fw/layer1: Add support CCCH combined/non-combined

We introduce the concept of CCCH mode. It can be either
 - NONE: receive BCCCH only
 - COMBINED: CCCH on a BCCH/CCCH+SDDCH/4
 - NON_COMBINED: CCCH on a BCCH/CCCH

There is also a new command to change the mode without having
to do the resync.

Currently, we keep the previous default behavior of requesting
a combined CCCH by default

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

9 files changed, 101 insertions, 7 deletions

diff --git a/include/l1a_l23_interface.h b/include/l1a_l23_interface.h
index 95ec82b2..741221bc 100644
--- a/include/l1a_l23_interface.h
+++ b/include/l1a_l23_interface.h
@@ -39,6 +39,14 @@
 #define L1CTL_RESET_REQ		14
 #define L1CTL_RESET_CONF	15
 #define L1CTL_DATA_CONF		16
+#define L1CTL_CCCH_MODE_REQ	17
+#define L1CTL_CCCH_MODE_CONF	18
+
+enum ccch_mode {
+	CCCH_MODE_NONE = 0,
+	CCCH_MODE_NON_COMBINED,
+	CCCH_MODE_COMBINED,
+};
 
 /*
  * NOTE: struct size. We do add manual padding out of the believe
@@ -84,6 +92,12 @@ struct l1ctl_fbsb_conf {
 	/* FIXME: contents of cell_info ? */
 } __attribute__((packed));
 
+/* CCCH mode was changed */
+struct l1ctl_ccch_mode_conf {
+	uint8_t ccch_mode;	/* enum ccch_mode */
+	uint8_t padding[3];
+} __attribute__((packed));
+
 /* data on the CCCH was found. This is following the header */
 struct l1ctl_data_ind {
 	uint8_t data[23];
@@ -117,7 +131,7 @@ struct l1ctl_fbsb_req {
 	uint8_t num_freqerr_avg;
 	uint8_t flags;		/* L1CTL_FBSB_F_* */
 	uint8_t sync_info_idx;
-	uint8_t reserved;
+	uint8_t ccch_mode;	/* enum ccch_mode */
 } __attribute__((packed));
 
 #define L1CTL_FBSB_F_FB0	(1 << 0)
@@ -125,6 +139,15 @@ struct l1ctl_fbsb_req {
 #define L1CTL_FBSB_F_SB		(1 << 2)
 #define L1CTL_FBSB_F_FB01SB	(L1CTL_FBSB_F_FB0|L1CTL_FBSB_F_FB1|L1CTL_FBSB_F_SB)
 
+/*
+ * msg for CCCH_MODE_REQ
+ * the l1_info_ul header is in front
+ */
+struct l1ctl_ccch_mode_req {
+	uint8_t ccch_mode;	/* enum ccch_mode */
+	uint8_t padding[3];
+} __attribute__((packed));
+
 /* the l1_info_ul header is in front */
 struct l1ctl_rach_req {
 	uint8_t ra;
diff --git a/src/host/layer23/include/osmocom/l1ctl.h b/src/host/layer23/include/osmocom/l1ctl.h
index 48aeaadd..2bcbdb32 100644
--- a/src/host/layer23/include/osmocom/l1ctl.h
+++ b/src/host/layer23/include/osmocom/l1ctl.h
@@ -20,7 +20,10 @@ int tx_ph_rach_req(struct osmocom_ms *ms);
 int tx_ph_dm_est_req(struct osmocom_ms *ms, uint16_t band_arfcn, uint8_t chan_nr);
 /* Transmit FBSB_REQ */
 int l1ctl_tx_fbsb_req(struct osmocom_ms *ms, uint16_t arfcn,
-		      uint8_t flags, uint16_t timeout, uint8_t sync_info_idx);
+		      uint8_t flags, uint16_t timeout, uint8_t sync_info_idx,
+		      uint8_t ccch_mode);
+
+int l1ctl_tx_ccch_mode_req(struct osmocom_ms *ms, uint8_t ccch_mode);
 
 int l1ctl_tx_echo_req(struct osmocom_ms *ms, unsigned int len);
 
