Are you sure those are valid memory locations in User mode? It looks like you are trying to access physical addresses. You cannot do that directly in Linux due to the Memory Management Unit. You have to ask the MMU to map the physical addresses to virtual addresses in your application's memory space. Peekpoke is a command line utility for reading and writing memory addresses. Here is a sample of the sourcecode for peekpoke taken from the DM3730 BSP:
#include <stdio.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
char *prog_name;
void usage(void)
{
fprintf(stderr, "%s: usage:\n", prog_name);
fprintf(stderr, " -d Turn on debug\n");
fprintf(stderr, " -b Read/Write a byte\n");
fprintf(stderr, " -h Read/Write a short\n");
fprintf(stderr, " -l Read/Write a long\n");
fprintf(stderr, " -c <count> Read <count> values\n");
fprintf(stderr, " -r <addr> Read at physical address <addr>\n");
fprintf(stderr, " -w <addr> <val> Write <val> at physical address <addr>\n");
exit(-1);
}
int main(int argc, char *argv[])
{
unsigned long address, addr, offset;
unsigned long val;
int i, j, nm;
char *p, cmd;
int mode;
int dev_mem;
int pagesize = getpagesize();
int val_size = 1;
int cnt = 1;
int debug = 0;
/* Get program name */
prog_name = strrchr(argv[0], '/');
if (prog_name)
prog_name++;
else
prog_name = argv[0];
if (argc < 2)
usage();
dev_mem = open("/dev/mem", O_RDWR|O_SYNC);
mode = 2; /* assume byte */
for (i=1; i<argc; ++i) {
if (debug)
printf("%s:%d argv[%d]='%s' argc %d\n", __FUNCTION__, __LINE__, i, argv[i], argc);
p = argv[i];
if (!strcmp(p, "-d")) {
debug = 1;
} else if (!strcmp(p, "-c")) {
if (i+1 >= argc)
usage();
i++;
cnt = strtoul(argv[i], NULL, 0);
if (debug)
printf("%d: argv[%d]: '%s' = %x\n", __LINE__, i, argv[i], cnt);
} else if (!strcmp(p, "-b")) {
val_size = 1;
} else if (!strcmp(p, "-h")) {
val_size = 2;
} else if (!strcmp(p, "-l")) {
val_size = 4;
} else if (!strcmp(p, "-w")) {
if (i +2 >= argc)
usage();
cmd = 'w';
i++;
addr = strtoul(argv[i], NULL, 0);
if (debug)
printf("%d: argv[%d]: '%s' = %x\n", __LINE__, i, argv[i], addr);
i++;
val = strtoul(argv[i], NULL, 0);
if (debug)
printf("%d: argv[%d]: '%s' = %x\n", __LINE__, i, argv[i], val);
} else if (!strcmp(p, "-r")) {
if (i +1 >= argc)
usage();
cmd = 'r';
i++;
addr = strtoul(argv[i], NULL, 0);
if (debug)
printf("%d: argv[%d]: '%s' = %x\n", __LINE__, i, argv[i], addr);
} else {
usage();
}
if (cmd != 'r' && cmd != 'w')
continue;
if (cmd == 'w')
cnt = 1;
for (j=0; j<cnt; ++j) {
offset = addr & (pagesize-1);
address = (unsigned long) mmap(0, pagesize,
PROT_READ|PROT_WRITE,
MAP_SHARED, dev_mem,
addr & ~(pagesize - 1));
mode = val_size * 2;
if (debug)
printf("%d: cmd %c mode %d val_size %d\n", __LINE__, cmd, mode, val_size);
if (cmd == 'r') {
switch(mode) {
case 2:
val = *(unsigned char *)(address + offset);
nm = 'b';
break;
case 4:
val = *(unsigned short *)(address + offset);
nm = 'h';
break;
case 8:
val = *(unsigned long *)(address + offset);
nm = 'l';
break;
}
printf("%08x /%c -> %0*x\n", addr, nm, mode, val);
} else {
switch(mode) {
case 2:
*(unsigned char *)(address + offset) = val;
nm = 'b';
break;
case 4:
*(unsigned short *)(address + offset) = val;
nm = 'h';
break;
case 8:
*(unsigned long *)(address + offset) = val;
nm = 'l';
break;
}
printf("%08x /%c = %0*x\n", addr, nm, mode, val);
}
munmap((void *)address, pagesize);
addr += val_size;
}
cmd = 0;
}
return 0;
}