gpiolib: have a single place of calling set_config()

Instead of calling the gpiochip's set_config() callback directly and
checking its existence every time - just add a new routine that performs
this check internally. Call it in gpio_set_config() and
gpiod_set_transitory(). Also call it in gpiod_set_debounce() and drop
the check for chip->set() as it's irrelevant to this config option.
Signed-off-by: NBartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -3042,6 +3042,15 @@ EXPORT_SYMBOL_GPL(gpiochip_free_own_desc);
  * rely on gpio_request() having been called beforehand.
  */
 
+static int gpio_do_set_config(struct gpio_chip *gc, unsigned int offset,
+			      enum pin_config_param mode)
+{
+	if (!gc->set_config)
+		return -ENOTSUPP;
+
+	return gc->set_config(gc, offset, mode);
+}
+
 static int gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 			   enum pin_config_param mode)
 {
@@ -3060,7 +3069,7 @@ static int gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 	}
 
 	config = PIN_CONF_PACKED(mode, arg);
-	return gc->set_config ? gc->set_config(gc, offset, config) : -ENOTSUPP;
+	return gpio_do_set_config(gc, offset, mode);
 }
 
 static int gpio_set_bias(struct gpio_chip *chip, struct gpio_desc *desc)
@@ -3294,15 +3303,9 @@ int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
 
 	VALIDATE_DESC(desc);
 	chip = desc->gdev->chip;
-	if (!chip->set || !chip->set_config) {
-		gpiod_dbg(desc,
-			  "%s: missing set() or set_config() operations\n",
-			  __func__);
-		return -ENOTSUPP;
-	}
 
 	config = pinconf_to_config_packed(PIN_CONFIG_INPUT_DEBOUNCE, debounce);
-	return chip->set_config(chip, gpio_chip_hwgpio(desc), config);
+	return gpio_do_set_config(chip, gpio_chip_hwgpio(desc), config);
 }
 EXPORT_SYMBOL_GPL(gpiod_set_debounce);
 
@@ -3339,7 +3342,7 @@ int gpiod_set_transitory(struct gpio_desc *desc, bool transitory)
 	packed = pinconf_to_config_packed(PIN_CONFIG_PERSIST_STATE,
 					  !transitory);
 	gpio = gpio_chip_hwgpio(desc);
-	rc = chip->set_config(chip, gpio, packed);
+	rc = gpio_do_set_config(chip, gpio, packed);
 	if (rc == -ENOTSUPP) {
 		dev_dbg(&desc->gdev->dev, "Persistence not supported for GPIO %d\n",
 				gpio);