greybus: legacy: look up protocol at connection creation

Look up legacy protocol at connection create instead of at init.

Note that we can now look up the protocol before even creating the
actual connection. This is needed to be able to set a connection request
handler when creating the connection rather than when enabling it.
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/legacy.c

@@ -15,7 +15,7 @@
 struct legacy_connection {
 	struct gb_connection *connection;
 	bool initialized;
-	u8 protocol_id;
+	struct gb_protocol *protocol;
 };
 
 struct legacy_data {
@@ -39,42 +39,6 @@ static int legacy_connection_get_version(struct gb_connection *connection)
 	return 0;
 }
 
-static int legacy_connection_bind_protocol(struct legacy_connection *lc)
-{
-	struct gb_connection *connection = lc->connection;
-	struct gb_protocol *protocol;
-	u8 major, minor;
-
-	/*
-	 * The legacy protocols have always been looked up using a hard-coded
-	 * version of 0.1, despite (or perhaps rather, due to) the fact that
-	 * module version negotiation could not take place until after the
-	 * protocol was bound.
-	 */
-	major = 0;
-	minor = 1;
-
-	protocol = gb_protocol_get(lc->protocol_id, major, minor);
-	if (!protocol) {
-		dev_err(&connection->hd->dev,
-				"protocol 0x%02x version %u.%u not found\n",
-				lc->protocol_id, major, minor);
-		return -EPROTONOSUPPORT;
-	}
-	connection->protocol = protocol;
-
-	return 0;
-}
-
-static void legacy_connection_unbind_protocol(struct gb_connection *connection)
-{
-	struct gb_protocol *protocol = connection->protocol;
-
-	gb_protocol_put(protocol);
-
-	connection->protocol = NULL;
-}
-
 static int legacy_request_handler(struct gb_operation *operation)
 {
 	struct gb_protocol *protocol = operation->connection->protocol;
@@ -91,10 +55,6 @@ static int legacy_connection_init(struct legacy_connection *lc)
 	dev_dbg(&connection->bundle->dev, "%s - %s\n", __func__,
 			connection->name);
 
-	ret = legacy_connection_bind_protocol(lc);
-	if (ret)
-		return ret;
-
 	if (connection->protocol->request_recv)
 		handler = legacy_request_handler;
 	else
@@ -102,7 +62,7 @@ static int legacy_connection_init(struct legacy_connection *lc)
 
 	ret = gb_connection_enable(connection, handler);
 	if (ret)
-		goto err_unbind_protocol;
+		return ret;
 
 	ret = legacy_connection_get_version(connection);
 	if (ret)
@@ -118,8 +78,6 @@ static int legacy_connection_init(struct legacy_connection *lc)
 
 err_disable:
 	gb_connection_disable(connection);
-err_unbind_protocol:
-	legacy_connection_unbind_protocol(connection);
 
 	return ret;
 }
@@ -135,8 +93,6 @@ static void legacy_connection_exit(struct legacy_connection *lc)
 
 	connection->protocol->connection_exit(connection);
 
-	legacy_connection_unbind_protocol(connection);
-
 	lc->initialized = false;
 }
 
@@ -145,20 +101,57 @@ static int legacy_connection_create(struct legacy_connection *lc,
 					struct greybus_descriptor_cport *desc)
 {
 	struct gb_connection *connection;
+	struct gb_protocol *protocol;
+	u8 major, minor;
+	int ret;
+
+	/*
+	 * The legacy protocols have always been looked up using a hard-coded
+	 * version of 0.1, despite (or perhaps rather, due to) the fact that
+	 * module version negotiation could not take place until after the
+	 * protocol was bound.
+	 */
+	major = 0;
+	minor = 1;
+
+	protocol = gb_protocol_get(desc->protocol_id, major, minor);
+	if (!protocol) {
+		dev_err(&bundle->dev,
+				"protocol 0x%02x version %u.%u not found\n",
+				desc->protocol_id, major, minor);
+		return -EPROTONOSUPPORT;
+	}
 
 	connection = gb_connection_create(bundle, le16_to_cpu(desc->id));
-	if (IS_ERR(connection))
-		return PTR_ERR(connection);
+	if (IS_ERR(connection)) {
+		ret = PTR_ERR(connection);
+		goto err_protocol_put;
+	}
+
+	/*
+	 * NOTE: We need to keep a pointer to the protocol in the actual
+	 *       connection structure for now.
+	 */
+	connection->protocol = protocol;
 
 	lc->connection = connection;
-	lc->protocol_id = desc->protocol_id;
+	lc->protocol = protocol;
 
 	return 0;
+
+err_protocol_put:
+	gb_protocol_put(protocol);
+
+	return ret;
 }
 
 static void legacy_connection_destroy(struct legacy_connection *lc)
 {
+	lc->connection->protocol = NULL;
+
 	gb_connection_destroy(lc->connection);
+
+	gb_protocol_put(lc->protocol);
 }
 
 static int legacy_probe(struct gb_bundle *bundle,