gpio: stp-xway: use gpiochip data pointer

This makes the driver use the data pointer added to the gpio_chip
to store a pointer to the state container instead of relying on
container_of().

Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-stp-xway.c

@@ -100,8 +100,7 @@ struct xway_stp {
  */
 static void xway_stp_set(struct gpio_chip *gc, unsigned gpio, int val)
 {
-	struct xway_stp *chip =
-		container_of(gc, struct xway_stp, gc);
+	struct xway_stp *chip = gpiochip_get_data(gc);
 
 	if (val)
 		chip->shadow |= BIT(gpio);
@@ -135,8 +134,7 @@ static int xway_stp_dir_out(struct gpio_chip *gc, unsigned gpio, int val)
  */
 static int xway_stp_request(struct gpio_chip *gc, unsigned gpio)
 {
-	struct xway_stp *chip =
-		container_of(gc, struct xway_stp, gc);
+	struct xway_stp *chip = gpiochip_get_data(gc);
 
 	if ((gpio < 8) && (chip->reserved & BIT(gpio))) {
 		dev_err(gc->parent, "GPIO %d is driven by hardware\n", gpio);
@@ -260,7 +258,7 @@ static int xway_stp_probe(struct platform_device *pdev)
 
 	ret = xway_stp_hw_init(chip);
 	if (!ret)
-		ret = gpiochip_add(&chip->gc);
+		ret = gpiochip_add_data(&chip->gc, chip);
 
 	if (!ret)
 		dev_info(&pdev->dev, "Init done\n");