devmem2.c

#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 = NULL, *virt_addr = NULL;

unsigned long read_result, writeval;

off_t target;

int access_type = 'w';

if(argc

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 */

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 = (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'. ", 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;

}

-

Modify devmem2.c to work as a function(s) rather than a main function. This function should be able to work with gpio devices from 0 through 127. The function should be able to manipulate the gpio registers for a given device. The header gpio-info.h is available for your use. Think about how to handle the gpio registers that work with banks rather than devices, for example GPIO REVISION and GPIO CLEARDATAOUT