l1sap: check if BTS model supports interference reporting

Currently, only osmo-bts-trx is capable of reporting the interference
levels to L1SAP.  Thus it does not make sense to trigger the averaging
logic and send empty reports over the A-bis/RSL and the PCUIF.

Change-Id: Ic17eb46bdca3c33ac4d6e560a093b635b75424a5
Related: SYS#5313

include/osmo-bts/bts.h

@@ -62,6 +62,8 @@ const char *btsvariant2str(enum gsm_bts_type_variant v);
 /* Whether the BTS model requires RadioCarrier MO to be in Enabled state
  * (OPSTARTed) before OPSTARTing the RadioChannel MOs. See OS#5157 */
 #define BTS_INTERNAL_FLAG_NM_RCHANNEL_DEPENDS_RCARRIER	(1 << 2)
+/* Whether the BTS model reports interference measurements to L1SAP. */
+#define BTS_INTERNAL_FLAG_INTERF_MEAS			(1 << 3)
 
 /* BTS implementation flags (internal use, not exposed via OML) */
 #define bts_internal_flag_get(bts, flag) \

src/common/l1sap.c

@@ -667,7 +667,8 @@ static int l1sap_info_time_ind(struct gsm_bts *bts,
 	}
 
 	/* Report interference levels to the BSC */
-	l1sap_interf_meas_report(bts);
+	if (bts_internal_flag_get(bts, BTS_INTERNAL_FLAG_INTERF_MEAS))
+		l1sap_interf_meas_report(bts);
 
 	return 0;
 }

src/osmo-bts-trx/main.c

@@ -151,6 +151,7 @@ int bts_model_init(struct gsm_bts *bts)
 	osmo_bts_set_feature(bts->features, BTS_FEAT_ACCH_TEMP_OVP);
 
 	bts_internal_flag_set(bts, BTS_INTERNAL_FLAG_MEAS_PAYLOAD_COMB);
+	bts_internal_flag_set(bts, BTS_INTERNAL_FLAG_INTERF_MEAS);
 
 	return 0;
 }