iio: sensors-core: st: Support sensors which don't have a Data Ready pin

Not all ST's sensors support data ready, so let's make the declaration
of one conditional.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/common/st_sensors/st_sensors_core.c

@@ -198,21 +198,17 @@ int st_sensors_set_axis_enable(struct iio_dev *indio_dev, u8 axis_enable)
 }
 EXPORT_SYMBOL(st_sensors_set_axis_enable);
 
-int st_sensors_init_sensor(struct iio_dev *indio_dev,
-					struct st_sensors_platform_data *pdata)
+static int st_sensors_set_drdy_int_pin(struct iio_dev *indio_dev,
+				       struct st_sensors_platform_data *pdata)
 {
-	int err;
 	struct st_sensor_data *sdata = iio_priv(indio_dev);
 
-	mutex_init(&sdata->tb.buf_lock);
-
 	switch (pdata->drdy_int_pin) {
 	case 1:
 		if (sdata->sensor->drdy_irq.mask_int1 == 0) {
 			dev_err(&indio_dev->dev,
 					"DRDY on INT1 not available.\n");
-			err = -EINVAL;
-			goto init_error;
+			return -EINVAL;
 		}
 		sdata->drdy_int_pin = 1;
 		break;
@@ -220,17 +216,29 @@ int st_sensors_init_sensor(struct iio_dev *indio_dev,
 		if (sdata->sensor->drdy_irq.mask_int2 == 0) {
 			dev_err(&indio_dev->dev,
 					"DRDY on INT2 not available.\n");
-			err = -EINVAL;
-			goto init_error;
+			return -EINVAL;
 		}
 		sdata->drdy_int_pin = 2;
 		break;
 	default:
 		dev_err(&indio_dev->dev, "DRDY on pdata not valid.\n");
-		err = -EINVAL;
-		goto init_error;
+		return -EINVAL;
 	}
 
+	return 0;
+}
+
+int st_sensors_init_sensor(struct iio_dev *indio_dev,
+					struct st_sensors_platform_data *pdata)
+{
+	struct st_sensor_data *sdata = iio_priv(indio_dev);
+	int err = 0;
+
+	mutex_init(&sdata->tb.buf_lock);
+
+	if (pdata)
+		err = st_sensors_set_drdy_int_pin(indio_dev, pdata);
+
 	err = st_sensors_set_enable(indio_dev, false);
 	if (err < 0)
 		goto init_error;
@@ -266,6 +274,9 @@ int st_sensors_set_dataready_irq(struct iio_dev *indio_dev, bool enable)
 	u8 drdy_mask;
 	struct st_sensor_data *sdata = iio_priv(indio_dev);
 
+	if (!sdata->sensor->drdy_irq.addr)
+		return 0;
+
 	/* Enable/Disable the interrupt generator 1. */
 	if (sdata->sensor->drdy_irq.ig1.en_addr > 0) {
 		err = st_sensors_write_data_with_mask(indio_dev,