greybus: connection: add per-connection request handlers

Add a connection request-handler field to struct gb_connection that is
set when the connection is enabled.

This is a step towards removing the legacy protocol abstraction from
core, and will also be used to implement unidirectional connection
states (e.g. only outgoing operations are allowed).
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/connection.c

@@ -387,7 +387,8 @@ static int gb_connection_protocol_get_version(struct gb_connection *connection)
 	return 0;
 }
 
-int gb_connection_enable(struct gb_connection *connection)
+int gb_connection_enable(struct gb_connection *connection,
+				gb_request_handler_t handler)
 {
 	int ret;
 
@@ -400,6 +401,7 @@ int gb_connection_enable(struct gb_connection *connection)
 		goto err_hd_cport_disable;
 
 	spin_lock_irq(&connection->lock);
+	connection->handler = handler;
 	connection->state = GB_CONNECTION_STATE_ENABLED;
 	spin_unlock_irq(&connection->lock);
 
@@ -435,15 +437,28 @@ void gb_connection_disable(struct gb_connection *connection)
 }
 EXPORT_SYMBOL_GPL(gb_connection_disable);
 
+static int gb_legacy_request_handler(struct gb_operation *operation)
+{
+	struct gb_protocol *protocol = operation->connection->protocol;
+
+	return protocol->request_recv(operation->type, operation);
+}
+
 int gb_connection_legacy_init(struct gb_connection *connection)
 {
+	gb_request_handler_t handler;
 	int ret;
 
 	ret = gb_connection_bind_protocol(connection);
 	if (ret)
 		return ret;
 
-	ret = gb_connection_enable(connection);
+	if (connection->protocol->request_recv)
+		handler = gb_legacy_request_handler;
+	else
+		handler = NULL;
+
+	ret = gb_connection_enable(connection, handler);
 	if (ret)
 		goto err_unbind_protocol;
 

drivers/staging/greybus/connection.h

@@ -20,6 +20,10 @@ enum gb_connection_state {
 	GB_CONNECTION_STATE_DESTROYING	= 3,
 };
 
+struct gb_operation;
+
+typedef int (*gb_request_handler_t)(struct gb_operation *);
+
 struct gb_connection {
 	struct gb_host_device		*hd;
 	struct gb_interface		*intf;
@@ -31,6 +35,8 @@ struct gb_connection {
 	struct list_head		hd_links;
 	struct list_head		bundle_links;
 
+	gb_request_handler_t		handler;
+
 	struct gb_protocol		*protocol;
 	u8				protocol_id;
 	u8				major;
@@ -62,7 +68,8 @@ static inline bool gb_connection_is_static(struct gb_connection *connection)
 	return !connection->intf;
 }
 
-int gb_connection_enable(struct gb_connection *connection);
+int gb_connection_enable(struct gb_connection *connection,
+					gb_request_handler_t handler);
 void gb_connection_disable(struct gb_connection *connection);
 
 int gb_connection_legacy_init(struct gb_connection *connection);

drivers/staging/greybus/operation.c

@@ -218,15 +218,11 @@ static void gb_message_cancel(struct gb_message *message)
 static void gb_operation_request_handle(struct gb_operation *operation)
 {
 	struct gb_connection *connection = operation->connection;
-	struct gb_protocol *protocol = connection->protocol;
 	int status;
 	int ret;
 
-	if (!protocol)
-		return;
-
-	if (protocol->request_recv) {
-		status = protocol->request_recv(operation->type, operation);
+	if (connection->handler) {
+		status = connection->handler(operation);
 	} else {
 		dev_err(&connection->hd->dev,
 			"%s: unexpected incoming request of type 0x%02x\n",