abis_rsl: parse cm3 and indicate ACCH repetition cap to BTSpmaier/acch

In order to activate FACCH/SACCH repetition on the BTS, the classmark 3
IE in the CLASSMARK CHANGE message must be parsed and depending on the
Repeated ACCH Capability bit the RSL_IE_OSMO_REP_ACCH_CAP is added to
the RSL CHAN ACT und RSL CHAN MODE MODIFY. Since
RSL_IE_OSMO_REP_ACCH_CAP is a propritary IE, it may only be added for
BTS type osmo-bts.

Change-Id: I39ae439d05562b35b2e47774dc92f8789fea1a57
Depends: libosmocore Ic8b2bfd00330235f5bed00771e421588abfaac1f
Related: OS#4796 SYS#5114

3 files changed, 39 insertions, 0 deletions

diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index ed40e360f..d75cb5073 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -322,6 +322,10 @@ struct gsm_subscriber_connection {
 			enum subscr_sccp_state state;
 		} lb;
 	} lcs;
+
+	/* Set to true when Repeated ACCH Capability bit in Classmark 3 is set.
+	 * see also: 3GPP TS 24.008, section 10.5.1.7 */
+	bool repeated_acch_capability;
 };
 
 
diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c
index 858c683e1..1d4285354 100644
--- a/src/osmo-bsc/abis_rsl.c
+++ b/src/osmo-bsc/abis_rsl.c
@@ -457,6 +457,28 @@ static void mr_config_for_bts(struct gsm_lchan *lchan, struct msgb *msg)
 		     lchan->mr_bts_lv + 1);
 }
 
+/* indicate FACCH/SACCH Repetition to be performed by BTS,
+ * see also: 3GPP TS 44.006, section 10 and 11 */
+static void put_rsl_ie_osmo_rep_acch_cap(struct gsm_lchan *lchan, struct msgb *msg)
+{
+	uint8_t val[1];
+
+	if (!lchan->conn)
+		return;
+
+	/* The RSL_IE_OSMO_REP_ACCH_CAP IE is a proprietary IE, that can only
+	 * be used with osmo-bts type BTSs */
+	if (conn_get_bts(lchan->conn)->model->type != GSM_BTS_TYPE_OSMOBTS)
+		return;
+
+	if (lchan->conn && lchan->conn->repeated_acch_capability)
+		val[0] = 0x01;
+	else
+		val[0] = 0x00;
+
+	msgb_tlv_put(msg, RSL_IE_OSMO_REP_ACCH_CAP, sizeof(val), val);
+}
+
 /* Chapter 8.4.1 */
 int rsl_tx_chan_activ(struct gsm_lchan *lchan, uint8_t act_type, uint8_t ho_ref)
 {
@@ -552,6 +574,7 @@ int rsl_tx_chan_activ(struct gsm_lchan *lchan, uint8_t act_type, uint8_t ho_ref)
 	   better skip sending it unless we know for sure what each expects. */
 
 	mr_config_for_bts(lchan, msg);
+	put_rsl_ie_osmo_rep_acch_cap(lchan, msg);
 
 	msg->dst = trx->rsl_link;
 
@@ -590,6 +613,7 @@ int rsl_chan_mode_modify_req(struct gsm_lchan *lchan)
 	}
 
 	mr_config_for_bts(lchan, msg);
+	put_rsl_ie_osmo_rep_acch_cap(lchan, msg);
 
 	msg->dst = lchan->ts->trx->rsl_link;
 
diff --git a/src/osmo-bsc/gsm_08_08.c b/src/osmo-bsc/gsm_08_08.c
index 2c51c958a..354797249 100644
--- a/src/osmo-bsc/gsm_08_08.c
+++ b/src/osmo-bsc/gsm_08_08.c
@@ -34,6 +34,7 @@
 #include <osmocom/bsc/lcs_loc_req.h>
 
 #include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/protocol/gsm_04_08.h>
 #include <osmocom/gsm/gsm0808.h>
 #include <osmocom/gsm/mncc.h>
 #include <osmocom/gsm/gsm48.h>
@@ -582,6 +583,7 @@ void bsc_cm_update(struct gsm_subscriber_connection *conn,
 		   const uint8_t *cm3, uint8_t cm3_len)
 {
 	struct gsm48_classmark2 *cm2_parsed = (struct gsm48_classmark2 *)cm2;
+        struct gsm48_classmark3 cm3_parsed;
 	int8_t rc8;
 	int rc;
 	struct msgb *resp;
@@ -602,6 +604,15 @@ void bsc_cm_update(struct gsm_subscriber_connection *conn,
 	}
 	conn_update_ms_power_class(conn, rc8);
 
+        rc = gsm48_decode_classmark3(&cm3_parsed, cm3, cm3_len);
+	if (rc < 0) {
+		LOGP(DMSC, LOGL_NOTICE, "Unable to decode classmark3 during CM Update.\n");
+	} else {
+		conn->repeated_acch_capability = false;
+		if (cm3_parsed.repeated_acch_capability)
+			conn->repeated_acch_capability = true;
+	}
+
 	if (!msc_connected(conn))
 		return;