devmem2.c #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <errno.h> #include <signal.h> #include <fcntl.h> #include...

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devmem2.c

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

#include <errno.h>

#include <signal.h>

#include <fcntl.h>

#include <ctype.h>

#include <termios.h>

#include <sys/types.h>

#include <sys/mman.h>

#define FATAL do { fprintf(stderr, "Error at line %d, file %s (%d) [%s]\n", \

__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 = NULL, *virt_addr = NULL;

unsigned long read_result, writeval;

off_t target;

int access_type = 'w';

if(argc < 2) {

fprintf(stderr, "\nUsage:\t%s { address } [ type [ data ] ]\n"

"\taddress : memory address to act upon\n"

"\ttype : access operation type : [b]yte, [h]alfword, [w]ord\n"

"\tdata : data to be written\n\n",

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.\n");

fflush(stdout);

/* Map one page */

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.\n", map_base);

fflush(stdout);

virt_addr = (void *)((char *)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'.\n", access_type);

exit(2);

}

printf("Value at address 0x%X (%p): 0x%X\n", 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\n", writeval, read_result);

fflush(stdout);

}

if(munmap(map_base, MAP_SIZE) == -1) FATAL;

close(fd);

return 0;

}

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Answer 1

Answer #1

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <inttypes.h>

#define printerr(fmt,...) do { fprintf(stderr, fmt, ## __VA_ARGS__); fflush(stderr); } while(0)

#define VER_STR "devmem version T/C (http://git.io/vZ5iD) rev.0.3e"

int f_dbg = 0;

static void usage(const char *cmd)
{
fprintf(stderr, "\nUsage:\t%s [-switches] address [ type [ data ] ]\n"
"\taddress : memory address to act upon\n"
"\ttype : access operation type : [b]yte, [h]alfword, [w]ord\n"
"\tdata : data to be written\n\n"
"Switches:\n"
"\t-r : read back after write\n"
"\t-a : do not check alignment\n"
"\t--version | -V : print version\n"
"\n",
cmd);
}

int main(int argc, char **argv)
{
int fd;
void *map_base, *virt_addr;
unsigned long read_result = -1, writeval=-1;
uint64_t target;
int access_type = 'w';
int access_size = 4;
unsigned int pagesize = (unsigned)getpagesize(); /* or sysconf(_SC_PAGESIZE) */
unsigned int map_size = pagesize;
unsigned offset;
char *endp = NULL;
int f_readback = 0; // flag to read back after write
int f_align_check = 1; // flag to require alignment
const char *progname = argv[0];
int opt;

opterr = 0;
while ((opt = getopt(argc, argv, "+raAdV")) != -1) {
switch(opt) {
case 'r':
f_readback = 1;
break;
case 'a':
f_align_check = 0;
break;
case 'A':
// Absolute address mode. Does nothing now, for future compat.;
break;
case 'd':
f_dbg = 1;
break;
case 'V':
printf(VER_STR "\n");
exit(0);
default:
if ( (!argv[optind]) || 0 == strcmp(argv[optind], "--help")) {
usage(progname);
exit(1);
}

if (0 == strncmp(argv[optind], "--vers", 6)) {
printf(VER_STR "\n");
exit(0);
}

printerr("Unknown long option: %s\n", argv[optind]);
exit(2);
}
}

argc -= optind - 1;
argv += optind - 1;

if (argc < 2 || argc > 4) {
usage(progname);
exit(1);
}

if (argc > 2) {
if (!isdigit(argv[1][0])) {
// Allow access_type be 1st arg, then swap 1st and 2nd
char *t = argv[2];
argv[2] = argv[1];
argv[1] = t;
}

access_type = tolower(argv[2][0]);
if (argv[2][1] )
access_type = '?';
}

errno = 0;
target = strtoull(argv[1], &endp, 0);
if (errno != 0 || (endp && 0 != *endp)) {
printerr("Invalid memory address: %s\n", argv[1]);
exit(2);
}

switch (access_type) {
case 'b':
access_size = 1;
break;
case 'w':
access_size = 4;
break;
case 'h':
access_size = 2;
break;
default:
printerr("Illegal data type: %s\n", argv[2]);
exit(2);
}

if ((target + access_size -1) < target) {
printerr("ERROR: rolling over end of memory\n");
exit(2);
}

if ( (sizeof(off_t) < sizeof(int64_t)) && (target > UINT32_MAX) ) {
printerr("The address %s > 32 bits. Try to rebuild in 64-bit mode.\n", argv[1]);
// Consider mmap2() instead of this check
exit(2);
}

offset = (unsigned int)(target & (pagesize-1));
if (offset + access_size > pagesize ) {
// Access straddles page boundary: add another page:
map_size += pagesize;
}

if (f_dbg) {
printerr("Address: %#" PRIX64 " op.size=%d\n", target, access_size);
}
if (f_align_check && offset & (access_size - 1)) {
printerr("ERROR: address not aligned on %d!\n", access_size);
exit(2);
}

fd = open("/dev/mem", O_RDWR | O_SYNC);
if (fd == -1) {
printerr("Error opening /dev/mem (%d) : %s\n", errno, strerror(errno));
exit(1);
}
//printf("/dev/mem opened.\n");
//fflush(stdout);

map_base = mmap(0, map_size, PROT_READ | PROT_WRITE, MAP_SHARED,
fd,
target & ~((typeof(target))pagesize-1));
if (map_base == (void *) -1) {
printerr("Error mapping (%d) : %s\n", errno, strerror(errno));
exit(1);
}
//printf("Memory mapped at address %p.\n", map_base);
//fflush(stdout);

virt_addr = map_base + offset;

if (argc > 3) {
errno = 0;
writeval = strtoul(argv[3], &endp, 0);
if (errno || (endp && 0 != *endp)) {
printerr("Invalid data value: %s\n", argv[3]);
exit(2);
}

if (access_size < sizeof(writeval) && 0 != (writeval >> (access_size * 8))) {
printerr("ERROR: Data value %s does not fit in %d byte(s)\n", argv[3], access_size);
exit(2);
}

switch (access_size) {
case 1:
*((volatile uint8_t *) virt_addr) = writeval;
break;
case 2:
*((volatile uint16_t *) virt_addr) = writeval;
break;
case 4:
*((volatile uint32_t *) virt_addr) = writeval;
break;
}

if (f_dbg) {
printerr("Address: %#" PRIX64 " Written: %#lX\n", target, writeval);
fflush(stdout);
}
}

if (argc <= 3 || f_readback) {
switch (access_size) {
case 1:
read_result = *((volatile uint8_t *) virt_addr);
break;
case 2:
read_result = *((volatile uint16_t *) virt_addr);
break;
case 4:
read_result = *((volatile uint32_t *) virt_addr);
break;
}

//printf("Value at address 0x%lld (%p): 0x%lu\n", (long long)target, virt_addr, read_result);
//fflush(stdout);
if (f_readback && argc > 3)
printf("Written 0x%lx; readback 0x%lx\n", writeval, read_result);
else
printf("%08lX\n", read_result);
fflush(stdout);
}

if (munmap(map_base, map_size) != 0) {
printerr("ERROR munmap (%d) %s\n", errno, strerror(errno));
}

close(fd);

return 0;
}

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Answer 2

devmem2.c #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <errno.h> #include <signal.h> #include <fcntl.h> #include...

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