[PATCH 1/8] dmaengine: Add API to combine configuration and preparation (sg and single)

[Frank Li]

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 and callback device_prep_slave_sg_config that combines
configuration and preparation into a single operation. If the configuration
argument is passed as NULL, fall back to the existing implementation.

Signed-off-by: Frank Li <Frank.Li at nxp.com>
---
 include/linux/dmaengine.h | 64 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 57 insertions(+), 7 deletions(-)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 99efe2b9b4ea9844ca6161208362ef18ef111d96..6c563549133a28e26f1bdc367372b1e4a748afcf 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -835,6 +835,8 @@ 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
+ *	(Depericated, use @device_prep_slave_sg_config)
+ * @device_prep_slave_sg_config: prepares a slave dma operation
  * @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 +936,11 @@ 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_slave_sg_config)(
+		struct dma_chan *chan, struct scatterlist *sgl,
+		unsigned int sg_len, enum dma_transfer_direction direction,
+		unsigned long flags, struct dma_slave_config *config,
+		void *context);
 	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 +981,44 @@ 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_slave_single_config(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;
 	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 || !chan->device)
+		return NULL;
+
+	if (chan->device->device_prep_slave_sg_config)
+		return chan->device->device_prep_slave_sg_config(chan, &sg, 1,
+					dir, flags, config, NULL);
+
+	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_slave_single_config(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
@@ -1009,17 +1038,38 @@ 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(
+static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg_config(
 	struct dma_chan *chan, struct scatterlist *sgl,	unsigned int sg_len,
-	enum dma_transfer_direction dir, unsigned long flags)
+	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_slave_sg_config)
+		return chan->device->device_prep_slave_sg_config(chan, sgl,
+								 sg_len, dir,
+								 flags, config,
+								 NULL);
+	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_slave_sg_config(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(

-- 
2.34.1