Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753747Ab1CISbm (ORCPT ); Wed, 9 Mar 2011 13:31:42 -0500 Received: from 29.mail-out.ovh.net ([87.98.216.213]:33207 "HELO 29.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752596Ab1CISbj (ORCPT ); Wed, 9 Mar 2011 13:31:39 -0500 From: =?UTF-8?q?Eric=20B=C3=A9nard?= To: linux-kernel@vger.kernel.org Cc: gregkh@suse.de, alan@lxorguk.ukuu.org.uk, =?UTF-8?q?Eric=20B=C3=A9nard?= Subject: [PATCH v2 1/2] n_gsm: add a documentation Date: Wed, 9 Mar 2011 19:24:48 +0100 Message-Id: <1299695089-2994-1-git-send-email-eric@eukrea.com> X-Mailer: git-send-email 1.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Ovh-Tracer-Id: 14264588871616605464 X-Ovh-Remote: 82.233.81.124 (tal33-3-82-233-81-124.fbx.proxad.net) X-Ovh-Local: 213.186.33.20 (ns0.ovh.net) X-Spam-Check: DONE|U 0.5/N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4210 Lines: 116 * this documentation gives some details on how to get the n_gsm line discipline to work with modems supporting 07.10 basic option. * it was tested on Telit and Simcom modems. Signed-off-by: Eric Bénard --- v2 : small updates following Michal's review Documentation/serial/n_gsm.txt | 89 ++++++++++++++++++++++++++++++++++++++++ 1 files changed, 89 insertions(+), 0 deletions(-) create mode 100644 Documentation/serial/n_gsm.txt diff --git a/Documentation/serial/n_gsm.txt b/Documentation/serial/n_gsm.txt new file mode 100644 index 0000000..397f41a --- /dev/null +++ b/Documentation/serial/n_gsm.txt @@ -0,0 +1,89 @@ +n_gsm.c GSM 0710 tty multiplexor HOWTO +=================================================== + +This line discipline implements the GSM 07.10 multiplexing protocol +detailed in the following 3GPP document : +http://www.3gpp.org/ftp/Specs/archive/07_series/07.10/0710-720.zip + +This document give some hints on how to use this driver with GPRS and 3G +modems connected to a physical serial port. + +How to use it +------------- +1- initialize the modem in 0710 mux mode (usually AT+CMUX= command) through +its serial port. Depending on the modem used, you can pass more or less +parameters to this command, +2- switch the serial line to using the n_gsm line discipline by using +TIOCSETD ioctl, +3- configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl, + +Major parts of the initialization program : +(a good starting point is util-linux-ng/sys-utils/ldattach.c) +#include +#define N_GSM0710 21 /* GSM 0710 Mux */ +#define DEFAULT_SPEED B115200 +#define SERIAL_PORT /dev/ttyS0 + + int ldisc = N_GSM0710; + struct gsm_config c; + struct termios configuration; + + /* open the serial port connected to the modem */ + fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY); + + /* configure the serial port : speed, flow control ... */ + + /* send the AT commands to switch the modem to CMUX mode + and check that it's succesful (should return OK) */ + write(fd, "AT+CMUX=0\r", 10); + + /* experience showed that some modems need some time before + being able to answer to the first MUX packet so a delay + may be needed here in some case */ + sleep(3); + + /* use n_gsm line discipline */ + ioctl(fd, TIOCSETD, &ldisc); + + /* get n_gsm configuration */ + ioctl(fd, GSMIOC_GETCONF, &c); + /* we are initiator and need encoding 0 (basic) */ + c.initiator = 1; + c.encapsulation = 0; + /* our modem defaults to a maximum size of 127 bytes */ + c.mru = 127; + c.mtu = 127; + /* set the new configuration */ + ioctl(fd, GSMIOC_SETCONF, &c); + + /* and wait for ever to keep the line discipline enabled */ + daemon(0,0); + pause(); + +4- create the devices corresponding to the "virtual" serial ports (take care, +each modem has its configuration and some DLC have dedicated functions, +for example GPS), starting with minor 1 (DLC0 is reserved for the management +of the mux) + +MAJOR=`cat /proc/devices |grep gsmtty | awk '{print $1}` +for i in `seq 1 4`; do + mknod /dev/ttygsm$i c $MAJOR $i +done + +5- use these devices as plain serial ports. +for example, it's possible : +- and to use gnokii to send / receive SMS on ttygsm1 +- to use ppp to establish a datalink on ttygsm2 + +6- first close all virtual ports before closing the physical port. + +Additional Documentation +------------------------ +More practical details on the protocol and how it's supported by industrial +modems can be found in the following documents : +http://www.telit.com/module/infopool/download.php?id=616 +http://www.u-blox.com/images/downloads/Product_Docs/LEON-G100-G200-MuxImplementation_ApplicationNote_%28GSM%20G1-CS-10002%29.pdf +http://www.sierrawireless.com/Support/Downloads/AirPrime/WMP_Series/~/media/Support_Downloads/AirPrime/Application_notes/CMUX_Feature_Application_Note-Rev004.ashx +http://wm.sim.com/sim/News/photo/2010721161442.pdf + +11-03-08 - Eric Bénard - -- 1.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/