Linux在应用层读写寄存器的方法

可以通过操作/dev/mem设备文件，以及mmap函数，将寄存器的地址映射到用户空间，直接在应用层对寄存器进行操作，示例如下：

[cpp] view plain copy







#include <stdio.h>

#include <stdlib.h>

#include <time.h>

#include <unistd.h>

#include <fcntl.h>

#include <unistd.h>

#include <sys/mman.h>

#define AUDIO_REG_BASE (0xB800E000)

#define MAP_SIZE 0xFF

static int dev_fd;

int main(int argc, char **argv)

{

dev_fd = open("/dev/mem", O_RDWR | O_NDELAY);

if (dev_fd < 0)

{

printf("open(/dev/mem) failed.");

return 0;

}

unsigned char *map_base=(unsigned char * )mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, dev_fd, AUDIO_REG_BASE );

printf("%x \n", *(volatile unsigned int *)(map_base+0x38)); //打印该寄存器地址的value

#if 1 // LINE IN

printf("%x \n", *(volatile unsigned int *)(map_base+0x30));

*(volatile unsigned int *)(map_base + 0x30) = 0x208121bc; //修改该寄存器地址的value

usleep(1000000);

*(volatile unsigned int *)(map_base + 0x30) &= ~(0x1<<16); //修改该寄存器地址的value

usleep(1000000);

printf("%x \n", *(volatile unsigned int *)(map_base+0x30));

#endif

if(dev_fd)

close(dev_fd);

munmap(map_base,MAP_SIZE);//解除映射关系

return 0;

}