iio: sensors-core: st: Allow full-scale to be an optional feature

Some chips either don't support it or fail to provide adequate documentation,
so sometimes it's impossible to enable the feature even if it is supported.
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/common/st_sensors/st_sensors_core.c

@@ -235,10 +235,13 @@ int st_sensors_init_sensor(struct iio_dev *indio_dev,
 	if (err < 0)
 		goto init_error;
 
-	err = st_sensors_set_fullscale(indio_dev,
-						sdata->current_fullscale->num);
-	if (err < 0)
-		goto init_error;
+	if (sdata->current_fullscale) {
+		err = st_sensors_set_fullscale(indio_dev,
+					       sdata->current_fullscale->num);
+		if (err < 0)
+			goto init_error;
+	} else
+		dev_info(&indio_dev->dev, "Full-scale not possible\n");
 
 	err = st_sensors_set_odr(indio_dev, sdata->odr);
 	if (err < 0)

drivers/iio/pressure/st_pressure_core.c

@@ -226,8 +226,10 @@ int st_press_common_probe(struct iio_dev *indio_dev,
 	indio_dev->channels = pdata->sensor->ch;
 	indio_dev->num_channels = ARRAY_SIZE(st_press_channels);
 
-	pdata->current_fullscale = (struct st_sensor_fullscale_avl *)
-						&pdata->sensor->fs.fs_avl[0];
+	if (pdata->sensor->fs.addr != 0)
+		pdata->current_fullscale = (struct st_sensor_fullscale_avl *)
+			&pdata->sensor->fs.fs_avl[0];
+
 	pdata->odr = pdata->sensor->odr.odr_avl[0].hz;
 
 	if (!plat_data)