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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: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200723005848.31907-6-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Serge Semin 2020-07-23 03:58:43 +03:00 committed by Vinod Koul
parent b1b40b8fe7
commit 3b6d694eb3
2 changed files with 14 additions and 0 deletions
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10
drivers/dma/dmaengine.c
View File

@ -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);

4
include/linux/dmaengine.h
View File

@ -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);