Commit 95ec3fdf authored by Jonathan Cameron's avatar Jonathan Cameron
Browse files

iio: core: Introduce iio_push_to_buffers_with_ts_unaligned() 



Whilst it is almost always possible to arrange for scan data to be
read directly into a buffer that is suitable for passing to
iio_push_to_buffers_with_timestamp(), there are a few places where
leading data needs to be skipped over.

For these cases introduce a function that will allocate an appropriate
sized and aligned bounce buffer (if not already allocated) and copy
the unaligned data into that before calling
iio_push_to_buffers_with_timestamp() on the bounce buffer.
We tie the lifespace of this buffer to that of the iio_dev.dev
which should ensure no memory leaks occur.

Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: default avatarNuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210613151039.569883-2-jic23@kernel.org
parent b18831cc

drivers/iio/industrialio-buffer.c

+46 −0
Original line number Diff line number Diff line
@@ -1731,6 +1731,52 @@ int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data) 
}

EXPORT_SYMBOL_GPL(iio_push_to_buffers);



/**

 * iio_push_to_buffers_with_ts_unaligned() - push to registered buffer,

 *    no alignment or space requirements.

 * @indio_dev:		iio_dev structure for device.

 * @data:		channel data excluding the timestamp.

 * @data_sz:		size of data.

 * @timestamp:		timestamp for the sample data.

 *

 * This special variant of iio_push_to_buffers_with_timestamp() does

 * not require space for the timestamp, or 8 byte alignment of data.

 * It does however require an allocation on first call and additional

 * copies on all calls, so should be avoided if possible.

 */

int iio_push_to_buffers_with_ts_unaligned(struct iio_dev *indio_dev,

					  const void *data,

					  size_t data_sz,

					  int64_t timestamp)

{

	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);



	/*

	 * Conservative estimate - we can always safely copy the minimum

	 * of either the data provided or the length of the destination buffer.

	 * This relaxed limit allows the calling drivers to be lax about

	 * tracking the size of the data they are pushing, at the cost of

	 * unnecessary copying of padding.

	 */

	data_sz = min_t(size_t, indio_dev->scan_bytes, data_sz);

	if (iio_dev_opaque->bounce_buffer_size !=  indio_dev->scan_bytes) {

		void *bb;



		bb = devm_krealloc(&indio_dev->dev,

				   iio_dev_opaque->bounce_buffer,

				   indio_dev->scan_bytes, GFP_KERNEL);

		if (!bb)

			return -ENOMEM;

		iio_dev_opaque->bounce_buffer = bb;

		iio_dev_opaque->bounce_buffer_size = indio_dev->scan_bytes;

	}

	memcpy(iio_dev_opaque->bounce_buffer, data, data_sz);

	return iio_push_to_buffers_with_timestamp(indio_dev,

						  iio_dev_opaque->bounce_buffer,

						  timestamp);

}

EXPORT_SYMBOL_GPL(iio_push_to_buffers_with_ts_unaligned);



/**

 * iio_buffer_release() - Free a buffer's resources

 * @ref: Pointer to the kref embedded in the iio_buffer struct

include/linux/iio/buffer.h

+4 −0
Original line number Diff line number Diff line
@@ -38,6 +38,10 @@ static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev, 
	return iio_push_to_buffers(indio_dev, data);

}



int iio_push_to_buffers_with_ts_unaligned(struct iio_dev *indio_dev,

					  const void *data, size_t data_sz,

					  int64_t timestamp);



bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,

				   const unsigned long *mask);

include/linux/iio/iio-opaque.h

+4 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
 * @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

 * @bounce_buffer:		for devices that call iio_push_to_buffers_with_timestamp_unaligned()

 * @bounce_buffer_size:		size of currently allocate bounce buffer

 * @scan_index_timestamp:	cache of the index to the timestamp

 * @clock_id:			timestamping clock posix identifier

 * @chrdev:			associated character device
@@ -50,6 +52,8 @@ struct iio_dev_opaque { 
	int				groupcounter;

	struct attribute_group		legacy_scan_el_group;

	struct attribute_group		legacy_buffer_group;

	void				*bounce_buffer;

	size_t				bounce_buffer_size;



	unsigned int			scan_index_timestamp;

	clockid_t			clock_id;