154 lines
4.6 KiB
ReStructuredText
154 lines
4.6 KiB
ReStructuredText
==============================
|
|
GSM 0710 tty multiplexor HOWTO
|
|
==============================
|
|
|
|
.. contents:: :local:
|
|
|
|
This line discipline implements the GSM 07.10 multiplexing protocol
|
|
detailed in the following 3GPP document:
|
|
|
|
https://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
|
|
=============
|
|
|
|
Config Initiator
|
|
----------------
|
|
|
|
#. 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.
|
|
|
|
#. Switch the serial line to using the n_gsm line discipline by using
|
|
``TIOCSETD`` ioctl.
|
|
|
|
#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
|
|
|
|
#. Obtain base gsmtty number for the used serial port.
|
|
|
|
Major parts of the initialization program
|
|
(a good starting point is util-linux-ng/sys-utils/ldattach.c)::
|
|
|
|
#include <stdio.h>
|
|
#include <stdint.h>
|
|
#include <linux/gsmmux.h>
|
|
#include <linux/tty.h>
|
|
|
|
#define DEFAULT_SPEED B115200
|
|
#define SERIAL_PORT /dev/ttyS0
|
|
|
|
int ldisc = N_GSM0710;
|
|
struct gsm_config c;
|
|
struct termios configuration;
|
|
uint32_t first;
|
|
|
|
/* 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 successful (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);
|
|
/* get first gsmtty device node */
|
|
ioctl(fd, GSMIOC_GETFIRST, &first);
|
|
printf("first muxed line: /dev/gsmtty%i\n", first);
|
|
|
|
/* and wait for ever to keep the line discipline enabled */
|
|
daemon(0,0);
|
|
pause();
|
|
|
|
#. Use these devices as plain serial ports.
|
|
|
|
For example, it's possible:
|
|
|
|
- to use *gnokii* to send / receive SMS on ``ttygsm1``
|
|
- to use *ppp* to establish a datalink on ``ttygsm2``
|
|
|
|
#. First close all virtual ports before closing the physical port.
|
|
|
|
Note that after closing the physical port the modem is still in multiplexing
|
|
mode. This may prevent a successful re-opening of the port later. To avoid
|
|
this situation either reset the modem if your hardware allows that or send
|
|
a disconnect command frame manually before initializing the multiplexing mode
|
|
for the second time. The byte sequence for the disconnect command frame is::
|
|
|
|
0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9
|
|
|
|
Config Requester
|
|
----------------
|
|
|
|
#. Receive ``AT+CMUX=`` command through its serial port, initialize mux mode
|
|
config.
|
|
|
|
#. Switch the serial line to using the *n_gsm* line discipline by using
|
|
``TIOCSETD`` ioctl.
|
|
|
|
#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
|
|
|
|
#. Obtain base gsmtty number for the used serial port::
|
|
|
|
#include <stdio.h>
|
|
#include <stdint.h>
|
|
#include <linux/gsmmux.h>
|
|
#include <linux/tty.h>
|
|
#define DEFAULT_SPEED B115200
|
|
#define SERIAL_PORT /dev/ttyS0
|
|
|
|
int ldisc = N_GSM0710;
|
|
struct gsm_config c;
|
|
struct termios configuration;
|
|
uint32_t first;
|
|
|
|
/* open the serial port */
|
|
fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
|
|
|
|
/* configure the serial port : speed, flow control ... */
|
|
|
|
/* get serial data and check "AT+CMUX=command" parameter ... */
|
|
|
|
/* use n_gsm line discipline */
|
|
ioctl(fd, TIOCSETD, &ldisc);
|
|
|
|
/* get n_gsm configuration */
|
|
ioctl(fd, GSMIOC_GETCONF, &c);
|
|
/* we are requester and need encoding 0 (basic) */
|
|
c.initiator = 0;
|
|
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);
|
|
/* get first gsmtty device node */
|
|
ioctl(fd, GSMIOC_GETFIRST, &first);
|
|
printf("first muxed line: /dev/gsmtty%i\n", first);
|
|
|
|
/* and wait for ever to keep the line discipline enabled */
|
|
daemon(0,0);
|
|
pause();
|
|
|
|
11-03-08 - Eric Bénard - <eric@eukrea.com>
|