Use qbit-TA to update Timing Advance

Separate qbit-TA to TA conversion into separate function and use it for
computing and updating Timing Advance.

Note: the code was tested with TA=0 only to make sure it does not
introduce regressions.

Change-Id: I96fdbb20b09fb85fdd9fb6dcf3c25f6bee7f80e4
Fixes: OS#1531

src/bts.cpp

@@ -478,8 +478,7 @@ int BTS::rcv_rach(uint16_t ra, uint32_t Fn, int16_t qta, uint8_t is_11bit,
 	int rc;
 	int plen;
 	uint8_t usf = 7;
-	uint8_t tsc;
-	uint16_t ta;
+	uint8_t tsc, ta = qta2ta(qta);
 	uint16_t ms_class = 0;
 	uint16_t priority = 0;
 
@@ -490,13 +489,6 @@ int BTS::rcv_rach(uint16_t ra, uint32_t Fn, int16_t qta, uint8_t is_11bit,
 
 	sb = is_single_block(ra, burst_type, is_11bit, &ms_class, &priority);
 
-	if (qta < 0)
-		qta = 0;
-	if (qta > 252)
-		qta = 252;
-
-	ta = qta >> 2;
-
 	if (sb) {
 		rc = sba()->alloc(&trx_no, &ts_no, &sb_fn, ta);
 		if (rc < 0)
@@ -1475,6 +1467,23 @@ int gprs_rlcmac_pdch::rcv_block_gprs(uint8_t *data, uint32_t fn,
 	return rc;
 }
 
+void bts_update_tbf_ta(const char *p, uint32_t fn, uint8_t trx_no, uint8_t ts,
+		       uint8_t ta)
+{
+	struct gprs_rlcmac_ul_tbf *tbf =
+		bts_main_data()->bts->ul_tbf_by_poll_fn(fn, trx_no, ts);
+	if (!tbf)
+		LOGP(DL1IF, LOGL_DEBUG, "[%s] update TA = %u ignored due to "
+		     "unknown UL TBF on TRX = %d, TS = %d, FN = %d\n",
+		     p, ta, trx_no, ts, fn);
+	else if (tbf->ta() != ta) {
+		LOGP(DL1IF, LOGL_INFO, "[%s] Updating TA %u -> %u on "
+		     "TRX = %d, TS = %d, FN = %d\n",
+		     p, tbf->ta(), ta, trx_no, ts, fn);
+		tbf->set_ta(ta);
+	}
+}
+
 gprs_rlcmac_tbf *gprs_rlcmac_pdch::tbf_from_list_by_tfi(
 		LListHead<gprs_rlcmac_tbf> *tbf_list, uint8_t tfi,
 		enum gprs_rlcmac_tbf_direction dir)

src/bts.h

@@ -143,6 +143,15 @@ struct gprs_rlcmac_trx {
 #endif
 };
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+void bts_update_tbf_ta(const char *p, uint32_t fn, uint8_t trx_no, uint8_t ts,
+		       uint8_t ta);
+#ifdef __cplusplus
+}
+#endif
+
 /**
  * This is the data from C. As soon as our minimal compiler is gcc 4.7
  * we can start to compile pcu_vty.c with c++ and remove the split.

src/osmo-bts-litecell15/lc15_l1_if.c

@@ -32,6 +32,7 @@
 #include <lc15_l1_if.h>
 #include <gprs_debug.h>
 #include <pcu_l1_if.h>
+#include <bts.h>
 
 extern void *tall_pcu_ctx;
 
@@ -204,6 +205,8 @@ static int handle_ph_data_ind(struct lc15l1_hdl *fl1h,
 			data_ind->msgUnitParam.u8Size-1);
 
 	get_meas(&meas, &data_ind->measParam);
+	bts_update_tbf_ta("PH-DATA", data_ind->u32Fn, fl1h->trx_no,
+			  data_ind->u8Tn, qta2ta(meas.bto));
 
 	switch (data_ind->sapi) {
 	case GsmL1_Sapi_Pdtch:
@@ -235,31 +238,12 @@ static int handle_ph_data_ind(struct lc15l1_hdl *fl1h,
 
 static int handle_ph_ra_ind(struct lc15l1_hdl *fl1h, GsmL1_PhRaInd_t *ra_ind)
 {
-	uint8_t acc_delay;
-
 	if (ra_ind->measParam.fLinkQuality < MIN_QUAL_RACH)
 		return 0;
 
