Documentation/networking/device_drivers/wwan/t7xx.rst

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Documentation/networking/device_drivers/wwan/t7xx.rst
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Support Tooling And Documentation: documentation
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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

Sysfs
=====
The driver provides sysfs interfaces to userspace.

t7xx_mode
---------
The sysfs interface provides userspace with access to the device mode, this
interface supports read and write operations.

Device mode:

- ``unknown`` represents that device in unknown status
- ``ready`` represents that device in ready status
- ``reset`` represents that device in reset status
- ``fastboot_switching`` represents that device in fastboot switching status
- ``fastboot_download`` represents that device in fastboot download status
- ``fastboot_dump`` represents that device in fastboot dump status

Read from userspace to get the current device mode.

::
  $ cat /sys/bus/pci/devices/${bdf}/t7xx_mode

Write from userspace to set the device mode.

::
  $ echo fastboot_switching > /sys/bus/pci/devices/${bdf}/t7xx_mode

Annotation

Implementation Notes