trxcon: implement Ready-to-Receive PHYIF API

This API is going to be used by osmo-trx-ms for inquiring the l1sched
about an lchan state before attempting to demodulate a Downlink burst.

Change-Id: I9a71b8a59733f4dd908b760c5e23ea3d624afb1a
Related: OS#5599

src/host/trxcon/include/osmocom/bb/l1sched/l1sched.h

@@ -162,6 +162,16 @@ struct l1sched_burst_ind {
 	size_t burst_len;
 };
 
+/* Probed lchan is active */
+#define L1SCHED_PROBE_F_ACTIVE		(1 << 0)
+
+/* RTR (Ready-to-Receive) probe */
+struct l1sched_probe {
+	uint32_t flags; /* see L1SCHED_PROBE_F_* above */
+	uint32_t fn;
+	uint8_t tn;
+};
+
 typedef int l1sched_lchan_rx_func(struct l1sched_lchan_state *lchan,
 				  const struct l1sched_burst_ind *bi);
 
@@ -477,6 +487,8 @@ void l1sched_prim_flush_queue(struct llist_head *list);
 
 int l1sched_handle_rx_burst(struct l1sched_state *sched,
 			    struct l1sched_burst_ind *bi);
+int l1sched_handle_rx_probe(struct l1sched_state *sched,
+			    struct l1sched_probe *probe);
 
 /* Shared declarations for lchan handlers */
 extern const uint8_t l1sched_nb_training_bits[8][26];

src/host/trxcon/include/osmocom/bb/trxcon/phyif.h

@@ -75,6 +75,20 @@ struct trxcon_phyif_rts_ind {
 	uint8_t tn;
 };
 
+/* RTR.ind - Ready-to-Receive indicaton */
+struct trxcon_phyif_rtr_ind {
+	uint32_t fn;
+	uint8_t tn;
+};
+
+/* The probed lchan is active */
+#define TRXCON_PHYIF_RTR_F_ACTIVE	(1 << 0)
+
+/* RTR.rsp - Ready-to-Receive response */
+struct trxcon_phyif_rtr_rsp {
+	uint32_t flags; /* see TRXCON_PHYIF_RTR_F_* above */
+};
+
 /* BURST.req - a burst to be transmitted */
 struct trxcon_phyif_burst_req {
 	uint32_t fn;
@@ -99,6 +113,8 @@ int trxcon_phyif_handle_burst_ind(void *priv, const struct trxcon_phyif_burst_in
 int trxcon_phyif_handle_clock_ind(void *priv, uint32_t fn);
 
 int trxcon_phyif_handle_rts_ind(void *priv, const struct trxcon_phyif_rts_ind *rts);
+int trxcon_phyif_handle_rtr_ind(void *priv, const struct trxcon_phyif_rtr_ind *ind,
+				struct trxcon_phyif_rtr_rsp *rsp);
 
 int trxcon_phyif_handle_cmd(void *phyif, const struct trxcon_phyif_cmd *cmd);
 int trxcon_phyif_handle_rsp(void *priv, const struct trxcon_phyif_rsp *rsp);

src/host/trxcon/src/sched_trx.c

@@ -804,6 +804,36 @@ int l1sched_handle_rx_burst(struct l1sched_state *sched,
 	return 0;
 }
 
+int l1sched_handle_rx_probe(struct l1sched_state *sched,
+			    struct l1sched_probe *probe)
+{
+	struct l1sched_ts *ts = sched->ts[probe->tn];
+	const struct l1sched_tdma_frame *frame;
+	struct l1sched_lchan_state *lchan;
+	unsigned int offset;
+
+	/* Check whether required timeslot is allocated and configured */
+	if (ts == NULL || ts->mf_layout == NULL)
+		return -EINVAL;
+
+	/* Get frame from multiframe */
+	offset = probe->fn % ts->mf_layout->period;
+	frame = &ts->mf_layout->frames[offset];
+
+	if (l1sched_lchan_desc[frame->dl_chan].rx_fn == NULL)
+		return -ENODEV;
+
+	/* Find the appropriate logical channel */
+	lchan = l1sched_find_lchan(ts, frame->dl_chan);
+	if (lchan == NULL)
+		return -ENODEV;
+
+	if (lchan->active)
+		probe->flags |= L1SCHED_PROBE_F_ACTIVE;
+
+	return 0;
+}
+
 #define MEAS_HIST_FIRST(hist) \
 	(&hist->buf[0])
 #define MEAS_HIST_LAST(hist) \

src/host/trxcon/src/trxcon_shim.c

@@ -233,6 +233,25 @@ int trxcon_phyif_handle_rts_ind(void *priv, const struct trxcon_phyif_rts_ind *r
 	return l1sched_handle_burst_req(trxcon->sched, &br);
 }
 
+int trxcon_phyif_handle_rtr_ind(void *priv, const struct trxcon_phyif_rtr_ind *ind,
+				struct trxcon_phyif_rtr_rsp *rsp)
+{
+	struct trxcon_inst *trxcon = priv;
+	struct l1sched_probe probe = {
+		.fn = ind->fn,
+		.tn = ind->tn,
+	};
+
+	l1sched_handle_rx_probe(trxcon->sched, &probe);
+
+	memset(rsp, 0x00, sizeof(*rsp));
+
+	if (probe.flags & L1SCHED_PROBE_F_ACTIVE)
+		rsp->flags |= TRXCON_PHYIF_RTR_F_ACTIVE;
+
+	return 0;
+}
+
 int trxcon_phyif_handle_burst_ind(void *priv, const struct trxcon_phyif_burst_ind *phybi)
 {
 	struct trxcon_inst *trxcon = priv;