pcu_sock: activate/deactivate PDCH on pcu reconnect

When the PCU is disconnected while the BSC keeps running the PDCH should
be closed. Also the PDCH should be reopened when the PCU is
reconnected.

Change-Id: I9ea0c53a5e68a51c781ef43bae71f947cdb95678
Related: OS#5198
---
M doc/timeslot.msc
M include/osmocom/bsc/pcu_if.h
M include/osmocom/bsc/timeslot_fsm.h
M src/osmo-bsc/pcu_sock.c
M src/osmo-bsc/timeslot_fsm.c
5 files changed, 116 insertions(+), 13 deletions(-)

diff --git a/doc/timeslot.msc b/doc/timeslot.msc
index 02e7bb3..0fd1458 100644
--- a/doc/timeslot.msc
+++ b/doc/timeslot.msc
@@ -1,5 +1,5 @@
 msc {
-	bts [label="MS/BTS"], bsc[label="BSC"], bsc_ts[label="BSC timeslot FSM"], bsc_lchan[label="BSC lchan FSM"];
+	bts [label="MS/BTS"], bsc[label="BSC"], bsc_ts[label="BSC timeslot FSM"], bsc_lchan[label="BSC lchan FSM"], pcu_sock[label="PCU socket"];
 
 	bsc_ts abox bsc_ts [label="NOT_INITIALIZED"];
 
@@ -88,6 +88,24 @@
 	bsc_ts rbox bsc_ts [label="Continue at 'IN_USE' above"];
 	...;
 	...;
+	bts rbox bsc_lchan [label="on PCU disconnect (Ericsson RBS)
+			for all timeslots in state PDCH:" ];
+	bsc_ts abox bsc_ts [label="PDCH"];
+	bsc_ts <- pcu_sock [label="TS_EV_PDCH_DEACT"];
+	bts note bsc_ts [label="PDCH release, see WAIT_PDCH_DEACT above"];
+	...;
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	...;
+	...;
+	bts rbox bsc_lchan [label="on PCU reconnect (Ericsson RBS)
+			for all timeslots in state UNUSED:" ];
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	bsc_ts <- pcu_sock [label="TS_EV_PDCH_ACT"];
+	bts note bsc_ts [label="PDCH activation, see WAIT_PDCH_ACT above"];
+	...;
+	bsc_ts abox bsc_ts [label="PDCH"];
+	...;
+	...;
 
 	bts rbox bsc_lchan [label="on erratic event"];
 	bsc_ts -> bsc_lchan [label="LCHAN_EV_TS_ERROR"];
diff --git a/include/osmocom/bsc/pcu_if.h b/include/osmocom/bsc/pcu_if.h
index 3c34cdf..2a2afa8 100644
--- a/include/osmocom/bsc/pcu_if.h
+++ b/include/osmocom/bsc/pcu_if.h
@@ -14,6 +14,9 @@
 	struct llist_head upqueue;	/* queue for sending messages */
 };
 
+/* Check if BTS has a PCU connection */
+bool pcu_connected(struct gsm_bts *bts);
+
 /* PCU relevant information has changed; Inform PCU (if connected) */
 void pcu_info_update(struct gsm_bts *bts);
 
diff --git a/include/osmocom/bsc/timeslot_fsm.h b/include/osmocom/bsc/timeslot_fsm.h
index cea1e4c..c1b61b8 100644
--- a/include/osmocom/bsc/timeslot_fsm.h
+++ b/include/osmocom/bsc/timeslot_fsm.h
@@ -36,10 +36,18 @@
 	TS_EV_RSL_DOWN,
 	TS_EV_LCHAN_REQUESTED,
 	TS_EV_LCHAN_UNUSED,
+
+	/* RSL responses received from the BTS: */
 	TS_EV_PDCH_ACT_ACK,
 	TS_EV_PDCH_ACT_NACK,
 	TS_EV_PDCH_DEACT_ACK,
 	TS_EV_PDCH_DEACT_NACK,
+
+	/* BSC co-located PCU disconnects from PCU socket, deactivate PDCH */
+	TS_EV_PDCH_DEACT,
+
+	/* BSC co-located PCU (re)connects to PCU socket, activate PDCH */
+	TS_EV_PDCH_ACT,
 };
 
