[PATCH v2 1/8] dmaengine: Add matching device node validation in __dma_request_channel()

[Baolin Wang]

When user try to request one DMA channel by __dma_request_channel(), it won't
validate if it is the correct DMA device to request, that will lead each DMA
engine driver to validate the correct device node in their filter function
if it is necessary.

Thus we can add the matching device node validation in the DMA engine core,
to remove all of device node validation in the drivers.

Tested-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---
 drivers/dma/dmaengine.c   |   10 ++++++++--
 drivers/dma/of-dma.c      |    4 ++--
 include/linux/dmaengine.h |   12 ++++++++----
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 3a11b10..610080c 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -641,11 +641,13 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
  * @mask: capabilities that the channel must satisfy
  * @fn: optional callback to disposition available channels
  * @fn_param: opaque parameter to pass to dma_filter_fn
+ * @np: device node to look for DMA channels
  *
  * Returns pointer to appropriate DMA channel on success or NULL.
  */
 struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
-				       dma_filter_fn fn, void *fn_param)
+				       dma_filter_fn fn, void *fn_param,
+				       struct device_node *np)
 {
 	struct dma_device *device, *_d;
 	struct dma_chan *chan = NULL;
@@ -653,6 +655,10 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
 	/* Find a channel */
 	mutex_lock(&dma_list_mutex);
 	list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
+		/* Finds a DMA controller with matching device node */
+		if (np && device->dev->of_node && np != device->dev->of_node)
+			continue;
+
 		chan = find_candidate(device, mask, fn, fn_param);
 		if (!IS_ERR(chan))
 			break;
@@ -769,7 +775,7 @@ struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
 	if (!mask)
 		return ERR_PTR(-ENODEV);
 
-	chan = __dma_request_channel(mask, NULL, NULL);
+	chan = __dma_request_channel(mask, NULL, NULL, NULL);
 	if (!chan) {
 		mutex_lock(&dma_list_mutex);
 		if (list_empty(&dma_device_list))
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index 91fd395..6b43d04 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -316,8 +316,8 @@ struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
 	if (count != 1)
 		return NULL;
 
-	return dma_request_channel(info->dma_cap, info->filter_fn,
-			&dma_spec->args[0]);
+	return __dma_request_channel(&info->dma_cap, info->filter_fn,
+				     &dma_spec->args[0], dma_spec->np);
 }
 EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
 
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index d49ec5c..504085b 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1314,7 +1314,8 @@ static inline enum dma_status dma_async_is_complete(dma_cookie_t cookie,
 enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
 void dma_issue_pending_all(void);
 struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
-					dma_filter_fn fn, void *fn_param);
+				       dma_filter_fn fn, void *fn_param,
+				       struct device_node *np);
 struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name);
 
 struct dma_chan *dma_request_chan(struct device *dev, const char *name);
@@ -1339,7 +1340,9 @@ static inline void dma_issue_pending_all(void)
 {
 }
 static inline struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
-					      dma_filter_fn fn, void *fn_param)
+						     dma_filter_fn fn,
+						     void *fn_param,
+						     struct device_node *np)
 {
 	return NULL;
 }
@@ -1411,7 +1414,8 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
 void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
 struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
 struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
-#define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
+#define dma_request_channel(mask, x, y) \
+	__dma_request_channel(&(mask), x, y, NULL)
 #define dma_request_slave_channel_compat(mask, x, y, dev, name) \
 	__dma_request_slave_channel_compat(&(mask), x, y, dev, name)
 
@@ -1429,6 +1433,6 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
 	if (!fn || !fn_param)
 		return NULL;
 
-	return __dma_request_channel(mask, fn, fn_param);
+	return __dma_request_channel(mask, fn, fn_param, NULL);
 }
 #endif /* DMAENGINE_H */
-- 
1.7.9.5