iio: adc: ad4130: only set GPIO_CTRL if pin is unused

Currently, GPIO_CTRL bits are set even if the pins are used for
measurements.

GPIO_CTRL bits should only be set if the pin is not used for
other functionality.

Fix this by only setting the GPIO_CTRL bits if the pin has no
other function.

Fixes: 6209406 ("iio: adc: ad4130: add AD4130 driver")
Signed-off-by: Cosmin Tanislav <demonsingur@gmail.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240207132007.253768-2-demonsingur@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: Demon000

drivers/iio/adc/ad4130.c

@@ -1891,10 +1891,14 @@ static int ad4130_setup(struct iio_dev *indio_dev)
 		return ret;
 
 	/*
-	 * Configure all GPIOs for output. If configured, the interrupt function
-	 * of P2 takes priority over the GPIO out function.
+	 * Configure unused GPIOs for output. If configured, the interrupt
+	 * function of P2 takes priority over the GPIO out function.
 	 */
-	val =  AD4130_IO_CONTROL_GPIO_CTRL_MASK;
+	val = 0;
+	for (i = 0; i < AD4130_MAX_GPIOS; i++)
+		if (st->pins_fn[i + AD4130_AIN2_P1] == AD4130_PIN_FN_NONE)
+			val |= FIELD_PREP(AD4130_IO_CONTROL_GPIO_CTRL_MASK, BIT(i));
+
 	val |= FIELD_PREP(AD4130_IO_CONTROL_INT_PIN_SEL_MASK, st->int_pin_sel);
 
 	ret = regmap_write(st->regmap, AD4130_IO_CONTROL_REG, val);