msc: clarify msc_api and msc_ifaces scopes

1 files changed, 17 insertions, 12 deletions

diff --git a/openbsc/include/openbsc/msc_ifaces.h b/openbsc/include/openbsc/msc_ifaces.h
index ace6ea11d..dc2b9e1da 100644
--- a/openbsc/include/openbsc/msc_ifaces.h
+++ b/openbsc/include/openbsc/msc_ifaces.h
@@ -3,13 +3,19 @@
 #include <osmocom/core/msgb.h>
 #include <openbsc/gsm_data.h>
 
-/* This callback structure allows linking specific components without having to
- * include entire infrastructures of external libraries. For example, a unit
- * test does not need to link against external ASN1 libraries if it is never
- * going to encode actual outgoing messages. It is up to each building scope to
- * plug meaningful sending/receiving callback functions, or to have mere dummy
- * implementations. */
-struct msc_api {
+/* These are the interfaces of the MSC layer towards the BSC and RNC, i.e. in
+ * the direction towards the mobile device (MS aka UE).
+ *
+ * 2G will use the A-interface,
+ * 3G aka UMTS will use the Iu-interface (for the MSC, it's IuCS).
+ *
+ * Below callback structures allows linking parts of the MSC code without
+ * having to include entire infrastructures of external libraries. For example,
+ * a unit test does not need to link against external ASN1 libraries if it is
+ * never going to encode actual outgoing messages. It is up to each building
+ * scope to plug real world functions or to have mere dummy implementations. */
+
+extern struct {
 
 	struct {
 		/* libmsc calls this to send out messages to an A-interface */
@@ -19,12 +25,11 @@ struct msc_api {
 	struct {
 		/* libmsc calls this to send out messages to an Iu-interface */
 		int (*tx)(struct msgb *msg, uint8_t sapi);
-	} iu;
-};
+	} iu_cs;
+
+} msc_ifaces;
+
 
-/* TODO does this belong to openbsc/gsm_04_08.h ?? */
-int msc_compl_l3(struct gsm_subscriber_connection *conn, struct msgb *msg,
-		 uint16_t chosen_channel);
 
 /* Depending on conn->via_iface (A or IuCS), submit msg to the proper link api. */
 extern int msc_submit_dtap(struct gsm_subscriber_connection *conn,