Decouple handling of Measurement Report from lapdm

This is a preparation commit in order to move power loops up in the
stack in order to have DTXu information available, in order to decide
whether SUB or FULL ul measurements should be used in the MS Power
Control Loop.

Function rsl_tx_meas_res() is stripped from code changing state, and it
simply encodes content and transmits the message.

Change-Id: Id67259ec9ac4c2c33bd0eef3f64450affbe3fb9f

5 files changed, 44 insertions, 28 deletions

diff --git a/include/osmo-bts/measurement.h b/include/osmo-bts/measurement.h
index 45f275f1..481b7bed 100644
--- a/include/osmo-bts/measurement.h
+++ b/include/osmo-bts/measurement.h
@@ -20,4 +20,6 @@ bool ts45008_83_is_sub(struct gsm_lchan *lchan, uint32_t fn);
 
 int is_meas_complete(struct gsm_lchan *lchan, uint32_t fn);
 
+int handle_ms_meas_report(struct gsm_lchan *lchan, struct gsm48_hdr *gh, unsigned int len);
+
 #endif
diff --git a/include/osmo-bts/rsl.h b/include/osmo-bts/rsl.h
index 4e79de5e..16630067 100644
--- a/include/osmo-bts/rsl.h
+++ b/include/osmo-bts/rsl.h
@@ -34,6 +34,6 @@ void ipacc_dyn_pdch_complete(struct gsm_bts_trx_ts *ts, int rc);
 
 int rsl_tx_cbch_load_indication(struct gsm_bts *bts, bool ext_cbch, bool overflow, uint8_t amount);
 
-int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len, const struct lapdm_entity *le);
+int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len, int timing_offset);
 
 #endif // _RSL_H */
diff --git a/src/common/l1sap.c b/src/common/l1sap.c
index 2ebd39a2..7e04a3ae 100644
--- a/src/common/l1sap.c
+++ b/src/common/l1sap.c
@@ -1606,8 +1606,7 @@ static int l1sap_ph_data_ind(struct gsm_bts_trx *trx,
 			 * lack the measurement report from the MS side. See
 			 * also rsl.c:lapdm_rll_tx_cb() */
 			LOGPGT(DL1P, LOGL_INFO, &g_time, "Lost SACCH block, faking meas reports and ms pwr\n");
-			le = &lchan->lapdm_ch.lapdm_acch;
-			rsl_tx_meas_res(lchan, NULL, 0, le);
+			handle_ms_meas_report(lchan, NULL, 0);
 
 			radio_link_timeout(lchan, true);
 			lchan_ms_ta_ctrl(lchan, lchan->ta_ctrl.current, lchan->meas.ms_toa256);
diff --git a/src/common/measurement.c b/src/common/measurement.c
index a1c91a9d..5b46f794 100644
--- a/src/common/measurement.c
+++ b/src/common/measurement.c
@@ -776,3 +776,35 @@ void lchan_meas_reset(struct gsm_lchan *lchan)
 	memset(&lchan->meas, 0, sizeof(lchan->meas));
 	lchan->meas.last_fn = LCHAN_FN_DUMMY;
 }
+
+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);
+}
+
+/* Called every time a Measurement Result (TS 08.58 8.4.8) is received from
+ * lower layers and has to be forwarded to BSC */
+int handle_ms_meas_report(struct gsm_lchan *lchan, struct gsm48_hdr *gh, unsigned int len)
+{
+	int timing_offset, rc;
+	struct lapdm_entity *le;
+
+	le = &lchan->lapdm_ch.lapdm_acch;
+
+	timing_offset = ms_to_valid(lchan) ? ms_to2rsl(lchan, le) : -1;
+	rc = rsl_tx_meas_res(lchan, (uint8_t *)gh, len, timing_offset);
+
+	/* Reset state for next iteration */
+	lchan->meas.res_nr++;
+	lchan->tch.dtx.dl_active = false;
+	lchan->meas.flags &= ~LC_UL_M_F_OSMO_EXT_VALID;
+	lchan->meas.flags &= ~LC_UL_M_F_L1_VALID;
+	lchan->ms_t_offs = -1;
+	lchan->p_offs = -1;
+	return rc;
+}
diff --git a/src/common/rsl.c b/src/common/rsl.c
index 742270d3..e13160e1 100644
--- a/src/common/rsl.c
+++ b/src/common/rsl.c
@@ -3490,16 +3490,6 @@ static int handle_gprs_susp_req(struct msgb *msg)
 	return rc;
 }
 
