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\n"
         "bic r0,r0, #0x80\n"
         "msr cpsr, r0\n"
         :::"r0"
     );

     //step 2: set GIC (cgi) enable
     ICCICR_CPU0 = ;//cpu接口控制寄存器（总开关）
     ICCPMR_CPU0 =0xff;//中断总优先级（门槛）
     ICDDCR = ;//本中断开关
     ICDIPR2_CPU0 = ( << );//本中断优先级
     ICDIPTR2_CPU0 = ( << );//目标cpu
     ICDISER0_CPU0 = ( << );//启用本中断

     //step 3: set interrupt source
     ICDSGIR =  | ( << );

     printf("welcom back\n");
 }

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

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

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

 }

 void memcpy(unsigned char *dest, unsigned char *src, int len)
 {
     int i = ;
     for(i = ; 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 = ;
     mmu =  | ( << ) | ( << ) | ( << );
     __asm__ __volatile__ (
         "mov r0, #3\n"
         "MCR p15, 0, r0, c3, c0, 0\n"//设置为管理员
         "MCR p15, 0, %0, c2, c0, 0\n"//设置表的地址
         "MCR p15, 0, %1, c1, c0, 0\n"//开启mmu
         :
         :    "r" (addr), "r" (mmu)
         :
     );

 }

 __asm__(

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

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

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

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

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

 "pre_abt:\n"

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

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

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

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

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

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

 "fiq:\n"

     ".global vector_start\n"
 "vector_start: \n"
     ".word vector \n "

 );

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

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

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

 }

运行结果如下：