The application which initializes the n_gsm ldisc may like to set
individual default parameters for each DLCI or take over of the application
specific DLCI configuration completely. This is currently not possible.
It is either possible to set common default parameters for all DLCIs or let
the user application set its DLCI specific configuration parameters.
Add support of GSMIOC_GETCONF_DLCI and GSMIOC_SETCONF_DLCI for the n_gsm
ldisc handle to support DLCI specific parameter configuration upfront.
Add a code example for this use case to the n_gsm documentation.
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20230315105354.6234-3-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Parameter negotiation has been introduced with
commit 92f1f0c329 ("tty: n_gsm: add parameter negotiation support")
However, means to set individual parameters per DLCI are not yet
implemented. Furthermore, it is currently not possible to keep a DLCI half
open until the user application sets the right parameters for it. This is
required to allow a user application to set its specific parameters before
the underlying link is established. Otherwise, the link is opened and
re-established right afterwards if the user application sets incompatible
parameters. This may be an unexpected behavior for the peer.
Add parameter 'wait_config' to 'gsm_config' to support setups where the
DLCI specific user application sets its specific parameters after open()
and before the link gets fully established. Setting this to zero disables
the user application specific DLCI configuration option.
Add the ioctls 'GSMIOC_GETCONF_DLCI' and 'GSMIOC_SETCONF_DLCI' for the
ldisc and virtual ttys. This gets/sets the DLCI specific parameters and may
trigger a reconnect of the DLCI if incompatible values have been set. Only
the parameters for the DLCI associated with the virtual tty can be set or
retrieved if called on these.
Add remark within the documentation to introduce the new ioctls.
Link: https://lore.kernel.org/oe-kbuild-all/202302281856.S9Lz4gHB-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20230315105354.6234-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010.
See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516
The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to
the newer 27.010 here. Chapters 5.4.6.3.4 and 5.1.8.1.3 describe the test
command which can be used to test the mux connection between both sides.
Currently, no algorithm is implemented to make use of this command. This
requires that each multiplexed upper layer protocol supervises the
underlying muxer connection to handle possible connection losses.
Introduce ioctl commands and functions to optionally enable keep alive
handling via the test command as described in chapter 5.4.6.3.4. A single
incrementing octet "ka_num" is being used for unique identification of each
single keep alive packet. Retries will use the same "ka_num" value as the
original packet. Retry count and interval are taken from the general
parameters N2 and T2.
Add usage description and basic example for the new ioctl to the n_gsm
documentation.
Note that support for the test command is mandatory and already present in
the muxer implementation since the very first version.
Also note that the previous ioctl structure gsm_config cannot be extended
due to missing checks against zero of the field "unused".
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20230214122737.1976-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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>
All of the URLs give 404. There is a little point to preserve them. If
really need be, we could try archive.org if the documents are not there
by a chance.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It is a tty_driver, not serial -- uart_driver. So move it to the tty
docs dir too. (The same as the driver itself.)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We have n_tty documented in Documentation/driver-api/tty/. n_gsm belongs
there too, so move from serial/ to tty/ too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220411110143.10019-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
