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在最近的工程中，需要用到PS/2键盘和鼠标作为控制输入，所以在网上找了一些相关的资料，内容很丰富，看来已经有很多人做过了这方面的编程。本篇Blog算是实践总结，为以后的开发积累一些基础知识。

MicroBlaze支持重启（reset）,中断（ interrupt）, 暂停（break）和异常（ exception）。这里粗略的介绍：

• reset
  当 外部按键发出reset信号或者XMD通过MDM（MicroBlaze Debug module）发出reset信号，这些信号都会被proc_sys_reset模块接收，然后该模块产生一个16周期长的高电平信号至 MicroBlaze的MB_RESET管脚。MicroBlaze响应reset, PC 寄存器指向0x0地址，依照向量表中代码执行。
• exception
  异常是MicroBlaze对内部运行发生错误的情况发做出的响应，这些情况包括：非法指令，指令和数据总线错误和未对齐的访问(unaligned access)。如除0操作，非法操作码异常，数据总线异常等。
• break
  break 分为software break和hardware break。hardware break，这时MDM模块的输出端口Ext_BRK和Ext_NM_BRK跟MicroBlaze对应的输入端口相连。一旦break响应，暂停返回地 址（break return address）自动装入R16寄存器中。而software break通过brk和brki指令来完成。
• interrupt
  MicroBlaze 只支持一个外部中断源（连接于Interrupt 端口），所以需要多个中断输入的话，就得添加中断控制器(xps_intc)了。只有当机器状态寄存器(Machine Status Register,MSR)中的中断使能位（interrupt enable）置'1'，MicroBlaze才能响应中断。MicroBlaze响应中断，PC指向中断向量(地址：0x10)，R14存储了中断返回 地址。

注：具体细节问题，请见参考1。

注：该表格来自于MicroBlaze参考手册，见参考1

下面具体介绍如何对MicroBlaze进行中断编程。

1. 中断信号的物理连接
   system.mhs文件定义了物理硬件的相关信息，包括总线架构、外围设备、处理器、系统内部信号互连和地址空间等。所以这里就通过MHS定义文件给出关于中断信号互连的信息。
   当然MicroBlaze的中断输入，可以配置成电平触发或者边沿触发，在配置MicroBlaze的GUI或者在MicroBlaze.mpd中通过设置 C_INTERRUPT_IS_EDGE ，C_EDGE_IS_POSITIVE来完成对中断的触发的配置。

   BEGIN microblaze   . . .    PORT MB_RESET = mb_reset  PORT Interrupt = Interrupt END BEGIN xps_uartlite . . .    PORT Interrupt = RS232_Uart_1_Interrupt END BEGIN xps_intc . . .  PORT Irq = Interrupt  PORT Intr = RS232_Uart_1_Interrupt&plb_ps2_controller_0_IP2INTC_Irpt END BEGIN plb_ps2_controller . . .  PORT IP2INTC_Irpt = plb_ps2_controller_0_IP2INTC_Irpt PORT mouse_clk = plb_ps2_controller_0_mouse_clk PORT mouse_data = plb_ps2_controller_0_mouse_data PORT key_clk = plb_ps2_controller_0_key_clk PORT key_data = plb_ps2_controller_0_key_data END

   
   
2. EDK提供的驱动以及相关函数的介绍
   
   

   void microblaze_enable_interrupts(void) 该函数使MicroBlaze可以响应中断，即MSR中的“interrupt enable”位置’1’; void microblaze_disable_interrupts(void) 该函数使MicroBlaze不能响应中断，即MSR中的“interrupt enable”位置 ’0’; 这几个函数都定义包含在$EDK_project/microblaze_0/include/mb_interface.h 头文件中

   
   

   XIntc_Initialize(&InterruptController, (Xuint16)INTC_DEVICE_ID); 该函数用于初始化中断控制器，主要包括初始化XIntc的结构体，初始化向量列表，以及所有中断源输入禁用，中断输出禁用。 int XIntc_Connect(XIntc * InstancePtr, u8 Id,     XInterruptHandler Handler, void *CallBackRef) 中断源的标示和相关中断处理程序的连接。 XIntc_Start(XIntcInstancePtr, XIN_REAL_MODE); 该函数使得中断控制器输出的中断信号启用。XIN_REAL_MODE 意思是只允许硬件中断(hardware interrupt) void XIntc_Enable(XIntc * InstancePtr, u8 Id) 该函数使得对应ID的中断源输入启用 这几个函数定义在$EDK_project/microblaze_0/libsrc/intc_v1_11_a/src/xintc.c 需要包含的头文件：xintc.h

