[PATCH v5 06/61] dmaengine: Introduce a device_config callback

From: Maxime Ripard
Date: Mon Nov 17 2014 - 08:49:32 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>
Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
include/linux/dmaengine.h | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 4d912575fec0..f797cb81355f 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -607,6 +607,8 @@ 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
@@ -673,6 +675,9 @@ 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_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);

@@ -696,6 +701,9 @@ 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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