struct gpio_pin *gpio_pin_by_name(const char *name) {
	struct gpio_pin *pin;

	for (pin = gpio_pins; *pin->name; pin++) {
		if (!strcmp(pin->name, name)) {
			return pin;
		}
	}

	log_error("pin named %s not found", name);

	return NULL;
}

// A GPIO pin number must only occur once.
struct gpio_pin *gpio_pin_by_num(unsigned num) {
	int ipin = 0;
	while(*(gpio_pins[ipin].name)) {
		if (gpio_pins[ipin].pin.gpio == num) {
			return &(gpio_pins[ipin]);
		}
		ipin++;
	}

	log_error("pin numbered %u not found", num);

	return NULL;
}


struct gpio_pin *gpio_pin_by_attr_name(const char *name) {
	struct gpio_pin *pin;

	for (pin = gpio_pins; *pin->name; pin++) {
		if (!strcmp(pin->pin.label, name)) {
			return pin;
		}
	}

	log_error("pin with attr name %s not found", name);

	return NULL;
}

ssize_t mts_attr_show_gpio_pin(struct device *dev,
			struct device_attribute *attr,
			char *buf)
{
	int value;
	struct gpio_pin *pin = gpio_pin_by_attr_name(attr->attr.name);

	if (!pin) {
		return -ENODEV;
	}

	mutex_lock(&mts_io_mutex);

	value = gpio_get_value(pin->pin.gpio);

	mutex_unlock(&mts_io_mutex);

	if (value < 0) {
		return value;
	}

	if (pin->active_low) {
		value = !value;
	}

	return sprintf(buf, "%d\n", value);
}

static ssize_t mts_attr_store_gpio_pin(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	int value;
	struct gpio_pin *pin = gpio_pin_by_attr_name(attr->attr.name);

	if (!pin) {
		return -ENODEV;
	}

	if (sscanf(buf, "%i", &value) != 1) {
		return -EINVAL;
	}

	if (pin->active_low) {
		value = !value;
	}

	mutex_lock(&mts_io_mutex);

	gpio_set_value(pin->pin.gpio, value);

	mutex_unlock(&mts_io_mutex);

	return count;
}

static int reset_gpio_pin(struct gpio_pin *pin, unsigned int delay_ms, unsigned int value)
{
	if (!pin) {
		return -ENODEV;
	}

	gpio_set_value(pin->pin.gpio, value);

	mdelay(delay_ms);

	gpio_set_value(pin->pin.gpio, !value);

	return 0;
}