ASCI: NCH / NOTIFICATION support

This adds very minimalistic support for notification of VBS/VGCS calls.

Minimalistic in that we
* only notify via PCH (not via NCH or FACCH)
* only include notification in otherwise empty PAGING TYPE 1

This means that notification will cease to work once the PCH becomes too
loaded and we never would send otherwise empty PAGING TYPE 1 anymore.

Change-Id: I6f6f72d9a0123cb519b341d72a124aaa2117370e
Requires: libosmocore.git I9586b5cb8514010d9358fcfc97c3d34741294522
Related: OS#5781

3 files changed, 63 insertions, 0 deletions

diff --git a/include/osmo-bts/Makefile.am b/include/osmo-bts/Makefile.am
index 0e45d708..1a072871 100644
--- a/include/osmo-bts/Makefile.am
+++ b/include/osmo-bts/Makefile.am
@@ -32,5 +32,6 @@ noinst_HEADERS = \
 	dtx_dl_amr_fsm.h \
 	ta_control.h \
 	nm_common_fsm.h \
+	notification.h \
 	osmux.h \
 	$(NULL)
diff --git a/include/osmo-bts/bts.h b/include/osmo-bts/bts.h
index 296aa0d6..92900890 100644
--- a/include/osmo-bts/bts.h
+++ b/include/osmo-bts/bts.h
@@ -290,6 +290,11 @@ struct gsm_bts {
 		bool pni;		/* Primary Notification Identifier */
 	} etws;
 
+	/* Advanced Speech Call Items (VBS/VGCS) + NCH related bits */
+	struct {
+		struct llist_head notifications;
+	} asci;
+
 	struct paging_state *paging_state;
 	struct llist_head bsc_oml_hosts;
 	unsigned int rtp_jitter_buf_ms;
diff --git a/include/osmo-bts/notification.h b/include/osmo-bts/notification.h
new file mode 100644
index 00000000..3d05acc6
--- /dev/null
+++ b/include/osmo-bts/notification.h
@@ -0,0 +1,57 @@
+/* Maintain and generate ASCI notifications */
+
+/*
+ * (C) 2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: AGPL-3.0+
+ *
+ * Author: Harald Welte
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+/* one [concurrent] ASCI (VBS/VGCS) notification */
+struct asci_notification {
+	struct llist_head list;	/* linked to bts->asci.notifications */
+
+	/* Group call reference (TS 24.008 10.5.1.9 "Descriptive group or broadcast call reference") */
+	uint8_t group_call_ref[5];
+
+	/* Group Channel Description (TS 44.018 10.5.2.14b) */
+	struct {
+		bool present;
+		uint8_t value[255];
+		uint8_t len;
+	} chan_desc;
+
+	/* NCH DRX Information (TS 48.058 9.3.47) */
+	struct {
+		bool present;
+		struct rsl_ie_nch_drx_info value;
+	} nch_drx_info;
+};
+
+int bts_asci_notification_add(struct gsm_bts *bts, const uint8_t *group_call_ref, const uint8_t *chan_desc,
+			      uint8_t chan_desc_len, const struct rsl_ie_nch_drx_info *nch_drx_info);
+
+int bts_asci_notification_del(struct gsm_bts *bts, const uint8_t *group_call_ref);
+
+int bts_asci_notification_reset(struct gsm_bts *bts);
+
+const struct asci_notification *bts_asci_notification_get_next(struct gsm_bts *bts);
+
+void append_group_call_information(struct bitvec *bv, const uint8_t *gcr, const uint8_t *ch_desc, uint8_t ch_desc_len);