[PATCH 14/15] iio: buffer-dmaengine: Add support for cyclic buffers

[Paul Cercueil <paul@crapouillou.net>]

Handle the IIO_BUFFER_DMABUF_CYCLIC flag to support cyclic buffers.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/iio/buffer/industrialio-buffer-dma.c      |  1 +
 .../iio/buffer/industrialio-buffer-dmaengine.c    | 15 ++++++++++++---
 include/linux/iio/buffer-dma.h                    |  3 +++
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c
index fb39054d8c15..6658f103ee17 100644
--- a/drivers/iio/buffer/industrialio-buffer-dma.c
+++ b/drivers/iio/buffer/industrialio-buffer-dma.c
@@ -933,6 +933,7 @@ int iio_dma_buffer_enqueue_dmabuf(struct iio_buffer *buffer,
 	}
 
 	dma_block->bytes_used = iio_dmabuf->bytes_used ?: dma_block->size;
+	dma_block->cyclic = iio_dmabuf->flags & IIO_BUFFER_DMABUF_CYCLIC;
 
 	switch (dma_block->state) {
 	case IIO_BLOCK_STATE_QUEUED:
diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
index 57a8b2e4ba3c..952e2160a11e 100644
--- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c
+++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
@@ -81,9 +81,18 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue,
 	if (!block->bytes_used || block->bytes_used > max_size)
 		return -EINVAL;
 
-	desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,
-		block->phys_addr, block->bytes_used, dma_dir,
-		DMA_PREP_INTERRUPT);
+	if (block->cyclic) {
+		desc = dmaengine_prep_dma_cyclic(dmaengine_buffer->chan,
+						 block->phys_addr,
+						 block->size,
+						 block->bytes_used,
+						 dma_dir, 0);
+	} else {
+		desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,
+						   block->phys_addr,
+						   block->bytes_used, dma_dir,
+						   DMA_PREP_INTERRUPT);
+	}
 	if (!desc)
 		return -ENOMEM;
 
diff --git a/include/linux/iio/buffer-dma.h b/include/linux/iio/buffer-dma.h
index 85e55fe35282..27639fdf7b54 100644
--- a/include/linux/iio/buffer-dma.h
+++ b/include/linux/iio/buffer-dma.h
@@ -42,6 +42,7 @@ enum iio_block_state {
  * @phys_addr: Physical address of the blocks memory
  * @queue: Parent DMA buffer queue
  * @state: Current state of the block
+ * @cyclic: True if this is a cyclic buffer
  * @fileio: True if this buffer is used for fileio mode
  * @dmabuf: Underlying DMABUF object
  */
@@ -65,6 +66,8 @@ struct iio_dma_buffer_block {
 	 */
 	enum iio_block_state state;
 
+	bool cyclic;
+
 	bool fileio;
 	struct dma_buf *dmabuf;
 };
-- 
2.33.0