dmaengine: Add API to combine configuration and preparation (sg and single)

Previously, configuration and preparation required two separate calls. This
works well when configuration is done only once during initialization.

However, in cases where the burst length or source/destination address must
be adjusted for each transfer, calling two functions is verbose and
requires additional locking to ensure both steps complete atomically.

Add a new API dmaengine_prep_config_single() and dmaengine_prep_config_sg()
and callback device_prep_config_sg() that combines configuration and
preparation into a single operation. If the configuration argument is
passed as NULL, fall back to the existing implementation.

Tested-by: Niklas Cassel <cassel@kernel.org>
Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260521-dma_prep_config-v7-1-1f73f4899883@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 55 insertions, 8 deletions

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index b3d251c9734e..defa377d2ef5 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -835,6 +835,7 @@ struct dma_filter {
  *	where the address and size of each segment is located in one entry of
  *	the dma_vec array.
  * @device_prep_slave_sg: prepares a slave dma operation
+ * @device_prep_config_sg: prepares a slave DMA operation with dma_slave_config
  * @device_prep_dma_cyclic: prepare a cyclic dma operation suitable for audio.
  *	The function takes a buffer of size buf_len. The callback function will
  *	be called after period_len bytes have been transferred.
@@ -934,6 +935,10 @@ struct dma_device {
 		struct dma_chan *chan, struct scatterlist *sgl,
 		unsigned int sg_len, enum dma_transfer_direction direction,
 		unsigned long flags, void *context);
+	struct dma_async_tx_descriptor *(*device_prep_config_sg)(
+		struct dma_chan *chan, struct scatterlist *sgl,
+		unsigned int sg_len, enum dma_transfer_direction direction,
+		unsigned long flags, struct dma_slave_config *config);
 	struct dma_async_tx_descriptor *(*device_prep_dma_cyclic)(
 		struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
 		size_t period_len, enum dma_transfer_direction direction,
@@ -974,22 +979,44 @@ static inline bool is_slave_direction(enum dma_transfer_direction direction)
 	       (direction == DMA_DEV_TO_DEV);
 }
 
-static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single(
-	struct dma_chan *chan, dma_addr_t buf, size_t len,
-	enum dma_transfer_direction dir, unsigned long flags)
+static inline struct dma_async_tx_descriptor *
+dmaengine_prep_config_single(struct dma_chan *chan, dma_addr_t buf, size_t len,
+			     enum dma_transfer_direction dir,
+			     unsigned long flags,
+			     struct dma_slave_config *config)
 {
 	struct scatterlist sg;
+
+	if (!chan || !chan->device)
+		return NULL;
+
 	sg_init_table(&sg, 1);
 	sg_dma_address(&sg) = buf;
 	sg_dma_len(&sg) = len;
 
-	if (!chan || !chan->device || !chan->device->device_prep_slave_sg)
+	if (chan->device->device_prep_config_sg)
+		return chan->device->device_prep_config_sg(chan, &sg, 1, dir,
+							   flags, config);
+
+	if (config)
+		if (dmaengine_slave_config(chan, config))
+			return NULL;
+
+	if (!chan->device->device_prep_slave_sg)
 		return NULL;
 
 	return chan->device->device_prep_slave_sg(chan, &sg, 1,
 						  dir, flags, NULL);
 }
 
+static inline struct dma_async_tx_descriptor *
+dmaengine_prep_slave_single(struct dma_chan *chan, dma_addr_t buf, size_t len,
+			    enum dma_transfer_direction dir,
+			    unsigned long flags)
+{
+	return dmaengine_prep_config_single(chan, buf, len, dir, flags, NULL);
+}
+
 /**
  * dmaengine_prep_peripheral_dma_vec() - Prepare a DMA scatter-gather descriptor
  * @chan: The channel to be used for this descriptor
@@ -1010,17 +1037,37 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec(
 							    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)
+static inline struct dma_async_tx_descriptor *
+dmaengine_prep_config_sg(struct dma_chan *chan, struct scatterlist *sgl,
+			 unsigned int sg_len, enum dma_transfer_direction dir,
+			 unsigned long flags, struct dma_slave_config *config)
 {
-	if (!chan || !chan->device || !chan->device->device_prep_slave_sg)
+	if (!chan || !chan->device)
+		return NULL;
+
+	if (chan->device->device_prep_config_sg)
+		return chan->device->device_prep_config_sg(chan, sgl, sg_len,
+				dir, flags, config);
+
+	if (config)
+		if (dmaengine_slave_config(chan, config))
+			return NULL;
+
+	if (!chan->device->device_prep_slave_sg)
 		return NULL;
 
 	return chan->device->device_prep_slave_sg(chan, sgl, sg_len,
 						  dir, flags, NULL);
 }
 
+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)
+{
+	return dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, NULL);
+}
+
 #ifdef CONFIG_RAPIDIO_DMA_ENGINE
 struct rio_dma_ext;
 static inline struct dma_async_tx_descriptor *dmaengine_prep_rio_sg(