/* WOTCH DOG register */#define     WTCON           (*(volatile unsigned long *)0x53000000)/* SDRAM regisers */#define     MEM_CTL_BASE    0x48000000#define     SDRAM_BASE      0x30000000/* NAND Flash registers */#define NFCONF              (*(volatile unsigned int  *)0x4e000000)#define NFCMD               (*(volatile unsigned char *)0x4e000004)#define NFADDR              (*(volatile unsigned char *)0x4e000008)#define NFDATA              (*(volatile unsigned char *)0x4e00000c)#define NFSTAT              (*(volatile unsigned char *)0x4e000010)/*GPIO registers*/#define GPBCON              (*(volatile unsigned long *)0x56000010)#define GPBDAT              (*(volatile unsigned long *)0x56000014)#define GPFCON              (*(volatile unsigned long *)0x56000050)#define GPFDAT              (*(volatile unsigned long *)0x56000054)#define GPFUP               (*(volatile unsigned long *)0x56000058)#define GPGCON              (*(volatile unsigned long *)0x56000060)#define GPGDAT              (*(volatile unsigned long *)0x56000064)#define GPGUP               (*(volatile unsigned long *)0x56000068)#define GPHCON              (*(volatile unsigned long *)0x56000070)#define GPHDAT              (*(volatile unsigned long *)0x56000074)#define GPHUP               (*(volatile unsigned long *)0x56000078)/*UART registers*/#define ULCON0              (*(volatile unsigned long *)0x50000000)#define UCON0               (*(volatile unsigned long *)0x50000004)#define UFCON0              (*(volatile unsigned long *)0x50000008)#define UMCON0              (*(volatile unsigned long *)0x5000000c)#define UTRSTAT0            (*(volatile unsigned long *)0x50000010)#define UTXH0               (*(volatile unsigned char *)0x50000020)#define URXH0               (*(volatile unsigned char *)0x50000024)#define UBRDIV0             (*(volatile unsigned long *)0x50000028)/*interrupt registes*/#define SRCPND              (*(volatile unsigned long *)0x4A000000)#define INTMOD              (*(volatile unsigned long *)0x4A000004)#define INTMSK              (*(volatile unsigned long *)0x4A000008)#define PRIORITY            (*(volatile unsigned long *)0x4A00000c)#define INTPND              (*(volatile unsigned long *)0x4A000010)#define INTOFFSET           (*(volatile unsigned long *)0x4A000014)#define SUBSRCPND           (*(volatile unsigned long *)0x4A000018)#define INTSUBMSK           (*(volatile unsigned long *)0x4A00001c)/*external interrupt registers*/#define EINTMASK            (*(volatile unsigned long *)0x560000a4)#define EINTPEND            (*(volatile unsigned long *)0x560000a8)/*clock registers*/#define    LOCKTIME        (*(volatile unsigned long *)0x4c000000)#define    MPLLCON        (*(volatile unsigned long *)0x4c000004)#define    UPLLCON        (*(volatile unsigned long *)0x4c000008)#define    CLKCON        (*(volatile unsigned long *)0x4c00000c)#define    CLKSLOW        (*(volatile unsigned long *)0x4c000010)#define    CLKDIVN        (*(volatile unsigned long *)0x4c000014)/*PWM & Timer registers*/#define    TCFG0        (*(volatile unsigned long *)0x51000000)#define    TCFG1        (*(volatile unsigned long *)0x51000004)#define    TCON        (*(volatile unsigned long *)0x51000008)#define    TCNTB0        (*(volatile unsigned long *)0x5100000c)#define    TCMPB0        (*(volatile unsigned long *)0x51000010)#define    TCNTO0        (*(volatile unsigned long *)0x51000014)#define GSTATUS1    (*(volatile unsigned long *)0x560000B0)

void uart0_init(void);void putc(unsigned char c);unsigned char getc(void);int isDigit(unsigned char c);int isLetter(unsigned char c);

