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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-16 15:11:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-16 15:11:04 -0700
commite6bee325e49f17c65c1fd66e9e8b348c85788341 (patch)
treebcc9e5d8e82efa9009edd481a837cc3626360091 /Documentation
parenta5e6b135bdff649e4330f98e2e80dbb1984f7e77 (diff)
parent6ae705b23be8da52d3163be9d81e9b767876aaf9 (diff)
Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6
* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (76 commits) pch_uart: reference clock on CM-iTC pch_phub: add new device ML7213 n_gsm: fix UIH control byte : P bit should be 0 n_gsm: add a documentation serial: msm_serial_hs: Add MSM high speed UART driver tty_audit: fix tty_audit_add_data live lock on audit disabled tty: move cd1865.h to drivers/staging/tty/ Staging: tty: fix build with epca.c driver pcmcia: synclink_cs: fix prototype for mgslpc_ioctl() Staging: generic_serial: fix double locking bug nozomi: don't use flush_scheduled_work() tty/serial: Relax the device_type restriction from of_serial MAINTAINERS: Update HVC file patterns tty: phase out of ioctl file pointer for tty3270 as well tty: forgot to remove ipwireless from drivers/char/pcmcia/Makefile pch_uart: Fix DMA channel miss-setting issue. pch_uart: fix exclusive access issue pch_uart: fix auto flow control miss-setting issue pch_uart: fix uart clock setting issue pch_uart : Use dev_xxx not pr_xxx ... Fix up trivial conflicts in drivers/misc/pch_phub.c (same patch applied twice, then changes to the same area in one branch)
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/serial/n_gsm.txt89
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diff --git a/Documentation/serial/n_gsm.txt b/Documentation/serial/n_gsm.txt
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+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 <linux/gsmmux.h>
+#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 BĂ©nard - <eric@eukrea.com>