How to set my memory device as EMMC or GPMC am437x gp evm

I am currently trying to evaluate the /dev/mem device. I have written the following program

#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 masks    */
/* for read and write  */
/********************************************************************/

//#define ADDR_RANGE_MASK 0xE2000FFF                                      // "00111111111111" Allows only the the
                                                                          // 12 first bit's to be set since we use the
                                                                          // first 12 bits for addressing in the FPGA
//#define READ_MASK 0xE2001FFF                                            // "01111111111111" read bit 1 & write bit 0
//#define WRITE_MASK 0xE2002FFF                                           // "10111111111111" read bit 0 & write bit 1
//#define BASE_ADDR 0xE2000000                                            //CS_2 range starts @ 0xE2000000
/********************************************************************/
/*  Define size to allocate */
/********************************************************************/
#define MAP_SIZE 4096UL                                                   // needs to be looked at....
#define MAP_MASK (MAP_SIZE - 4)

int main(int argc, char **argv) {
   int fd;
   void *map_base, *virt_addr;
   unsigned long read_result, writeval;
   off_t target;
         if(argc < 2){                                                    //error message in case of wrong input
           fprintf (stderr, "\nUsage:\t%s { address } [ data ]\n"
              "\taddress : memory address to act upon\n"
              "\tdata : data to be written (32bit)\n\n"
              "To [i]nitialize type only i leaving out the addresses \n\n",
              argv[0] );
          exit(1);
         }

/********************************************************************/
/*  Init */
/********************************************************************/

if(strcmp(argv[1],"i" ) == 0 )                                           //strcmp() returns 0 if strings are the same (case sensitive)
{
    printf ("init started.\n");
    target = 0x31080240;
  //              Open /dev/mem file & error handling
    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 (0x31080240) mapped at address %p.\n", map_base);
    fflush (stdout);
  // start WRITE
    virt_addr = map_base + (target & MAP_MASK);
    writeval = 0x2;                                                        //32Bit data bus setting for static memory of CS_2
          *((unsigned long *) virt_addr) = writeval;
          printf ("Written 0x%X\n", writeval);
          fflush (stdout);
          printf ("init successful\nRestart program to write or read data\n\n");
  // stop WRITE
}
else
  /********************************************************************/
  /*  Read/Write */
  /********************************************************************/
{
target = strtoul (argv[1], 0, 0);                                         // Parsing the input & leaving out leading 0 & 0x's
// Open /dev/mem file & error handling
   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 = map_base + (target & MAP_MASK);
// start READ
   if (argc <= 2) {
         read_result = *((unsigned long *) virt_addr); //unsigned long fits the 32 bit bus data
         printf("read_result: %d \n",read_result);
// stop READ
         printf ("Value at address 0x%X (%p): 0x%X\n", target, virt_addr, read_result);
         fflush (stdout);
}
// start WRITE if there is data to write given in the arguments
         if (argc > 2) {
       writeval = strtoul(argv[2], 0, 0);
         *((unsigned long *) virt_addr) = writeval;
         printf ("Written 0x%X\n", writeval);
         fflush (stdout);
}
// stop WRITE
}

/********************************************************************/
/*  UnMap one page  */
/********************************************************************/
  if (munmap(map_base, MAP_SIZE) == -1) FATAL;
  close (fd);
  return 0;
}

I can see from the schematics that the EMMC and GPMC shares the same memory device. How will i be able to toggle between the emmc and gpmc in Kernel level.
 Is there any reference document for this operation.

Regards

-Ash