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authorLinus Torvalds <torvalds@linux-foundation.org>2022-06-03 11:08:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-06-03 11:08:40 -0700
commit932c2989b59008e530ffcc7c7e6ef507a28b28ca (patch)
tree5d51787f2ace2b9a2fd2393662818fd14aa219be /Documentation/driver-api/serial/n_gsm.rst
parent4ad680f083ec360e0991c453e18a38ed9ae500d7 (diff)
parent25e02ba60f0fbe65ba07553b5b2b8867726273c4 (diff)
downloadlinux-932c2989b59008e530ffcc7c7e6ef507a28b28ca.tar.bz2
Merge tag 'tty-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty and serial driver updates from Greg KH: "Here is the big set of tty and serial driver updates for 5.19-rc1. Lots of tiny cleanups in here, the major stuff is: - termbit cleanups and unification by Ilpo. A much needed change that goes a long way to making things simpler for all of the different arches - tty documentation cleanups and movements to their own place in the documentation tree - old tty driver cleanups and fixes from Jiri to bring some existing drivers into the modern world - RS485 cleanups and unifications to make it easier for individual drivers to support this mode instead of having to duplicate logic in each driver - Lots of 8250 driver updates and additions - new device id additions - n_gsm continued fixes and cleanups - other minor serial driver updates and cleanups All of these have been in linux-next for weeks with no reported issues" * tag 'tty-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (166 commits) tty: Rework receive flow control char logic pcmcia: synclink_cs: Don't allow CS5-6 serial: stm32-usart: Correct CSIZE, bits, and parity serial: st-asc: Sanitize CSIZE and correct PARENB for CS7 serial: sifive: Sanitize CSIZE and c_iflag serial: sh-sci: Don't allow CS5-6 serial: txx9: Don't allow CS5-6 serial: rda-uart: Don't allow CS5-6 serial: digicolor-usart: Don't allow CS5-6 serial: uartlite: Fix BRKINT clearing serial: cpm_uart: Fix build error without CONFIG_SERIAL_CPM_CONSOLE serial: core: Do stop_rx in suspend path for console if console_suspend is disabled tty: serial: qcom-geni-serial: Remove uart frequency table. Instead, find suitable frequency with call to clk_round_rate. dt-bindings: serial: renesas,em-uart: Add RZ/V2M clock to access the registers serial: 8250_fintek: Check SER_RS485_RTS_* only with RS485 Revert "serial: 8250_mtk: Make sure to select the right FEATURE_SEL" serial: msm_serial: disable interrupts in __msm_console_write() serial: meson: acquire port->lock in startup() serial: 8250_dw: Use dev_err_probe() serial: 8250_dw: Use devm_add_action_or_reset() ...
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-==============================
-GSM 0710 tty multiplexor HOWTO
-==============================
-
-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
--------------
-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.
-
-1.2 switch the serial line to using the n_gsm line discipline by using
- TIOCSETD ioctl.
-
-1.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
-
-1.4 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();
-
-1.5 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
-
-1.6 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.
-
-2. config requester
-^^^^^^^^^^^^^^^^^^^^^
-
-2.1 receive string "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.
-
-2.3 configure the mux using GSMIOC_GETCONF / GSMIOC_SETCONF ioctl.
-
-2.4 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();
-
-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 BĂ©nard - <eric@eukrea.com>