#include "s3c24xx.h"#include "serial.h"#define TXD0READY   (1<<2)#define RXD0READY   (1)#define PCLK            50000000    // init.c中的clock_init函数设置PCLK为50MHz#define UART_CLK        PCLK        //  UART0的时钟源设为PCLK#define UART_BAUD_RATE  115200      // 波特率#define UART_BRD        ((UART_CLK  / (UART_BAUD_RATE * 16)) - 1)/* * 初始化UART0 * 115200,8N1,无流控 */void uart0_init(void){    GPHCON  |= 0xa0;    // GPH2,GPH3用作TXD0,RXD0    GPHUP   = 0x0c;     // GPH2,GPH3内部上拉    ULCON0  = 0x03;     // 8N1(8个数据位，无较验，1个停止位)    UCON0   = 0x05;     // 查询方式，UART时钟源为PCLK    UFCON0  = 0x00;     // 不使用FIFO    UMCON0  = 0x00;     // 不使用流控    UBRDIV0 = UART_BRD; // 波特率为115200}/* * 发送一个字符 */void putc(unsigned char c){    /* 等待，直到发送缓冲区中的数据已经全部发送出去 */    while (!(UTRSTAT0 & TXD0READY));        /* 向UTXH0寄存器中写入数据，UART即自动将它发送出去 */    UTXH0 = c;}/* * 接收字符 */unsigned char getc(void){    /* 等待，直到接收缓冲区中的有数据 */    while (!(UTRSTAT0 & RXD0READY));        /* 直接读取URXH0寄存器，即可获得接收到的数据 */    return URXH0;}/* * 判断一个字符是否数字 */int isDigit(unsigned char c){    if (c >= ‘0‘ && c <= ‘9‘)        return 1;    else        return 0;       }/* * 判断一个字符是否英文字母 */int isLetter(unsigned char c){    if (c >= ‘a‘ && c <= ‘z‘)        return 1;    else if (c >= ‘A‘ && c <= ‘Z‘)        return 1;           else        return 0;}

/* * init.c: 进行一些初始化 */ #include "s3c24xx.h" void disable_watch_dog(void);void clock_init(void);void memsetup(void);void copy_steppingstone_to_sdram(void);/* * 关闭WATCHDOG，否则CPU会不断重启 */void disable_watch_dog(void){    WTCON = 0;  // 关闭WATCHDOG很简单，往这个寄存器写0即可}#define S3C2410_MPLL_200MHZ     ((0x5c<<12)|(0x04<<4)|(0x00))#define S3C2440_MPLL_200MHZ     ((0x5c<<12)|(0x01<<4)|(0x02))/* * 对于MPLLCON寄存器，[19:12]为MDIV，[9:4]为PDIV，[1:0]为SDIV * 有如下计算公式： *  S3C2410: MPLL(FCLK) = (m * Fin)/(p * 2^s) *  S3C2440: MPLL(FCLK) = (2 * m * Fin)/(p * 2^s) *  其中: m = MDIV + 8, p = PDIV + 2, s = SDIV * 对于本开发板，Fin = 12MHz * 设置CLKDIVN，令分频比为：FCLK:HCLK:PCLK=1:2:4， * FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */void clock_init(void){    // LOCKTIME = 0x00ffffff;   // 使用默认值即可    CLKDIVN  = 0x03;            // FCLK:HCLK:PCLK=1:2:4, HDIVN=1,PDIVN=1    /* 如果HDIVN非0，CPU的总线模式应该从“fast bus mode”变为“asynchronous bus mode” */__asm__(    "mrc    p15, 0, r1, c1, c0, 0\n"        /* 读出控制寄存器 */     "orr    r1, r1, #0xc0000000\n"          /* 设置为“asynchronous bus mode” */    "mcr    p15, 0, r1, c1, c0, 0\n"        /* 写入控制寄存器 */    );    /* 判断是S3C2410还是S3C2440 */    if ((GSTATUS1 == 0x32410000) || (GSTATUS1 == 0x32410002))    {        MPLLCON = S3C2410_MPLL_200MHZ;  /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */    }    else    {        MPLLCON = S3C2440_MPLL_200MHZ;  /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */    }       }/* * 设置存储控制器以使用SDRAM */void memsetup(void){    volatile unsigned long *p = (volatile unsigned long *)MEM_CTL_BASE;    /* 这个函数之所以这样赋值，而不是像前面的实验(比如mmu实验)那样将配置值     * 写在数组中，是因为要生成”位置无关的代码”，使得这个函数可以在被复制到     * SDRAM之前就可以在steppingstone中运行     */    /* 存储控制器13个寄存器的值 */    p[0] = 0x22011110;     //BWSCON    p[1] = 0x00000700;     //BANKCON0    p[2] = 0x00000700;     //BANKCON1    p[3] = 0x00000700;     //BANKCON2    p[4] = 0x00000700;     //BANKCON3      p[5] = 0x00000700;     //BANKCON4    p[6] = 0x00000700;     //BANKCON5    p[7] = 0x00018005;     //BANKCON6    p[8] = 0x00018005;     //BANKCON7        /* REFRESH,     * HCLK=12MHz:  0x008C07A3,     * HCLK=100MHz: 0x008C04F4     */     p[9]  = 0x008C04F4;    p[10] = 0x000000B1;     //BANKSIZE    p[11] = 0x00000030;     //MRSRB6    p[12] = 0x00000030;     //MRSRB7}void copy_steppingstone_to_sdram(void){    unsigned int *pdwSrc  = http://www.mamicode.com/(unsigned int *)0;    unsigned int *pdwDest = (unsigned int *)0x30000000;        while (pdwSrc < (unsigned int *)4096)    {        *pdwDest = *pdwSrc;        pdwDest++;        pdwSrc++;    }}

