[PATCH 3/9] dmaengine: Introduce a device_config callback

From: Maxime Ripard
Date: Sat Sep 27 2014 - 04:59:04 EST

The fact that the channel configuration is done in device_control is rather
misleading, since it's not really advertised as such, plus, the fact that the
framework exposes a function of its own makes it not really intuitive, while
we're losing the type checking whenever we pass that unsigned long argument.

Add a device_config callback to dma_device, with a fallback on the old
behaviour for now for existing drivers to opt in.

Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
include/linux/dmaengine.h | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index f4b71ce1a0a6..7937f81e5e2e 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -608,6 +608,8 @@ struct dma_tx_state {
* The function takes a buffer of size buf_len. The callback function will
* be called after period_len bytes have been transferred.
* @device_prep_interleaved_dma: Transfer expression in a generic way.
+ * @device_config: Pushes a new configuration to a channel, return 0 or an error
+ * code
* @device_control: manipulate all pending operations on a channel, returns
* zero or error code
* @device_tx_status: poll for transaction completion, the optional
@@ -662,7 +664,6 @@ struct dma_device {
struct scatterlist *dst_sg, unsigned int dst_nents,
struct scatterlist *src_sg, unsigned int src_nents,
unsigned long flags);
struct dma_async_tx_descriptor *(*device_prep_slave_sg)(
struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction direction,
@@ -674,9 +675,11 @@ struct dma_device {
struct dma_async_tx_descriptor *(*device_prep_interleaved_dma)(
struct dma_chan *chan, struct dma_interleaved_template *xt,
unsigned long flags);
- int (*device_control)(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
- unsigned long arg);

+ int (*device_config)(struct dma_chan *chan,
+ struct dma_slave_config *config);
+ int (*device_control)(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+ unsigned long arg);
enum dma_status (*device_tx_status)(struct dma_chan *chan,
dma_cookie_t cookie,
struct dma_tx_state *txstate);
@@ -697,6 +700,9 @@ static inline int dmaengine_device_control(struct dma_chan *chan,
static inline int dmaengine_slave_config(struct dma_chan *chan,
struct dma_slave_config *config)
+ if (chan->device->device_config)
+ return chan->device->device_config(chan, config);
return dmaengine_device_control(chan, DMA_SLAVE_CONFIG,
(unsigned long)config);

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