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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>
authored by
Jiri Slaby
and committed by
Greg Kroah-Hartman
7fb4028f
e937eb43
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Documentation/driver-api/tty/n_gsm.rst
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Documentation/driver-api/tty/n_gsm.rst
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GSM 0710 tty multiplexor HOWTO
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==============================
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.. contents:: :local:
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This line discipline implements the GSM 07.10 multiplexing protocol
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detailed in the following 3GPP document:
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···
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modems connected to a physical serial port.
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How to use it
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-------------
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1. config initiator
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^^^^^^^^^^^^^^^^^^^^^
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=============
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1.1 initialize the modem in 0710 mux mode (usually AT+CMUX= command) through
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its serial port. Depending on the modem used, you can pass more or less
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parameters to this command.
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Config Initiator
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----------------
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1.2 switch the serial line to using the n_gsm line discipline by using
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TIOCSETD ioctl.
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#. Initialize the modem in 0710 mux mode (usually ``AT+CMUX=`` command) through
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its serial port. Depending on the modem used, you can pass more or less
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parameters to this command.
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1.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
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#. Switch the serial line to using the n_gsm line discipline by using
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``TIOCSETD`` ioctl.
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1.4 obtain base gsmtty number for the used serial port.
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#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
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Major parts of the initialization program :
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(a good starting point is util-linux-ng/sys-utils/ldattach.c)::
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#. Obtain base gsmtty number for the used serial port.
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#include <stdio.h>
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#include <stdint.h>
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#include <linux/gsmmux.h>
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#include <linux/tty.h>
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#define DEFAULT_SPEED B115200
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#define SERIAL_PORT /dev/ttyS0
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Major parts of the initialization program
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(a good starting point is util-linux-ng/sys-utils/ldattach.c)::
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int ldisc = N_GSM0710;
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struct gsm_config c;
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struct termios configuration;
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uint32_t first;
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#include <stdio.h>
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#include <stdint.h>
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#include <linux/gsmmux.h>
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#include <linux/tty.h>
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/* open the serial port connected to the modem */
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fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
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#define DEFAULT_SPEED B115200
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#define SERIAL_PORT /dev/ttyS0
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/* configure the serial port : speed, flow control ... */
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int ldisc = N_GSM0710;
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struct gsm_config c;
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struct termios configuration;
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uint32_t first;
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/* send the AT commands to switch the modem to CMUX mode
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and check that it's successful (should return OK) */
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write(fd, "AT+CMUX=0\r", 10);
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/* open the serial port connected to the modem */
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fd = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
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/* experience showed that some modems need some time before
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being able to answer to the first MUX packet so a delay
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may be needed here in some case */
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sleep(3);
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/* configure the serial port : speed, flow control ... */
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/* use n_gsm line discipline */
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ioctl(fd, TIOCSETD, &ldisc);
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/* send the AT commands to switch the modem to CMUX mode
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and check that it's successful (should return OK) */
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write(fd, "AT+CMUX=0\r", 10);
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/* get n_gsm configuration */
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ioctl(fd, GSMIOC_GETCONF, &c);
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/* we are initiator and need encoding 0 (basic) */
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c.initiator = 1;
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c.encapsulation = 0;
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/* our modem defaults to a maximum size of 127 bytes */
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c.mru = 127;
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c.mtu = 127;
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/* set the new configuration */
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ioctl(fd, GSMIOC_SETCONF, &c);
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/* get first gsmtty device node */
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ioctl(fd, GSMIOC_GETFIRST, &first);
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printf("first muxed line: /dev/gsmtty%i\n", first);
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/* experience showed that some modems need some time before
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being able to answer to the first MUX packet so a delay
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may be needed here in some case */
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sleep(3);
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/* and wait for ever to keep the line discipline enabled */
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daemon(0,0);
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pause();
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/* use n_gsm line discipline */
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ioctl(fd, TIOCSETD, &ldisc);
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1.5 use these devices as plain serial ports.
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/* get n_gsm configuration */
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ioctl(fd, GSMIOC_GETCONF, &c);
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/* we are initiator and need encoding 0 (basic) */
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c.initiator = 1;
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c.encapsulation = 0;
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/* our modem defaults to a maximum size of 127 bytes */
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c.mru = 127;
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c.mtu = 127;
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/* set the new configuration */
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ioctl(fd, GSMIOC_SETCONF, &c);
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/* get first gsmtty device node */
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ioctl(fd, GSMIOC_GETFIRST, &first);
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printf("first muxed line: /dev/gsmtty%i\n", first);
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for example, it's possible:
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/* and wait for ever to keep the line discipline enabled */
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daemon(0,0);
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pause();
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- and to use gnokii to send / receive SMS on ttygsm1
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- to use ppp to establish a datalink on ttygsm2
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#. Use these devices as plain serial ports.
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1.6 first close all virtual ports before closing the physical port.
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For example, it's possible:
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- to use *gnokii* to send / receive SMS on ``ttygsm1``
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- to use *ppp* to establish a datalink on ``ttygsm2``
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#. First close all virtual ports before closing the physical port.
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Note that after closing the physical port the modem is still in multiplexing
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mode. This may prevent a successful re-opening of the port later. To avoid
···
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a disconnect command frame manually before initializing the multiplexing mode
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for the second time. The byte sequence for the disconnect command frame is::
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0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9.
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0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9
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2. config requester
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^^^^^^^^^^^^^^^^^^^^^
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Config Requester
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----------------
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2.1 receive string "AT+CMUX= command" through its serial port,initialize
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mux mode config
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#. Receive ``AT+CMUX=`` command through its serial port, initialize mux mode
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config.
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2.2 switch the serial line to using the n_gsm line discipline by using
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TIOCSETD ioctl.
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#. Switch the serial line to using the *n_gsm* line discipline by using
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``TIOCSETD`` ioctl.
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2.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
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#. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
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2.4 obtain base gsmtty number for the used serial port::
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#. Obtain base gsmtty number for the used serial port::
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#include <stdio.h>
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#include <stdint.h>
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#include <linux/gsmmux.h>
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#include <linux/tty.h>
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#define DEFAULT_SPEED B115200
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#define SERIAL_PORT /dev/ttyS0
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#include <stdio.h>
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#include <stdint.h>
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#include <linux/gsmmux.h>
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#include <linux/tty.h>
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#define DEFAULT_SPEED B115200
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#define SERIAL_PORT /dev/ttyS0
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int ldisc = N_GSM0710;
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struct gsm_config c;