3. C语言编程实例
   

   /* *Date      2010-12-27 *author    Qi Yao *decription main function code for interrupt program *           such as timer or keyboard and mouse interrupt. */ /* FPGA includes */ #include      /* for printf */ #include     /* for usleep */ #include "xparameters.h" #include "xutil.h" #include "xintc.h" #include "plb_ps2_controller.h" #include "mb_interface.h" #define INTC_DEVICE_ID XPAR_INTC_0_DEVICE_ID int init_input(void); XStatus SetUpInterruptSystem(XIntc *XIntcInstancePtr); static XIntc InterruptController;/*Instance of the Interrupt Control*/ /** * Input interrupt handler */ void PS2_InterruptHandler(void *CallbackRef) {     u32 mouse_state, keybd_state, flags;     Xuint32 baseaddr = (Xuint32) XPAR_PLB_PS2_CONTROLLER_0_BASEADDR;     /* read information from device registers */     keybd_state = ((u32 *)baseaddr)[0];     mouse_state = ((u32 *)baseaddr)[1];     flags       = PLB_PS2_CONTROLLER_mReadReg(baseaddr, PLB_PS2_CONTROLLER_INTR_IPISR_OFFSET);     if (flags & EVENT_FROM_MOUSE)         /*mouse event handler*/         handle_mouse_event(mouse_state);     if (flags & EVENT_FROM_KEYBD)         /*keyboard event handler*/         handle_keybd_event(keybd_state);     /* clear interrupt flags in PS/2 controller */     PLB_PS2_CONTROLLER_mWriteReg(baseaddr, PLB_PS2_CONTROLLER_INTR_IPISR_OFFSET, flags); } XStatus init_input(void) {     XStatus Status;     Xuint32 baseaddr = (Xuint32) XPAR_PLB_PS2_CONTROLLER_0_BASEADDR;     /* initialize PS/2 interrupts */     PLB_PS2_CONTROLLER_mWriteReg(baseaddr, PLB_PS2_CONTROLLER_INTR_DIER_OFFSET, 0);     PLB_PS2_CONTROLLER_mWriteReg(baseaddr, PLB_PS2_CONTROLLER_INTR_DGIER_OFFSET, 0xFFFFFFFF);     PLB_PS2_CONTROLLER_mWriteReg(baseaddr, PLB_PS2_CONTROLLER_INTR_IPIER_OFFSET, 0xFFFFFFFF);     PLB_PS2_CONTROLLER_mWriteReg(baseaddr, PLB_PS2_CONTROLLER_INTR_IPISR_OFFSET, 0);     /* initialize Interrupt controller */     Status = XIntc_Initialize(&InterruptController, (Xuint16)INTC_DEVICE_ID);     if (Status != XST_SUCCESS)     {        return XST_FAILURE;    }     Status = XIntc_SelfTest(&InterruptController);     if (Status != XST_SUCCESS)     {    return XST_FAILURE;    }     /*      * Connect a device driver handler that will be called when an interrupt      * for the device occurs, the device driver handler performs the specific      * interrupt processing for the device      */     Status = XIntc_Connect(XIntcInstancePtr, XPAR_XPS_INTC_0_PLB_PS2_CONTROLLER_0_IP2INTC_IRPT_INTR,                            (XInterruptHandler)PS2_InterruptHandler,                            (void *)0);     if (Status != XST_SUCCESS)     {        return XST_FAILURE;}     /*      * Start the interrupt controller such that interrupts are enabled for      * all devices that cause interrupts, specify simulation mode so that      * an interrupt can be caused by software rather than a real hardware      * interrupt      */     Status = XIntc_Start(XIntcInstancePtr, XIN_REAL_MODE);     if (Status != XST_SUCCESS)     {         return XST_FAILURE;     }     /*      * Enable the interrupt for the device and then cause (simulate) an      * interrupt so the handlers will be called      */     XIntc_Enable(XIntcInstancePtr, XPAR_XPS_INTC_0_PLB_PS2_CONTROLLER_0_IP2INTC_IRPT_INTR);     /*      * Enable the Interrupts for the MicroBlaze Processor      */     microblaze_enable_interrupts();     return XST_SUCCESS; } int main(void){     /*Initialization*/     init_input();     /*wait for interrupt*/     while(1);    return 1; }

4. 汇编代码详解
   使用mb-objdump工具对实例进行了反汇编，想看看到底是个什么情况
   

   Disassembly of section .vectors.reset: 00000000 <_start>:    0:    b0009000     imm    -28672    4:    b8080000     brai    0                                   #main()程序起始地址是0x90000000 Disassembly of section .vectors.sw_exception: 00000008 <_vector_sw_exception>:    8:    b0009000     imm    -28672    c:    b8080438     brai    1080 Disassembly of section .vectors.interrupt: 00000010 <_vector_interrupt>:   10:    b0009000     imm    -28672   14:    b8080474     brai    1140                         #中断处理程序起始地址是0x90000474 Disassembly of section .vectors.hw_exception: 00000020 <_vector_hw_exception>:   20:    b0009000     imm    -28672   24:    b8080450     brai    1104 90000474 <__interrupt_handler>:                 #中断处理程序起始地址和汇编代码 90000474: 3021ffb0  addik r1, r1, -80 90000478: f9e10000  swi r15, r1, 0 9000047c: f8610020  swi r3, r1, 32 90000480: f8810024  swi r4, r1, 36 90000484: f8a10028  swi r5, r1, 40 90000488: f8c1002c  swi r6, r1, 44 9000048c: f8e10030  swi r7, r1, 48 90000490: f9010034  swi r8, r1, 52 90000494: f9210038  swi r9, r1, 56 90000498: f941003c  swi r10, r1, 60 9000049c: f9610040  swi r11, r1, 64 900004a0: f9810044  swi r12, r1, 68 900004a4: fa210048  swi r17, r1, 72

5. 总结
   主要描述了MicroBlaze的中断的基本原理，以及编程。

参考文献：

1. MicroBlaze Processor Reference Guide
   http://www.xilinx.com/support/documentation/sw_manuals/mb_ref_guide.pdf
2. Using and Creating Interrupt-based Systems
   http://www.xilinx.com/support/documentation/application_notes/xapp778.pdf
3. Embedded System Tools Reference Manual
   http://www.xilinx.com/support/documentation/sw_manuals/edk10_est_rm.pdf
4. Process System Reset Module
   http://www.xilinx.com/support/documentation/ip_documentation/processor_sys_reset.pdf