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DMAEngine: Define interleaved transfer request api

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Define a new api that could be used for doing fancy data transfers
like interleaved to contiguous copy and vice-versa.
Traditional SG_list based transfers tend to be very inefficient in
such cases as where the interleave and chunk are only a few bytes,
which call for a very condensed api to convey pattern of the transfer.
This api supports all 4 variants of scatter-gather and contiguous transfer.

Of course, neither can this api help transfers that don't lend to DMA by
nature, i.e, scattered tiny read/writes with no periodic pattern.

Also since now we support SLAVE channels that might not provide
device_prep_slave_sg callback but device_prep_interleaved_dma,
remove the BUG_ON check.

Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Acked-by: Barry Song <Baohua.Song@csr.com>
[renamed dmaxfer_template to dma_interleaved_template
 did fixup after the enum dma_transfer_merge]
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
This commit is contained in:
Jassi Brar
2011-10-13 12:33:30 +05:30
committed by Vinod Koul
parent e0d23ef29e
commit b14dab792d
3 changed files with 85 additions and 5 deletions
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78
include/linux/dmaengine.h
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@ -71,10 +71,10 @@ enum dma_transaction_type {
DMA_ASYNC_TX,
DMA_SLAVE,
DMA_CYCLIC,
};
DMA_INTERLEAVE,
/* last transaction type for creation of the capabilities mask */
#define DMA_TX_TYPE_END (DMA_CYCLIC + 1)
DMA_TX_TYPE_END,
};
/**
* enum dma_transfer_direction - dma transfer mode and direction indicator
@ -90,6 +90,74 @@ enum dma_transfer_direction {
DMA_DEV_TO_DEV,
};
/**
* Interleaved Transfer Request
* ----------------------------
* A chunk is collection of contiguous bytes to be transfered.
* The gap(in bytes) between two chunks is called inter-chunk-gap(ICG).
* ICGs may or maynot change between chunks.
* A FRAME is the smallest series of contiguous {chunk,icg} pairs,
* that when repeated an integral number of times, specifies the transfer.
* A transfer template is specification of a Frame, the number of times
* it is to be repeated and other per-transfer attributes.
*
* Practically, a client driver would have ready a template for each
* type of transfer it is going to need during its lifetime and
* set only 'src_start' and 'dst_start' before submitting the requests.
*
*
* | Frame-1 | Frame-2 | ~ | Frame-'numf' |
* |====....==.===...=...|====....==.===...=...| ~ |====....==.===...=...|
*
* == Chunk size
* ... ICG
*/
/**
* struct data_chunk - Element of scatter-gather list that makes a frame.
* @size: Number of bytes to read from source.
* size_dst := fn(op, size_src), so doesn't mean much for destination.
* @icg: Number of bytes to jump after last src/dst address of this
* chunk and before first src/dst address for next chunk.
* Ignored for dst(assumed 0), if dst_inc is true and dst_sgl is false.
* Ignored for src(assumed 0), if src_inc is true and src_sgl is false.
*/
struct data_chunk {
size_t size;
size_t icg;
};
/**
* struct dma_interleaved_template - Template to convey DMAC the transfer pattern
* and attributes.
* @src_start: Bus address of source for the first chunk.
* @dst_start: Bus address of destination for the first chunk.
* @dir: Specifies the type of Source and Destination.
* @src_inc: If the source address increments after reading from it.
* @dst_inc: If the destination address increments after writing to it.
* @src_sgl: If the 'icg' of sgl[] applies to Source (scattered read).
* Otherwise, source is read contiguously (icg ignored).
* Ignored if src_inc is false.
* @dst_sgl: If the 'icg' of sgl[] applies to Destination (scattered write).
* Otherwise, destination is filled contiguously (icg ignored).
* Ignored if dst_inc is false.
* @numf: Number of frames in this template.
* @frame_size: Number of chunks in a frame i.e, size of sgl[].
* @sgl: Array of {chunk,icg} pairs that make up a frame.
*/
struct dma_interleaved_template {
dma_addr_t src_start;
dma_addr_t dst_start;
enum dma_transfer_direction dir;
bool src_inc;
bool dst_inc;
bool src_sgl;
bool dst_sgl;
size_t numf;
size_t frame_size;
struct data_chunk sgl[0];
};
/**
* enum dma_ctrl_flags - DMA flags to augment operation preparation,
* control completion, and communicate status.
@ -445,6 +513,7 @@ struct dma_tx_state {
* @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.
* @device_prep_interleaved_dma: Transfer expression in a generic way.
* @device_control: manipulate all pending operations on a channel, returns
* zero or error code
* @device_tx_status: poll for transaction completion, the optional
@ -509,6 +578,9 @@ struct dma_device {
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);
struct dma_async_tx_descriptor *(*device_prep_interleaved_dma)(
struct dma_chan *chan, struct dma_interleaved_template *xt,
unsigned long flags);
int (*device_control)(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
unsigned long arg);