gpioanalyser/gpio-raw.cpp

#include "gpio-raw.h"

int  mem_fd;
char *gpio_mem, *gpio_map;
char *spi0_mem, *spi0_map;


// I/O access
volatile unsigned *gpio;

//
// Set up a memory regions to access GPIO
//
bool setup_io()
{
   /* open /dev/mem */
   if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) {
      /*printf("can't open /dev/mem \n");
      exit (-1);*/
     return false;
   }

   /* mmap GPIO */

   // Allocate MAP block
   if ((gpio_mem = (char*)malloc(BLOCK_SIZE + (PAGE_SIZE-1))) == NULL) {
      /*printf("allocation error \n");
      exit (-1);*/
     return false;
   }

   // Make sure pointer is on 4K boundary
   if ((unsigned long)gpio_mem % PAGE_SIZE)
     gpio_mem += PAGE_SIZE - ((unsigned long)gpio_mem % PAGE_SIZE);

   // Now map it
   gpio_map = (char *)mmap(
      (caddr_t)gpio_mem,
      BLOCK_SIZE,
      PROT_READ|PROT_WRITE,
      MAP_SHARED|MAP_FIXED,
      mem_fd,
      GPIO_BASE
   );

   if ((long)gpio_map < 0) {
      /*printf("mmap error %d\n", (int)gpio_map);
      exit (-1);*/
     return false;
   }

   // Always use volatile pointer!
   gpio = (volatile unsigned *)gpio_map;
  return true;

} // setup_io