lib: lte_link_control: Skip parsing of unexpected %NCELLMEAS notif

Added check to skip %NCELLMEAS notification parsing when neighbor
cell measurement has not been requested by calling
lte_lc_neighbor_cell_measurement(). If the neighbor cell measurement
is triggered by sending the AT%NCELLMEAS AT command to the modem,
LTE LC does not know how the received notification should be parsed,
sometimes leading to a parsing error.

Signed-off-by: Tommi Kangas <tommi.kangas@nordicsemi.no>

lib/lte_link_control/modules/ncellmeas.c

@@ -667,6 +667,16 @@ static void at_handler_ncellmeas(const char *response)
 		goto exit;
 	}
 
+	if (k_sem_count_get(&ncellmeas_idle_sem) > 0) {
+		/* No need to parse the notification because neighbor cell measurement
+		 * has not been requested.
+		 */
+		LOG_DBG("%%NCELLMEAS notification not parsed because "
+			"lte_lc_neighbor_cell_measurement() not called");
+
+		goto exit;
+	}
+
 	if (ncellmeas_params.search_type > LTE_LC_NEIGHBOR_SEARCH_TYPE_EXTENDED_COMPLETE) {
 		at_handler_ncellmeas_gci(response);
 		goto exit;
@@ -783,6 +793,24 @@ int ncellmeas_start(struct lte_lc_ncellmeas_params *params)
 	return err;
 }
 
+static void ncellmeas_cancel_timeout_work_fn(struct k_work *work)
+{
+	struct lte_lc_evt evt = {0};
+
+	if (k_sem_count_get(&ncellmeas_idle_sem) == 0) {
+		LOG_DBG("No %%NCELLMEAS notification received after AT%%NCELLMEASSTOP, "
+			"sending empty results");
+
+		evt.type = LTE_LC_EVT_NEIGHBOR_CELL_MEAS;
+		evt.cells_info.current_cell.id = LTE_LC_CELL_EUTRAN_ID_INVALID;
+		event_handler_list_dispatch(&evt);
+
+		k_sem_give(&ncellmeas_idle_sem);
+	}
+}
+
+K_WORK_DELAYABLE_DEFINE(ncellmeas_cancel_timeout_work, ncellmeas_cancel_timeout_work_fn);
+
 int ncellmeas_cancel(void)
 {
 	LOG_DBG("Cancelling");
@@ -793,7 +821,11 @@ int ncellmeas_cancel(void)
 		err = -EFAULT;
 	}
 
-	k_sem_give(&ncellmeas_idle_sem);
+	/* Transition to idle happens when %NCELLMEAS notification is received. However, if modem
+	 * had not yet started the measurement, no notification is sent and we need a timeout to
+	 * handle it.
+	 */
+	k_work_schedule(&ncellmeas_cancel_timeout_work, K_SECONDS(1));
 
 	return err;
 }

tests/lib/location/src/location_test.c

@@ -1017,7 +1017,9 @@ void test_location_cellular_cancel_during_ncellmeas(void)
 
 	err = location_request_cancel();
 	TEST_ASSERT_EQUAL(0, err);
-	k_sleep(K_MSEC(1));
+
+	/* Need to wait a bit because no %NCELLMEAS notification is sent after AT%NCELLMEASSTOP. */
+	k_sleep(K_SECONDS(2));
 }
 
 /* Test cellular timeout during the 1st NCELLMEAS. */

tests/lib/lte_lc_api/src/lte_lc_api_test.c

@@ -2384,6 +2384,18 @@ void test_lte_lc_neighbor_cell_measurement_fail(void)
 	TEST_ASSERT_EQUAL(-EFAULT, ret);
 }
 