-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);
-}
-
 struct osmo_bts_supp_meas_info {
 	int16_t toa256_mean;
 	int16_t toa256_min;
@@ -3507,8 +3497,8 @@ struct osmo_bts_supp_meas_info {
 	uint16_t toa256_std_dev;
 } __attribute__((packed));
 
-/* Compose and send 8.4.8 MEASUREMENT RESult via RSL */
-int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len, const struct lapdm_entity *le)
+/* Compose and send 8.4.8 MEASUREMENT RESult via RSL. (timing_offset=-1 -> not present) */
+int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len, int timing_offset)
 {
 	struct msgb *msg;
 	uint8_t meas_res[16];
@@ -3534,13 +3524,12 @@ int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len, const stru
 	     lchan->meas.ul_res.full.rx_qual,
 	     lchan->meas.ul_res.sub.rx_qual,
 	     lchan->meas.l1_info.ms_pwr,
-	     lchan->meas.l1_info.ta, l3_len, ms_to2rsl(lchan, le) - MEAS_MAX_TIMING_ADVANCE);
+	     lchan->meas.l1_info.ta, l3_len, timing_offset - MEAS_MAX_TIMING_ADVANCE);
 
-	msgb_tv_put(msg, RSL_IE_MEAS_RES_NR, lchan->meas.res_nr++);
+	msgb_tv_put(msg, RSL_IE_MEAS_RES_NR, lchan->meas.res_nr);
 	size_t ie_len = gsm0858_rsl_ul_meas_enc(&lchan->meas.ul_res,
 						lchan->tch.dtx.dl_active,
 						meas_res);
-	lchan->tch.dtx.dl_active = false;
 	if (ie_len >= 3) {
 		if (bts->supp_meas_toa256 && lchan->meas.flags & LC_UL_M_F_OSMO_EXT_VALID) {
 			struct osmo_bts_supp_meas_info *smi;
@@ -3558,24 +3547,18 @@ int rsl_tx_meas_res(struct gsm_lchan *lchan, uint8_t *l3, int l3_len, const stru
 			smi->toa256_min = htons(ta256 + lchan->meas.ext.toa256_min);
 			smi->toa256_max = htons(ta256 + lchan->meas.ext.toa256_max);
 			smi->toa256_std_dev = htons(lchan->meas.ext.toa256_std_dev);
-			lchan->meas.flags &= ~LC_UL_M_F_OSMO_EXT_VALID;
 		}
 		msgb_tlv_put(msg, RSL_IE_UPLINK_MEAS, ie_len, meas_res);
-		lchan->meas.flags &= ~LC_UL_M_F_RES_VALID;
 	}
 	msgb_tv_put(msg, RSL_IE_BS_POWER, lchan->bs_power_ctrl.current / 2);
 	if (lchan->meas.flags & LC_UL_M_F_L1_VALID) {
 		msgb_tv_fixed_put(msg, RSL_IE_L1_INFO, sizeof(lchan->meas.l1_info), (uint8_t*)&lchan->meas.l1_info);
-		lchan->meas.flags &= ~LC_UL_M_F_L1_VALID;
 	}
 
-	if (l3 && l3_len > 0)
+	if (l3 && l3_len > 0) {
 		msgb_tl16v_put(msg, RSL_IE_L3_INFO, l3_len, l3);
-	if (ms_to_valid(lchan)) {
-		if (l3 && l3_len > 0)
-			msgb_tv_put(msg, RSL_IE_MS_TIMING_OFFSET, ms_to2rsl(lchan, le));
-		lchan->ms_t_offs = -1;
-		lchan->p_offs = -1;
+		if (timing_offset != -1)
+			msgb_tv_put(msg, RSL_IE_MS_TIMING_OFFSET, timing_offset);
 	}
 
 	rsl_dch_push_hdr(msg, RSL_MT_MEAS_RES, chan_nr);
@@ -3629,7 +3612,7 @@ int lapdm_rll_tx_cb(struct msgb *msg, struct lapdm_entity *le, void *ctx)
 		}
 
 		repeated_dl_facch_active_decision(lchan, msgb_l3(msg), msgb_l3len(msg));
-		rc = rsl_tx_meas_res(lchan, msgb_l3(msg), msgb_l3len(msg), le);
+		rc = handle_ms_meas_report(lchan, (struct gsm48_hdr *)msgb_l3(msg), msgb_l3len(msg));
 		msgb_free(msg);
 		return rc;
 	} else if (rslms_is_gprs_susp_req(msg)) {