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09a61f5025
Add I/O plugin for mISDN stack that is included in the linux kernel since version 2.6.27. The in-kernel mISDN stack uses a socket based interface (AF_ISDN), data and control commands are exchanged via datagram messages. This makes writing a driver that doesn't use a separate (per-span) thread to handle all incoming events a bit tricky, because responses to control messages and incoming data are mixed and interfacing with the synchronous FreeTDM I/O API is problematic. B(*)/D-channel handling: The current version uses misdn_wait() to poll() for activity on the non-blocking channel sockets and misdn_read() to receive and handle all pending events up to the first PH_DATA_IND (data) message (which is what the caller of the read method is actually after). In case no data has been received, misdn_read() returns FTDM_SUCCESS with *datalen = 0, which is OK for all the signalling modules tested (ftmod_libpri and (out-of-tree) ftmod_isdn). To send data, misdn_write() is called, which just sends a PH_DATA_REQ message to the mISDN channel socket. (*) B-channels use a per-channel timerfd as a timing reference for 'ready-for-write' poll()ing in misdn_wait(). This is a workaround for a limitation of mISDN sockets, which do not support POLLOUT waiting on b-channel sockets (in a useful way). Sending/receiving of data works the same way as on d-channels, otherwise. The module has received some minimal testing using a beronet single-port HFC E1 and a HFC4-S quad-port BRI card on linux-3.0.x. --- Limitations --- - Only the most basic features have been implemented (alarms, sending/receiving data/audio). - Spans are limited to E1 and BRI/BRI_PTMP trunk types. - D-Channels only work on 16 for PRI and 3 for BRI. - NT/TE mode information is not available from freetdm.conf / at configure_span()-time so the module assumes TE mode, which should be only a problem for cards that can change the port configuration (pin-out) from software. - Current design (b-channel timerfd / misdn_wait()/_read()/_write()) should be fine for most SoHo use-cases (scalability / cpu usage / timing precision). --- Requirements --- - mISDNif.h header (/usr/include/mISDN/mISDNif.h), provided by mISDNuser (http://isdn.eversberg.eu/download/lcr-1.7/mISDNuser-20100525.tar.gz). - Linux kernel with mISDN and timerfd enabled (>= 2.6.27) and libc with timerfd support. mISDN options can be found in the: "Device Drivers" -> "ISDN support" -> "Modular ISDN driver" section of make menuconfig. Timerfd is usually enabled by default. The FreeTDM configure script will check for missing mISDNif.h header and timerfd support and print a message. You should see the following in the summary screen on success: ftmod_misdn........................ yes NOTE: Forcing mISDN support using the "--with-misdn" configure option, will cause the configure script to fail on the first missing dependency. --- Usage --- To use the module, make sure you have mISDN support in the kernel (kernel modules loaded or kernel with built-in mISDN running), the "misdn_info" application shipped with mISDNuser will output a list of available mISDN ports on your system, e.g.: Found 5 ports Port 0 'hfc-4s.1-1': TE/NT-mode BRI S/T (for phone lines & phones) 2 B-channels: 1-2 B-protocols: RAW HDLC X75slp ... Port 4 'hfc-e1.2': TE/NT-mode PRI E1 (for phone lines & E1 devices) 30 B-channels: 1-15 17-31 B-protocols: RAW HDLC X75slp NOTE: ftmod_misdn will print an error message if mISDN support is not available, or if there are no ports installed. - Example freetdm.conf settings [span misdn BRI_1] trunk_type => BRI_PTMP b-channel => 0:1,2 d-channel => 0:3 [span misdn PRI_1] trunk_type => E1 b-channel => hfc-e1.2:1-15,17-31 d-channel => hfc-e1.2:16 Signed-off-by: Stefan Knoblich <stkn@openisdn.net>
FreeTDM http://wiki.freeswitch.org/wiki/FreeTDM