 	DEBUGP(DL1IF, "Rx PH-RA.ind");
-
-	/* check for under/overflow / sign */
-	if (ra_ind->measParam.i16BurstTiming < 0)
-		acc_delay = 0;
-	else
-		acc_delay = ra_ind->measParam.i16BurstTiming >> 2;
-
-	LOGP(DL1IF, LOGL_NOTICE, "got (P)RACH request, TA = %u (ignored)\n",
-		acc_delay);
-
-#warning "The (P)RACH request is just dropped here"
-
-#if 0
-	if (acc_delay > bts->max_ta) {
-		LOGP(DL1C, LOGL_INFO, "ignoring RACH request %u > max_ta(%u)\n",
-		     acc_delay, btsb->max_ta);
-		return 0;
-	}
-#endif
+	bts_update_tbf_ta("PH-RA", ra_ind->u32Fn, fl1h->trx_no, ra_ind->u8Tn,
+			  qta2ta(ra_ind->measParam.i16BurstTiming));
 
 	return 0;
 }

src/osmo-bts-sysmo/sysmo_l1_if.c

@@ -13,6 +13,7 @@
 #include <sysmo_l1_if.h>
 #include <gprs_debug.h>
 #include <pcu_l1_if.h>
+#include <bts.h>
 
 extern void *tall_pcu_ctx;
 
@@ -189,6 +190,8 @@ static int handle_ph_data_ind(struct femtol1_hdl *fl1h,
 			data_ind->msgUnitParam.u8Size-1);
 
 	get_meas(&meas, &data_ind->measParam);
+	bts_update_tbf_ta("PH-DATA", data_ind->u32Fn, fl1h->trx_no,
+			  data_ind->u8Tn, qta2ta(meas.bto));
 
 	switch (data_ind->sapi) {
 	case GsmL1_Sapi_Pdtch:
@@ -220,33 +223,14 @@ static int handle_ph_data_ind(struct femtol1_hdl *fl1h,
 
 static int handle_ph_ra_ind(struct femtol1_hdl *fl1h, GsmL1_PhRaInd_t *ra_ind)
 {
-	uint8_t acc_delay;
-
 	pcu_rx_ra_time(ra_ind->u16Arfcn, ra_ind->u32Fn, ra_ind->u8Tn);
 
 	if (ra_ind->measParam.fLinkQuality < MIN_QUAL_RACH)
 		return 0;
 
 	DEBUGP(DL1IF, "Rx PH-RA.ind");
-
-	/* check for under/overflow / sign */
-	if (ra_ind->measParam.i16BurstTiming < 0)
-		acc_delay = 0;
-	else
-		acc_delay = ra_ind->measParam.i16BurstTiming >> 2;
-
-	LOGP(DL1IF, LOGL_NOTICE, "got (P)RACH request, TA = %u (ignored)\n",
-		acc_delay);
-
-#warning "The (P)RACH request is just dropped here"
-
-#if 0
-	if (acc_delay > bts->max_ta) {
-		LOGP(DL1C, LOGL_INFO, "ignoring RACH request %u > max_ta(%u)\n",
-		     acc_delay, btsb->max_ta);
-		return 0;
-	}
-#endif
+	bts_update_tbf_ta("PH-RA", ra_ind->u32Fn, fl1h->trx_no, ra_ind->u8Tn,
+			  qta2ta(ra_ind->measParam.i16BurstTiming));
 
 	return 0;
 }

src/pcu_l1_if.h

@@ -33,6 +33,15 @@ extern "C" {
 }
 #endif
 
+static inline uint8_t qta2ta(int16_t qta)
+{
+	if (qta < 0)
+		return 0;
+	if (qta > 252)
+		qta = 252;
+	return qta >> 2;
+}
+
 /*
  * L1 Measurement values
  */