Add MS TO to RSL measurements

Add optional MS timing offset (3GPP TS 45.010 § 1.2) to RSL MEASUREMENT
RESULT (3GPP TS 48.058 § 8.4.8). The value is calculated either directly
from corresponding BTS measurement or from 3GPP TS 48.058 § 9.3.17
Access Delay (for known TA) and is invalidated after RSL report is sent
until new measurement indication or RACH is received.

Change-Id: I4dfe5c48834a083e757d5de3236a02e15a238b28
Related: OS#1574

2 files changed, 44 insertions, 5 deletions

diff --git a/src/common/l1sap.c b/src/common/l1sap.c
index 35920967..57a858ce 100644
--- a/src/common/l1sap.c
+++ b/src/common/l1sap.c
@@ -431,6 +431,27 @@ static int l1sap_info_time_ind(struct gsm_bts *bts,
 
 	return 0;
 }
+
+static inline void set_ms_to_data(struct gsm_lchan *lchan, int16_t data, bool set_ms_to)
+{
+	if (!lchan)
+		return;
+
+	if (data + 63 > 255) { /* According to 3GPP TS 48.058 §9.3.37 Timing Offset field cannot exceed 255 */
+		LOGP(DL1P, LOGL_ERROR, "Attempting to set invalid Timing Offset value %d (MS TO = %u)!\n",
+		     data, set_ms_to);
+		return;
+	}
+
+	if (set_ms_to) {
+		lchan->ms_t_offs = data + 63;
+		lchan->p_offs = -1;
+	} else {
+		lchan->p_offs = data + 63;
+		lchan->ms_t_offs = -1;
+	}
+}
+
 /* measurement information received from bts model */
 static int l1sap_info_meas_ind(struct gsm_bts_trx *trx,
 	struct osmo_phsap_prim *l1sap,
@@ -456,6 +477,9 @@ static int l1sap_info_meas_ind(struct gsm_bts_trx *trx,
 	ulm.ber10k = info_meas_ind->ber10k;
 	ulm.inv_rssi = info_meas_ind->inv_rssi;
 
+	/* we assume that symbol period is 1 bit: */
+	set_ms_to_data(lchan, info_meas_ind->ta_offs_qbits / 4, true);
+
 	lchan_new_ul_meas(lchan, &ulm);
 
 	return 0;
@@ -1021,6 +1045,9 @@ static int l1sap_ph_rach_ind(struct gsm_bts_trx *trx,
 		return 0;
 	}
 
+	/* According to 3GPP TS 48.058 § 9.3.17 Access Delay is expressed same way as TA (number of symbols) */
+	set_ms_to_data(get_lchan_by_chan_nr(trx, rach_ind->chan_nr), acc_delay, false);
+
 	/* check for handover rach */
 	if (!L1SAP_IS_CHAN_RACH(rach_ind->chan_nr))
 		return l1sap_handover_rach(trx, l1sap, rach_ind);
diff --git a/src/common/rsl.c b/src/common/rsl.c
index 1d0bcea7..5fe5a1d3 100644
--- a/src/common/rsl.c
+++ b/src/common/rsl.c
@@ -2220,8 +2220,18 @@ static int rslms_is_meas_rep(struct msgb *msg)
 	return 0;
 }
 
+static inline uint8_t ms_to2rsl(const struct gsm_lchan *lchan, const struct lapdm_entity *le)
+{
+	return (lchan->ms_t_offs >= 0) ? lchan->ms_t_offs : (lchan->p_offs - le->ta);
+}
+
+static inline bool ms_to_valid(const struct gsm_lchan *lchan)
+{
+	return (lchan->ms_t_offs >= 0) || (lchan->p_offs >= 0);
+}
+
 /* 8.4.8 MEASUREMENT RESult */
-static int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len)
+static int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len, const struct lapdm_entity *le)
 {
 	struct msgb *msg;
 	uint8_t meas_res[16];
@@ -2253,7 +2263,11 @@ static int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len)
 		lchan->meas.flags &= ~LC_UL_M_F_L1_VALID;
 	}
 	msgb_tl16v_put(msg, RSL_IE_L3_INFO, l3_len, l3);
-		//msgb_tv_put(msg, RSL_IE_MS_TIMING_OFFSET, FIXME);
+	if (ms_to_valid(lchan)) {
+		msgb_tv_put(msg, RSL_IE_MS_TIMING_OFFSET, ms_to2rsl(lchan, le));
+		lchan->ms_t_offs = -1;
+		lchan->p_offs = -1;
+	}
 
 	rsl_dch_push_hdr(msg, RSL_MT_MEAS_RES, chan_nr);
 	msg->trx = lchan->ts->trx;
@@ -2267,8 +2281,6 @@ int lapdm_rll_tx_cb(struct msgb *msg, struct lapdm_entity *le, void *ctx)
 	struct gsm_lchan *lchan = ctx;
 	struct abis_rsl_common_hdr *rh;
 
-	/* NOTE: Parameter lapdm_entity *le is ignored */
-
 	OSMO_ASSERT(msg);
 	rh = msgb_l2(msg);
 
@@ -2306,7 +2318,7 @@ int lapdm_rll_tx_cb(struct msgb *msg, struct lapdm_entity *le, void *ctx)
 			return 0;
 		}
 
-		rc = rsl_tx_meas_res(lchan, msgb_l3(msg), msgb_l3len(msg));
+		rc = rsl_tx_meas_res(lchan, msgb_l3(msg), msgb_l3len(msg), le);
 		msgb_free(msg);
 		return rc;
 	} else {