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author | Dan Williams <dan.j.williams@intel.com> | 2009-01-06 11:38:15 -0700 |
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committer | Dan Williams <dan.j.williams@intel.com> | 2009-01-06 11:38:15 -0700 |
commit | 59b5ec21446b9239d706ab237fb261d525b75e81 (patch) | |
tree | a437a354e84d311104829ca0e8b00b0ec8cb05c4 /include/linux/dmaengine.h | |
parent | f67b45999205164958de4ec0658d51fa4bee066d (diff) | |
download | linux-3.10-59b5ec21446b9239d706ab237fb261d525b75e81.tar.gz linux-3.10-59b5ec21446b9239d706ab237fb261d525b75e81.tar.bz2 linux-3.10-59b5ec21446b9239d706ab237fb261d525b75e81.zip |
dmaengine: introduce dma_request_channel and private channels
This interface is primarily for device-to-memory clients which need to
search for dma channels with platform-specific characteristics. The
prototype is:
struct dma_chan *dma_request_channel(dma_cap_mask_t mask,
dma_filter_fn filter_fn,
void *filter_param);
When the optional 'filter_fn' parameter is set to NULL
dma_request_channel simply returns the first channel that satisfies the
capability mask. Otherwise, when the mask parameter is insufficient for
specifying the necessary channel, the filter_fn routine can be used to
disposition the available channels in the system. The filter_fn routine
is called once for each free channel in the system. Upon seeing a
suitable channel filter_fn returns DMA_ACK which flags that channel to
be the return value from dma_request_channel. A channel allocated via
this interface is exclusive to the caller, until dma_release_channel()
is called.
To ensure that all channels are not consumed by the general-purpose
allocator the DMA_PRIVATE capability is provided to exclude a dma_device
from general-purpose (memory-to-memory) consideration.
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'include/linux/dmaengine.h')
-rw-r--r-- | include/linux/dmaengine.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 57a43adfc39..fe40bc020af 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -89,6 +89,7 @@ enum dma_transaction_type { DMA_MEMSET, DMA_MEMCPY_CRC32C, DMA_INTERRUPT, + DMA_PRIVATE, DMA_SLAVE, }; @@ -224,6 +225,18 @@ typedef enum dma_state_client (*dma_event_callback) (struct dma_client *client, struct dma_chan *chan, enum dma_state state); /** + * typedef dma_filter_fn - callback filter for dma_request_channel + * @chan: channel to be reviewed + * @filter_param: opaque parameter passed through dma_request_channel + * + * When this optional parameter is specified in a call to dma_request_channel a + * suitable channel is passed to this routine for further dispositioning before + * being returned. Where 'suitable' indicates a non-busy channel that + * satisfies the given capability mask. + */ +typedef enum dma_state_client (*dma_filter_fn)(struct dma_chan *chan, void *filter_param); + +/** * struct dma_client - info on the entity making use of DMA services * @event_callback: func ptr to call when something happens * @cap_mask: only return channels that satisfy the requested capabilities @@ -472,6 +485,9 @@ void dma_async_device_unregister(struct dma_device *device); void dma_run_dependencies(struct dma_async_tx_descriptor *tx); struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type); void dma_issue_pending_all(void); +#define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y) +struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, void *fn_param); +void dma_release_channel(struct dma_chan *chan); /* --- Helper iov-locking functions --- */ |