一、
@****************************************************************************** @ File：head.S @ 功能：初始化，设置中断模式、系统模式的栈，设置好中断处理函数 @****************************************************************************** .extern main .text .global _start _start: @****************************************************************************** @ 中断向量，本程序中，除Reset和HandleIRQ外，其它异常都没有使用 @****************************************************************************** b Reset @ 0x04: 未定义指令中止模式的向量地址 HandleUndef: b HandleUndef @ 0x08: 管理模式的向量地址，通过SWI指令进入此模式 HandleSWI: b HandleSWI @ 0x0c: 指令预取终止导致的异常的向量地址 HandlePrefetchAbort: b HandlePrefetchAbort @ 0x10: 数据访问终止导致的异常的向量地址 HandleDataAbort: b HandleDataAbort @ 0x14: 保留 HandleNotUsed: b HandleNotUsed @ 0x18: 中断模式的向量地址 b HandleIRQ @ 0x1c: 快中断模式的向量地址 HandleFIQ: b HandleFIQ 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 clock_init @ 设置MPLL，改变FCLK、HCLK、PCLK，设置时钟。 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: msr cpsr_c, #0xd2 @ 进入中断模式 ldr sp, =4096 @ 设置中断模式栈指针 msr cpsr_c, #0xdf @ 进入系统模式 ldr sp, =0x34000000 @ 设置系统模式栈指针， bl init_led @ 初始化LED的GPIO管脚 bl timer0_init @ 初始化定时器0 bl init_irq @ 调用中断初始化函数，在init.c中 msr cpsr_c, #0x5f @ 设置I-bit=0，开IRQ中断 ldr lr, =halt_loop @ 设置返回地址 ldr pc, =main @ 调用main函数 halt_loop: b halt_loop HandleIRQ: sub lr, lr, #4 @ 计算返回地址 stmdb sp!, { r0-r12,lr } @ 保存使用到的寄存器 @ 注意，此时的sp是中断模式的sp @ 初始值是上面设置的4096 ldr lr, =int_return @ 设置调用ISR即EINT_Handle函数后的返回地址 ldr pc, =Timer0_Handle @ 调用中断服务函数，在interrupt.c中 int_return: ldmia sp!, { r0-r12,pc }^ @ 中断返回, ^表示将spsr的值复制到cpsr
二、
1 /* 2 * init.c: 进行一些初始化 3 */ 4 5 #include "s3c24xx.h" 6 7 void disable_watch_dog(void); 8 void clock_init(void); 9 void memsetup(void); 10 void copy_steppingstone_to_sdram(void); 11 void init_led(void); 12 void timer0_init(void); 13 void init_irq(void); 14 15 /* 16 * 关闭WATCHDOG，否则CPU会不断重启 17 */ 18 void disable_watch_dog(void) 19 { 20 WTCON = 0; // 关闭WATCHDOG很简单，往这个寄存器写0即可 21 } 22 23 24 25 //设置MPLL 26 #define S3C2410_MPLL_200MHZ ((0x5c<<12)|(0x04<<4)|(0x00)) 27 #define S3C2440_MPLL_200MHZ ((0x5c<<12)|(0x01<<4)|(0x02)) //MDIV[19:12]=1011100=92,PDIV[9:4]=100=4,SDIV[1:0]=00=0 28 /* 29 * 对于MPLLCON寄存器，[19:12]为MDIV，[9:4]为PDIV，[1:0]为SDIV 30 * 有如下计算公式： 31 * S3C2410: MPLL(FCLK) = (m * Fin)/(p * 2^s) 32 * S3C2410: MPLL(FCLK) = (2 * m * Fin)/(p * 2^s) 33 * 其中: m = MDIV + 8, p = PDIV + 2, s = SDIV 34 * 对于本开发板，Fin = 12MHz 35 * 设置CLKDIVN，令分频比为：FCLK:HCLK:PCLK=1:2:4， 36 * FCLK=200MHz,HCLK=100MHz,PCLK=50MHz 37 */ 38 39 40 //设置分频 41 void clock_init(void) 42 { 43 // LOCKTIME = 0x00ffffff; // 使用默认值即可,设置MPLL寄存器后，等待时间LOCKTIME默认，MPLL输出稳定 44 CLKDIVN = 0x03; // FCLK:HCLK:PCLK=1:2:4, HDIVN=1,PDIVN=1；时钟分频控制寄存器CLKDIVN，设置分频 45 46 /* 如果HDIVN非0，CPU的总线模式应该从“fast bus mode”变为“asynchronous bus mode” */ 47 __asm__( 48 "mrc p15, 0, r1, c1, c0, 0\n" /* 读出控制寄存器 */ 49 "orr r1, r1, #0xc0000000\n" /* 设置为“asynchronous bus mode” */ 50 "mcr p15, 0, r1, c1, c0, 0\n" /* 写入控制寄存器 */ 51 ); 52 53 /* 判断是S3C2410还是S3C2440 */ 54 if ((GSTATUS1 == 0x32410000) || (GSTATUS1 == 0x32410002)) 55 { 56 MPLLCON = S3C2410_MPLL_200MHZ; /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */ 57 } 58 else 59 { 60 MPLLCON = S3C2440_MPLL_200MHZ; /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */ 