| Message ID | 20240605110845.86740-2-paul@crapouillou.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iio: new DMABUF based API v10 | expand |
On 05-06-24, 13:08, Paul Cercueil wrote: > This function can be used to initiate a scatter-gather DMA transfer, > where the address and size of each segment is located in one entry of > the dma_vec array. > > The major difference with dmaengine_prep_slave_sg() is that it supports > specifying the lengths of each DMA transfer; as trying to override the > length of the transfer with dmaengine_prep_slave_sg() is a very tedious > process. The introduction of a new API function is also justified by the > fact that scatterlists are on their way out. > > Note that dmaengine_prep_interleaved_dma() is not helpful either in that > case, as it assumes that the address of each segment will be higher than > the one of the previous segment, which we just cannot guarantee in case > of a scatter-gather transfer. This looks good to me, but is missing Documentation changes for this API, pls add that > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> > Signed-off-by: Nuno Sa <nuno.sa@analog.com> > > --- > v3: New patch > > v5: Replace with function dmaengine_prep_slave_dma_vec(), and struct > 'dma_vec'. > Note that at some point we will need to support cyclic transfers > using dmaengine_prep_slave_dma_vec(). Maybe with a new "flags" > parameter to the function? > > v7: > - Renamed *device_prep_slave_dma_vec() -> device_prep_peripheral_dma_vec(); > - Added a new flag parameter to the function as agreed between Paul > and Vinod. I renamed the first parameter to prep_flags as it's supposed to > be used (I think) with enum dma_ctrl_flags. I'm not really sure how that API > can grow but I was thinking in just having a bool cyclic parameter (as the > first intention of the flags is to support cyclic transfers) but ended up > "respecting" the previously agreed approach. > > v10: > - Add kernel doc to dmaengine_prep_peripheral_dma_vec() > - Remove extra flags parameter > --- > include/linux/dmaengine.h | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h > index 752dbde4cec1..9fc03068cabc 100644 > --- a/include/linux/dmaengine.h > +++ b/include/linux/dmaengine.h > @@ -160,6 +160,16 @@ struct dma_interleaved_template { > struct data_chunk sgl[]; > }; > > +/** > + * struct dma_vec - DMA vector > + * @addr: Bus address of the start of the vector > + * @len: Length in bytes of the DMA vector > + */ > +struct dma_vec { > + dma_addr_t addr; > + size_t len; > +}; > + > /** > * enum dma_ctrl_flags - DMA flags to augment operation preparation, > * control completion, and communicate status. > @@ -910,6 +920,10 @@ struct dma_device { > struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)( > struct dma_chan *chan, unsigned long flags); > > + struct dma_async_tx_descriptor *(*device_prep_peripheral_dma_vec)( > + struct dma_chan *chan, const struct dma_vec *vecs, > + size_t nents, enum dma_transfer_direction direction, > + unsigned long flags); > struct dma_async_tx_descriptor *(*device_prep_slave_sg)( > struct dma_chan *chan, struct scatterlist *sgl, > unsigned int sg_len, enum dma_transfer_direction direction, > @@ -973,6 +987,25 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single( > dir, flags, NULL); > } > > +/** > + * dmaengine_prep_peripheral_dma_vec() - Prepare a DMA scatter-gather descriptor > + * @chan: The channel to be used for this descriptor > + * @vecs: The array of DMA vectors that should be transferred > + * @nents: The number of DMA vectors in the array > + * @dir: Specifies the direction of the data transfer > + * @flags: DMA engine flags > + */ > +static inline struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec( > + struct dma_chan *chan, const struct dma_vec *vecs, size_t nents, > + enum dma_transfer_direction dir, unsigned long flags) > +{ > + if (!chan || !chan->device || !chan->device->device_prep_peripheral_dma_vec) > + return NULL; > + > + return chan->device->device_prep_peripheral_dma_vec(chan, vecs, nents, > + 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) > -- > 2.43.0
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 752dbde4cec1..9fc03068cabc 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -160,6 +160,16 @@ struct dma_interleaved_template { struct data_chunk sgl[]; }; +/** + * struct dma_vec - DMA vector + * @addr: Bus address of the start of the vector + * @len: Length in bytes of the DMA vector + */ +struct dma_vec { + dma_addr_t addr; + size_t len; +}; + /** * enum dma_ctrl_flags - DMA flags to augment operation preparation, * control completion, and communicate status. @@ -910,6 +920,10 @@ struct dma_device { struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)( struct dma_chan *chan, unsigned long flags); + struct dma_async_tx_descriptor *(*device_prep_peripheral_dma_vec)( + struct dma_chan *chan, const struct dma_vec *vecs, + size_t nents, enum dma_transfer_direction direction, + unsigned long flags); struct dma_async_tx_descriptor *(*device_prep_slave_sg)( struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, enum dma_transfer_direction direction, @@ -973,6 +987,25 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single( dir, flags, NULL); } +/** + * dmaengine_prep_peripheral_dma_vec() - Prepare a DMA scatter-gather descriptor + * @chan: The channel to be used for this descriptor + * @vecs: The array of DMA vectors that should be transferred + * @nents: The number of DMA vectors in the array + * @dir: Specifies the direction of the data transfer + * @flags: DMA engine flags + */ +static inline struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec( + struct dma_chan *chan, const struct dma_vec *vecs, size_t nents, + enum dma_transfer_direction dir, unsigned long flags) +{ + if (!chan || !chan->device || !chan->device->device_prep_peripheral_dma_vec) + return NULL; + + return chan->device->device_prep_peripheral_dma_vec(chan, vecs, nents, + 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)