Re: [PATCH v3 4/7] of: address: Add support for the parent DMA bus

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On 11/02/2019 15:02, Maxime Ripard wrote:
Some SoCs have devices that are using a separate bus from the main bus to
perform DMA.

These buses might have some restrictions and/or different mapping than from
the CPU side, so we'd need to express those using the usual dma-ranges, but
using a different DT node than the node's parent.

Now that the generic interconnect bindings are available, we can model an
interconnect with the reserved name "dma" for those use-cases.

Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>
---
  drivers/of/address.c | 34 +++++++++++++++++++++++++++++++---
  1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 4c5dc21c71ca..0e9d87a664f5 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -583,8 +583,8 @@ static u64 __of_translate_address(struct device_node *dev,
  	/* Increase refcount at current level */
  	of_node_get(dev);
+ *host = NULL;
  	if (!parent) {
-		*host = NULL;
  		/* Get parent & match bus type */
  		parent = of_get_parent(dev);
  		if (parent == NULL)
@@ -678,12 +678,34 @@ u64 of_translate_address(struct device_node *dev, const __be32 *in_addr)
  }
  EXPORT_SYMBOL(of_translate_address);
+static struct device_node *__of_get_dma_parent(struct device_node *np)
+{
+	struct of_phandle_args args;
+	unsigned int index;
+	int ret;
+
+	ret = of_property_match_string(np, "interconnect-names", "dma");
+	if (ret < 0)
+		return of_get_parent(np);

Don't you need to propagate ret to index here?

Robin.

+
+	ret = of_parse_phandle_with_args(np, "interconnects",
+					 "#interconnect-cells",
+					 index, &args);
+	if (ret < 0)
+		return of_get_parent(np);
+
+	return of_node_get(args.np);
+}
+
  u64 of_translate_dma_address(struct device_node *dev, const __be32 *in_addr)
  {
+	struct device_node *parent;
  	struct device_node *host;
  	u64 ret;
- ret = __of_translate_address(dev, NULL, in_addr, "dma-ranges", &host);
+	parent = __of_get_dma_parent(dev);
+	ret = __of_translate_address(dev, parent, in_addr, "dma-ranges", &host);
+	of_node_put(parent);
if (host) {
  		of_node_put(host);
@@ -911,9 +933,15 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
  		return -EINVAL;
while (1) {
+		struct device_node *parent;
+
  		naddr = of_n_addr_cells(node);
  		nsize = of_n_size_cells(node);
-		node = of_get_next_parent(node);
+
+		parent = __of_get_dma_parent(node);
+		of_node_put(node);
+
+		node = parent;
  		if (!node)
  			break;
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