【S5PV210_视频编解码项目】裸机开发：实现按键的外部中断处理

加粗样式本文所作内容：
基于S5PV210芯片实现按键的外部中断处理程序，搭建中断处理流程框架

S5PV210对于中断处理的操作流程

1 外部中断得到触发：

1）外部中断在初始化阶段得到使能
2）外界达到了外部中断的触发条件

2 跳转到向量表：

1）异常向量表在初始化阶段进行了配置ISR处理程序
2）ISR处理程序包含了保护现场和回复现场的功能
3）ISR处理程序能够跳转到中断总ISR_handel程序

3 跳转到对应中断号的中断处理程序

1）对应中断号的中断得到初始化使能
2）在ISR_handel中找到对应出现的中断号
3）在ISR_handel中跳转到对应该中断号的isr中

S5PV210实现外部中断处理的程序流

初始化阶段

1）首先初始化异常向量表：

 //初始化异常向量表r_exception_reset = (unsigned int)reset_exception;r_exception_undef = (unsigned int)undef_exception;r_exception_sotf_int = (unsigned int)sotf_int_exception;r_exception_prefetch = (unsigned int)prefetch_exception;r_exception_data = (unsigned int)data_exception;r_exception_irq = (unsigned int)IRQ_handle;r_exception_fiq = (unsigned int)IRQ_handle;

2）然后初始化芯片的中断系统：先全部中断号禁止中断，然后中断工作模式为IRQ，然后清除中断跳转寄存器

 //禁止所有中断VIC0INTENCLEAR = 0xFFFFFFFF;VIC1INTENCLEAR = 0xFFFFFFFF;VIC2INTENCLEAR = 0xFFFFFFFF;VIC3INTENCLEAR = 0xFFFFFFFF;//配置中断类型 (默认全部为IRQ工作模式)VIC0INTSELECT = 0x0;VIC1INTSELECT = 0x0;VIC2INTSELECT = 0x0;VIC3INTSELECT = 0x0;//清除中断跳转寄存器VIC0ADDR = 0;VIC1ADDR = 0;VIC2ADDR = 0;VIC3ADDR = 0;

3）设置想要调试的外部中断：设置对应GPIO的工作模式外外部中断模式，使能对应的外部中断，设置外部中断的触发方式

//配置IO引脚为外部中断工作模式rGPH0CON |= (0xFF<<8); rGPH2CON |= (0xFFFF<<0);//配置对应外部中断号下中断触发形式：下降沿触发rEXT_INT_0_CON &= ~(0xFF<<8);	rEXT_INT_0_CON |= ((2<<8)|(2<<12));		rEXT_INT_2_CON &= ~(0xFFFF<<0);rEXT_INT_2_CON |= ((2<<0)|(2<<4)|(2<<8)|(2<<12));	/*设置为0表示使能中断*/rEXT_INT_0_MASK &= ~(3<<2);	rEXT_INT_2_MASK &= ~(0x0f<<0);/*软件写1 表示清除flag*/rEXT_INT_0_PEND |= (3<<2);rEXT_INT_2_PEND |= (0x0F<<0);

实现中断处理流程

1）实现第一阶段的异常向量表跳转程序：汇编实现（保存现场-跳转IRQ处理程序-现场恢复）

IRQ_handle:// 设置IRQ模式下的栈指针ldr sp, =IRQ_STACK// 保存现场// 保存LR寄存器 lr寄存器先减去4（ARM的流水线机制）sub lr, lr, #4// 保存R0-R12寄存器stmfd sp!, {r0-r12, lr}// 跳转到真正的中断处理程序bl irq_handler// 回复现场ldmfd sp!, {r0-r12, pc}^

2）实现中断处理第二阶段：寻找中断编号，寻找中断编号对应的isr

/*1-根据状态寄存器 找到对应的中断控制器位置（VIC0/1/2/3）*/unsigned long vicaddr[4] = {VIC0ADDR,VIC1ADDR,VIC2ADDR,VIC3ADDR};void (*isr)(void) = NULL;unsigned int i = 0;for(i=0; i<3 ; i++){if(intc_getvicirqstatus(i)){/*2-根据中断控制器位置，跳转到对应中断控制器的vectaddr中拿到对应的中断isr*/isr = (void (*)(void)) vicaddr[i];break; }}(*isr)();

3）使能对应外部中断的中断编号，配置对应该中断编号的isr程序

//根据中断号 将对应的中断回调函数绑定在VECTADDR寄存器中
void intc_setvectaddr(unsigned long intnum, void (*handler)(void))
{if(intnum < 32){( *((volatile unsigned long *)(VIC0VECTADDR + 4*(intnum - 0))) ) = (unsigned)handler;}else if(intnum < 64){( *((volatile unsigned long *)(VIC0VECTADDR + 4*(intnum - 32))) ) = (unsigned)handler;}else if(intnum < 96){( *((volatile unsigned long *)(VIC0VECTADDR + 4*(intnum - 64))) ) = (unsigned)handler;}else if(intnum < 128){( *((volatile unsigned long *)(VIC0VECTADDR + 4*(intnum - 96))) ) = (unsigned)handler;}else{printf("ERR!:intc_setvectaddr err: intnum out of max of SOC\n");}return;
}

//根据中断号将对应中断使能
void intc_enable(unsigned long intnum)
{unsigned int sTemp = 0;if(intnum < 32){sTemp = VIC0INTENABLE;sTemp |= (1<<(intnum - 0));VIC0INTENABLE = sTemp;}else if(intnum < 64){sTemp = VIC1INTENABLE;sTemp |= (1<<(intnum - 32));VIC1INTENABLE = sTemp;}else if(intnum < 96){sTemp = VIC2INTENABLE;sTemp |= (1<<(intnum - 64));VIC2INTENABLE = sTemp;}else if(intnum < 128){sTemp = VIC3INTENABLE;sTemp |= (1<<(intnum - 96));VIC3INTENABLE = sTemp;}else{VIC0INTENABLE = 0xFFFFFFFF;VIC1INTENABLE = 0xFFFFFFFF;VIC2INTENABLE = 0xFFFFFFFF;VIC3INTENABLE = 0xFFFFFFFF;printf("ERR!:intc_enable err: intnum out of max of SOC\n");}
}