dma: add support for scatterlist to scatterlist copy

This adds support for scatterlist to scatterlist DMA transfers. A
similar interface is exposed by the fsldma driver (through the DMA_SLAVE
API) and by the ste_dma40 driver (through an exported function).

This patch paves the way for making this type of copy operation a part
of the generic DMAEngine API. Futher patches will add support in
individual drivers.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 8 insertions, 0 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 9d31d5eb95c1..db403b8ccabd 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -690,6 +690,8 @@ int dma_async_device_register(struct dma_device *device)
                 !device->device_prep_dma_memset);
         BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
                 !device->device_prep_dma_interrupt);
+        BUG_ON(dma_has_cap(DMA_SG, device->cap_mask) &&
+                !device->device_prep_dma_sg);
         BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
                 !device->device_prep_slave_sg);
         BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index e2106495cc11..2c9ee98f6c77 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -64,6 +64,7 @@ enum dma_transaction_type {
         DMA_PQ_VAL,
         DMA_MEMSET,
         DMA_INTERRUPT,
+        DMA_SG,
         DMA_PRIVATE,
         DMA_ASYNC_TX,
         DMA_SLAVE,
@@ -473,6 +474,11 @@ struct dma_device {
                 unsigned long flags);
         struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)(
                 struct dma_chan *chan, unsigned long flags);
+        struct dma_async_tx_descriptor *(*device_prep_dma_sg)(
+                struct dma_chan *chan,
+                struct scatterlist *dst_sg, unsigned int dst_nents,
+                struct scatterlist *src_sg, unsigned int src_nents,
+                unsigned long flags);
 
         struct dma_async_tx_descriptor *(*device_prep_slave_sg)(
                 struct dma_chan *chan, struct scatterlist *sgl,