uio.c

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/******************************************************************************
 *  Copyright (c) 2016, Xilinx, Inc.
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/******************************************************************************
 *
 *
 * @file uio.c
 *
 * Functions to interact with linux UIO. No safe checks here, so users must
 * know what they are doing.
 *
 * <pre>
 * MODIFICATION HISTORY:
 *
 * Ver   Who  Date     Changes
 * ----- --- ------- -----------------------------------------------
 * 1.00a yrq 12/05/17 Initial release
 *
 * </pre>
 *
 *****************************************************************************/
 
#include "uio.h"
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
 
/******************************************************************************
 * Function to set the UIO device.
 * @param   uio_index is the uio index in /dev list.
 * @param   length is the length of the MMAP in bytes.
 * @return  A pointer pointing to the MMAP of the UIO.
 *****************************************************************************/
void *setUIO(int uio_index, int length) {
  char uio_buf[32];
  int uio_fd;
  void *uio_ptr;
 
  sprintf(uio_buf, "/dev/uio%d", uio_index);
  uio_fd = open(uio_buf, O_RDWR);
  if (uio_fd < 1) {
    printf("Invalid UIO device file: %s.\n", uio_buf);
  }
  // mmap the UIO devices
  uio_ptr = mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_SHARED, uio_fd, 0);
  return uio_ptr;
}
 
/******************************************************************************
 * Function to set the UIO device.
 * @param   uio_ptr is the uio pointer to be freed.
 * @param   length is the length of the MMAP.
 * @return  0 on success; -1 otherwise.
 *****************************************************************************/
int unsetUIO(void *uio_ptr, int length) { return munmap(uio_ptr, length); }