Adding direct access to DSP of sysmoBTS for PDTCH traffice

In order to use this feature, sysmoBTS requires option "-M", otherwise
the traffic is forwarded through socket interface.

This is essential, if PCU runs on processor of sysmoBTS. The reaction
time and delay of PDTCH frames could heavily degrade proper packet flow.

1 files changed, 145 insertions, 0 deletions

diff --git a/src/sysmo_l1_fwd.c b/src/sysmo_l1_fwd.c
new file mode 100644
index 00000000..535a7f00
--- /dev/null
+++ b/src/sysmo_l1_fwd.c
@@ -0,0 +1,145 @@
+/* Interface handler for Sysmocom L1 (forwarding) */
+
+/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/write_queue.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/gsm/gsm_utils.h>
+
+#include <sysmocom/femtobts/superfemto.h>
+#include <sysmocom/femtobts/gsml1prim.h>
+#include <sysmocom/femtobts/gsml1const.h>
+#include <sysmocom/femtobts/gsml1types.h>
+
+#include "gprs_debug.h"
+#include "sysmo_l1_if.h"
+
+
+#define L1FWD_L1_PORT   9999
+#define L1FWD_SYS_PORT  9998
+#define L1FWD_TCH_PORT  9997
+#define L1FWD_PDTCH_PORT 9996
+
+static const uint16_t fwd_udp_ports[] = {
+	[MQ_SYS_WRITE]	= L1FWD_SYS_PORT,
+	[MQ_L1_WRITE]	= L1FWD_L1_PORT,
+	[MQ_TCH_WRITE]	= L1FWD_TCH_PORT,
+	[MQ_PDTCH_WRITE]= L1FWD_PDTCH_PORT,
+};
+
+static int fwd_read_cb(struct osmo_fd *ofd)
+{
+	struct msgb *msg = msgb_alloc_headroom(sizeof(SuperFemto_Prim_t) + 128,
+		128, "udp_rx");
+	struct femtol1_hdl *fl1h = ofd->data;
+	int rc;
+
+	if (!msg)
+		return -ENOMEM;
+
+	msg->l1h = msg->data;
+	rc = read(ofd->fd, msg->l1h, msgb_tailroom(msg));
+	if (rc < 0) {
+		LOGP(DL1IF, LOGL_ERROR, "Short read from UDP\n");
+		msgb_free(msg);
+		return rc;
+	} else if (rc == 0) {
+		LOGP(DL1IF, LOGL_ERROR, "Len=0 from UDP\n");
+		msgb_free(msg);
+		return rc;
+	}
+	msgb_put(msg, rc);
+
+	if (ofd->priv_nr == MQ_SYS_WRITE)
+		rc = l1if_handle_sysprim(fl1h, msg);
+	else
+		rc = l1if_handle_l1prim(ofd->priv_nr, fl1h, msg);
+
+	return rc;
+}
+
+static int prim_write_cb(struct osmo_fd *ofd, struct msgb *msg)
+{
+	/* write to the fd */
+	return write(ofd->fd, msg->head, msg->len);
+}
+
+int l1if_transport_open(int q, struct femtol1_hdl *fl1h)
+{
+	int rc;
+	char *bts_host = getenv("L1FWD_BTS_HOST");
+
+	printf("sizeof(GsmL1_Prim_t) = %zu\n", sizeof(GsmL1_Prim_t));
+	printf("sizeof(SuperFemto_Prim_t) = %zu\n", sizeof(SuperFemto_Prim_t));
+
+	if (!bts_host) {
+		fprintf(stderr, "You have to set the L1FWD_BTS_HOST environment variable\n");
+		exit(2);
+	}
+
+	struct osmo_wqueue *wq = &fl1h->write_q[q];
+	struct osmo_fd *ofd = &wq->bfd;
+
+	osmo_wqueue_init(wq, 10);
+	wq->write_cb = prim_write_cb;
+	wq->read_cb = fwd_read_cb;
+
+	ofd->data = fl1h;
+	ofd->priv_nr = q;
+	ofd->when |= BSC_FD_READ;
+
+	rc = osmo_sock_init_ofd(ofd, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP,
+				bts_host, fwd_udp_ports[q],
+				OSMO_SOCK_F_CONNECT);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+int l1if_transport_close(int q, struct femtol1_hdl *fl1h)
+{
+	struct osmo_wqueue *wq = &fl1h->write_q[q];
+	struct osmo_fd *ofd = &wq->bfd;
+
+	osmo_wqueue_clear(wq);
+	osmo_fd_unregister(ofd);
+	close(ofd->fd);
+	
+	return 0;
+}