diff --git a/src/host/layer23/src/app_phone.c b/src/host/layer23/src/app_phone.c
index 17083d78..7258f569 100644
--- a/src/host/layer23/src/app_phone.c
+++ b/src/host/layer23/src/app_phone.c
@@ -44,7 +44,9 @@ static int signal_cb(unsigned int subsys, unsigned int signal,
 	switch (signal) {
 	case S_L1CTL_RESET:
 		ms = signal_data;
-		return l1ctl_tx_fbsb_req(ms, ms->test_arfcn, L1CTL_FBSB_F_FB01SB, 100, 0);
+		return l1ctl_tx_fbsb_req(ms, ms->test_arfcn,
+		                         L1CTL_FBSB_F_FB01SB, 100, 0,
+		                         CCCH_MODE_COMBINED);
 		break;
 	}
 	return 0;
diff --git a/src/host/layer23/src/bcch_scan.c b/src/host/layer23/src/bcch_scan.c
index a8bd11cf..c542129a 100644
--- a/src/host/layer23/src/bcch_scan.c
+++ b/src/host/layer23/src/bcch_scan.c
@@ -154,7 +154,8 @@ static int _cinfo_start_arfcn(unsigned int band_arfcn)
 
 	/* ask L1 to try to tune to new ARFCN */
 	/* FIXME: decode band */
-	rc = l1ctl_tx_fbsb_req(fps.ms, band_arfcn, L1CTL_FBSB_F_FB01SB, 100, 0);
+	rc = l1ctl_tx_fbsb_req(fps.ms, band_arfcn,
+	                       L1CTL_FBSB_F_FB01SB, 100, 0, CCCH_MODE_COMBINED);
 	if (rc < 0)
 		return rc;
 
diff --git a/src/host/layer23/src/gsm322.c b/src/host/layer23/src/gsm322.c
index 8536a103..9ffc7693 100644
--- a/src/host/layer23/src/gsm322.c
+++ b/src/host/layer23/src/gsm322.c
@@ -222,7 +222,8 @@ int gsm322_cs_sendmsg(struct osmocom_ms *ms, struct msgb *msg)
 static int gsm322_sync_to_cell(struct osmocom_ms *ms, struct gsm322_cellsel *cs)
 {
 	return l1ctl_tx_fbsb_req(ms, cs->arfcn,
-	                         L1CTL_FBSB_F_FB01SB, 100, 0);
+	                         L1CTL_FBSB_F_FB01SB, 100, 0,
+				 CCCH_MODE_COMBINED);
 }
 
 static void gsm322_unselect_cell(struct gsm322_cellsel *cs)
diff --git a/src/host/layer23/src/l1ctl.c b/src/host/layer23/src/l1ctl.c
index 63628b0f..1239b99c 100644
--- a/src/host/layer23/src/l1ctl.c
+++ b/src/host/layer23/src/l1ctl.c
@@ -233,7 +233,8 @@ int tx_ph_data_req(struct osmocom_ms *ms, struct msgb *msg,
 
 /* Transmit FBSB_REQ */
 int l1ctl_tx_fbsb_req(struct osmocom_ms *ms, uint16_t arfcn,
-		      uint8_t flags, uint16_t timeout, uint8_t sync_info_idx)
+		      uint8_t flags, uint16_t timeout, uint8_t sync_info_idx,
+		      uint8_t ccch_mode)
 {
 	struct msgb *msg;
 	struct l1ctl_fbsb_req *req;
@@ -253,6 +254,23 @@ int l1ctl_tx_fbsb_req(struct osmocom_ms *ms, uint16_t arfcn,
 	req->num_freqerr_avg = 3;
 	req->flags = flags;
 	req->sync_info_idx = sync_info_idx;
+	req->ccch_mode = ccch_mode;
+
+	return osmo_send_l1(ms, msg);
+}
+
+/* Transmit L1CTL_CCCH_MODE_REQ */
+int l1ctl_tx_ccch_mode_req(struct osmocom_ms *ms, uint8_t ccch_mode)
+{
+	struct msgb *msg;
+	struct l1ctl_ccch_mode_req *req;
+
+	msg = osmo_l1_alloc(L1CTL_CCCH_MODE_REQ);
+	if (!msg)
+		return -1;
+
+	req = (struct l1ctl_ccch_mode_req *) msgb_put(msg, sizeof(*req));
+	req->ccch_mode = ccch_mode;
 
