ARM中的中斷
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其中，中斷分為?
Supports three interrupt types:
Private Peripheral Interrupt (PPI）一個中斷源對應一個CPU
Software Generated Interrupt (SGI) CPU對應CPU
Shared Peripheral Interrupt (SPI) 一個中斷源對應多個CPU
今天的例子是用SGI中斷來實現的，在處理中斷的時候，主要分三步：
//step 1: cpu cpsr
CPU允許中斷
20 __asm__ __volatile__(
21 "mrs r0, cpsrn"
22 "bic r0, r0, #0x80n"http://設置CPSR的I位，將IRQ位打開
23 "msr cpsr, r0n"
24 ::: "r0"
25 );
26
27//step 2: GIC
GIC
28 ICCICR_CPU0 = 1;//CPU接口控制寄存器
29 ICCPMR_CPU0 = 0xff;//中斷優先標志寄存器
30 ICDDCR = 1;//設置本中斷的開關
31 ICDIPR0_CPU0 = (0x00 << 0);//本中斷的優先級
32 ICDIPTR0_CPU0 = 1;//選擇指定的CPU
33 ICDISER0_CPU0 = (1 << 0);//設置本中斷開啟
34 各個寄存器描述如下：詳細見4412 782頁
35//step 3: interrupt source
中斷源
36 ICDSGIR = 0 (1 << 16) (0 << 24);//SGI控制寄存器CPUTargetList.TargetListFi lte
37 printf("welcome back! n");
下面是代碼：
1 #include"regs.h"2 3 int (*printf)(char *, ...) = 0xc3e114d8;4 5 void init_ttb(unsigned long *addr);6 void enable_mmu(void);7 unsigned long data_abort_init();8 void memcopy(unsigned long* dest,unsigned long* source,int len);9 void do_irq();10 11 int main()12 {13 *(unsigned long *)0x66 = do_irq;14 unsigned long source_addr=data_abort_init();15 printf("swi_souce addr is %xn",source_addr);16 memcopy(0x60,source_addr,0x1);17 enable_mmu();18 19 //step 1: cpu cpsr20 __asm__ __volatile__(21 "mrs r0, cpsrn"22 "bic r0, r0, #0x80n"http://設置CPSR的I位，將IRQ位打開23 "msr cpsr, r0n"24 ::: "r0"25 );26 27 //step 2: GIC 28 ICCICR_CPU0 = 1;//CPU接口控制寄存器29 ICCPMR_CPU0 = 0xff;//中斷優先標志寄存器30 ICDDCR = 1;//設置本中斷的開關31 ICDIPR0_CPU0 = (0x00 << 0);//本中斷的優先級32 ICDIPTR0_CPU0 = 1;//選擇指定的CPU33 ICDISER0_CPU0 = (1 << 0);//設置本中斷開啟34 35 //step 3: interrupt source36 ICDSGIR = 0 (1 << 16) (0 << 24);//SGI控制寄存器CPUTargetList.TargetListFi lte37 printf("welcome back! n");38 }39 40 void do_irq()41 {42 unsigned long data = ICCIAR_CPU0;43 unsigned long irq_id = data & 0x3ff;44 unsigned long cpu_id = (data >> 10) & 0x7;45 ICCEOIR_CPU0 = irq_id (cpu_id << 10);46 printf("irq is %d, cpu is %dn", irq_id, cpu_id);47 }48 49 void memcopy(unsigned long* dest, unsigned long* source,int len)50 {51 int i=0;;52 for(i=0;i> 20] = pa 2;154 //2的目的是將0-2位置為10此時將是小頁模式4K155 }156 157 //00-10 ==== 6070158 for(va=0x00; va<=0x10; va+=0x100){159 pa = va+0x60;160 addr[va >> 20] = pa 2;161 }162 163 //10-14 ==== 1014164 for(va=0x10; va<=0x14; va+=0x100){165 pa = va;166 addr[va >> 20] = pa 2;167 }168 169 //30-40 ==== 5060170 for(va=0x30; va<0x40; va+=0x100){171 pa = va + 0x20;172 addr[va >> 20] = pa 2;173 }174 }175 176 void enable_mmu(void)177 178 {179 unsigned long addr = 0x70;180 init_ttb(addr);181 //step:初始化頁表182 183 unsigned long mmu = 1 (1 << 1) (1 << 8);184 //將MMU的第0,1,8位置1185 __asm__ __volatile__(186 "mov r0, #3n"187 "MCR p15, 0, r0, c3, c0, 0n"http://manager188 "MCR p15, 0, %0, c2, c0, 0n"http://addr 189 "MCR p15, 0, %1, c1, c0, 0n"http:// enable mmu190 :191 : "r" (addr), "r" (mmu)192 : "r0"193 );194 printf("MMU is enable!n");195 }196 在代碼中，主函數其他的部分在前面都已經說了，已不再說。主要是在VICTOR函數中，將處理中斷的部分，做成了一個函數，以后更容易修改處理的部分。
void do_irq()
41 {
42 unsigned long data = ICCIAR_CPU0;//取出IRQ ID 和CPU ID
43 unsigned long irq_id = data & 0x3ff;
44 unsigned long cpu_id = (data >> 10) & 0x7;
45 ICCEOIR_CPU0 = irq_id (cpu_id << 10);//清除CPU
46 printf("irq is %d, cpu is %dn", irq_id, cpu_id);
47 }
//總的來說，在以前的基礎上面，今天主要認識了GIC的配置，更重要的是，中斷分為四步：
1，CPU開
2，GIC配置
3，中斷源
4，處理中斷，清中斷
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