On 25/08/17 21:59, Dave Jiang wrote:
> Adding a dmaengine transaction operation that allows copy to/from a
> scatterlist and a flat buffer.
Apologies if I'm late to the party, but doesn't DMA_SG already cover
this use-case? As far as I can see, all this does is save the caller
from setting up a single-entry scatterlist to describe the buffer - even
if such a simplified interface is justified it seems like something that
could be implemented as a wrapper around dmaengine_prep_dma_sg() rather
than the providers having to implement a whole extra callback.
Robin.
>
> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> ---
> Documentation/dmaengine/provider.txt | 3 +++
> drivers/dma/dmaengine.c | 2 ++
> include/linux/dmaengine.h | 19 +++++++++++++++++++
> 3 files changed, 24 insertions(+)
>
> diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt
> index a75f52f..6241e36 100644
> --- a/Documentation/dmaengine/provider.txt
> +++ b/Documentation/dmaengine/provider.txt
> @@ -181,6 +181,9 @@ Currently, the types available are:
> - Used by the client drivers to register a callback that will be
> called on a regular basis through the DMA controller interrupt
>
> + * DMA_MEMCPY_SG
> + - The device supports scatterlist to/from memory.
> +
> * DMA_PRIVATE
> - The devices only supports slave transfers, and as such isn't
> available for async transfers.
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 428b141..4d2c4e1 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -937,6 +937,8 @@ 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_MEMCPY_SG, device->cap_mask) &&
> + !device->device_prep_dma_memcpy_sg);
> BUG_ON(dma_has_cap(DMA_CYCLIC, device->cap_mask) &&
> !device->device_prep_dma_cyclic);
> BUG_ON(dma_has_cap(DMA_INTERLEAVE, device->cap_mask) &&
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 64fbd38..0c91411 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -67,6 +67,7 @@ enum dma_transaction_type {
> DMA_PQ_VAL,
> DMA_MEMSET,
> DMA_MEMSET_SG,
> + DMA_MEMCPY_SG,
> DMA_INTERRUPT,
> DMA_PRIVATE,
> DMA_ASYNC_TX,
> @@ -692,6 +693,7 @@ struct dma_filter {
> * @device_prep_dma_pq_val: prepares a pqzero_sum operation
> * @device_prep_dma_memset: prepares a memset operation
> * @device_prep_dma_memset_sg: prepares a memset operation over a scatter list
> + * @device_prep_dma_memcpy_sg: prepares memcpy between scatterlist and buffer
> * @device_prep_dma_interrupt: prepares an end of chain interrupt operation
> * @device_prep_slave_sg: prepares a slave dma operation
> * @device_prep_dma_cyclic: prepare a cyclic dma operation suitable for audio.
> @@ -768,6 +770,10 @@ struct dma_device {
> struct dma_async_tx_descriptor *(*device_prep_dma_memset_sg)(
> struct dma_chan *chan, struct scatterlist *sg,
> unsigned int nents, int value, unsigned long flags);
> + struct dma_async_tx_descriptor *(*device_prep_dma_memcpy_sg)(
> + struct dma_chan *chan,
> + struct scatterlist *sg, unsigned int sg_nents,
> + dma_addr_t buf, bool to_sg, unsigned long flags);
> struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)(
> struct dma_chan *chan, unsigned long flags);
>
> @@ -899,6 +905,19 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_memcpy(
> len, flags);
> }
>
> +static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_memcpy_sg(
> + struct dma_chan *chan, struct scatterlist *sg,
> + unsigned int sg_nents, dma_addr_t buf, bool to_sg,
> + unsigned long flags)
> +{
> + if (!chan || !chan->device ||
> + !chan->device->device_prep_dma_memcpy_sg)
> + return NULL;
> +
> + return chan->device->device_prep_dma_memcpy_sg(chan, sg, sg_nents,
> + buf, to_sg, flags);
> +}
> +
> /**
> * dmaengine_terminate_all() - Terminate all active DMA transfers
> * @chan: The channel for which to terminate the transfers
>
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