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authorSascha Hauer <s.hauer@pengutronix.de>2010-09-30 13:56:32 +0000
committerDan Williams <dan.j.williams@intel.com>2010-10-05 15:49:26 -0700
commit782bc950d84e404422ba21008fd51ee894c8d231 (patch)
treec8a10b80bcc571c6de8a19c39b0f447ca61039d6 /include
parentb30a3f6257ed2105259b404d419b4964e363928c (diff)
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dmaengine: add possibility for cyclic transfers
Cyclic transfers are useful for audio where a single buffer divided in periods has to be transfered endlessly until stopped. After being prepared the transfer is started using the dma_async_descriptor->tx_submit function. dma_async_descriptor->callback is called after each period. The transfer is stopped using the DMA_TERMINATE_ALL callback. While being used for cyclic transfers the channel cannot be used for other transfer types. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Cc: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/dmaengine.h9
1 files changed, 8 insertions, 1 deletions
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index c61d4ca27bc..32cd84b4747 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -67,10 +67,11 @@ enum dma_transaction_type {
DMA_PRIVATE,
DMA_ASYNC_TX,
DMA_SLAVE,
+ DMA_CYCLIC,
};
/* last transaction type for creation of the capabilities mask */
-#define DMA_TX_TYPE_END (DMA_SLAVE + 1)
+#define DMA_TX_TYPE_END (DMA_CYCLIC + 1)
/**
@@ -422,6 +423,9 @@ struct dma_tx_state {
* @device_prep_dma_memset: prepares a memset operation
* @device_prep_dma_interrupt: prepares an end of chain interrupt operation
* @device_prep_slave_sg: prepares a slave dma operation
+ * @device_prep_dma_cyclic: prepare a cyclic dma operation suitable for audio.
+ * The function takes a buffer of size buf_len. The callback function will
+ * be called after period_len bytes have been transferred.
* @device_control: manipulate all pending operations on a channel, returns
* zero or error code
* @device_tx_status: poll for transaction completion, the optional
@@ -478,6 +482,9 @@ struct dma_device {
struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_data_direction direction,
unsigned long flags);
+ struct dma_async_tx_descriptor *(*device_prep_dma_cyclic)(
+ struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
+ size_t period_len, enum dma_data_direction direction);
int (*device_control)(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
unsigned long arg);