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

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 @@ msc {
 	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"];

include/osmocom/bsc/pcu_if.h

@@ -14,6 +14,9 @@ struct pcu_sock_state {
 	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);
 

include/osmocom/bsc/timeslot_fsm.h

@@ -36,10 +36,18 @@ enum ts_fsm_event {
 	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_is_pchan_switching(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config
 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);

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 @@ static const char *sapi_string[] = {
 	[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 @@ static void pcu_sock_close(struct pcu_sock_state *state)
 	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 @@ static void pcu_sock_close(struct pcu_sock_state *state)
 #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 @@ static int pcu_sock_accept(struct osmo_fd *bfd, unsigned int flags)
 	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 @@ static int pcu_sock_accept(struct osmo_fd *bfd, unsigned int flags)
 
 	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;
 }
 

src/osmo-bsc/timeslot_fsm.c

@@ -341,6 +341,11 @@ static void ts_fsm_unused_pdch_act(struct osmo_fsm_inst *fi)
 		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 @@ static void ts_fsm_unused(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 		/* ignored. */
 		return;
 
+	case TS_EV_PDCH_ACT:
+		ts_fsm_unused_pdch_act(fi);
+		return;
+
 	default:
 		OSMO_ASSERT(false);
 	}
@@ -531,6 +540,10 @@ static void ts_fsm_pdch(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 			}
 		}
 
+	case TS_EV_PDCH_DEACT:
+		ts_fsm_pdch_deact(fi);
+		return;
+
 	case TS_EV_LCHAN_UNUSED:
 		/* ignored */
 		return;
@@ -889,6 +902,7 @@ static const struct osmo_fsm_state ts_fsm_states[] = {
 		.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 @@ static const struct osmo_fsm_state ts_fsm_states[] = {
 		.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 @@ static const struct value_string ts_fsm_event_names[] = {
 	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 @@ bool ts_usable_as_pchan(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config as_
 
 	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);
+}