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 b252b20..13a5807 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;