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：

巴特西

Tiny4412中断介绍

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