From mboxrd@z Thu Jan 1 00:00:00 1970 From: s.hauer@pengutronix.de (Sascha Hauer) Date: Mon, 16 Aug 2010 13:07:48 +0200 Subject: [PATCH 1/3] dmaengine: add possibility for cyclic transfers In-Reply-To: <1281956870-12463-1-git-send-email-s.hauer@pengutronix.de> References: <1281956870-12463-1-git-send-email-s.hauer@pengutronix.de> Message-ID: <1281956870-12463-2-git-send-email-s.hauer@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Cc: Haavard Skinnemoen --- drivers/dma/dmaengine.c | 2 ++ include/linux/dmaengine.h | 6 +++++- 2 files changed, 7 insertions(+), 1 deletions(-) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 9d31d5e..e5e79ce 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -692,6 +692,8 @@ int dma_async_device_register(struct dma_device *device) !device->device_prep_dma_interrupt); BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) && !device->device_prep_slave_sg); + BUG_ON(dma_has_cap(DMA_CYCLIC, device->cap_mask) && + !device->device_prep_dma_cyclic); BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) && !device->device_control); diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index c61d4ca..0df7864 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) /** @@ -478,6 +479,9 @@ 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); -- 1.7.1