static struct kobject *mts_lora_kobject;

static void mts_load_lora_port(void)
{
	// create lora/ subdir
	mts_lora_kobject = kobject_create_and_add("lora", &mts_io_platform_device->dev.kobj);

	if (sysfs_create_group(mts_lora_kobject, attr_group_lora)) {
		log_error("failed to create lora attributes");
	}
}

static void	mts_teardown_lora_port(void)
{
	// clean up "lora/" kobject if it exists
	if (mts_lora_kobject) {
		kobject_put(mts_lora_kobject);
	}
}

static ssize_t mts_attr_show_lora_product_info(struct device *dev,
			struct device_attribute *at, char *buf)
{
	ssize_t value;
	char label[32];
        struct kobject *kobj = (struct kobject *)dev;
        struct kobj_attribute *attr = (struct kobj_attribute *)at;

	snprintf(label, sizeof label, "%s/%s", kobj->name, attr->attr.name);

	if (strcmp(label, "lora/eui") == 0) {
			value = sprintf(buf, "%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X\n",
				id_eeprom.lora_eui[0],
				id_eeprom.lora_eui[1],
				id_eeprom.lora_eui[2],
				id_eeprom.lora_eui[3],
				id_eeprom.lora_eui[4],
				id_eeprom.lora_eui[5],
				id_eeprom.lora_eui[6],
				id_eeprom.lora_eui[7]);
	}
	else if (strcmp(label, "lora/product-id") == 0) {
		value = sprintf(buf, "%.32s\n", id_eeprom.lora_product_id);
	}
	else if (strcmp(label, "lora/hw-version") == 0) {
		value = sprintf(buf, "%.32s\n", id_eeprom.lora_hw_version);
	}
	else {
		log_error("attribute '%s' not found", label);
		value = -1;
	}
	return value;
}

static ssize_t mts_attr_show_lora_gpio_pin(struct device *dev,
			struct device_attribute *at,
			char *buf)
{
	int value;
	struct gpio_pin *pin;
        struct kobject *kobj = (struct kobject *)dev;
        struct kobj_attribute *attr = (struct kobj_attribute *)at;

	char pin_label[32];
	snprintf(pin_label, sizeof pin_label, "%s/%s", kobj->name, attr->attr.name); // ex. lora/reset

	pin = gpio_pin_by_attr_name(pin_label);
	if (!pin) {
		return -ENODEV;
	}

	mutex_lock(&mts_io_mutex);
	if (pin->do_gpio_desc) {
		value = gpiod_get_value(pin->desc);
	} else {
		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_lora_gpio_pin(struct device *dev,
			struct device_attribute *at, const char *buf, size_t count)
{
	int value;
	struct gpio_pin *pin;
	char pin_label[32];
        struct kobject *kobj = (struct kobject *)dev;
        struct kobj_attribute *attr = (struct kobj_attribute *)at;

	snprintf(pin_label, sizeof pin_label, "%s/%s", kobj->name, attr->attr.name); // ex. lora/reset

	pin = gpio_pin_by_attr_name(pin_label);
	if (!pin) {
		return -ENODEV;
	}

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

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

	mutex_lock(&mts_io_mutex);

	if (pin->do_gpio_desc) {
		gpiod_set_value(pin->desc, value);
	} else {
		gpio_set_value(pin->pin.gpio, value);
	}
	mutex_unlock(&mts_io_mutex);

	return count;
}