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dw_dmac: add cyclic API to DW DMA driver

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This patch adds a cyclic DMA interface to the DW DMA driver. This is
very useful if you want to use the DMA controller in combination with a
sound device which uses cyclic buffers.

Using a DMA channel for cyclic DMA will disable the possibility to use
it as a normal DMA engine until the user calls the cyclic free function
on the DMA channel. Also a cyclic DMA list can not be prepared if the
channel is already active.

Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Hans-Christian Egtvedt
2009-04-01 15:47:02 +02:00
committed by Dan Williams
parent 0f571515c3
commit d9de451989
3 changed files with 356 additions and 2 deletions
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19
include/linux/dw_dmac.h
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@@ -74,4 +74,23 @@ struct dw_dma_slave {
#define DWC_CFGL_HS_DST_POL (1 << 18) /* dst handshake active low */
#define DWC_CFGL_HS_SRC_POL (1 << 19) /* src handshake active low */
/* DMA API extensions */
struct dw_cyclic_desc {
struct dw_desc **desc;
unsigned long periods;
void (*period_callback)(void *param);
void *period_callback_param;
};
struct dw_cyclic_desc *dw_dma_cyclic_prep(struct dma_chan *chan,
dma_addr_t buf_addr, size_t buf_len, size_t period_len,
enum dma_data_direction direction);
void dw_dma_cyclic_free(struct dma_chan *chan);
int dw_dma_cyclic_start(struct dma_chan *chan);
void dw_dma_cyclic_stop(struct dma_chan *chan);
dma_addr_t dw_dma_get_src_addr(struct dma_chan *chan);
dma_addr_t dw_dma_get_dst_addr(struct dma_chan *chan);
#endif /* DW_DMAC_H */