用户态下直接操作GPIO/寄存器（linux应用篇）

野性酷女 2021-07-26 18:23 312阅读 0赞

> CPU：F1C100S  
> 目标系统：linux5.2\*\*

**实验目的：** 点亮LED灯。

PE4---LED1
    PE5---LED2
    PE6---LED3

**实现方法：** 写一个c程序通过mmap方法直接来操作寄存器。

#include <stdio.h>
    #include <stdlib.h>
    #include <fcntl.h>
    #include <sys/mman.h>
    #include <time.h>
    #include <unistd.h>
    #include <string.h>
    
    #define GPIO_REG_BASE 0x01C20800 //GPIO物理基地址 (小页4kb)
    #define MAP_SIZE 0x400 //MMU页大小
    #define GPIO_BASE_OFFSET (GPIO_REG_BASE & 0X00000FFF) //GPIO基地址偏移计算
    #define GPIO_PAGE_OFFSET (GPIO_REG_BASE & 0XFFFFF000) //获得页偏移
    
    #define rPE_CFG0 0X90 //PE_CFG0寄存器地址偏移
    #define rPE_DAT 0XA0 //PE_DAT寄存器地址偏移
    #define rPE_PULL0 0XAC //PE_PULL0寄存器地址偏移
    
    int GPIOE_456_ON(unsigned char *MAP_BASE);//点亮PE4，PE5，PE6 这3盏LED
    int  GPIOE_456_OFF(unsigned char *MAP_BASE);//关闭PE4，PE5，PE6 这3盏LED
    
    int main(int argc, char **argv)
    { 
     static int dev_fd;
     unsigned char *map_base;
    /*参数验证*/
    	if(argc!=2 || (strcmp(argv[1],"on") && strcmp(argv[1],"off"))){ 
       	 printf("argv_error!please input 'on' or 'off'!\n");
     	   exit (0);
    	}
    
        dev_fd = open("/dev/mem", O_RDWR );
        if (dev_fd < 0){ 
            printf("open(/dev/mem) failed.\n");
            return 0;
        }
    
    map_base = (unsigned char *)mmap(NULL, 0x400,PROT_READ | PROT_WRITE, MAP_SHARED,dev_fd, GPIO_PAGE_OFFSET); //把物理地址映射到虚拟地址
    if(*map_base)  printf("mmap_fail!\n"); //是否映射成功
    
    if(!strcmp(argv[1],"on")) GPIOE_456_ON(map_base); //点亮PE4，PE5，PE6 这3盏LED
    if(!strcmp(argv[1],"off")) GPIOE_456_OFF(map_base);//关闭PE4，PE5，PE6 这3盏LED
      //usleep(1000000);
        if(dev_fd) close(dev_fd);
        munmap(map_base,MAP_SIZE);//解除映射关系
        return 0;
    }
    
    
    //GPIOE_456_ON
    int  GPIOE_456_ON(unsigned char *MAP_BASE)
    { 
    unsigned int PE_CFG0,PE_DAT;
    PE_CFG0=*(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_CFG0);
    PE_DAT=*(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_DAT);
    *(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_CFG0)=((PE_CFG0 & 0XF000FFFF)|0X01110000);
    *(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_DAT)=((PE_DAT & 0XFFFFFF8F)|0X00000070);
    }
    //GPIOE_456_OFF
    int  GPIOE_456_OFF(unsigned char *MAP_BASE)
    { 
    unsigned int PE_CFG0,PE_DAT;
    PE_CFG0=*(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_CFG0);
    PE_DAT=*(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_DAT);
    *(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_CFG0)=((PE_CFG0 & 0XF000FFFF)|0X01110000);
    *(volatile unsigned int *)(MAP_BASE+GPIO_BASE_OFFSET+rPE_DAT)=((PE_DAT & 0XFFFFFF8F));
    }

**编译代码并测试**

# ./led2 on			/*点亮所有LED灯*/
    # ./led2 off		/*开闭所有LED灯*/