[PATCH 01/18] dmaengine: of-dma: Add support for optional router configuration callback

[Peter Ujfalusi]

Additional configuration for the DMA event router might be needed for a
channel which can not be done during device_alloc_chan_resources callback
since the router information is not yet present for the drivers.

If there is a need for additional configuration for the channel if DMA
router is in use, then the driver can implement the device_router_config
callback.

Signed-off-by: Peter Ujfalusi <peter.ujfal...@ti.com>
---
 drivers/dma/of-dma.c      | 10 ++++++++++
 include/linux/dmaengine.h |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index 8a4f608904b9..ec00b20ae8e4 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -75,8 +75,18 @@ static struct dma_chan *of_dma_router_xlate(struct 
of_phandle_args *dma_spec,
                ofdma->dma_router->route_free(ofdma->dma_router->dev,
                                              route_data);
        } else {
+               int ret = 0;
+
                chan->router = ofdma->dma_router;
                chan->route_data = route_data;
+
+               if (chan->device->device_router_config)
+                       ret = chan->device->device_router_config(chan);
+
+               if (ret) {
+                       dma_release_channel(chan);
+                       chan = ERR_PTR(ret);
+               }
        }
 
        /*
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index dd357a747780..d6197fe875af 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -800,6 +800,7 @@ struct dma_filter {
  *     by tx_status
  * @device_alloc_chan_resources: allocate resources and return the
  *     number of allocated descriptors
+ * @device_router_config: optional callback for DMA router configuration
  * @device_free_chan_resources: release DMA channel's resources
  * @device_prep_dma_memcpy: prepares a memcpy operation
  * @device_prep_dma_xor: prepares a xor operation
@@ -874,6 +875,7 @@ struct dma_device {
        enum dma_residue_granularity residue_granularity;
 
        int (*device_alloc_chan_resources)(struct dma_chan *chan);
+       int (*device_router_config)(struct dma_chan *chan);
        void (*device_free_chan_resources)(struct dma_chan *chan);
 
        struct dma_async_tx_descriptor *(*device_prep_dma_memcpy)(
-- 
Peter

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