From 59b5ec21446b9239d706ab237fb261d525b75e81 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 6 Jan 2009 11:38:15 -0700 Subject: 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 Acked-by: Maciej Sosnowski Signed-off-by: Dan Williams --- include/linux/dmaengine.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'include') diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 57a43adfc39e..fe40bc020af6 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, }; @@ -223,6 +224,18 @@ struct dma_client; 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 @@ -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 --- */ -- cgit v1.2.1