greybus: connection: add api to {en,dis}able unipro fct flow

In order to support mailbox-free control cport init on the bridges the AP must
be able to enable/disable the flow of unipro fct tokens. Add a new API that
will enable or disable on APBA the flow of fct tokens.
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Fabien Parent <fparent@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/connection.c

@@ -274,6 +274,34 @@ static void gb_connection_hd_cport_disable(struct gb_connection *connection)
 	hd->driver->cport_disable(hd, connection->hd_cport_id);
 }
 
+static int gb_connection_hd_fct_flow_enable(struct gb_connection *connection)
+{
+	struct gb_host_device *hd = connection->hd;
+	int ret;
+
+	if (!hd->driver->fct_flow_enable)
+		return 0;
+
+	ret = hd->driver->fct_flow_enable(hd, connection->hd_cport_id);
+	if (ret) {
+		dev_err(&hd->dev, "%s: failed to enable FCT flow: %d\n",
+			connection->name, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void gb_connection_hd_fct_flow_disable(struct gb_connection *connection)
+{
+	struct gb_host_device *hd = connection->hd;
+
+	if (!hd->driver->fct_flow_disable)
+		return;
+
+	hd->driver->fct_flow_disable(hd, connection->hd_cport_id);
+}
+
 /*
  * Request the SVC to create a connection from AP's cport to interface's
  * cport.

drivers/staging/greybus/hd.h

@@ -25,6 +25,8 @@ struct gb_hd_driver {
 	int (*latency_tag_disable)(struct gb_host_device *hd, u16 cport_id);
 	int (*output)(struct gb_host_device *hd, void *req, u16 size, u8 cmd,
 		      bool async);
+	int (*fct_flow_enable)(struct gb_host_device *hd, u16 cport_id);
+	int (*fct_flow_disable)(struct gb_host_device *hd, u16 cport_id);
 };
 
 struct gb_host_device {