Add vty command "radio-link-timeout infinite" for uplink rx testing

When we are performing Rx sensitivity testing on a BTS, we want to
deactivate the connection failure criterion / radio link timeout, i.e.
no matter how many SACCH frames in uplink are failed to decode, the BTS
should never close the channel.

OsmoBTS Change-Id I736f21f6528db5c16fa80cdb905af20673797be5 covers a way
how this behavior can be requested from the BTS via an OML attribute.
This patch adds support to the BSC to actually set that attribute.

Do not use this in production networks, as the BTS will keep open radio
channels indefinitely even if the phone is gone and no longer
transmitting anything.  This is a pure testing feature.

Change-Id: I6cb94e0f024934f7baeeb728ca9ed3042fbf16d2

1 files changed, 38 insertions, 2 deletions

diff --git a/openbsc/src/libcommon/gsm_data.c b/openbsc/src/libcommon/gsm_data.c
index 8830ce144..db7de082d 100644
--- a/openbsc/src/libcommon/gsm_data.c
+++ b/openbsc/src/libcommon/gsm_data.c
@@ -323,8 +323,7 @@ struct gsm_bts *gsm_bts_alloc_register(struct gsm_network *net, enum gsm_bts_typ
 	bts->si_common.chan_desc.bs_pa_mfrms = RSL_BS_PA_MFRMS_5; /* paging frames */
 	bts->si_common.chan_desc.bs_ag_blks_res = 1; /* reserved AGCH blocks */
 	bts->si_common.chan_desc.t3212 = 5; /* Use 30 min periodic update interval as sane default */
-	set_radio_link_timeout(&bts->si_common.cell_options, 32);
-				/* Use RADIO LINK TIMEOUT of 32 seconds */
+	gsm_bts_set_radio_link_timeout(bts, 32); /* Use RADIO LINK TIMEOUT of 32 */
 
 	llist_add_tail(&bts->list, &net->bts_list);
 
@@ -435,3 +434,40 @@ int bts_depend_check(struct gsm_bts *bts)
 	}
 	return 1;
 }
+
+/* get the radio link timeout (based on SACCH decode errors, according
+ * to algorithm specified in TS 05.08 section 5.2.  A value of -1
+ * indicates we should use an infinitely long timeout, which only works
+ * with OsmoBTS as the BTS implementation */
+int gsm_bts_get_radio_link_timeout(const struct gsm_bts *bts)
+{
+	const struct gsm48_cell_options *cell_options = &bts->si_common.cell_options;
+
+	if (bts->infinite_radio_link_timeout)
+		return -1;
+	else {
+		/* Encoding as per Table 10.5.21 of TS 04.08 */
+		return (cell_options->radio_link_timeout + 1) << 2;
+	}
+}
+
+/* set the radio link timeout (based on SACCH decode errors, according
+ * to algorithm specified in TS 05.08 Section 5.2.  A value of -1
+ * indicates we should use an infinitely long timeout, which only works
+ * with OsmoBTS as the BTS implementation */
+void gsm_bts_set_radio_link_timeout(struct gsm_bts *bts, int value)
+{
+	struct gsm48_cell_options *cell_options = &bts->si_common.cell_options;
+
+	if (value < 0)
+		bts->infinite_radio_link_timeout = true;
+	else {
+		bts->infinite_radio_link_timeout = false;
+		/* Encoding as per Table 10.5.21 of TS 04.08 */
+		if (value < 4)
+			value = 4;
+		if (value > 64)
+			value = 64;
+		cell_options->radio_link_timeout = (value >> 2) - 1;
+	}
+}