Documentation: tty: n_gsm, use power of ReST

Reformat the whole document, so that automatic numbering and TOC is
properly generated.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2022-04-11 13:01:43 +02:00 committed by Greg Kroah-Hartman
parent e937eb43b8
commit 7fb4028fbb

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@ -2,6 +2,8 @@
GSM 0710 tty multiplexor HOWTO
==============================
.. contents:: :local:
This line discipline implements the GSM 07.10 multiplexing protocol
detailed in the following 3GPP document:
@ -11,79 +13,81 @@ 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. config initiator
^^^^^^^^^^^^^^^^^^^^^
=============
1.1 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.
Config Initiator
----------------
1.2 switch the serial line to using the n_gsm line discipline by using
TIOCSETD ioctl.
#. 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.
1.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
#. Switch the serial line to using the n_gsm line discipline by using
``TIOCSETD`` ioctl.
1.4 obtain base gsmtty number for the used serial port.
#. 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)::
#. 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
Major parts of the initialization program
(a good starting point is util-linux-ng/sys-utils/ldattach.c)::
int ldisc = N_GSM0710;
struct gsm_config c;
struct termios configuration;
uint32_t first;
#include <stdio.h>
#include <stdint.h>
#include <linux/gsmmux.h>
#include <linux/tty.h>
/* open the serial port connected to the modem */
fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
#define DEFAULT_SPEED B115200
#define SERIAL_PORT /dev/ttyS0
/* configure the serial port : speed, flow control ... */
int ldisc = N_GSM0710;
struct gsm_config c;
struct termios configuration;
uint32_t first;
/* 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);
/* open the serial port connected to the modem */
fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
/* 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);
/* configure the serial port : speed, flow control ... */
/* use n_gsm line discipline */
ioctl(fd, TIOCSETD, &ldisc);
/* 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);
/* 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);
/* 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);
/* and wait for ever to keep the line discipline enabled */
daemon(0,0);
pause();
/* use n_gsm line discipline */
ioctl(fd, TIOCSETD, &ldisc);
1.5 use these devices as plain serial ports.
/* 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);
for example, it's possible:
/* and wait for ever to keep the line discipline enabled */
daemon(0,0);
pause();
- and to use gnokii to send / receive SMS on ttygsm1
- to use ppp to establish a datalink on ttygsm2
#. Use these devices as plain serial ports.
1.6 first close all virtual ports before closing the physical port.
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
@ -91,27 +95,27 @@ Major parts of the initialization program :
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.
0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9
2. config requester
^^^^^^^^^^^^^^^^^^^^^
Config Requester
----------------
2.1 receive string "AT+CMUX= command" through its serial port,initialize
mux mode config
#. Receive ``AT+CMUX=`` command through its serial port, initialize mux mode
config.
2.2 switch the serial line to using the n_gsm line discipline by using
TIOCSETD ioctl.
#. Switch the serial line to using the *n_gsm* line discipline by using
``TIOCSETD`` ioctl.
2.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
2.4 obtain base gsmtty number for the used serial port::
#. 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
#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;