refactor gpio

struct GPIODescriptor {
  GPIO &gpio;
  const GPIOHandler handler;
  const char *name;
};

const unsigned int number_of_gpios = 5;
const GPIODescriptor gpio_descriptors[number_of_gpios] = {
    GPIODescriptor{my_gpios[0], joy_down_irq_handler, "joy_down"},
    GPIODescriptor{my_gpios[1], joy_left_irq_handler, "joy_left"},
    GPIODescriptor{my_gpios[2], joy_up_irq_handler, "joy_up"},
    GPIODescriptor{my_gpios[3], joy_button_irq_handler, "joy_button"},
    GPIODescriptor{my_gpios[4], joy_right_irq_handler, "joy_right"},
};

bool request_threaded_irq(const GPIODescriptor &gpio_descriptor) {
  const auto irq = gpio_to_irq(gpio_descriptor.gpio);
  const auto error_code = request_threaded_irq(
      irq, gpio_descriptor.handler, NULL,
      IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING, gpio_descriptor.name, NULL);
  const bool was_successful = error_code >= 0;
  return was_successful;
}

unsigned int try_to_initialize_gpios() {
  unsigned int successfully_initialized_gpios = 0;
  for (unsigned int index = 0; index < number_of_gpios; index++) {
    const auto was_successful = request_threaded_irq(gpio_descriptors[index]);
    if (not was_successful)
      break;
    else
      successfully_initialized_gpios = index + 1;
  }
  return successfully_initialized_gpios;
}

void free_gpios(unsigned int up_to_gpio) {
  for (unsigned int index = 0; index < up_to_gpio; index++) {
    const auto irq = gpio_to_irq(gpio_descriptors[index].gpio);
    free_irq(irq, NULL);
  }
}

int initialize_gpios() {
  auto successfully_initialized_gpios = try_to_initialize_gpios();
  if (successfully_initialized_gpios != number_of_gpios) {
    free_gpios(successfully_initialized_gpios);
    irq_error();
    return -1;
  }
  return 0;
}