[RFC PATCH 5/5] drivers core: Find device connections also from device graphs

[Heikki Krogerus]

If connections between devices are described in OF graph or
ACPI device graph, we can find them by using the
fwnode_graph_*() functions.

Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
---
 drivers/base/devcon.c | 48 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 45 insertions(+), 3 deletions(-)

diff --git a/drivers/base/devcon.c b/drivers/base/devcon.c
index d427e806cd73..9c446ef84dd1 100644
--- a/drivers/base/devcon.c
+++ b/drivers/base/devcon.c
@@ -7,10 +7,45 @@
  */
 
 #include <linux/device.h>
+#include <linux/property.h>
 
 static DEFINE_MUTEX(devcon_lock);
 static LIST_HEAD(devcon_list);
 
+static void *
+fwnode_graph_devcon_match(struct fwnode_handle *fwnode,
+			  const char *con_id, void *data,
+			  void *(*match)(struct device_connection *con,
+					 int ep, void *data))
+{
+	struct device_connection con = { .id = con_id };
+	struct fwnode_handle *ep;
+	const char *val;
+	void *ret;
+	int err;
+
+	fwnode_graph_for_each_endpoint(fwnode, ep) {
+		con.fwnode = fwnode_graph_get_remote_port_parent(ep);
+
+		if (con_id) {
+			err = fwnode_property_read_string(con.fwnode, "name",
+							  &val);
+			if (err || strcmp(con_id, val)) {
+				fwnode_handle_put(con.fwnode);
+				continue;
+			}
+		}
+
+		ret = match(&con, -1, data);
+		fwnode_handle_put(con.fwnode);
+		if (ret) {
+			fwnode_handle_put(ep);
+			return ret;
+		}
+	}
+	return NULL;
+}
+
 /**
  * device_connection_find_match - Find physical connection to a device
  * @dev: Device with the connection
@@ -23,10 +58,11 @@ static LIST_HEAD(devcon_list);
  * caller is expecting to be returned.
  */
 void *device_connection_find_match(struct device *dev, const char *con_id,
-			       void *data,
-			       void *(*match)(struct device_connection *con,
-					      int ep, void *data))
+				   void *data,
+				   void *(*match)(struct device_connection *con,
+						  int ep, void *data))
 {
+	struct fwnode_handle *fwnode = dev_fwnode(dev);
 	const char *devname = dev_name(dev);
 	struct device_connection *con;
 	void *ret = NULL;
@@ -35,6 +71,12 @@ void *device_connection_find_match(struct device *dev, const char *con_id,
 	if (!match)
 		return NULL;
 
+	if (fwnode) {
+		ret = fwnode_graph_devcon_match(fwnode, con_id, data, match);
+		if (ret)
+			return ret;
+	}
+
 	mutex_lock(&devcon_lock);
 
 	list_for_each_entry(con, &devcon_list, list) {
-- 
2.19.1