61 } 62 } 63 64 65 66 /* 67 * 设置存储控制器以使用SDRAM 68 */ 69 void memsetup(void) 70 { 71 volatile unsigned long *p = (volatile unsigned long *)MEM_CTL_BASE; 72 73 /* 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 74 * 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 75 * SDRAM之前就可以在steppingstone中运行 76 */ 77 /* 存储控制器13个寄存器的值 */ 78 p[0] = 0x22011110; //BWSCON 79 p[1] = 0x00000700; //BANKCON0 80 p[2] = 0x00000700; //BANKCON1 81 p[3] = 0x00000700; //BANKCON2 82 p[4] = 0x00000700; //BANKCON3 83 p[5] = 0x00000700; //BANKCON4 84 p[6] = 0x00000700; //BANKCON5 85 p[7] = 0x00018005; //BANKCON6 86 p[8] = 0x00018005; //BANKCON7 87 88 /* REFRESH, 89 * HCLK=12MHz: 0x008C07A3, 90 * HCLK=100MHz: 0x008C04F4 91 */ 92 p[9] = 0x008C04F4; 93 p[10] = 0x000000B1; //BANKSIZE 94 p[11] = 0x00000030; //MRSRB6 95 p[12] = 0x00000030; //MRSRB7 96 } 97 98 99 100 101 //复制代码到SDRAM 102 void copy_steppingstone_to_sdram(void) 103 { 104 unsigned int *pdwSrc = (unsigned int *)0; 105 unsigned int *pdwDest = (unsigned int *)0x30000000; 106 107 while (pdwSrc < (unsigned int *)4096) 108 { 109 *pdwDest = *pdwSrc; 110 pdwDest++; 111 pdwSrc++; 112 } 113 } 114 115 116 117 118 119 120 /* 121 * LED1-4对应GPB5、GPB6、GPB7、GPB8 122 * 配置引脚为输出 123 */ 124 #define GPB5_out (1<<(5*2)) // LED1 125 #define GPB6_out (1<<(6*2)) // LED2 126 #define GPB7_out (1<<(7*2)) // LED3 127 #define GPB8_out (1<<(8*2)) // LED4 128 129 /* 130 * K1-K4对应GPG11、GPG3、GPF2、GPF3 131 */ 132 #define GPG11_eint (2<<(11*2)) // K1,EINT19 133 #define GPG3_eint (2<<(3*2)) // K2,EINT11 134 #define GPF3_eint (2<<(3*2)) // K3,EINT3 135 #define GPF2_eint (2<<(2*2)) // K4,EINT2 136 137 void init_led(void) 138 { 139 GPBCON = GPB5_out | GPB6_out | GPB7_out | GPB8_out ; 140 } 141 142 143 144 145 146 // 用定时器0设置0.5s产生一次中断 147 /* 148 * Timer input clock Frequency = PCLK / {prescaler value+1} / {divider value} 149 * {prescaler value} = 0~255 150 * {divider value} = 2, 4, 8, 16 151 * 本实验的Timer0的时钟频率=100MHz/(99+1)/(16)=62500Hz 152 * 设置Timer0 0.5秒钟触发一次中断： 153 */ 154 void timer0_init(void) 155 { 156 TCFG0 = 99; // 预分频器0 = 99 157 TCFG1 = 0x03; // 选择16分频 158 TCNTB0 = 31250; // 0.5秒钟触发一次中断 159 TCON |= (1<<1); // 手动更新 160 TCON = 0x09; // 自动加载，清“手动更新”位，启动定时器0 161 } 162 163 /* 164 * 定时器0中断使能，中断屏蔽寄存器屏蔽位设置为0，使能 165 */ 166 void init_irq(void) 167 { 168 // 定时器0中断使能 169 INTMSK &= (~(1<<10)); 170 }
三、
1 #include "s3c24xx.h" 2 3 4 5 //发生中断时，处理的函数 6 void Timer0_Handle(void) 7 { 8 /* 9 * 每次中断令4个LED改变状态 10 */ 11 if(INTOFFSET == 10) 12 { 13 GPBDAT = ~(GPBDAT & (0xf << 5)); 14 } 15 //清中断 16 SRCPND = 1 << INTOFFSET; 17 INTPND = INTPND; 18 }
四、
1 void EINT_Handle();
五、
1 int main(void) 2 { 3 while(1); 4 return 0; 5 }
六、
1 objs := head.o init.o interrupt.o main.o 2 3 timer.bin: $(objs) 4 arm-linux-ld -Ttimer.lds -o timer_elf $^ 5 arm-linux-objcopy -O binary -S timer_elf $@ 6 arm-linux-objdump -D -m arm timer_elf > timer.dis 7 8 %.o:%.c 9 arm-linux-gcc -Wall -O2 -c -o $@ $< 10 11 %.o:%.S 12 arm-linux-gcc -Wall -O2 -c -o $@ $< 13 14 clean: 15 rm -f timer.bin timer_elf timer.dis *.o 16
七、
1 /*连接函数*/ 2 3 SECTIONS { 4 . = 0x30000000; 5 .text : { *(.text) } 6 .rodata ALIGN(4) : {*(.rodata)} 7 .data ALIGN(4) : { *(.data) } 8 .bss ALIGN(4) : { *(.bss) *(COMMON) } 9 }
