i2c: core: Add support for 'i2c-bus' subnode

If the 'i2c-bus' device-tree node is present for an I2C adapter then
parse this subnode for I2C slaves.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/i2c/i2c-core.c

@@ -1411,7 +1411,7 @@ static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
 
 static void of_i2c_register_devices(struct i2c_adapter *adap)
 {
-	struct device_node *node;
+	struct device_node *bus, *node;
 
 	/* Only register child devices if the adapter has a node pointer set */
 	if (!adap->dev.of_node)
@@ -1419,11 +1419,17 @@ static void of_i2c_register_devices(struct i2c_adapter *adap)
 
 	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
 
-	for_each_available_child_of_node(adap->dev.of_node, node) {
+	bus = of_get_child_by_name(adap->dev.of_node, "i2c-bus");
+	if (!bus)
+		bus = of_node_get(adap->dev.of_node);
+
+	for_each_available_child_of_node(bus, node) {
 		if (of_node_test_and_set_flag(node, OF_POPULATED))
 			continue;
 		of_i2c_register_device(adap, node);
 	}
+
+	of_node_put(bus);
 }
 
 static int of_dev_node_match(struct device *dev, void *data)