gpiolib: Avoid calling chip->request() for unused gpios

Add a check for unused gpios to avoid chip->request() call to client
driver for unused gpios.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -2267,6 +2267,7 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
 	struct gpio_chip	*chip = desc->gdev->chip;
 	int			status;
 	unsigned long		flags;
+	unsigned		offset;
 
 	spin_lock_irqsave(&gpio_lock, flags);
 
@@ -2285,7 +2286,11 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
 	if (chip->request) {
 		/* chip->request may sleep */
 		spin_unlock_irqrestore(&gpio_lock, flags);
-		status = chip->request(chip, gpio_chip_hwgpio(desc));
+		offset = gpio_chip_hwgpio(desc);
+		if (gpiochip_line_is_valid(chip, offset))
+			status = chip->request(chip, offset);
+		else
+			status = -EINVAL;
 		spin_lock_irqsave(&gpio_lock, flags);
 
 		if (status < 0) {