mzapo_phys.c

/*******************************************************************
  Simple program to check LCD functionality on MicroZed
  based MZ_APO board designed by Petr Porazil at PiKRON

  mzapo_phys.h      - mapping of the physical address to process

  (C) Copyright 2017 by Pavel Pisa
      e-mail:   pisa@cmp.felk.cvut.cz
      homepage: http://cmp.felk.cvut.cz/~pisa
      company:  http://www.pikron.com/
      license:  any combination of GPL, LGPL, MPL or BSD licenses

 *******************************************************************/

#define _POSIX_C_SOURCE 200112L

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

#include "mzapo_phys.h"

const char *map_phys_memdev="/dev/mem";

void *map_phys_address(off_t region_base, size_t region_size, int opt_cached)
{
  unsigned long mem_window_size;
  unsigned long pagesize;
  unsigned char *mm;
  unsigned char *mem;
  int fd;

  fd = open(map_phys_memdev, O_RDWR | (!opt_cached? O_SYNC: 0));
  if (fd < 0) {
    fprintf(stderr, "cannot open %s\n", map_phys_memdev);
    return NULL;
  }

  pagesize=sysconf(_SC_PAGESIZE);

  mem_window_size = ((region_base & (pagesize-1)) + region_size + pagesize-1) & ~(pagesize-1);

  mm = (unsigned char *)mmap(NULL, mem_window_size, PROT_WRITE|PROT_READ,
              MAP_SHARED, fd, region_base & ~(pagesize-1));
  mem = mm + (region_base & (pagesize-1));

  if (mm == MAP_FAILED) {
    fprintf(stderr,"mmap error\n");
    return NULL;
  }

  return (void *)mem;
}