Function wiringPiGlobalMemoryAccess

wiringPi/wiringPi.c:3383–3434

int wiringPiGlobalMemoryAccess(void)
{
  const char* gpiomemGlobal;
  int fd=-1;
  unsigned int MMAP_size;
  unsigned int BaseAddr, PWMAddr;

  piBoard();
  if (piRP1Model()) {
    GetRP1Memory();
    gpiomemGlobal = pciemem_RP1;
    MMAP_size = pciemem_RP1_Size;
    BaseAddr  = 0x00000000;
    PWMAddr	  = 0x00000000;  //not supported so far
  } else {
    gpiomemGlobal = gpiomem_global;
    MMAP_size = BLOCK_SIZE;
    BaseAddr	= piGpioBase + 0x00200000 ;
    PWMAddr	  = piGpioBase + 0x0020C000 ;
  }

  if ((fd = open (gpiomemGlobal, O_RDWR | O_SYNC | O_CLOEXEC)) >0) {
    int returnvalue = 1; // OK

    uint32_t * lgpio = (uint32_t *)mmap(0, MMAP_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, BaseAddr) ;
    if (lgpio == MAP_FAILED) {
      returnvalue = 0;
      if (wiringPiDebug)
        fprintf(stderr,"wiringPiGlobalMemoryAccess: mmap (GPIO 0x%X,0x%X) failed: %s\n", BaseAddr, MMAP_size, strerror (errno)) ;
    } else {
      munmap(lgpio, MMAP_size);
      if (piRP1Model()) {
        returnvalue = 2;    // GPIO & PWM accessible (same area, nothing to mmap)
      } else {
        //check PWM area
        uint32_t* lpwm = (uint32_t *)mmap(0, BLOCK_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, PWMAddr) ;
        if (lpwm == MAP_FAILED) {
          returnvalue = 1;    // only GPIO accessible
          if (wiringPiDebug)
            fprintf(stderr,"wiringPiGlobalMemoryAccess: mmap (PWM 0x%X,0x%X) failed: %s\n", PWMAddr, MMAP_size, strerror (errno)) ;
        } else {
          returnvalue = 2;  // GPIO & PWM accessible
          munmap(lpwm, BLOCK_SIZE);
        }
      }
    }

    close(fd);
    return returnvalue;
  }
  return 0;  // Failed!
}

/*
 * wiringPiSetup: