trxcon/scheduler: add PDTCH channel support

Change-Id: I1176576f54c1d68e79cc6ac37d61a9033f7018dd

4 files changed, 214 insertions, 4 deletions

diff --git a/src/host/trxcon/Makefile.am b/src/host/trxcon/Makefile.am
index 7095cb59..b51db02f 100644
--- a/src/host/trxcon/Makefile.am
+++ b/src/host/trxcon/Makefile.am
@@ -32,6 +32,7 @@ trxcon_SOURCES = \
 # Scheduler
 trxcon_SOURCES += \
 	sched_lchan_common.c \
+	sched_lchan_pdtch.c \
 	sched_lchan_desc.c \
 	sched_lchan_xcch.c \
 	sched_lchan_tchf.c \
diff --git a/src/host/trxcon/sched_lchan_desc.c b/src/host/trxcon/sched_lchan_desc.c
index 8b2b5e10..93639a37 100644
--- a/src/host/trxcon/sched_lchan_desc.c
+++ b/src/host/trxcon/sched_lchan_desc.c
@@ -25,10 +25,6 @@
 
 #include "sched_trx.h"
 
-/* TODO: implement */
-#define tx_pdtch_fn	NULL
-#define rx_pdtch_fn	NULL
-
 /* Forward declaration of handlers */
 int rx_data_fn(struct trx_instance *trx, struct trx_ts *ts,
 	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
@@ -58,6 +54,12 @@ int rx_tchh_fn(struct trx_instance *trx, struct trx_ts *ts,
 int tx_tchh_fn(struct trx_instance *trx, struct trx_ts *ts,
 	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid);
 
+int rx_pdtch_fn(struct trx_instance *trx, struct trx_ts *ts,
+	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
+	sbit_t *bits, int8_t rssi, int16_t toa256);
+
+int tx_pdtch_fn(struct trx_instance *trx, struct trx_ts *ts,
+	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid);
 
