1 files changed, 80 insertions, 0 deletions
diff --git a/include/osmocom/bsc/handover_fsm.h b/include/osmocom/bsc/handover_fsm.h
new file mode 100644
index 000000000..f2ce732e9
--- /dev/null
+++ b/include/osmocom/bsc/handover_fsm.h
@@ -0,0 +1,80 @@
+/* Handover FSM API for intra-BSC and inter-BSC MT (to this BSC) Handover.
+ * (For inter-BSC MO, from this BSC, see handover_inter_mo_fsm.c) */
+#pragma once
+
+#include <osmocom/bsc/debug.h>
+#include <osmocom/bsc/handover.h>
+
+const char *handover_status(struct gsm_subscriber_connection *conn);
+
+/* This macro automatically includes a final \n, if omitted. */
+#define LOG_HO(conn, level, fmt, args...) do { \
+	if (conn->ho.fi) \
+		LOGPFSML(conn->ho.fi, level, "%s: " fmt "%s", \
+			 handover_status(conn), \
+			 ## args, LOG_ADD_NEWLINE(fmt)); \
+	else \
+		LOGP(DHODEC, level, "%s: " fmt "%s", \
+		     handover_status(conn), \
+		     ## args, LOG_ADD_NEWLINE(fmt)); \
+	} while(0)
+
+/* Terminology:
+ * Intra-Cell: stays within one BTS, this should actually be an Assignment.
+ * Intra-BSC: stays within one BSC, but moves between BTSes.
+ * Inter-BSC: moves between BSCs.
+ * Inter-BSC MO: Mobile Originated: move away from this BSC to another one.
+ * Inter-BSC MT: Mobile Terminated: move from another BSC to this one.
+ */
+
+enum handover_fsm_state {
+	HO_ST_NOT_STARTED,
+
+	HO_ST_WAIT_LCHAN_ACTIVE,
+	HO_ST_WAIT_RR_HO_DETECT,
+	HO_ST_WAIT_RR_HO_COMPLETE,
+	HO_ST_WAIT_LCHAN_ESTABLISHED,
+	HO_ST_WAIT_MGW_ENDPOINT_TO_MSC,
+
+	/* The inter-BSC MO Handover FSM has completely separate states, but since it makes sense for it
+	 * to also live in conn->ho.fi, it should share the same event enum. From there it is merely
+	 * cosmetic to just include the separate fairly trivial states in the same FSM definition.
+	 * An inter-MO FSM is almost unnecessary. The sole reason is to wait whether the MSC indeed
+	 * clears the conn, and if not to log and count a failed handover attempt. */
+	MOHO_ST_WAIT_HO_COMMAND,
+	MOHO_ST_WAIT_CLEAR,
+};
+
+enum handover_fsm_event {
+	HO_EV_LCHAN_ACTIVE,
+	HO_EV_LCHAN_ESTABLISHED,
+	HO_EV_LCHAN_ERROR,
+	HO_EV_RR_HO_DETECT,
+	HO_EV_RR_HO_COMPLETE,
+	HO_EV_RR_HO_FAIL,
+	HO_EV_MSC_MGW_OK,
+	HO_EV_MSC_MGW_FAIL,
+	HO_EV_CONN_RELEASING,
+
+	MOHO_EV_BSSMAP_HO_COMMAND,
+};
+
+struct moho_rx_bssmap_ho_command {
+	const uint8_t *l3_info;
+	const uint8_t l3_info_len;
+};
+
+/* To be sent along with the HO_EV_RR_HO_DETECT */
+struct handover_rr_detect_data {
+	struct msgb *msg;
+	const uint8_t *access_delay;
+};
+
+void handover_start(struct handover_mo_req *req);
+void handover_start_inter_bsc_mt(struct gsm_subscriber_connection *conn,
+				 struct msgb *ho_request_msg);
+void handover_end(struct gsm_subscriber_connection *conn, enum handover_result result);
+
+const char *handover_status(struct gsm_subscriber_connection *conn);
+bool handover_is_sane(struct gsm_subscriber_connection *conn, struct gsm_lchan *old_lchan,
+		      struct gsm_lchan *new_lchan);