Re: [PATCH 3/8] device property: Helper to match multiple connections

Hi Björn,

(And thanks to Heikki for cc'ing me!)

On Thu, Dec 30, 2021 at 11:26:34AM +0200, Heikki Krogerus wrote:

+Andy, Dan and Sakari

On Mon, Dec 27, 2021 at 09:21:11PM -0800, Bjorn Andersson wrote:

quoted

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-C
connector. In this case the connector needs to belong to a graph with
multiple matching remote endpoints, and the TypeC controller needs to be
able to resolve them both.

Add a new API that allows this kind of lookup.

Signed-off-by: Bjorn Andersson <redacted>
---
 drivers/base/property.c  | 94 ++++++++++++++++++++++++++++++++++++++++
 include/linux/property.h |  5 +++
 2 files changed, 99 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index cbe4fa298413..0aa0296fd991 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c

@@ -1180,6 +1180,36 @@ 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) {
+			fwnode_handle_put(ep);
+			return count;
+		}
+
+		node = fwnode_graph_get_remote_port_parent(ep);
+		if (!fwnode_device_is_available(node))

The reference to node needs to be put here.

quoted

+			continue;
+
+		ret = match(node, con_id, data);
+		fwnode_handle_put(node);
+
+		if (ret)
+			matches[count++] = ret;
+	}
+	return count;
+}
+
 static void *
 fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
 		    void *data, devcon_match_fn_t match)

@@ -1202,6 +1232,35 @@ 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;
+	void *ret;
+	int i;

unsigned int, please.

quoted

+
+	for (i = 0; ; i++) {
+		if (count >= matches_len)
+			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)
+			matches[count++] = ret;
+	}
+
+	return count;
+}
+
 /**
  * fwnode_connection_find_match - Find connection from a device node
  * @fwnode: Device node with the connection

@@ -1229,3 +1288,38 @@ 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 the caller allocates the matches array, how does it know how large it
should be? Is there a need to provide a way to count the matches before
writing them to an array? Most similar functions do that by just setting the
array (matches) to NULL.

quoted

+ *
+ * Return: Number of matches resolved, of 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;
+
+	if (!fwnode || !match || !matches)
+		return -EINVAL;
+
+	count = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
+					    matches, matches_len);
+
+	return count + fwnode_devcon_matches(fwnode, con_id, data, match,
+					     matches + count,
+					     matches_len - count);
+}
+EXPORT_SYMBOL_GPL(fwnode_connection_find_matches);

diff --git a/include/linux/property.h b/include/linux/property.h
index 16f736c698a2..59484ccb260e 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h

@@ -444,6 +444,11 @@ 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 */
 

-- 
Kind regards,

Sakari Ailus

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