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, 6 insertions, 1 deletions

diff --git a/drivers/dma/dw_dmac_regs.h b/drivers/dma/dw_dmac_regs.h
index b252b202c5cf..13a580767031 100644
--- a/drivers/dma/dw_dmac_regs.h
+++ b/drivers/dma/dw_dmac_regs.h
@@ -126,6 +126,10 @@ struct dw_dma_regs {
 
 #define DW_REGLEN               0x400
 
+enum dw_dmac_flags {
+        DW_DMA_IS_CYCLIC = 0,
+};
+
 struct dw_dma_chan {
         struct dma_chan         chan;
         void __iomem            *ch_regs;
@@ -134,10 +138,12 @@ struct dw_dma_chan {
         spinlock_t              lock;
 
         /* these other elements are all protected by lock */
+        unsigned long           flags;
         dma_cookie_t            completed;
         struct list_head        active_list;
         struct list_head        queue;
         struct list_head        free_list;
+        struct dw_cyclic_desc   *cdesc;
 
         unsigned int            descs_allocated;
 };
@@ -158,7 +164,6 @@ static inline struct dw_dma_chan *to_dw_dma_chan(struct dma_chan *chan)
         return container_of(chan, struct dw_dma_chan, chan);
 }
 
-
 struct dw_dma {
         struct dma_device       dma;
         void __iomem            *regs;