        wait_ready();

        // 讀數據 

        for (; i < 4096 && count < len; i++)

        {

            dest[count++] = nand_get_data();

            addr++;

        }

        i = 0;            

    }

    // 取消片選 

    nand_deselect();

    return 0;

}

//對nand flash來說是一塊一塊的擦除，一塊是512K + 27.25K(OOB區)Byte

int nand_erase_block(unsigned long addr)

{

    int page = addr / 4096;

    nand_select();

    nand_cmd(0x60);

    nand_addr(page & 0xff);

    nand_addr((page >> 8) & 0xff);

    nand_addr((page >> 16) & 0xff);

    nand_cmd(0xd0);

    wait_ready();

    nand_deselect();

}

//燒寫的時候是一頁一頁的燒寫4K+218(OOB區),Page Program : (4K + 218)Byte

int nand_write(unsigned int nand_start, unsigned char * buf, unsigned int len)

{

    unsigned long count = 0;

    unsigned long addr  = nand_start;

    int i = nand_start % 4096;

    nand_select();

    while (count < len)

    {

        nand_cmd(0x80);

        nand_send_addr(addr);

        for (; i < 4096&& count < len; i++)

        {

            nand_send_data(buf[count++]);

            addr++;

        }

        nand_cmd(0x10);

        wait_ready();

        i = 0;        

    }

    nand_deselect();

}

int copy2ddr(unsigned int nand_start, unsigned int ddr_start, unsigned int len)

{

    int ret;

    // 初始化nand flash controller 

    nand_init();

    // 讀nand flash 

    ret = nand_read(nand_start, ddr_start, len);

    return ret;

}

====================================================================

main.c源碼：

#include "uart.h"

#include "types.h"

void nand_read_test(void)

{

    int i;

    char buf[100];

    unsigned long addr;

    unsigned long size;

    printf("enter the start address: ");

    scanf("%s", buf);

    addr = strtoul(buf, NULL, 0);

    printf("read addr = 0x%x\n\r", addr);

    printf("enter the size: ");

    scanf("%s", buf);

    size = strtoul(buf, NULL, 0);

    if (size > 100)

    {

        printf("the max size is 100\n\r");

        size = 100;

    }

    nand_read(addr, buf, size);

    printf("datas: \n\r");

    for (i = 0; i < size; i++)

    {

        printf("x ", buf[i]);

        if ((i+1) % 16 == 0)

        {

            printf("\n\r");

        }

    }

    printf("\n\r");

}

void nand_erase_test(void)

{

    char buf[100];

    unsigned long addr;

    printf("enter the start address: ");

    scanf("%s", buf);

    addr = strtoul(buf, NULL, 0);

    printf("erase addr = 0x%x\n\r", addr);

    nand_erase_block(addr);

}

void nand_write_test(void)

{

    char buf[100];

    unsigned long addr;

    unsigned long size;

    printf("enter the start address: ");

    scanf("%s", buf);

    addr = strtoul(buf, NULL, 0);

    printf("enter the string: ");

    scanf("%s", buf);

    size = strlen(buf) + 1;

    nand_write(addr, buf, size);

}

void update_program(void)

{

    unsigned char *buf = (unsigned char *)0x52000000;

    unsigned long len = 0;

    int have_begin = 0;

    int nodata_time = 0;

    unsigned char c;

    // 讀串口獲得數據 

    printf("\n\ruse gtkterm to send file\n\r", len);

    while (1)

    {

        if (getc_nowait(&buf[len]) == 0)

        {

            have_begin = 1;

            nodata_time = 0;

            len++;

        }

        else

        {

            if (have_begin)

            {

                nodata_time++;

            }            

        }

        if (nodata_time == 1000)

        {

            break;

        }

    }

    printf("have get %d bytes data\n\r", len);

    printf("press y to program: ");

    c = getc();

    if (c == 'y' || c == 'Y')

    {    

        // 燒寫到nand flash block 0 

        nand_erase_block(0);

        nand_write(0, buf, len);

        printf("update program successful\n\r");

    }

    else

    {

        printf("update program cancel\n\r");

    }

}

void run_program(void)

{

    unsigned char *buf = (unsigned char *)0x52000000;

    unsigned long len = 0;

    int have_begin = 0;

    int nodata_time = 0;

    void (*theProgram)(void);

    // 讀串口獲得數據 

    printf("\n\ruse gtkterm to send file\n\r", len);

    while (1)

    {

        if (getc_nowait(&buf[len]) == 0)

        {

            have_begin = 1;

            nodata_time = 0;

            len++;

        }

        else

        {

            if (have_begin)

            {

                nodata_time++;

            }            

        }

        if (nodata_time == 1000)

        {

            break;

        }

    }

    printf("have get %d bytes data\n\r", len);

    printf("jump to 0x52000000 to run it\n\r");

    theProgram = (void (*)(void))0x52000000;

    theProgram();        

}

int main()

{

    char c;

    init_uart();

    printf("can update program with serial port\n\r");

    while (1)

    {

#if 1        

        printf("[w] write the nand flash\n\r");

        printf("[r] read the nand flash\n\r");

        printf("[e] erase the nand flash\n\r");

        printf("[g] get file, and write to nand flash 0 block\n\r");

        printf("[x] get file to ddr(0x52000000), run it\n\r");

#else

        printf("[w] \n\r");

        printf("[r] \n\r");

        printf("[e] \n\r");

        printf("[g] \n\r");

        printf("[x] \n\r");

#endif        

        do {

            c = getc();

            if (c == '\n' || c == '\r')

            {

                printf("\n\r");

            }

            else

            {

                putc(c);

            }

        } while (c == '\n' || c == '\r');

        switch (c)

        {

            case 'w':

            case 'W':

            {

                nand_write_test();

                break;

            }

            case 'r':

            case 'R':

            {

                nand_read_test();

                break;

            }

            case 'e':

            case 'E':

            {

                nand_erase_test();

                break;

            }

            case 'g':

            case 'G':

            {

                update_program();

                break;

            }

            case 'x':

            case 'X':

            {

                run_program();

                break;

            }

        }

    }

    return 0;

}

====================================================================

Makefile文件：

CC      = arm-linux-gcc

LD      = arm-linux-ld

AR      = arm-linux-ar

OBJCOPY = arm-linux-objcopy

OBJDUMP = arm-linux-objdump

INCLUDEDIR     := $(shell pwd)/include

CFLAGS         := -Wall -O2 -fno-builtin-printf 

CPPFLAGS       := -nostdinc -I$(INCLUDEDIR)

export     CC AR LD OBJCOPY OBJDUMP INCLUDEDIR CFLAGS CPPFLAGS 

objs := start.o clock.o sdram.o nand.o main.o uart.o lib/libc.a

uart.bin: $(objs)

    ${LD} -Tuart.lds -o uart.elf $^

    ${OBJCOPY} -O binary -S uart.elf $@

    ${OBJDUMP} -D uart.elf > uart.dis

.PHONY : lib/libc.a

lib/libc.a:

    cd lib; make; cd ..

%.o:%.c

    ${CC} $(CPPFLAGS) $(CFLAGS) -c -o $@ $<