From bcb7b32f5ac40a6129461bc3b5c27ce7e0a848db Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Thu, 4 May 2023 15:26:39 +0200
Subject: ASCI: Add support for NOTIFICATION COMMAND (RSL) message

This message will be sent to each BTS with a VGCS/VBS channel to notify
the served MSs about ongoing group/broadcast calls. It is also used to
remove the notification, if the call is terminated.

Change-Id: I96ec0ee5d1a772a45f1ebfd64210718c8bf5aa58
Related: OS#4852
---
 include/osmocom/bsc/abis_rsl.h |  1 +
 src/osmo-bsc/abis_rsl.c        | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/osmocom/bsc/abis_rsl.h b/include/osmocom/bsc/abis_rsl.h
index 06880bf99..83e8f7d17 100644
--- a/include/osmocom/bsc/abis_rsl.h
+++ b/include/osmocom/bsc/abis_rsl.h
@@ -55,6 +55,7 @@ int rsl_encryption_cmd(struct msgb *msg);
 int rsl_paging_cmd(struct gsm_bts *bts, uint8_t paging_group,
 		   const struct osmo_mobile_identity *mi,
 		   uint8_t chan_needed, bool is_gprs);
+int rsl_notification_cmd(struct gsm_bts *bts, struct gsm_lchan *lchan, struct gsm0808_group_callref *gc, uint8_t *drx);
 int rsl_imm_assign_cmd(const struct gsm_bts *bts, uint8_t len, const uint8_t *val);
 int rsl_tx_imm_assignment(struct gsm_lchan *lchan);
 int rsl_tx_imm_ass_rej(struct gsm_bts *bts, struct gsm48_req_ref *rqd_ref);
diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c
index 0c3be1ae8..f6acd2f34 100644
--- a/src/osmo-bsc/abis_rsl.c
+++ b/src/osmo-bsc/abis_rsl.c
@@ -870,6 +870,45 @@ int rsl_paging_cmd(struct gsm_bts *bts, uint8_t paging_group,
 	return abis_rsl_sendmsg(msg);
 }
 
+/* Chapter 8.5.10: NOTIFICATION COMMAND */
+int rsl_notification_cmd(struct gsm_bts *bts, struct gsm_lchan *lchan, struct gsm0808_group_callref *gc, uint8_t *drx)
+{
+	struct abis_rsl_cchan_hdr *cch;
+	struct msgb *msg = rsl_msgb_alloc();
+	struct gsm48_chan_desc cd;
+	uint8_t sti = (lchan) ? RSL_CMD_INDICATOR_START : RSL_CMD_INDICATOR_STOP;
+	uint8_t *t;
+	int rc;
+
+	cch = (struct abis_rsl_cchan_hdr *) msgb_put(msg, sizeof(*cch));
+	rsl_init_cchan_hdr(cch, RSL_MT_NOT_CMD);
+	cch->chan_nr = RSL_CHAN_PCH_AGCH;
+
+	msgb_tlv_put(msg, RSL_IE_CMD_INDICATOR, 1, &sti);
+
+	/* Use TLV encoding from TS 08.08. Change different IE type. */
+	t = msg->tail;
+	gsm0808_enc_group_callref(msg, gc);
+	*t = RSL_IE_GROUP_CALL_REF;
+
+	if (lchan) {
+		memset(&cd, 0, sizeof(cd));
+		rc = gsm48_lchan2chan_desc(&cd, lchan, lchan->activate.tsc, true);
+		if (rc) {
+			LOG_LCHAN(lchan, LOGL_ERROR, "Error encoding Channel Number\n");
+			msgb_free(msg);
+			return rc;
+		}
+		msgb_tlv_put(msg, RSL_IE_CHAN_DESC, sizeof(cd), (const uint8_t *)&cd);
+
+		if (drx)
+			msgb_tlv_put(msg, RSL_IE_NCH_DRX_INFO, 1, drx);
+	}
+
+	msg->dst = bts->c0->rsl_link_primary;
+	return abis_rsl_sendmsg(msg);
+}
+
 int rsl_forward_layer3_info(struct gsm_lchan *lchan, const uint8_t *l3_info, uint8_t l3_info_len)
 {
 	struct msgb *msg;
-- 
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