 const struct trx_lchan_desc trx_lchan_desc[_TRX_CHAN_MAX] = {
 	{
diff --git a/src/host/trxcon/sched_lchan_pdtch.c b/src/host/trxcon/sched_lchan_pdtch.c
new file mode 100644
index 00000000..1a8987b3
--- /dev/null
+++ b/src/host/trxcon/sched_lchan_pdtch.c
@@ -0,0 +1,204 @@
+/*
+ * OsmocomBB <-> SDR connection bridge
+ * TDMA scheduler: handlers for DL / UL bursts on logical channels
+ *
+ * (C) 2018 by Vadim Yanitskiy <axilirator@gmail.com>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <stdint.h>
+
+#include <osmocom/core/logging.h>
+#include <osmocom/core/bits.h>
+
+#include <osmocom/gsm/gsm_utils.h>
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/coding/gsm0503_coding.h>
+
+#include "l1ctl_proto.h"
+#include "scheduler.h"
+#include "sched_trx.h"
+#include "logging.h"
+#include "trx_if.h"
+#include "trxcon.h"
+#include "l1ctl.h"
+
+int rx_pdtch_fn(struct trx_instance *trx, struct trx_ts *ts,
+	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid,
+	sbit_t *bits, int8_t rssi, int16_t toa256)
+{
+	const struct trx_lchan_desc *lchan_desc;
+	uint8_t l2[GPRS_L2_MAX_LEN], *mask;
+	int n_errors, n_bits_total, rc;
+	sbit_t *buffer, *offset;
+	uint32_t *first_fn;
+	size_t l2_len;
+
+	/* Set up pointers */
+	lchan_desc = &trx_lchan_desc[lchan->type];
+	first_fn = &lchan->rx_first_fn;
+	mask = &lchan->rx_burst_mask;
+	buffer = lchan->rx_bursts;
+
+	LOGP(DSCHD, LOGL_DEBUG, "Packet data received on %s: "
+		"fn=%u ts=%u bid=%u\n", lchan_desc->name, fn, ts->index, bid);
+
+	/* Reset internal state */
+	if (bid == 0) {
+		/* Clean up old measurements */
+		memset(&lchan->meas, 0x00, sizeof(lchan->meas));
+
+		*first_fn = fn;
+		*mask = 0x0;
+	}
+
+	/* Update mask */
+	*mask |= (1 << bid);
+
+	/* Update measurements */
+	lchan->meas.toa256_sum += toa256;
+	lchan->meas.rssi_sum += rssi;
+	lchan->meas.toa256_num++;
+	lchan->meas.rssi_num++;
+
+	/* Copy burst to buffer of 4 bursts */
+	offset = buffer + bid * 116;
+	memcpy(offset, bits + 3, 58);
+	memcpy(offset + 58, bits + 87, 58);
+
+	/* Wait until complete set of bursts */
+	if (bid != 3)
+		return 0;
+
+	/* Check for complete set of bursts */
+	if ((*mask & 0xf) != 0xf) {
+		LOGP(DSCHD, LOGL_ERROR, "Received incomplete data frame at "
+			"fn=%u (%u/%u) for %s\n", *first_fn,
+			(*first_fn) % ts->mf_layout->period,
+			ts->mf_layout->period,
+			lchan_desc->name);
+
+		return -1;
+	}
+
+	/* Attempt to decode */
+	rc = gsm0503_pdtch_decode(l2, buffer,
+		NULL, &n_errors, &n_bits_total);
+	if (rc < 0) {
+		LOGP(DSCHD, LOGL_ERROR, "Received bad packet data frame "
+			"at fn=%u (%u/%u) for %s\n", *first_fn,
+			(*first_fn) % ts->mf_layout->period,
+			ts->mf_layout->period,
+			lchan_desc->name);
+	}
+
+	/* Determine L2 length */
+	l2_len = rc > 0 ? rc : 0;
+
+	/* Send a L2 frame to the higher layers */
+	sched_send_dt_ind(trx, ts, lchan,
+		l2, l2_len, n_errors, rc < 0, true);
+
+	return 0;
+}
+
+
+int tx_pdtch_fn(struct trx_instance *trx, struct trx_ts *ts,
+	struct trx_lchan_state *lchan, uint32_t fn, uint8_t bid)
+{
+	const struct trx_lchan_desc *lchan_desc;
+	ubit_t burst[GSM_BURST_LEN];
+	ubit_t *buffer, *offset;
+	const uint8_t *tsc;
+	uint8_t *mask;
+	int rc;
+
+	/* Set up pointers */
+	lchan_desc = &trx_lchan_desc[lchan->type];
+	mask = &lchan->tx_burst_mask;
+	buffer = lchan->tx_bursts;
+
+	if (bid > 0) {
+		/* If we have encoded bursts */
+		if (*mask)
+			goto send_burst;
+		else
+			return 0;
+	}
+
+	/* Encode payload */
+	rc = gsm0503_pdtch_encode(buffer, lchan->prim->payload,
+		lchan->prim->payload_len);
+	if (rc) {
+		LOGP(DSCHD, LOGL_ERROR, "Failed to encode L2 payload\n");
+
+		/* Forget this primitive */
+		sched_prim_drop(lchan);
+
+		return -EINVAL;
+	}
+
+send_burst:
+	/* Determine which burst should be sent */
+	offset = buffer + bid * 116;
+
+	/* Update mask */
+	*mask |= (1 << bid);
+
+	/* Choose proper TSC */
+	tsc = sched_nb_training_bits[trx->tsc];
+
+	/* Compose a new burst */
+	memset(burst, 0, 3); /* TB */
+	memcpy(burst + 3, offset, 58); /* Payload 1/2 */
+	memcpy(burst + 61, tsc, 26); /* TSC */
+	memcpy(burst + 87, offset + 58, 58); /* Payload 2/2 */
+	memset(burst + 145, 0, 3); /* TB */
+
+	LOGP(DSCHD, LOGL_DEBUG, "Transmitting %s fn=%u ts=%u burst=%u\n",
+		lchan_desc->name, fn, ts->index, bid);
+
+	/* Forward burst to scheduler */
+	rc = sched_trx_handle_tx_burst(trx, ts, lchan, fn, burst);
+	if (rc) {
+		/* Forget this primitive */
+		sched_prim_drop(lchan);
+
+		/* Reset mask */
+		*mask = 0x00;
+
+		return rc;
+	}
+
+	/* If we have sent the last (4/4) burst */
+	if ((*mask & 0x0f) == 0x0f) {
+		/* Confirm data / traffic sending */
+		sched_send_dt_conf(trx, ts, lchan, fn, true);
+
+		/* Forget processed primitive */
+		sched_prim_drop(lchan);
+
+		/* Reset mask */
+		*mask = 0x00;
+	}
+
+	return 0;
+}
diff --git a/src/host/trxcon/sched_trx.h b/src/host/trxcon/sched_trx.h
index 1f0dbc29..b7236d51 100644
--- a/src/host/trxcon/sched_trx.h
+++ b/src/host/trxcon/sched_trx.h
@@ -17,6 +17,9 @@
 #define GPRS_BURST_LEN		GSM_BURST_LEN
 #define EDGE_BURST_LEN		444
 
+#define GPRS_L2_MAX_LEN		54
+#define EDGE_L2_MAX_LEN		155
+
 #define TRX_CH_LID_DEDIC	0x00
 #define TRX_CH_LID_SACCH	0x40