From 353fa5a14d0a02ef383bfaa4f6a7273024f94d2f Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Tue, 13 Jun 2023 13:44:32 +0200
Subject: ASCI: Add support for sending RSL UNIT-DATA towards BTS

This is required to send UPLINK FREE and UPLINK BUSY messages to the
BTS.

Change-Id: I25e80f079989a4c7dede58c327c22b958784f3ff
Related: OS#4852
---
 include/osmocom/bsc/abis_rsl.h |  1 +
 src/osmo-bsc/abis_rsl.c        | 25 +++++++++++++++++++++++++
 src/osmo-bsc/gsm_04_08_rr.c    |  9 +++++++++
 3 files changed, 35 insertions(+)

diff --git a/include/osmocom/bsc/abis_rsl.h b/include/osmocom/bsc/abis_rsl.h
index 83e8f7d17..3da0d6ce4 100644
--- a/include/osmocom/bsc/abis_rsl.h
+++ b/include/osmocom/bsc/abis_rsl.h
@@ -62,6 +62,7 @@ int rsl_tx_imm_ass_rej(struct gsm_bts *bts, struct gsm48_req_ref *rqd_ref);
 int gsm48_send_rr_ass_cmd(struct gsm_lchan *dest_lchan, struct gsm_lchan *lchan, uint8_t power_command);
 
 int rsl_data_request(struct msgb *msg, uint8_t link_id);
+int rsl_unit_data_request(struct msgb *msg, uint8_t link_id);
 int rsl_establish_request(struct gsm_lchan *lchan, uint8_t link_id);
 int rsl_relase_request(struct gsm_lchan *lchan, uint8_t link_id);
 
diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c
index d7f5c3320..99c2822a8 100644
--- a/src/osmo-bsc/abis_rsl.c
+++ b/src/osmo-bsc/abis_rsl.c
@@ -1157,6 +1157,31 @@ int rsl_data_request(struct msgb *msg, uint8_t link_id)
 	return abis_rsl_sendmsg(msg);
 }
 
+/* Send "UNIT DATA REQUEST" message with given L3 Info payload */
+/* Chapter 8.3.11 */
+int rsl_unit_data_request(struct msgb *msg, uint8_t link_id)
+{
+	int chan_nr;
+
+	if (msg->lchan == NULL) {
+		LOGP(DRSL, LOGL_ERROR, "cannot send UNIT DATA REQUEST to unknown lchan\n");
+		msgb_free(msg);
+		return -EINVAL;
+	}
+
+	chan_nr = gsm_lchan2chan_nr(msg->lchan, true);
+	if (chan_nr < 0) {
+		msgb_free(msg);
+		return chan_nr;
+	}
+
+	rsl_rll_push_l3(msg, RSL_MT_UNIT_DATA_REQ, chan_nr, link_id, 1);
+
+	msg->dst = rsl_chan_link(msg->lchan);
+
+	return abis_rsl_sendmsg(msg);
+}
+
 /* Send "ESTABLISH REQUEST" message with given L3 Info payload */
 /* Chapter 8.3.1 */
 int rsl_establish_request(struct gsm_lchan *lchan, uint8_t link_id)
diff --git a/src/osmo-bsc/gsm_04_08_rr.c b/src/osmo-bsc/gsm_04_08_rr.c
index ae54cf504..5c2b0f88a 100644
--- a/src/osmo-bsc/gsm_04_08_rr.c
+++ b/src/osmo-bsc/gsm_04_08_rr.c
@@ -57,6 +57,15 @@ int gsm48_sendmsg(struct msgb *msg)
 	return rsl_data_request(msg, 0);
 }
 
+int gsm48_sendmsg_unit(struct msgb *msg)
+{
+	if (msg->lchan)
+		msg->dst = rsl_chan_link(msg->lchan);
+
+	msg->l3h = msg->data;
+	return rsl_unit_data_request(msg, 0);
+}
+
 /* Section 9.1.8 / Table 9.9 */
 struct chreq {
 	uint8_t val;
-- 
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