iio: core: move @scan_index_timestamp to struct iio_dev_opaque

No reason for this cached value to be exposed to drivers so move it
to the opaque structure.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Link: https://lore.kernel.org/r/20210426174911.397061-6-jic23@kernel.org

drivers/iio/industrialio-buffer.c

@@ -601,8 +601,10 @@ static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
 
 static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
 {
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
 	return iio_storage_bytes_for_si(indio_dev,
-					indio_dev->scan_index_timestamp);
+					iio_dev_opaque->scan_index_timestamp);
 }
 
 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
@@ -1469,6 +1471,7 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
 					     struct iio_dev *indio_dev,
 					     int index)
 {
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	struct iio_dev_attr *p;
 	struct attribute **attr;
 	int ret, i, attrn, scan_el_attrcount, buffer_attrcount;
@@ -1495,7 +1498,7 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
 				goto error_cleanup_dynamic;
 			scan_el_attrcount += ret;
 			if (channels[i].type == IIO_TIMESTAMP)
-				indio_dev->scan_index_timestamp =
+				iio_dev_opaque->scan_index_timestamp =
 					channels[i].scan_index;
 		}
 		if (indio_dev->masklength && buffer->scan_mask == NULL) {

include/linux/iio/iio-opaque.h

@@ -22,6 +22,7 @@
  * @groupcounter:		index of next attribute group
  * @legacy_scan_el_group:	attribute group for legacy scan elements attribute group
  * @legacy_buffer_group:	attribute group for legacy buffer attributes group
+ * @scan_index_timestamp:	cache of the index to the timestamp
  * @debugfs_dentry:		device specific debugfs dentry
  * @cached_reg_addr:		cached register address for debugfs reads
  * @read_buf:			read buffer to be used for the initial reg read
@@ -44,6 +45,9 @@ struct iio_dev_opaque {
 	int				groupcounter;
 	struct attribute_group		legacy_scan_el_group;
 	struct attribute_group		legacy_buffer_group;
+
+	unsigned int			scan_index_timestamp;
+
 #if defined(CONFIG_DEBUG_FS)
 	struct dentry			*debugfs_dentry;
 	unsigned			cached_reg_addr;

include/linux/iio/iio.h

@@ -501,7 +501,6 @@ struct iio_buffer_setup_ops {
  *			channels
  * @active_scan_mask:	[INTERN] union of all scan masks requested by buffers
  * @scan_timestamp:	[INTERN] set if any buffers have requested timestamp
- * @scan_index_timestamp:[INTERN] cache of the index to the timestamp
  * @trig:		[INTERN] current device trigger (buffer modes)
  * @pollfunc:		[DRIVER] function run on trigger being received
  * @pollfunc_event:	[DRIVER] function run on events trigger being received
@@ -532,7 +531,6 @@ struct iio_dev {
 	unsigned			masklength;
 	const unsigned long		*active_scan_mask;
 	bool				scan_timestamp;
-	unsigned			scan_index_timestamp;
 	struct iio_trigger		*trig;
 	struct iio_poll_func		*pollfunc;
 	struct iio_poll_func		*pollfunc_event;