[PATCH v3 1/6] device property: Helper to match multiple connections

[Bjorn Andersson]

In some cases multiple connections with the same connection id
needs to be resolved from a fwnode graph.

One such example is when separate hardware is used for performing muxing
and/or orientation switching of the SuperSpeed and SBU lines in a USB
Type-C connector. In this case the connector needs to belong to a graph
with multiple matching remote endpoints, and the Type-C controller needs
to be able to resolve them both.

Add a new API that allows this kind of lookup.

Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
---

Changes since v2:
- Allow the caller of the new api to pass a matches of NULL, to count possible
  matches. I previously argued that this will cause memory leaks, but Andy
  pointed out that this depends on the caller and the match function.
- Fixed spelling mistakes in commit message and kernel-doc.
- Use two "count" variables to make the math clearer.

Changes since v1:
- Iterator in fwnode_devcon_matches() is now unsigned.
- fwnode_handle_put() node for unavailable nodes.
- Extended commit message on the subject of supporting dynamically sized
  "matches" array.

 drivers/base/property.c  | 107 +++++++++++++++++++++++++++++++++++++++
 include/linux/property.h |   5 ++
 2 files changed, 112 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index c0e94cce9c29..5cda205136f6 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -1218,6 +1218,40 @@ fwnode_graph_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
 	return NULL;
 }
 
+static unsigned int fwnode_graph_devcon_matches(struct fwnode_handle *fwnode,
+						const char *con_id, void *data,
+						devcon_match_fn_t match,
+						void **matches,
+						unsigned int matches_len)
+{
+	struct fwnode_handle *node;
+	struct fwnode_handle *ep;
+	unsigned int count = 0;
+	void *ret;
+
+	fwnode_graph_for_each_endpoint(fwnode, ep) {
+		if (count >= matches_len && matches) {
+			fwnode_handle_put(ep);
+			return count;
+		}
+
+		node = fwnode_graph_get_remote_port_parent(ep);
+		if (!fwnode_device_is_available(node)) {
+			fwnode_handle_put(node);
+			continue;
+		}
+
+		ret = match(node, con_id, data);
+		fwnode_handle_put(node);
+		if (ret) {
+			if (matches)
+				matches[count] = ret;
+			count++;
+		}
+	}
+	return count;
+}
+
 static void *
 fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
 		    void *data, devcon_match_fn_t match)
@@ -1240,6 +1274,37 @@ fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
 	return NULL;
 }
 
+static unsigned int fwnode_devcon_matches(struct fwnode_handle *fwnode,
+					  const char *con_id, void *data,
+					  devcon_match_fn_t match,
+					  void **matches,
+					  unsigned int matches_len)
+{
+	struct fwnode_handle *node;
+	unsigned int count = 0;
+	unsigned int i;
+	void *ret;
+
+	for (i = 0; ; i++) {
+		if (count >= matches_len && matches)
+			return count;
+
+		node = fwnode_find_reference(fwnode, con_id, i);
+		if (IS_ERR(node))
+			break;
+
+		ret = match(node, NULL, data);
+		fwnode_handle_put(node);
+		if (ret) {
+			if (matches)
+				matches[count] = ret;
+			count++;
+		}
+	}
+
+	return count;
+}
+
 /**
  * fwnode_connection_find_match - Find connection from a device node
  * @fwnode: Device node with the connection
@@ -1267,3 +1332,45 @@ void *fwnode_connection_find_match(struct fwnode_handle *fwnode,
 	return fwnode_devcon_match(fwnode, con_id, data, match);
 }
 EXPORT_SYMBOL_GPL(fwnode_connection_find_match);
+
+/**
+ * fwnode_connection_find_matches - Find connections from a device node
+ * @fwnode: Device node with the connection
+ * @con_id: Identifier for the connection
+ * @data: Data for the match function
+ * @match: Function to check and convert the connection description
+ * @matches: Array of pointers to fill with matches
+ * @matches_len: Length of @matches
+ *
+ * Find up to @matches_len connections with unique identifier @con_id between
+ * @fwnode and other device nodes. @match will be used to convert the
+ * connection description to data the caller is expecting to be returned
+ * through the @matches array.
+ * If @matches is NULL @matches_len is ignored and the total number of resolved
+ * matches is returned.
+ *
+ * Return: Number of matches resolved, or negative errno.
+ */
+int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
+				   const char *con_id, void *data,
+				   devcon_match_fn_t match,
+				   void **matches, unsigned int matches_len)
+{
+	unsigned int count_graph;
+	unsigned int count_ref;
+
+	if (!fwnode || !match)
+		return -EINVAL;
+
+	count_graph = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
+						  matches, matches_len);
+
+	matches += count_graph;
+	matches_len -= count_graph;
+
+	count_ref = fwnode_devcon_matches(fwnode, con_id, data, match,
+					  matches, matches_len);
+
+	return count_graph + count_ref;
+}
+EXPORT_SYMBOL_GPL(fwnode_connection_find_matches);
diff --git a/include/linux/property.h b/include/linux/property.h
index 4cd4b326941f..de7ff336d2c8 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -447,6 +447,11 @@ static inline void *device_connection_find_match(struct device *dev,
 	return fwnode_connection_find_match(dev_fwnode(dev), con_id, data, match);
 }
 
+int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
+				   const char *con_id, void *data,
+				   devcon_match_fn_t match,
+				   void **matches, unsigned int matches_len);
+
 /* -------------------------------------------------------------------------- */
 /* Software fwnode support - when HW description is incomplete or missing */
 
-- 
2.33.1