dw_dmac: add cyclic API to DW DMA driver

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>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/dw_dmac.h b/include/linux/dw_dmac.h
index d797dde247f..c8aad713a04 100644
--- a/include/linux/dw_dmac.h
+++ b/include/linux/dw_dmac.h
@@ -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 */