 	return osmo_send_l1(ms, msg);
 }
diff --git a/src/target/firmware/include/layer1/sync.h b/src/target/firmware/include/layer1/sync.h
index 171fb3bb..137ea9f8 100644
--- a/src/target/firmware/include/layer1/sync.h
+++ b/src/target/firmware/include/layer1/sync.h
@@ -13,6 +13,8 @@ struct l1_cell_info {
 	uint16_t	arfcn;
 	/* what's the BSIC of the cell (from SCH burst decoding) */
 	uint8_t		bsic;
+	/* Combined or non-combined CCCH */
+	uint8_t		ccch_mode; /* enum ccch_mode */
 	/* whats the delta of the cells current GSM frame number
 	 * compared to our current local frame number */
 	int32_t		fn_offset;
diff --git a/src/target/firmware/layer1/l23_api.c b/src/target/firmware/layer1/l23_api.c
index 72995c2e..90aef764 100644
--- a/src/target/firmware/layer1/l23_api.c
+++ b/src/target/firmware/layer1/l23_api.c
@@ -170,6 +170,41 @@ static void l1ctl_rx_reset_req(struct msgb *msg)
 	}
 }
 
+/* Transmit a L1CTL_CCCH_MODE_CONF */
+static void l1ctl_tx_ccch_mode_conf(uint8_t ccch_mode)
+{
+	struct msgb *msg = l1ctl_msgb_alloc(L1CTL_CCCH_MODE_CONF);
+	struct l1ctl_ccch_mode_conf *mode_conf;
+	mode_conf = (struct l1ctl_ccch_mode_conf *)
+				msgb_put(msg, sizeof(*mode_conf));
+	mode_conf->ccch_mode = ccch_mode;
+
+	l1_queue_for_l2(msg);
+}
+
+/* receive a L1CTL_CCCH_MODE_REQ from L23 */
+static void l1ctl_rx_ccch_mode_req(struct msgb *msg)
+{
+	struct l1ctl_hdr *l1h = (struct l1ctl_hdr *) msg->data;
+	struct l1ctl_ccch_mode_req *ccch_mode_req =
+		(struct l1ctl_ccch_mode_req *) l1h->data;
+	uint8_t ccch_mode = ccch_mode_req->ccch_mode;
+
+	/* pre-set the CCCH mode */
+	l1s.serving_cell.ccch_mode = ccch_mode;
+
+	/* Update task */
+	mframe_disable(MF_TASK_CCCH_COMB);
+	mframe_disable(MF_TASK_CCCH);
+
+	if (ccch_mode == CCCH_MODE_COMBINED)
+		mframe_enable(MF_TASK_CCCH_COMB);
+	else if (ccch_mode == CCCH_MODE_NON_COMBINED)
+		mframe_enable(MF_TASK_CCCH);
+
+	l1ctl_tx_ccch_mode_conf(ccch_mode);
+}
+
 /* callback from SERCOMM when L2 sends a message to L1 */
 static void l1a_l23_rx_cb(uint8_t dlci, struct msgb *msg)
 {
@@ -214,6 +249,9 @@ static void l1a_l23_rx_cb(uint8_t dlci, struct msgb *msg)
 		trf6151_rx_window(0, ntohs(sync_req->band_arfcn), 40, 0);
 		tpu_end_scenario();
 
+		/* pre-set the CCCH mode */
+		l1s.serving_cell.ccch_mode = sync_req->ccch_mode;
+
 		printd("Starting FCCH Recognition\n");
 		l1s_fbsb_req(1, sync_req);
 		break;
@@ -263,6 +301,9 @@ static void l1a_l23_rx_cb(uint8_t dlci, struct msgb *msg)
 	case L1CTL_RESET_REQ:
 		l1ctl_rx_reset_req(msg);
 		break;
+	case L1CTL_CCCH_MODE_REQ:
+		l1ctl_rx_ccch_mode_req(msg);
+		break;
 	}
 
 exit_msgbfree:
diff --git a/src/target/firmware/layer1/prim_fbsb.c b/src/target/firmware/layer1/prim_fbsb.c
index 0333017f..fe87996c 100644
--- a/src/target/firmware/layer1/prim_fbsb.c
+++ b/src/target/firmware/layer1/prim_fbsb.c
@@ -257,7 +257,10 @@ static int l1s_sbdet_resp(__unused uint8_t p1, uint8_t attempt,
 	l1s_reset_hw();
 	/* enable the MF Task for BCCH reading */
 	mframe_enable(MF_TASK_BCCH_NORM);
-	mframe_enable(MF_TASK_CCCH_COMB);
+	if (l1s.serving_cell.ccch_mode == CCCH_MODE_COMBINED)
+		mframe_enable(MF_TASK_CCCH_COMB);
+	else if (l1s.serving_cell.ccch_mode == CCCH_MODE_NON_COMBINED)
+		mframe_enable(MF_TASK_CCCH);
 
 	l1s_compl_sched(L1_COMPL_FB);