linux中应用层访问硬件的方法

#include
#include
#include
#include
#include
#include
#include
#include
#include

int main(int argc, char *argv[])
{
    int fd;
    unsigned long vaddr;
    unsigned long paddr;
    unsigned long value = 0;
    char *endstr;
    int set = 0;
    
    if(argc == 1)
    {
        printf("usage: reg [value]\n");
        return 1;
    }
    paddr = strtoul(argv[2],&endstr,16);
    if(!strcmp(argv[1],"set"))
    {
        set = 1;
        value = strtoul(argv[3],&endstr,16);
    }
    printf("addr = 0x%08X, value = 0x%08X\n",paddr,value);
 
    fd = open("/dev/mem", O_RDWR | O_NDELAY);
    if (fd == -1)
    {
        printf("mem dirver open fail\n");
        return 1;
    }
    vaddr = (unsigned long)mmap(0, 0x1000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, paddr&0xfffff000);
    if(set)
        *(unsigned long *)(vaddr+(paddr&0x00000fff)) = value;
    else
        printf("0x%08X\n",*(unsigned long *)(vaddr+(paddr&0xfff)));
    return 0;   
}