driver-api/tty/n_gsm.rst

10 	https://www.3gpp.org/ftp/Specs/archive/07_series/07.10/0710-720.zip
13 modems connected to a physical serial port.
19 ----------------
21 #. Initialize the modem in 0710 mux mode (usually ``AT+CMUX=`` command) through
22    its serial port. Depending on the modem used, you can pass more or less
25 #. Switch the serial line to using the n_gsm line discipline by using
28 #. Configure the mux using ``GSMIOC_GETCONF_EXT``/``GSMIOC_SETCONF_EXT`` ioctl if needed.
30 #. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
32 #. Configure DLCs using ``GSMIOC_GETCONF_DLCI``/``GSMIOC_SETCONF_DLCI`` ioctl for non-defaults.
34 #. Obtain base gsmtty number for the used serial port.
37    (a good starting point is util-linux-ng/sys-utils/ldattach.c)::
54       /* open the serial port connected to the modem */
57       /* configure the serial port : speed, flow control ... */
64          being able to answer to the first MUX packet so a delay
73       /* use keep-alive once every 5s for modem connection supervision */
102 #. Use these devices as plain serial ports.
106    - to use *gnokii* to send / receive SMS on ``ttygsm1``
107    - to use *ppp* to establish a datalink on ``ttygsm2``
112    mode. This may prevent a successful re-opening of the port later. To avoid
120 ----------------
122 #. Receive ``AT+CMUX=`` command through its serial port, initialize mux mode
125 #. Switch the serial line to using the *n_gsm* line discipline by using
128 #. Configure the mux using ``GSMIOC_GETCONF_EXT``/``GSMIOC_SETCONF_EXT``
131 #. Configure the mux using ``GSMIOC_GETCONF``/``GSMIOC_SETCONF`` ioctl.
133 #. Configure DLCs using ``GSMIOC_GETCONF_DLCI``/``GSMIOC_SETCONF_DLCI`` ioctl for non-defaults.
135 #. Obtain base gsmtty number for the used serial port::
151 	/* open the serial port */
154 	/* configure the serial port : speed, flow control ... */
156 	/* get serial data and check "AT+CMUX=command" parameter ... */
163 	/* use keep-alive once every 5s for peer connection supervision */
192 11-03-08 - Eric Bénard - <eric@eukrea.com>