struct gpio_pin *ap_mfser_pin_by_attr_name(const char *name) {
	struct gpio_pin *pin;
	char *pin_attr_name;

	if (!strcmp(name, "rs4xx-term-res:0")) {
		pin_attr_name = "ap1-gpio3";
	} else if (!strcmp(name, "rts-override:0")) {
		pin_attr_name = "ap1-gpio4";
	} else if (!strcmp(name, "rs4xx-term-res:1")) {
		pin_attr_name = "ap2-gpio3";
	} else if (!strcmp(name, "rts-override:1")) {
		pin_attr_name = "ap2-gpio4";
	} else {
		log_error("accessory card attribute %s not available", name);
		return NULL;
	}

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

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

	return NULL;
}


static ssize_t mts_attr_show_ap_mfser_pin(struct device *dev,
			struct device_attribute *attr,
			char *buf)
{
	int value;
	struct gpio_pin *pin = ap_mfser_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_ap_mfser_pin(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	int value;
	struct gpio_pin *pin = ap_mfser_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 ssize_t mts_attr_show_mfser_mode(struct device *dev,
			struct device_attribute *attr,
			char *buf)
{
	int ret;
	int modesel0;
	int modesel1;

	struct gpio_pin *pin_modesel0;
	struct gpio_pin *pin_modesel1;

	if (strstr(attr->attr.name, ":0")) {
		pin_modesel0 = gpio_pin_by_name("AP1_GPIO1");
		pin_modesel1 = gpio_pin_by_name("AP1_GPIO2");
	}
	else if (strstr(attr->attr.name, ":1")) {
		pin_modesel0 = gpio_pin_by_name("AP2_GPIO1");
		pin_modesel1 = gpio_pin_by_name("AP2_GPIO2");
	}
	else {
		log_error("unknown serial-mode attr %s", attr->attr.name);
		return -ENODEV;
	}

	if (!pin_modesel0 || !pin_modesel1)
		return -ENODEV;

	mutex_lock(&mts_io_mutex);

	modesel0 = gpio_get_value(pin_modesel0->pin.gpio);
	modesel1 = gpio_get_value(pin_modesel1->pin.gpio);

	if (modesel1 == 0 && modesel0 == 0)
		ret = sprintf(buf, "loopback\n");
	else if (modesel1 == 0 && modesel0 == 1)
		ret = sprintf(buf, "rs232\n");
	else if (modesel1 == 1 && modesel0 == 0)
		ret = sprintf(buf, "rs485-half\n");
	else if (modesel1 == 1 && modesel0 == 1)
		ret = sprintf(buf, "rs422-485-full\n");
	else
		ret = sprintf(buf, "error\n");

	mutex_unlock(&mts_io_mutex);

	return ret;
}

static ssize_t mts_attr_store_mfser_mode(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	int modesel0;
	int modesel1;
	struct gpio_pin *pin_modesel0;
	struct gpio_pin *pin_modesel1;

	if (strstr(attr->attr.name, ":0")) {
		pin_modesel0 = gpio_pin_by_name("AP1_GPIO1");
		pin_modesel1 = gpio_pin_by_name("AP1_GPIO2");
	}
	else if (strstr(attr->attr.name, ":1")) {
		pin_modesel0 = gpio_pin_by_name("AP2_GPIO1");
		pin_modesel1 = gpio_pin_by_name("AP2_GPIO2");
	}
	else {
		log_error("unknown serial-mode attr %s", attr->attr.name);
		return -ENODEV;
	}

	if (!pin_modesel0 || !pin_modesel1)
		return -ENODEV;

	if (!strcasecmp(buf, "loopback")) {
		modesel1 = 0;
		modesel0 = 0;
	}
	else if (!strcasecmp(buf, "rs232")) {
		modesel1 = 0;
		modesel0 = 1;
	}
	else if (!strcasecmp(buf, "rs485-half")) {
		modesel1 = 1;
		modesel0 = 0;
	}
	else if (!strcasecmp(buf, "rs422-485-full")) {
		modesel1 = 1;
		modesel0 = 1;
	}
	else  {
		return -EINVAL;
	}

	mutex_lock(&mts_io_mutex);

	gpio_set_value(pin_modesel0->pin.gpio, modesel0);
	gpio_set_value(pin_modesel1->pin.gpio, modesel1);

	mutex_unlock(&mts_io_mutex);

	return count;
}

/* accessory port 1 serial attributes */
static DEVICE_ATTR_MTS(dev_attr_ap1_serial_mode, "serial-mode:0", mts_attr_show_mfser_mode, mts_attr_store_mfser_mode);
static DEVICE_ATTR_MTS(dev_attr_ap1_rs4xx_term_res, "rs4xx-term-res:0", mts_attr_show_ap_mfser_pin, mts_attr_store_ap_mfser_pin);
static DEVICE_ATTR_MTS(dev_attr_ap1_rts_override, "rts-override:0", mts_attr_show_ap_mfser_pin, mts_attr_store_ap_mfser_pin);

static int ap1_mfser_attributes_size = 3;		// not including NULL at end

static struct attribute *ap1_mfser_attributes[] = {
	&dev_attr_ap1_serial_mode.attr,
	&dev_attr_ap1_rs4xx_term_res.attr,		// gpio3
	&dev_attr_ap1_rts_override.attr,		// gpio4
	NULL,
};

/* accessory port 2 serial attributes */
static DEVICE_ATTR_MTS(dev_attr_ap2_serial_mode, "serial-mode:1", mts_attr_show_mfser_mode, mts_attr_store_mfser_mode);
static DEVICE_ATTR_MTS(dev_attr_ap2_rs4xx_term_res, "rs4xx-term-res:1", mts_attr_show_ap_mfser_pin, mts_attr_store_ap_mfser_pin);
static DEVICE_ATTR_MTS(dev_attr_ap2_rts_override, "rts-override:1", mts_attr_show_ap_mfser_pin, mts_attr_store_ap_mfser_pin);

static int ap2_mfser_attributes_size = 3;		// not including NULL at end

static struct attribute *ap2_mfser_attributes[] = {
	&dev_attr_ap2_serial_mode.attr,
	&dev_attr_ap2_rs4xx_term_res.attr,		// gpio3
	&dev_attr_ap2_rts_override.attr,		// gpio4
	NULL,
};