 void ts_fsm_alloc(struct gsm_bts_trx_ts *ts);
@@ -52,3 +60,6 @@
 bool ts_usable_as_pchan(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config as_pchan, bool allow_pchan_switch);
 
 void ts_set_pchan_is(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config pchan_is);
+
+void ts_pdch_act(struct gsm_bts_trx_ts *ts);
+void ts_pdch_deact(struct gsm_bts_trx_ts *ts);
diff --git a/src/osmo-bsc/pcu_sock.c b/src/osmo-bsc/pcu_sock.c
index 1d5e56c..51b59c6 100644
--- a/src/osmo-bsc/pcu_sock.c
+++ b/src/osmo-bsc/pcu_sock.c
@@ -44,6 +44,7 @@
 #include <osmocom/bsc/gsm_04_08_rr.h>
 #include <osmocom/bsc/bts.h>
 #include <osmocom/bsc/bts_sm.h>
+#include <osmocom/bsc/timeslot_fsm.h>
 
 static int pcu_sock_send(struct gsm_bts *bts, struct msgb *msg);
 
@@ -58,11 +59,14 @@
 	[PCU_IF_SAPI_PCH_DT] =	"PCH_DT",
 };
 
-/* Check if BTS has a PCU connection */
-static bool pcu_connected(struct gsm_bts *bts)
+bool pcu_connected(struct gsm_bts *bts)
 {
 	struct pcu_sock_state *state = bts->pcu_state;
 
+	/* BSC co-located PCU is only supported for Ericsson RBS */
+	if (!is_ericsson_bts(bts))
+		return false;
+
 	if (!state)
 		return false;
 	if (state->conn_bfd.fd <= 0)
@@ -751,8 +755,7 @@
 	struct osmo_fd *bfd = &state->conn_bfd;
 	struct gsm_bts *bts;
 	struct gsm_bts_trx *trx;
-	struct gsm_bts_trx_ts *ts;
-	int i, j;
+	int j;
 
 	/* FIXME: allow multiple BTS */
 	bts = llist_entry(state->net->bts_list.next, struct gsm_bts, list);
@@ -773,15 +776,14 @@
 #endif
 
 	/* release PDCH */
-	for (i = 0; i < 8; i++) {
-		trx = gsm_bts_trx_num(bts, i);
-		if (!trx)
-			break;
-		for (j = 0; j < 8; j++) {
-			ts = &trx->ts[j];
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		for (j = 0; j < ARRAY_SIZE(trx->ts); j++) {
+			struct gsm_bts_trx_ts *ts = &trx->ts[j];
+			/* BSC co-located PCU applies only to Ericsson RBS, which supports only GSM_PCHAN_OSMO_DYN.
+			 * So we need to deact only on this pchan kind. */
 			if (ts->mo.nm_state.operational == NM_OPSTATE_ENABLED
-			    && ts->pchan_is == GSM_PCHAN_PDCH) {
-				printf("l1sap_chan_rel(trx,gsm_lchan2chan_nr(ts->lchan));\n");
+			    && ts->pchan_on_init == GSM_PCHAN_OSMO_DYN) {
+				ts_pdch_deact(ts);
 			}
 		}
 	}
@@ -908,9 +910,15 @@
 	struct pcu_sock_state *state = (struct pcu_sock_state *)bfd->data;
 	struct osmo_fd *conn_bfd = &state->conn_bfd;
 	struct sockaddr_un un_addr;
+	struct gsm_bts *bts;
+	struct gsm_bts_trx *trx;
+	int j;
 	socklen_t len;
 	int rc;
 
+	/* FIXME: allow multiple BTS */
+	bts = llist_entry(state->net->bts_list.next, struct gsm_bts, list);
+
 	len = sizeof(un_addr);
 	rc = accept(bfd->fd, (struct sockaddr *) &un_addr, &len);
 	if (rc < 0) {
@@ -939,6 +947,18 @@
 
