dmaengine: Add support for reporting DMA cached data amount

A DMA hardware can have big cache or FIFO and the amount of data sitting in
the DMA fabric can be an interest for the clients.

For example in audio we want to know the delay in the data flow and in case
the DMA have significantly large FIFO/cache, it can affect the latenc/delay

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Tero Kristo <t-kristo@ti.com>
Tested-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Link: https://lore.kernel.org/r/20191223110458.30766-6-peter.ujfalusi@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/dma/dmaengine.h b/drivers/dma/dmaengine.h
index 501c0b063f85..b0b97475707a 100644
--- a/drivers/dma/dmaengine.h
+++ b/drivers/dma/dmaengine.h
@@ -77,6 +77,7 @@ static inline enum dma_status dma_cookie_status(struct dma_chan *chan,
 		state->last = complete;
 		state->used = used;
 		state->residue = 0;
+		state->in_flight_bytes = 0;
 	}
 	return dma_async_is_complete(cookie, complete, used);
 }
@@ -87,6 +88,13 @@ static inline void dma_set_residue(struct dma_tx_state *state, u32 residue)
 		state->residue = residue;
 }
 
+static inline void dma_set_in_flight_bytes(struct dma_tx_state *state,
+					   u32 in_flight_bytes)
+{
+	if (state)
+		state->in_flight_bytes = in_flight_bytes;
+}
+
 struct dmaengine_desc_callback {
 	dma_async_tx_callback callback;
 	dma_async_tx_callback_result callback_result;