iio: stx104: Add support for GPIO names

This patch sets the gpio_chip names option with an array of GPIO line
names that match the manual documentation for the Apex Embedded Systems
STX104. This should make it easier for users to identify which GPIO line
corresponds to a respective GPIO pin on the device.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/stx104.c

@@ -256,6 +256,11 @@ static void stx104_gpio_set(struct gpio_chip *chip, unsigned int offset,
 	spin_unlock_irqrestore(&stx104gpio->lock, flags);
 }
 
+#define STX104_NGPIO 8
+static const char *stx104_names[STX104_NGPIO] = {
+	"DIN0", "DIN1", "DIN2", "DIN3", "DOUT0", "DOUT1", "DOUT2", "DOUT3"
+};
+
 static int stx104_probe(struct device *dev, unsigned int id)
 {
 	struct iio_dev *indio_dev;
@@ -309,7 +314,8 @@ static int stx104_probe(struct device *dev, unsigned int id)
 	stx104gpio->chip.parent = dev;
 	stx104gpio->chip.owner = THIS_MODULE;
 	stx104gpio->chip.base = -1;
-	stx104gpio->chip.ngpio = 8;
+	stx104gpio->chip.ngpio = STX104_NGPIO;
+	stx104gpio->chip.names = stx104_names;
 	stx104gpio->chip.get_direction = stx104_gpio_get_direction;
 	stx104gpio->chip.direction_input = stx104_gpio_direction_input;
 	stx104gpio->chip.direction_output = stx104_gpio_direction_output;