 	LOGP(DPCU, LOGL_NOTICE, "PCU socket connected to external PCU\n");
 
+	/* activate PDCH */
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		for (j = 0; j < ARRAY_SIZE(trx->ts); j++) {
+			struct gsm_bts_trx_ts *ts = &trx->ts[j];
+			/* (See comment in pcu_sock_close above) */
+			if (ts->mo.nm_state.operational == NM_OPSTATE_ENABLED
+			    && ts->pchan_on_init == GSM_PCHAN_OSMO_DYN) {
+				ts_pdch_act(ts);
+			}
+		}
+	}
+
 	return 0;
 }
 
diff --git a/src/osmo-bsc/timeslot_fsm.c b/src/osmo-bsc/timeslot_fsm.c
index 28e2aaa..16d7360 100644
--- a/src/osmo-bsc/timeslot_fsm.c
+++ b/src/osmo-bsc/timeslot_fsm.c
@@ -341,6 +341,11 @@
 		return;
 	}
 
+	if (!pcu_connected(bts)) {
+		LOG_TS(ts, LOGL_DEBUG, "PCU not connected: not activating PDCH.\n");
+		return;
+	}
+
 	osmo_fsm_inst_state_chg(fi, TS_ST_WAIT_PDCH_ACT, CHAN_ACT_DEACT_TIMEOUT,
 				T_CHAN_ACT_DEACT);
 }
@@ -408,6 +413,10 @@
 		/* ignored. */
 		return;
 
+	case TS_EV_PDCH_ACT:
+		ts_fsm_unused_pdch_act(fi);
+		return;
+
 	default:
 		OSMO_ASSERT(false);
 	}
@@ -531,6 +540,10 @@
 			}
 		}
 
+	case TS_EV_PDCH_DEACT:
+		ts_fsm_pdch_deact(fi);
+		return;
+
 	case TS_EV_LCHAN_UNUSED:
 		/* ignored */
 		return;
@@ -889,6 +902,7 @@
 		.in_event_mask = 0
 			| S(TS_EV_LCHAN_REQUESTED)
 			| S(TS_EV_LCHAN_UNUSED)
+			| S(TS_EV_PDCH_ACT)
 			,
 		.out_state_mask = 0
 			| S(TS_ST_WAIT_PDCH_ACT)
@@ -921,6 +935,7 @@
 		.in_event_mask = 0
 			| S(TS_EV_LCHAN_REQUESTED)
 			| S(TS_EV_LCHAN_UNUSED)
+			| S(TS_EV_PDCH_DEACT)
 			,
 		.out_state_mask = 0
 			| S(TS_ST_WAIT_PDCH_DEACT)
@@ -992,6 +1007,8 @@
 	OSMO_VALUE_STRING(TS_EV_PDCH_ACT_NACK),
 	OSMO_VALUE_STRING(TS_EV_PDCH_DEACT_ACK),
 	OSMO_VALUE_STRING(TS_EV_PDCH_DEACT_NACK),
+	OSMO_VALUE_STRING(TS_EV_PDCH_DEACT),
+	OSMO_VALUE_STRING(TS_EV_PDCH_ACT),
 	{}
 };
 
@@ -1105,3 +1122,23 @@
 
 	return true;
 }
+
+void ts_pdch_act(struct gsm_bts_trx_ts *ts)
+{
+	/* We send the activation event only when the timeslot is UNUSED. In all other cases the timeslot FSM
+	 * will automatically handle the activation at some later point. */
+	if (ts->fi->state != TS_ST_UNUSED)
+		return;
+
+	osmo_fsm_inst_dispatch(ts->fi, TS_EV_PDCH_ACT, NULL);
+}
+
+void ts_pdch_deact(struct gsm_bts_trx_ts *ts)
+{
+	/* We send the deactivation event only when the timeslot is active as PDCH. The timeslot FSM will check
+	 * if the PCU is available before activating the PDCH again. */
+	if (ts->fi->state != TS_ST_PDCH)
+		return;
+
+	osmo_fsm_inst_dispatch(ts->fi, TS_EV_PDCH_DEACT, NULL);
+}

