// s3c24xx.h // 2015.11.9 /* 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)
@****************************************************************************** @ head.S @ 设置SDRAM，将程序复制到SDRAM，然后跳到SDRAM继续执行 @ 2015.11.9 @****************************************************************************** .extern main .text .global _start _start: Reset: ldr sp, =4096 bl disable_watch_dog bl clock_init @ 设置MPLL，改变FCLK、HCLK、PCLK bl memsetup bl copy_steppingstone_to_sdram ldr pc, =on_sdram on_sdram: ldr sp, =0x34000000 ldr lr, =halt_loop @ 设置返回地址，c程序执行完后pc指针会指向lr中的地址 ldr pc, =main halt_loop: b halt_loop
// init.c // 2015.11.9 #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) * S3C2410: 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 " /* 读出控制寄存器 */ "orr r1, r1, #0xc0000000 " /* 设置为“asynchronous bus mode” */ "mcr p15, 0, r1, c1, c0, 0 " /* 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 = (unsigned int *)0; unsigned int *pdwDest = (unsigned int *)0x30000000; while (pdwSrc < (unsigned int *)4096) { *pdwDest = *pdwSrc; pdwDest++; pdwSrc++; } }
// serial.c // 2015.11.9 #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) // 115200,8N1,无流控 void uart0_init(void) { GPHCON |= 0xa0; // GPH2,GPH3用作TXD0,RXD0，分别在位[5:4]，[7:6]，设为10使用该功能 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; // 接收模式选择查询方式，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 } void putc(unsigned char c) { // 不断查询UTRSTAT0寄存器的位[2]，为1表示发送完毕 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; } unsigned char getc(void) { // 不断查询UTRSTAT0寄存器的位[1]，为1表示接收缓冲区有数据 while (!(UTRSTAT0 & RXD0READY)); // 直接读取URXH0寄存器，即可获得接收到的数据 return URXH0; } int isDigit(unsigned char c) { if (c >= '0' && c <= '9') return 1; else return 0; } int isLetter(unsigned char c) { if (c >= 'a' && c <= 'z') return 1; else if (c >= 'A' && c <= 'Z') return 1; else return 0; }
// serial.h // 2015.11.9 void uart0_init(void); void putc(unsigned char c); unsigned char getc(void); int isDigit(unsigned char c); int isLetter(unsigned char c);
// main.c // 2015.11.9 #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; }
/* uart.lds*/ SECTIONS { . = 0x30000000; .text : { *(.text) } /*所有文件的代码段链接成一个.text的代码段*/ .rodata ALIGN(4) : {*(.rodata)} .data ALIGN(4) : { *(.data) } .bss ALIGN(4) : { *(.bss) *(COMMON) } } /*.bss段，链接完后，占用的内存释放，不同于.data段一直占有内存。 .bss这个节包含程序还未初始化的数据，当操作系统装入这个程序时将把这些变量都置为0。 使用.bss比使用.data的优势在于，bss节在编译后不占用磁盘的空间，这样编译、连接生成的代码的尺寸会比较小。 */
objs := head.o init.o serial.o main.o uart.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