Tiny4412中断介绍

　　通过几天裸板驱动开发，今天对ARM的中断做一些简单总结，前面我们已经了解了ARM的7种异常模式，中断是异常模式的一种，在ARM中异常事件发生将会触发中断，但是，所有的中断都不能直接访问cpu，而是都统一由GIC（中断管理器）来管理；下面是samsung提供的模式图：

其中GIC管理的中断有分为：

　

　　（1）SGI：一个cpu中断另一个cpu（cpu0 ->cpu1）

　　（2）PPI：一个中断只能中断一个cpu

　　（3）SPI：一个中断可以中断多个cpu

　　处理一个中断大致需要三步：

　　（1）cpu permit interrupt （cpu允许中断）

　　（2）GIC enable （启用GIC）

　　（3）SET Interrupt source （设置中断源）

　　下面是用SGI实现的一个程序：

　　头文件：

#ifndef __BUNFLY_H
#define __BUNFLY_H

#define ICCICR_CPU0    (*(volatile unsigned long *)0x10480000)
#define ICCPMR_CPU0    (*(volatile unsigned long *)0x10480004)
#define ICDDCR        (*(volatile unsigned long *)0x10490000)
#define ICDIPR2_CPU0    (*(volatile unsigned long *)0x10490408)
#define ICDIPTR2_CPU0    (*(volatile unsigned long *)0x10490808)
#define ICDISER0_CPU0    (*(volatile unsigned long *)0x10490100)
#define ICDSGIR        (*(volatile unsigned long *)0x10490f00)
#define ICCEOIR_CPU0 (*(volatile unsigned long *)0x10480010)
#define ICCIAR_CPU0  (*(volatile unsigned long *)0x1048000c)

#endif    //__BUNFLY_H

#include "bunfly.h"

int (*printf)(char *, ...) = 0xc3e114d8;
void enable_mmu();
void init_table(unsigned long *addr);
void memcpy(unsigned char *dest, unsigned char *src, int len);
extern unsigned long  vector_start;
void do_irq();

int main()
{    
    memcpy(0x70000000, vector_start, 0x1000);    
    enable_mmu();

    *(unsigned long *)0x47000000 = do_irq;

    //step 1: set cpu permit interrupt
    __asm__ __volatile__(
        "mrs r0, cpsr
"
        "bic r0,r0, #0x80
"
        "msr cpsr, r0
"
        :::"r0"
    );

    //step 2: set GIC (cgi) enable
    ICCICR_CPU0 = 1;//cpu接口控制寄存器（总开关）
    ICCPMR_CPU0 =0xff;//中断总优先级（门槛）
    ICDDCR = 1;//本中断开关
    ICDIPR2_CPU0 = (3 << 9);//本中断优先级
    ICDIPTR2_CPU0 = (1 << 9);//目标cpu
    ICDISER0_CPU0 = (1 << 9);//启用本中断
    
    //step 3: set interrupt source
    ICDSGIR = 9 | (1 << 16);
        
    printf("welcom back
");
}

void do_irq()
{
    unsigned long ack_id = 0;
    unsigned long cpu_id = 0;
    unsigned long data = ICCIAR_CPU0;

    /*clean interrupt*/
    ack_id = data & 0x3ff;
    cpu_id = data & (0x7 << 10);
    ICCEOIR_CPU0 = ack_id | cpu_id;

    printf("this is interrupt
");
    printf("cup_id is %d
", cpu_id >> 10);
    printf("ack_id is %d
", ack_id);

}

void memcpy(unsigned char *dest, unsigned char *src, int len)
{
    int i = 0;
    for(i = 0; i < len; i++) {
        dest[i] = src[i];
    }
}

void enable_mmu()
{
    /*构建表*/
    unsigned long addr = 0x50000000;
    init_table(addr);
    /*打开mmu*/
    unsigned long mmu = 0;
    mmu = 1 | (1 << 1) | (1 << 3) | (1 << 8);
    __asm__ __volatile__ (
        "mov r0, #3
"
        "MCR p15, 0, r0, c3, c0, 0
"//设置为管理员
        "MCR p15, 0, %0, c2, c0, 0
"//设置表的地址
        "MCR p15, 0, %1, c1, c0, 0
"//开启mmu
        :    
        :    "r" (addr), "r" (mmu)
        :
    );

}

__asm__(

"vector: 
"
"    b reset
"
"    b und
"
"    b swi
"
"    b pre_abt
"
"    b data_abt
"
"    .word 0x0
"
"    b irq
"
"    b fiq
"
"reset:
"
"und:
"
"    mov sp, #0x47000000
"
"    stmdb sp!, {r0-r12, lr}
"

"    ldr r3, =0x47000004
"
"    ldr r2, [r3]
"
"    blx r2
"

"    mov sp, #0x47000000
"
"    ldmdb sp, {r0-r12, pc}^    
"

"swi:
"
"    mov sp, #0x47000000
"
"    stmdb sp!, {r0-r12, lr}^
"

"    mov sp, #0x47000000
"
"    ldmdb sp, {r0-r12, pc}^    
"

"pre_abt:
"

"data_abt:
"
"    mov sp, #0x47000000
"
"    sub lr, lr, #4
"
"    stmdb sp!, {r0-r12, lr}
"

"    ldr r3, =0x47000008
"
"    ldr r2, [r3]
"
"    blx r2
"

"    mov sp, #0x47000000
"
"    ldmdb sp, {r0-r12, pc}^    
"
"irq:
"

"    mov sp, #0x47000000
"
"    sub lr, lr, #4
"
"    stmdb sp!, {r0-r12, lr}
"

"    ldr r3, =0x47000000
"
"    ldr r2, [r3]
"
"    blx r2
"

"    mov sp, #0x47000000
"
"    ldmdb sp, {r0-r12, pc}^    
"

"fiq:
"

    ".global vector_start
"
"vector_start: 
"
    ".word vector 
 "

);

void init_table(unsigned long *addr)
{
    unsigned long va = 0;
    unsigned long phys = 0;

    //0x40000000-0x80000000 -> 0x40000000-0x80000000    
    for(va = 0x40000000; va < 0x80000000; va += 0x100000) {
        phys = va;
        addr[va >> 20] = phys | 2;
    }

    //0x10000000-0x14000000 -> 0x10000000-0x140000000    
    for(va = 0x10000000; va < 0x14000000; va += 0x100000) {
        phys = va;
        addr[va >> 20] = phys | 2;
    }
    //0x10000000-0x14000000 -> 0x10000000-0x140000000    
    for(va = 0x0; va < 0x10000000; va += 0x100000) {
        phys = va + 0x70000000;
        addr[va >> 20] = phys | 2;
    }
            
}

 运行结果如下：