#include "serial.h"int main(){    unsigned char c;    uart0_init();   // 波特率115200，8N1(8个数据位，无校验位，1个停止位)    while(1)    {        // 从串口接收数据后，判断其是否数字或子母，若是则加1后输出        c = getc();        if (isDigit(c) || isLetter(c))            putc(c+1);    }    return 0;}

@******************************************************************************@ File：head.S@ 功能：设置SDRAM，将程序复制到SDRAM，然后跳到SDRAM继续执行@******************************************************************************          .extern     main.text .global _start _start:Reset:                      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是位置无关码，相当于：PCnew = PC + 偏移                            @                      PCnew = (4+8) + 0x28 = 0x34        ldr pc, =disable_watch_dog        bl  clock_init          @ 设置MPLL，改变FCLK、HCLK、PCLK    bl  memsetup            @ 设置存储控制器以使用SDRAM    bl  copy_steppingstone_to_sdram     @ 复制代码到SDRAM中    ldr pc, =on_sdram                   @ 跳到SDRAM中继续执行on_sdram:    ldr sp, =0x34000000     @ 设置栈指针,SDRAM 64M    ldr lr, =halt_loop      @ 设置返回地址    ldr pc, =main           @ 调用main函数halt_loop:    b   halt_loop

SECTIONS {    . = 0x30000000;    .text          :   { *(.text) }    .rodata ALIGN(4) : {*(.rodata)}     .data ALIGN(4) : { *(.data) }    .bss ALIGN(4)  : { *(.bss)  *(COMMON) }}

objs := head.o init.o serial.o main.ouart.bin: $(objs)    arm-linux-ld -Tuart.lds -o uart_elf $^    arm-linux-objcopy -O binary -S uart_elf $@    arm-linux-objdump -D -m arm uart_elf > uart.dis    %.o:%.c    arm-linux-gcc -Wall -O2 -c -o $@ $<%.o:%.S    arm-linux-gcc -Wall -O2 -c -o $@ $<clean:    rm -f uart.bin uart_elf uart.dis *.o