+/* Test that no callbacks are triggered by an %NCELLMEAS notification when
+ * lte_lc_neighbor_cell_measurement() has not been called.
+ */
+void test_lte_lc_neighbor_cell_measurement_no_request(void)
+{
+	strcpy(at_notif,
+	       "%NCELLMEAS: 0,\"00112233\",\"98712\",\"0AB9\",4800,7,63,31,"
+	       "456,4800,8,60,29,4,3500,9,99,18,5,5300,11\r\n");
+
+	at_monitor_dispatch(at_notif);
+}
+
 void test_lte_lc_neighbor_cell_measurement_normal(void)
 {
 	int ret;
@@ -3366,11 +3378,90 @@ void test_lte_lc_neighbor_cell_measurement_gci_max_length(void)
 void test_lte_lc_neighbor_cell_measurement_cancel(void)
 {
 	int ret;
+	struct lte_lc_ncellmeas_params params = {
+		.search_type = LTE_LC_NEIGHBOR_SEARCH_TYPE_DEFAULT,
+		.gci_count = 0,
+	};
+	strcpy(at_notif,
+	       "%NCELLMEAS:0,\"00112233\",\"98712\",\"0AB9\",4800,7,63,31,"
+	       "456,4800,8,60,29,4,3500,9,99,18,5,5300,11\r\n");
+
+	lte_lc_callback_count_expected = 1;
+
+	test_event_data[0].type = LTE_LC_EVT_NEIGHBOR_CELL_MEAS;
+	test_event_data[0].cells_info.current_cell.mcc = 987;
+	test_event_data[0].cells_info.current_cell.mnc = 12;
+	test_event_data[0].cells_info.current_cell.id = 0x00112233;
+	test_event_data[0].cells_info.current_cell.tac = 0x0AB9;
+	test_event_data[0].cells_info.current_cell.earfcn = 7;
+	test_event_data[0].cells_info.current_cell.timing_advance = 4800;
+	test_event_data[0].cells_info.current_cell.timing_advance_meas_time = 11;
+	test_event_data[0].cells_info.current_cell.measurement_time = 4800;
+	test_event_data[0].cells_info.current_cell.phys_cell_id = 63;
+	test_event_data[0].cells_info.current_cell.rsrp = 31;
+	test_event_data[0].cells_info.current_cell.rsrq = 456;
+	test_event_data[0].cells_info.ncells_count = 2;
+	test_event_data[0].cells_info.gci_cells_count = 0;
+	test_neighbor_cells[0].earfcn = 8;
+	test_neighbor_cells[0].time_diff = 3500;
+	test_neighbor_cells[0].phys_cell_id = 60;
+	test_neighbor_cells[0].rsrp = 29;
+	test_neighbor_cells[0].rsrq = 4;
+	test_neighbor_cells[1].earfcn = 9;
+	test_neighbor_cells[1].time_diff = 5300;
+	test_neighbor_cells[1].phys_cell_id = 99;
+	test_neighbor_cells[1].rsrp = 18;
+	test_neighbor_cells[1].rsrq = 5;
+
+	__mock_nrf_modem_at_printf_ExpectAndReturn("AT%NCELLMEAS", EXIT_SUCCESS);
+
+	ret = lte_lc_neighbor_cell_measurement(&params);
+	TEST_ASSERT_EQUAL(EXIT_SUCCESS, ret);
 
 	__mock_nrf_modem_at_printf_ExpectAndReturn("AT%NCELLMEASSTOP", EXIT_SUCCESS);
+
 	ret = lte_lc_neighbor_cell_measurement_cancel();
 	TEST_ASSERT_EQUAL(EXIT_SUCCESS, ret);
 
+	at_monitor_dispatch(at_notif);
+}
+
+void test_lte_lc_neighbor_cell_measurement_cancel_no_notif(void)
+{
+	int ret;
+	struct lte_lc_ncellmeas_params params = {
+		.search_type = LTE_LC_NEIGHBOR_SEARCH_TYPE_DEFAULT,
+		.gci_count = 0,
+	};
+
+	lte_lc_callback_count_expected = 1;
+
+	test_event_data[0].type = LTE_LC_EVT_NEIGHBOR_CELL_MEAS;
+	test_event_data[0].cells_info.current_cell.id = LTE_LC_CELL_EUTRAN_ID_INVALID;
+
+	__mock_nrf_modem_at_printf_ExpectAndReturn("AT%NCELLMEAS", EXIT_SUCCESS);
+
+	ret = lte_lc_neighbor_cell_measurement(&params);
+	TEST_ASSERT_EQUAL(EXIT_SUCCESS, ret);
+
+	__mock_nrf_modem_at_printf_ExpectAndReturn("AT%NCELLMEASSTOP", EXIT_SUCCESS);
+
+	ret = lte_lc_neighbor_cell_measurement_cancel();
+	TEST_ASSERT_EQUAL(EXIT_SUCCESS, ret);
+
+	/* After lte_lc_neighbor_cell_measurement_cancel(), new measurement can not be started
+	 * before a %NCELLMEAS notification is received or a timeout happens.
+	 */
+	ret = lte_lc_neighbor_cell_measurement(&params);
+	TEST_ASSERT_EQUAL(-EINPROGRESS, ret);
+
+	k_sleep(K_MSEC(1));
+}
+
+void test_lte_lc_neighbor_cell_measurement_cancel_fail(void)
+{
+	int ret;
+
 	__mock_nrf_modem_at_printf_ExpectAndReturn("AT%NCELLMEASSTOP", -NRF_ENOMEM);
 	ret = lte_lc_neighbor_cell_measurement_cancel();
 	TEST_ASSERT_EQUAL(-EFAULT, ret);