[PATCH 1/2] dmaengine: add dmaengine_prep_slave_sg_context() to wrap prep_slave_sg

[Frank . Li]

From: Frank Li <Frank.Li@xxxxxxx>

Most DMA engine providers and consumers do not use the context argument
of prep_slave_sg().  A few do, however:

Consumers:
  sound/soc/sprd/sprd-pcm-compress.c

Providers:
  drivers/dma/sprd-dma.c - sprd_dma_prep_slave_sg() casts context to
    struct sprd_dma_linklist * to set up a linked list descriptor chain.
  drivers/dma/ti/k3-udma.c - udma_prep_slave_sg() passes context down
    to internal sub-functions for normal, PKTDMA, and BCDMA variants.
  drivers/dma/xilinx/xilinx_dma.c - xilinx_dma_prep_slave_sg() and
    xilinx_mcdma_prep_slave_sg() both cast context to u32 *app_w to
    write APP words into DMA descriptors.

Add dmaengine_prep_slave_sg_context() as a wrapper so consumers do not
need to access the DMA engine callback pointer directly.  This is a
preparatory step toward making DMA engine provider internals private.

Make it as deprecated.

Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---
 include/linux/dmaengine.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index c3a49a33307c6..b4589cad6d742 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1084,6 +1084,19 @@ dmaengine_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	return dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, NULL);
 }
 
+/* Depercated, don't use it except sound/soc/sprd/ */
+static inline struct dma_async_tx_descriptor *
+dmaengine_prep_slave_sg_context(struct dma_chan *chan, struct scatterlist *sgl,
+				unsigned int sg_len, enum dma_transfer_direction dir,
+				unsigned long flags, void *context)
+{
+	if (!chan->device->device_prep_slave_sg)
+		return NULL;
+
+	return chan->device->device_prep_slave_sg(chan, sgl, sg_len, dir,
+						  flags, context);
+}
+
 /**
  * dmaengine_prep_config_sg_safe - prepare a scatter-gather DMA transfer
  *                                 with atomic slave configuration update

-- 
2.43.0