greybus: define connection state

Define the state of a connection.  A connection will not be
enabled until it has been successfully set up.  Once it starts
getting torn down its state will move to "being destroyed".

Don't send any operation request messages unless the connection is
enabled.  And drop any incoming messages if if the connection is
not enabled.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
diff --git a/drivers/staging/greybus/connection.h b/drivers/staging/greybus/connection.h
index b5901a1..a16e52a 100644
--- a/drivers/staging/greybus/connection.h
+++ b/drivers/staging/greybus/connection.h
@@ -13,6 +13,14 @@
 
 #include "greybus.h"
 
+enum gb_connection_state {
+	GB_CONNECTION_STATE_INVALID	= 0,
+	GB_CONNECTION_STATE_DISABLED	= 1,
+	GB_CONNECTION_STATE_ENABLED	= 2,
+	GB_CONNECTION_STATE_ERROR	= 3,
+	GB_CONNECTION_STATE_DESTROYING	= 4,
+};
+
 struct gb_connection {
 	struct greybus_host_device	*hd;
 	struct gb_interface		*interface;
@@ -22,6 +30,7 @@
 	struct rb_node			hd_node;
 	struct list_head		interface_links;
 	enum greybus_protocol		protocol;
+	enum gb_connection_state	state;
 
 	struct list_head		operations;
 	struct rb_root			pending;	/* awaiting reponse */