gpio: mvebu: implement get_direction

struct gpio_chip documentation recommends to always implement this
callback function.

A more concrete motivation is to be able (in combination with
GPIOD_ASIS) to detect whether the bootloader has changed the state of a
GPIO signal.
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mvebu.c

@@ -376,6 +376,16 @@ static int mvebu_gpio_direction_output(struct gpio_chip *chip, unsigned int pin,
 	return 0;
 }
 
+static int mvebu_gpio_get_direction(struct gpio_chip *chip, unsigned int pin)
+{
+	struct mvebu_gpio_chip *mvchip = gpiochip_get_data(chip);
+	u32 u;
+
+	regmap_read(mvchip->regs, GPIO_IO_CONF_OFF + mvchip->offset, &u);
+
+	return !!(u & BIT(pin));
+}
+
 static int mvebu_gpio_to_irq(struct gpio_chip *chip, unsigned int pin)
 {
 	struct mvebu_gpio_chip *mvchip = gpiochip_get_data(chip);
@@ -1130,6 +1140,7 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
 	mvchip->chip.parent = &pdev->dev;
 	mvchip->chip.request = gpiochip_generic_request;
 	mvchip->chip.free = gpiochip_generic_free;
+	mvchip->chip.get_direction = mvebu_gpio_get_direction;
 	mvchip->chip.direction_input = mvebu_gpio_direction_input;
 	mvchip->chip.get = mvebu_gpio_get;
 	mvchip->chip.direction_output = mvebu_gpio_direction_output;