【linuxドライバ】組み込みLinuxによるメモリの直接読み書き(devmem)
7820 ワード
devmemツールソース
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define FATAL do { fprintf(stderr, "Error at line %d, file %s (%d) [%s]
", \
__LINE__, __FILE__, errno, strerror(errno)); exit(1); } while(0)
#define MAP_SIZE 4096UL
#define MAP_MASK (MAP_SIZE - 1)
int main(int argc, char **argv) {
int fd;
void *map_base, *virt_addr;
unsigned long read_result, writeval;
off_t target;
int access_type = 'w';
if(argc < 2) {
fprintf(stderr, "
Usage:\t%s { address } [ type [ data ] ]
"
"\taddress : memory address to act upon
"
"\ttype : access operation type : [b]yte, [h]alfword, [w]ord
"
"\tdata : data to be written
",
argv[0]);
exit(1);
}
target = strtoul(argv[1], 0, 0);//
if(argc > 2)
access_type = tolower(argv[2][0]);//
if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) FATAL;
printf("/dev/mem opened.
");
fflush(stdout);
/* Map one page */ // mmap
map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~MAP_MASK);
if(map_base == (void *) -1) FATAL;
printf("Memory mapped at address %p.
", map_base);
fflush(stdout);
virt_addr = map_base + (target & MAP_MASK);
switch(access_type) {
case 'b':
read_result = *((unsigned char *) virt_addr);
break;
case 'h':
read_result = *((unsigned short *) virt_addr);
break;
case 'w':
read_result = *((unsigned long *) virt_addr);
break;
default:
fprintf(stderr, "Illegal data type '%c'.
", access_type);
exit(2);
}
printf("Value at address 0x%X (%p): 0x%X
", target, virt_addr, read_result);
fflush(stdout);
if(argc > 3) {
writeval = strtoul(argv[3], 0, 0);
switch(access_type) {
case 'b':
*((unsigned char *) virt_addr) = writeval;
read_result = *((unsigned char *) virt_addr);
break;
case 'h':
*((unsigned short *) virt_addr) = writeval;
read_result = *((unsigned short *) virt_addr);
break;
case 'w':
*((unsigned long *) virt_addr) = writeval;
read_result = *((unsigned long *) virt_addr);
break;
}
printf("Written 0x%X; readback 0x%X
", writeval, read_result);
fflush(stdout);
}
if(munmap(map_base, MAP_SIZE) == -1) FATAL;
close(fd);
return 0;
}
devmemの使用方法
root@myzr:~# ./devmem
Usage: ./devmem { address } [ type [ data ] ]
address : memory address to act upon
type : access operation type : [b]yte, [h]alfword, [w]ord
data : data to be written
レジスタアドレスの表示
root@myzr:~# ./devmem 0x20e05e0
/dev/mem opened.
Memory mapped at address 0x76f99000.
Value at address 0x20E05E0 (0x76f995e0): 0x1B8B1
ライトレジスタ
root@myzr:~# ./devmem 0x209c000 b 1
/dev/mem opened.
Memory mapped at address 0x76f25000.
Value at address 0x209C000 (0x76f25000): 0x5C
Written 0x1; readback 0x5C
root@myzr:~#