Commit c9933d49 authored by Ricardo Martinez's avatar Ricardo Martinez Committed by David S. Miller
Browse files

net: wwan: t7xx: Add maintainers and documentation 



Adds maintainers and documentation for MediaTek t7xx 5G WWAN modem
device driver.

Signed-off-by: default avatarRicardo Martinez <ricardo.martinez@linux.intel.com>
Reviewed-by: default avatarLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: default avatarSergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent de49ea38

Documentation/networking/device_drivers/wwan/index.rst

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   :maxdepth: 2



   iosm

   t7xx



.. only::  subproject and html

Documentation/networking/device_drivers/wwan/t7xx.rst

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.. SPDX-License-Identifier: GPL-2.0-only



.. Copyright (C) 2020-21 Intel Corporation



.. _t7xx_driver_doc:



============================================

t7xx driver for MTK PCIe based T700 5G modem

============================================

The t7xx driver is a WWAN PCIe host driver developed for linux or Chrome OS platforms

for data exchange over PCIe interface between Host platform & MediaTek's T700 5G modem.

The driver exposes an interface conforming to the MBIM protocol [1]. Any front end

application (e.g. Modem Manager) could easily manage the MBIM interface to enable

data communication towards WWAN. The driver also provides an interface to interact

with the MediaTek's modem via AT commands.



Basic usage

===========

MBIM & AT functions are inactive when unmanaged. The t7xx driver provides

WWAN port userspace interfaces representing MBIM & AT control channels and does

not play any role in managing their functionality. It is the job of a userspace

application to detect port enumeration and enable MBIM & AT functionalities.



Examples of few such userspace applications are:



- mbimcli (included with the libmbim [2] library), and

- Modem Manager [3]



Management Applications to carry out below required actions for establishing

MBIM IP session:



- open the MBIM control channel

- configure network connection settings

- connect to network

- configure IP network interface



Management Applications to carry out below required actions for send an AT

command and receive response:



- open the AT control channel using a UART tool or a special user tool



Management application development

==================================

The driver and userspace interfaces are described below. The MBIM protocol is

described in [1] Mobile Broadband Interface Model v1.0 Errata-1.



MBIM control channel userspace ABI

----------------------------------



/dev/wwan0mbim0 character device

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The driver exposes an MBIM interface to the MBIM function by implementing

MBIM WWAN Port. The userspace end of the control channel pipe is a

/dev/wwan0mbim0 character device. Application shall use this interface for

MBIM protocol communication.



Fragmentation

~~~~~~~~~~~~~

The userspace application is responsible for all control message fragmentation

and defragmentation as per MBIM specification.



/dev/wwan0mbim0 write()

~~~~~~~~~~~~~~~~~~~~~~~

The MBIM control messages from the management application must not exceed the

negotiated control message size.



/dev/wwan0mbim0 read()

~~~~~~~~~~~~~~~~~~~~~~

The management application must accept control messages of up the negotiated

control message size.



MBIM data channel userspace ABI

-------------------------------



wwan0-X network device

~~~~~~~~~~~~~~~~~~~~~~

The t7xx driver exposes IP link interface "wwan0-X" of type "wwan" for IP

traffic. Iproute network utility is used for creating "wwan0-X" network

interface and for associating it with MBIM IP session.



The userspace management application is responsible for creating new IP link

prior to establishing MBIM IP session where the SessionId is greater than 0.



For example, creating new IP link for a MBIM IP session with SessionId 1:



  ip link add dev wwan0-1 parentdev wwan0 type wwan linkid 1



The driver will automatically map the "wwan0-1" network device to MBIM IP

session 1.



AT port userspace ABI

----------------------------------



/dev/wwan0at0 character device

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The driver exposes an AT port by implementing AT WWAN Port.

The userspace end of the control port is a /dev/wwan0at0 character

device. Application shall use this interface to issue AT commands.



The MediaTek's T700 modem supports the 3GPP TS 27.007 [4] specification.



References

==========

[1] *MBIM (Mobile Broadband Interface Model) Errata-1*



- https://www.usb.org/document-library/



[2] *libmbim "a glib-based library for talking to WWAN modems and devices which

speak the Mobile Interface Broadband Model (MBIM) protocol"*



- http://www.freedesktop.org/wiki/Software/libmbim/



[3] *Modem Manager "a DBus-activated daemon which controls mobile broadband

(2G/3G/4G/5G) devices and connections"*



- http://www.freedesktop.org/wiki/Software/ModemManager/



[4] *Specification # 27.007 - 3GPP*



- https://www.3gpp.org/DynaReport/27007.htm

MAINTAINERS

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F:	drivers/net/dsa/mt7530.*

F:	net/dsa/tag_mtk.c









MEDIATEK T7XX 5G WWAN MODEM DRIVER









M:	Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>









M:	Intel Corporation <linuxwwan@intel.com>









R:	Chiranjeevi Rapolu <chiranjeevi.rapolu@linux.intel.com>









R:	Liu Haijun <haijun.liu@mediatek.com>









R:	M Chetan Kumar <m.chetan.kumar@linux.intel.com>









R:	Ricardo Martinez <ricardo.martinez@linux.intel.com>









L:	netdev@vger.kernel.org









S:	Supported









F:	drivers/net/wwan/t7xx/

















MEDIATEK USB3 DRD IP DRIVER









M:	Chunfeng Yun <chunfeng.yun@mediatek.com>









L:	linux-usb@vger.kernel.org