Change in osmo-pcu[master]: BTS::parse_rach_ind(): properly handle EGPRS Packet Channel Request

[fixeria]

fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-pcu/+/18387 )


Change subject: BTS::parse_rach_ind(): properly handle EGPRS Packet Channel Request
......................................................................

BTS::parse_rach_ind(): properly handle EGPRS Packet Channel Request

Change-Id: Ia15761c33c8048d35c7f7bc93dbea781dd0894b7
---
M src/bts.cpp
1 file changed, 67 insertions(+), 4 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-pcu refs/changes/87/18387/1

diff --git a/src/bts.cpp b/src/bts.cpp
index 934bdef..c305e22 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -671,9 +671,68 @@
  * deprecated, no PACKET CHANNEL REQUEST exists, which means for GPRS we will
  * receive CCCH RACH which doesn't contain any mslot class. Hence in the end we
  * can only receive EGPRS mslot class through 11-bit EGPRS PACKET CHANNEL REQUEST. */
+static int parse_egprs_pkt_ch_req(uint16_t ra11, struct chan_req_params *chan_req)
+{
+	EGPRS_PacketChannelRequest_t req;
+	int rc;
+
+	rc = decode_egprs_pkt_ch_req(ra11, &req);
+	if (rc) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "Failed to decode "
+		     "EGPRS Packet Channel Request: rc=%d", rc);
+		return rc;
+	}
+
+	LOGP(DRLCMAC, LOGL_INFO, "Rx EGPRS Packet Channel Request: %s\n",
+	     get_value_string(egprs_pkt_ch_req_type_names, req.Type));
+
+	switch (req.Type) {
+	case EGPRS_PKT_CHAN_REQ_ONE_PHASE:
+		chan_req->egprs_mslot_class = req.Content.MultislotClass + 1;
+		chan_req->priority = req.Content.Priority + 1;
+		break;
+	case EGPRS_PKT_CHAN_REQ_SHORT:
+		chan_req->priority = req.Content.Priority + 1;
+		if (req.Content.NumberOfBlocks == 0)
+			chan_req->single_block = true;
+		break;
+	case EGPRS_PKT_CHAN_REQ_ONE_PHASE_RED_LATENCY:
+		chan_req->priority = req.Content.Priority + 1;
+		break;
+	/* Two phase access => single block is needed */
+	case EGPRS_PKT_CHAN_REQ_TWO_PHASE:
+	case EGPRS_PKT_CHAN_REQ_TWO_PHASE_IPA:
+		chan_req->priority = req.Content.Priority + 1;
+		chan_req->single_block = true;
+		break;
+
+	/* Neither unacknowledged RLC mode, nor emergency calls are supported */
+	case EGPRS_PKT_CHAN_REQ_ONE_PHASE_UNACK:
+	case EGPRS_PKT_CHAN_REQ_EMERGENCY_CALL:
+		LOGP(DRLCMAC, LOGL_NOTICE, "%s is not supported, rejecting\n",
+		     get_value_string(egprs_pkt_ch_req_type_names, req.Type));
+		return -ENOTSUP;
+
+	case EGPRS_PKT_CHAN_REQ_SIGNALLING:
+	case EGPRS_PKT_CHAN_REQ_SIGNALLING_IPA:
+	case EGPRS_PKT_CHAN_REQ_DEDICATED_CHANNEL:
+		/* TODO: IIUC, signalling needs only one block */
+		break;
+
+	default:
+		LOGP(DRLCMAC, LOGL_ERROR, "Unknown EGPRS Packet Channel Request "
+		     "type=0x%02x, probably a bug in CSN.1 codec\n", req.Type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int parse_rach_ind(const struct rach_ind_params *rip,
 			  struct chan_req_params *chan_req)
 {
+	int rc;
+
 	switch (rip->burst_type) {
 	case GSM_L1_BURST_TYPE_NONE:
 		LOGP(DRLCMAC, LOGL_ERROR, "RACH.ind contains no burst type, assuming TS0\n");
@@ -697,10 +756,9 @@
 			return -ENOTSUP;
 		}
 
-		/* EGPRS multislot class is only present in One Phase Access Request */
-		/* FIXME: properly parse EGPRS Packet Channel Request */
-		if ((rip->ra >> 10) == 0x00) /* .0xx xxx. .... */
-			chan_req->egprs_mslot_class = ((rip->ra & 0x3e0) >> 5) + 1;
+		rc = parse_egprs_pkt_ch_req(rip->ra, chan_req);
+		if (rc)
+			return rc;
 		break;
 	default:
 		LOGP(DRLCMAC, LOGL_ERROR, "RACH.ind contains unknown burst type 0x%02x "
@@ -766,6 +824,11 @@
 		chan_req.single_block = true;
 	}
 
+	/* TODO: handle Radio Priority (see 3GPP TS 44.060, table 11.2.5a.5) */
+	if (chan_req.priority > 0)
+		LOGP(DRLCMAC, LOGL_NOTICE, "EGPRS Packet Channel Request indicates "
+		     "Radio Priority %u, however we ignore it\n", chan_req.priority);
+
 	/* Should we allocate a single block or an Uplink TBF? */
 	if (chan_req.single_block) {
 		rc = sba()->alloc(&trx_no, &ts_no, &sb_fn, ta);

-- 
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Gerrit-Project: osmo-pcu
Gerrit-Branch: master
Gerrit-Change-Id: Ia15761c33c8048d35c7f7bc93dbea781dd0894b7
Gerrit-Change-Number: 18387
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria <axilirator at gmail.com>
Gerrit-MessageType: newchange
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