iio: core: Hide read accesses to iio_dev->currentmode

In order to later move this variable within the opaque structure, let's
create a helper for accessing it in read-only mode. This helper will be
exposed to device drivers and kept accessible for the few that could need
it. The write access to this variable however should be fully reserved to
the core so in a second step we will hide this variable into the opaque
structure.

Cc: Eugen Hristev <eugen.hristev@microchip.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20220207143840.707510-11-miquel.raynal@bootlin.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/bmc150-accel-core.c

@@ -1525,7 +1525,7 @@ static int bmc150_accel_buffer_postenable(struct iio_dev *indio_dev)
 	struct bmc150_accel_data *data = iio_priv(indio_dev);
 	int ret = 0;
 
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
+	if (iio_device_get_current_mode(indio_dev) == INDIO_BUFFER_TRIGGERED)
 		return 0;
 
 	mutex_lock(&data->mutex);
@@ -1557,7 +1557,7 @@ static int bmc150_accel_buffer_predisable(struct iio_dev *indio_dev)
 {
 	struct bmc150_accel_data *data = iio_priv(indio_dev);
 
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
+	if (iio_device_get_current_mode(indio_dev) == INDIO_BUFFER_TRIGGERED)
 		return 0;
 
 	mutex_lock(&data->mutex);

drivers/iio/adc/at91-sama5d2_adc.c

@@ -1117,7 +1117,7 @@ static int at91_adc_buffer_prepare(struct iio_dev *indio_dev)
 		return at91_adc_configure_touch(st, true);
 
 	/* if we are not in triggered mode, we cannot enable the buffer. */
-	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+	if (!(iio_device_get_current_mode(indio_dev) & INDIO_ALL_TRIGGERED_MODES))
 		return -EINVAL;
 
 	/* we continue with the triggered buffer */
@@ -1159,7 +1159,7 @@ static int at91_adc_buffer_postdisable(struct iio_dev *indio_dev)
 		return at91_adc_configure_touch(st, false);
 
 	/* if we are not in triggered mode, nothing to do here */
-	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+	if (!(iio_device_get_current_mode(indio_dev) & INDIO_ALL_TRIGGERED_MODES))
 		return -EINVAL;
 
 	/*

drivers/iio/industrialio-core.c

@@ -2070,6 +2070,17 @@ void iio_device_release_direct_mode(struct iio_dev *indio_dev)
 }
 EXPORT_SYMBOL_GPL(iio_device_release_direct_mode);
 
+/**
+ * iio_device_get_current_mode() - helper function providing read-only access to
+ *				   the @currentmode variable
+ * @indio_dev:			   IIO device structure for device
+ */
+int iio_device_get_current_mode(struct iio_dev *indio_dev)
+{
+	return indio_dev->currentmode;
+}
+EXPORT_SYMBOL_GPL(iio_device_get_current_mode);
+
 subsys_initcall(iio_init);
 module_exit(iio_exit);
 

include/linux/iio/iio.h

@@ -550,6 +550,7 @@ struct iio_dev {
 };
 
 int iio_device_id(struct iio_dev *indio_dev);
+int iio_device_get_current_mode(struct iio_dev *indio_dev);
 bool iio_buffer_enabled(struct iio_dev *indio_dev);
 
 const struct iio_chan_spec