iio: core: Move the currentmode entry to the opaque structure

This entry should, under no situation, be modified by device
drivers. Now that we have limited its read access to device drivers
really needing it and did so through a dedicated helper, we can
easily move this variable to the opaque structure in order to
prevent any further modification from non-authorized code (out of the
core, basically).

Signed-off-by: Miquel Raynal <[e-mail]>
Reviewed-by: Alexandru Ardelean <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/industrialio-buffer.c

···
 	indio_dev->active_scan_mask = config->scan_mask;
 	indio_dev->scan_timestamp = config->scan_timestamp;
 	indio_dev->scan_bytes = config->scan_bytes;
-	indio_dev->currentmode = config->mode;
+	iio_dev_opaque->currentmode = config->mode;
 
 	iio_update_demux(indio_dev);
 
···
 		}
 	}
 
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
+	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
 		ret = iio_trigger_attach_poll_func(indio_dev->trig,
 						   indio_dev->pollfunc);
 		if (ret)
···
 	return 0;
 
 err_detach_pollfunc:
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
+	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
 		iio_trigger_detach_poll_func(indio_dev->trig,
 					     indio_dev->pollfunc);
 	}
···
 	if (indio_dev->setup_ops->postdisable)
 		indio_dev->setup_ops->postdisable(indio_dev);
 err_undo_config:
-	indio_dev->currentmode = INDIO_DIRECT_MODE;
+	iio_dev_opaque->currentmode = INDIO_DIRECT_MODE;
 	indio_dev->active_scan_mask = NULL;
 
 	return ret;
···
 			ret = ret2;
 	}
 
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
+	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
 		iio_trigger_detach_poll_func(indio_dev->trig,
 					     indio_dev->pollfunc);
 	}
···
 
 	iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
 	indio_dev->active_scan_mask = NULL;
-	indio_dev->currentmode = INDIO_DIRECT_MODE;
+	iio_dev_opaque->currentmode = INDIO_DIRECT_MODE;
 
 	return ret;
 }

drivers/iio/industrialio-core.c

···
  */
 bool iio_buffer_enabled(struct iio_dev *indio_dev)
 {
-	return indio_dev->currentmode
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
+	return iio_dev_opaque->currentmode
 		& (INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE |
 		   INDIO_BUFFER_SOFTWARE);
 }
···
 
 /**
  * iio_device_get_current_mode() - helper function providing read-only access to
- *				   the @currentmode variable
+ *				   the opaque @currentmode variable
  * @indio_dev:			   IIO device structure for device
  */
 int iio_device_get_current_mode(struct iio_dev *indio_dev)
 {
-	return indio_dev->currentmode;
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
+	return iio_dev_opaque->currentmode;
 }
 EXPORT_SYMBOL_GPL(iio_device_get_current_mode);
 

drivers/iio/industrialio-trigger.c

···
 	int ret;
 
 	mutex_lock(&indio_dev->mlock);
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
+	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
 		mutex_unlock(&indio_dev->mlock);
 		return -EBUSY;
 	}

include/linux/iio/iio-opaque.h

···
  * struct iio_dev_opaque - industrial I/O device opaque information
  * @indio_dev:			public industrial I/O device information
  * @id:			used to identify device internally
+ * @currentmode:		operating mode currently in use, may be eventually
+ *				checked by device drivers but should be considered
+ *				read-only as this is a core internal bit
  * @driver_module:		used to make it harder to undercut users
  * @info_exist_lock:		lock to prevent use during removal
  * @trig_readonly:		mark the current trigger immutable
···
  */
 struct iio_dev_opaque {
 	struct iio_dev			indio_dev;
+	int				currentmode;
 	int				id;
 	struct module			*driver_module;
 	struct mutex			info_exist_lock;

include/linux/iio/iio.h

···
  *			also be filed up by the IIO core, as a result of
  *			enabling particular features in the driver
  *			(see iio_triggered_event_setup()).
- * @currentmode:	[INTERN] operating mode currently in use, may be
- *			eventually checked by device drivers but should be
- *			considered read-only as this is a core internal bit
  * @dev:		[DRIVER] device structure, should be assigned a parent
  *			and owner
  * @buffer:		[DRIVER] any buffer present
···
  */
 struct iio_dev {
 	int				modes;
-	int				currentmode;
 	struct device			dev;
 
 	struct iio_buffer		*buffer;