用户空间驱动的mmap映射失败 - Chinaunix

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
volatile unsigned int *map_base=NULL;
volatile unsigned int *GpbCon =NULL;
volatile unsigned int *GpbDat =NULL;
int main()
{
int fd,count=0;
fd = open("/dev/mem",0,O_RDWR|O_SYNC);
if(fd == -1 ){
perror("open failed ");
return -1;
}
map_base = (volatile unsigned int *)mmap(NULL,0x9,PROT_READ|PORT_WRITE,MAP_SHARED,fd,0x56000010);
// 0x56000010 这个是2440的 GPBCON的物理地址
if(map_base==NULL || map_base ==MAP_FAILED){
perror("sorry , can't map\n");
if(map_base ==MAP_FAILED)
printf("sorry ,MAP_FAILED\n");
close(fd);
return -1;
}else printf("map secessfully \n");
GpbCon = (volatile unsigned int *)(map_base);
GpbDat = (volatile unsigned int *)(map_base + 0x4); // GPB
*GpbCon &= ~(0xff<<10)|0x2<<5*2|0x2<<6*2|0x2<<7*2|0x2<<8*2;
*GpbDat = 0x0;
while(1){
*GpbDat = ~*GpbDat;
sleep(1000);
if(count++>5){
break;
}
}
munmap((void*)map_base,0x9);
close(fd);
return 0;
}

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