八、
1 /* WOTCH DOG register */ 2 #define WTCON (*(volatile unsigned long *)0x53000000) 3 4 /* SDRAM regisers */ 5 #define MEM_CTL_BASE 0x48000000 6 #define SDRAM_BASE 0x30000000 7 8 /* NAND Flash registers */ 9 #define NFCONF (*(volatile unsigned int *)0x4e000000) 10 #define NFCMD (*(volatile unsigned char *)0x4e000004) 11 #define NFADDR (*(volatile unsigned char *)0x4e000008) 12 #define NFDATA (*(volatile unsigned char *)0x4e00000c) 13 #define NFSTAT (*(volatile unsigned char *)0x4e000010) 14 15 /*GPIO registers*/ 16 #define GPBCON (*(volatile unsigned long *)0x56000010) 17 #define GPBDAT (*(volatile unsigned long *)0x56000014) 18 19 #define GPFCON (*(volatile unsigned long *)0x56000050) 20 #define GPFDAT (*(volatile unsigned long *)0x56000054) 21 #define GPFUP (*(volatile unsigned long *)0x56000058) 22 23 #define GPGCON (*(volatile unsigned long *)0x56000060) 24 #define GPGDAT (*(volatile unsigned long *)0x56000064) 25 #define GPGUP (*(volatile unsigned long *)0x56000068) 26 27 #define GPHCON (*(volatile unsigned long *)0x56000070) 28 #define GPHDAT (*(volatile unsigned long *)0x56000074) 29 #define GPHUP (*(volatile unsigned long *)0x56000078) 30 31 32 33 /*UART registers*/ 34 #define ULCON0 (*(volatile unsigned long *)0x50000000) 35 #define UCON0 (*(volatile unsigned long *)0x50000004) 36 #define UFCON0 (*(volatile unsigned long *)0x50000008) 37 #define UMCON0 (*(volatile unsigned long *)0x5000000c) 38 #define UTRSTAT0 (*(volatile unsigned long *)0x50000010) 39 #define UTXH0 (*(volatile unsigned char *)0x50000020) 40 #define URXH0 (*(volatile unsigned char *)0x50000024) 41 #define UBRDIV0 (*(volatile unsigned long *)0x50000028) 42 43 44 /*interrupt registes*/ 45 #define SRCPND (*(volatile unsigned long *)0x4A000000) 46 #define INTMOD (*(volatile unsigned long *)0x4A000004) 47 #define INTMSK (*(volatile unsigned long *)0x4A000008) 48 #define PRIORITY (*(volatile unsigned long *)0x4A00000c) 49 #define INTPND (*(volatile unsigned long *)0x4A000010) 50 #define INTOFFSET (*(volatile unsigned long *)0x4A000014) 51 #define SUBSRCPND (*(volatile unsigned long *)0x4A000018) 52 #define INTSUBMSK (*(volatile unsigned long *)0x4A00001c) 53 54 /*external interrupt registers*/ 55 #define EINTMASK (*(volatile unsigned long *)0x560000a4) 56 #define EINTPEND (*(volatile unsigned long *)0x560000a8) 57 58 /*clock registers*/ 59 #define LOCKTIME (*(volatile unsigned long *)0x4c000000) 60 #define MPLLCON (*(volatile unsigned long *)0x4c000004) 61 #define UPLLCON (*(volatile unsigned long *)0x4c000008) 62 #define CLKCON (*(volatile unsigned long *)0x4c00000c) 63 #define CLKSLOW (*(volatile unsigned long *)0x4c000010) 64 #define CLKDIVN (*(volatile unsigned long *)0x4c000014) 65 66 67 /*PWM & Timer registers*/ 68 #define TCFG0 (*(volatile unsigned long *)0x51000000) 69 #define TCFG1 (*(volatile unsigned long *)0x51000004) 70 #define TCON (*(volatile unsigned long *)0x51000008) 71 #define TCNTB0 (*(volatile unsigned long *)0x5100000c) 72 #define TCMPB0 (*(volatile unsigned long *)0x51000010) 73 #define TCNTO0 (*(volatile unsigned long *)0x51000014) 74 75 #define GSTATUS1 (*(volatile unsigned long *)0x560000B0)