diff --git a/Documentation/driver-api/tty/n_gsm.rst b/Documentation/driver-api/tty/n_gsm.rst index 04308a7a194a..35d7381515b0 100644 --- a/Documentation/driver-api/tty/n_gsm.rst +++ b/Documentation/driver-api/tty/n_gsm.rst @@ -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 - #include - #include - #include - #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 + #include + #include + #include - /* 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 - #include - #include - #include - #define DEFAULT_SPEED B115200 - #define SERIAL_PORT /dev/ttyS0 + #include + #include + #include + #include + #define DEFAULT_SPEED B115200 + #define SERIAL_PORT /dev/ttyS0 int ldisc = N_GSM0710; struct gsm_config c;