iio: buffer: cache timestamp offset in scan buffer

Cache the offset (in bytes) for the timestamp element in a scan buffer.
This will be used later to ensure proper alignment of the timestamp
element in the scan buffer.

The new field could not be placed in struct iio_dev_opaque because we
will need to access it in a static inline function later, so we make it
__private instead. It is only intended to be used by core IIO code.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 2c91b7659ce9..ecbaeecbe0ac 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -584,6 +584,8 @@ struct iio_buffer_setup_ops {
  *			and owner
  * @buffer:		[DRIVER] any buffer present
  * @scan_bytes:		[INTERN] num bytes captured to be fed to buffer demux
+ * @scan_timestamp_offset: [INTERN] cache of the offset (in bytes) for the
+ *			   timestamp in the scan buffer
  * @available_scan_masks: [DRIVER] optional array of allowed bitmasks. Sort the
  *			   array in order of preference, the most preferred
  *			   masks first.
@@ -610,6 +612,7 @@ struct iio_dev {
 
 	struct iio_buffer		*buffer;
 	int				scan_bytes;
+	unsigned int			__private scan_timestamp_offset;
 
 	const unsigned long		*available_scan_masks;
 	unsigned int			__private masklength;