[PATCH v3 01/11] dmaengine: Add API function dmaengine_prep_slave_dma_array()

[Paul Cercueil]

This function can be used to initiate a scatter-gather DMA transfer
where the DMA addresses and lengths are located inside arrays.

The major difference with dmaengine_prep_slave_sg() is that it supports
specifying the lengths of each DMA transfer; as trying to override the
length of the transfer with dmaengine_prep_slave_sg() is a very tedious
process. The introduction of a new API function is also justified by the
fact that scatterlists are on their way out.

Signed-off-by: Paul Cercueil <paul at crapouillou.net>

---
v3: New patch
---
 include/linux/dmaengine.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index c3656e590213..62efa28c009a 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -912,6 +912,11 @@ struct dma_device {
 	struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)(
 		struct dma_chan *chan, unsigned long flags);
 
+	struct dma_async_tx_descriptor *(*device_prep_slave_dma_array)(
+		struct dma_chan *chan, dma_addr_t *addrs,
+		size_t *lengths, size_t nb,
+		enum dma_transfer_direction direction,
+		unsigned long flags);
 	struct dma_async_tx_descriptor *(*device_prep_slave_sg)(
 		struct dma_chan *chan, struct scatterlist *sgl,
 		unsigned int sg_len, enum dma_transfer_direction direction,
@@ -974,6 +979,17 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single(
 						  dir, flags, NULL);
 }
 
+static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_dma_array(
+	struct dma_chan *chan, dma_addr_t *addrs, size_t *lengths,
+	size_t nb, enum dma_transfer_direction dir, unsigned long flags)
+{
+	if (!chan || !chan->device || !chan->device->device_prep_slave_dma_array)
+		return NULL;
+
+	return chan->device->device_prep_slave_dma_array(chan, addrs, lengths,
+							 nb, dir, flags);
+}
+
 static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
 	struct dma_chan *chan, struct scatterlist *sgl,	unsigned int sg_len,
 	enum dma_transfer_direction dir, unsigned long flags)
-- 
2.39.2