[PATCH v2 36/41] dmaengine: add support to provide error result from a DMA transation

[Dave Jiang <dave.jiang@xxxxxxxxx>]

Adding a new callback that will provide the error result for a transaction.
The result is allocated on the stack and the callback should create a copy
if it wishes to retain the information after exiting.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
 include/linux/dmaengine.h |   34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 95cf217..a43207e 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -441,6 +441,21 @@ typedef bool (*dma_filter_fn)(struct dma_chan *chan, void *filter_param);
 
 typedef void (*dma_async_tx_callback)(void *dma_async_param);
 
+enum dmaengine_tx_result {
+	DMA_TRANS_NOERROR = 0,
+	DMA_TRANS_READ_FAILED,
+	DMA_TRANS_WRITE_FAILED,
+	DMA_TRANS_ABORTED,
+};
+
+struct dmaengine_result {
+	enum dmaengine_tx_result result;
+	u32 residue;
+};
+
+typedef void (*dma_async_tx_callback_result)(void *dma_async_param,
+				const struct dmaengine_result *result);
+
 struct dmaengine_unmap_data {
 	u8 map_cnt;
 	u8 to_cnt;
@@ -478,6 +493,7 @@ struct dma_async_tx_descriptor {
 	dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
 	int (*desc_free)(struct dma_async_tx_descriptor *tx);
 	dma_async_tx_callback callback;
+	dma_async_tx_callback_result callback_result;
 	void *callback_param;
 	struct dmaengine_unmap_data *unmap;
 #ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
@@ -1374,6 +1390,7 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
 
 struct dmaengine_desc_callback {
 	dma_async_tx_callback callback;
+	dma_async_tx_callback_result callback_result;
 	void *callback_param;
 };
 
@@ -1382,15 +1399,26 @@ dmaengine_desc_get_callback(struct dma_async_tx_descriptor *tx,
 			    struct dmaengine_desc_callback *cb)
 {
 	cb->callback = tx->callback;
+	cb->callback_result = tx->callback_result;
 	cb->callback_param = tx->callback_param;
 }
 
 static inline void
 dmaengine_desc_callback_invoke(struct dmaengine_desc_callback *cb,
-			       void *result)
-{
-	if (cb->callback)
+			       struct dmaengine_result *result)
+{
+	struct dmaengine_result dummy_result = {
+		.result = DMA_TRANS_NOERROR,
+		.residue = 0
+	};
+
+	if (cb->callback_result) {
+		if (!result)
+			result = &dummy_result;
+		cb->callback_result(cb->callback_param, result);
+	} else if (cb->callback) {
 		cb->callback(cb->callback_param);
+	}
 }
 
 /* --- DMA device --- */

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