Commit 3b6d694e authored by Serge Semin's avatar Serge Semin Committed by Vinod Koul
Browse files

dmaengine: Introduce DMA-device device_caps callback 



There are DMA devices (like ours version of Synopsys DW DMAC) which have
DMA capabilities non-uniformly redistributed between the device channels.
In order to provide a way of exposing the channel-specific parameters to
the DMA engine consumers, we introduce a new DMA-device callback. In case
if provided it gets called from the dma_get_slave_caps() method and is
able to override the generic DMA-device capabilities.

Signed-off-by: default avatarSerge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200723005848.31907-6-Sergey.Semin@baikalelectronics.ru


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent b1b40b8f

drivers/dma/dmaengine.c

+10 −0
Original line number Diff line number Diff line
@@ -601,6 +601,16 @@ int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps) 
	caps->cmd_resume = !!device->device_resume;

	caps->cmd_terminate = !!device->device_terminate_all;



	/*

	 * DMA engine device might be configured with non-uniformly

	 * distributed slave capabilities per device channels. In this

	 * case the corresponding driver may provide the device_caps

	 * callback to override the generic capabilities with

	 * channel-specific ones.

	 */

	if (device->device_caps)

		device->device_caps(chan, caps);



	return 0;

}

EXPORT_SYMBOL_GPL(dma_get_slave_caps);

include/linux/dmaengine.h

+4 −0
Original line number Diff line number Diff line
@@ -801,6 +801,8 @@ struct dma_filter { 
 *	be called after period_len bytes have been transferred.

 * @device_prep_interleaved_dma: Transfer expression in a generic way.

 * @device_prep_dma_imm_data: DMA's 8 byte immediate data to the dst address

 * @device_caps: May be used to override the generic DMA slave capabilities

 *	with per-channel specific ones

 * @device_config: Pushes a new configuration to a channel, return 0 or an error

 *	code

 * @device_pause: Pauses any transfer happening on a channel. Returns
@@ -901,6 +903,8 @@ struct dma_device { 
		struct dma_chan *chan, dma_addr_t dst, u64 data,

		unsigned long flags);



	void (*device_caps)(struct dma_chan *chan,

			    struct dma_slave_caps *caps);

	int (*device_config)(struct dma_chan *chan,

			     struct dma_slave_config *config);

	int (*device_pause)(struct dma_chan *chan);

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