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iio: buffer: cache timestamp offset in scan buffer

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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>
This commit is contained in:
David Lechner 2026-03-07 19:44:11 -06:00 committed by Jonathan Cameron
parent 78abd04ea1
commit cb27d8c18f
2 changed files with 14 additions and 3 deletions
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14
drivers/iio/industrialio-buffer.c
View File

@ -765,7 +765,8 @@ static int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
const unsigned long *mask, bool timestamp,
unsigned int *scan_bytes)
unsigned int *scan_bytes,
unsigned int *timestamp_offset)
{
unsigned int bytes = 0;
int length, i, largest = 0;
@ -787,6 +788,10 @@ static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
return length;
bytes = ALIGN(bytes, length);
if (timestamp_offset)
*timestamp_offset = bytes;
bytes += length;
largest = max(largest, length);
}
@ -848,7 +853,7 @@ static int iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
return 0;
ret = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
buffer->scan_timestamp, &bytes);
buffer->scan_timestamp, &bytes, NULL);
if (ret)
return ret;
@ -892,6 +897,7 @@ struct iio_device_config {
unsigned int watermark;
const unsigned long *scan_mask;
unsigned int scan_bytes;
unsigned int scan_timestamp_offset;
bool scan_timestamp;
};
@ -997,7 +1003,8 @@ static int iio_verify_update(struct iio_dev *indio_dev,
}
ret = iio_compute_scan_bytes(indio_dev, scan_mask, scan_timestamp,
&config->scan_bytes);
&config->scan_bytes,
&config->scan_timestamp_offset);
if (ret)
return ret;
@ -1155,6 +1162,7 @@ static int iio_enable_buffers(struct iio_dev *indio_dev,
indio_dev->active_scan_mask = config->scan_mask;
ACCESS_PRIVATE(indio_dev, scan_timestamp) = config->scan_timestamp;
indio_dev->scan_bytes = config->scan_bytes;
ACCESS_PRIVATE(indio_dev, scan_timestamp_offset) = config->scan_timestamp_offset;
iio_dev_opaque->currentmode = config->mode;
iio_update_demux(indio_dev);

3
include/linux/iio/iio.h
View File

@ -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;