diff --git a/Documentation/networking/device_drivers/wwan/index.rst b/Documentation/networking/device_drivers/wwan/index.rst index 1cb8c7371401..370d8264d5dc 100644 --- a/Documentation/networking/device_drivers/wwan/index.rst +++ b/Documentation/networking/device_drivers/wwan/index.rst @@ -9,6 +9,7 @@ Contents: :maxdepth: 2 iosm + t7xx .. only:: subproject and html diff --git a/Documentation/networking/device_drivers/wwan/t7xx.rst b/Documentation/networking/device_drivers/wwan/t7xx.rst new file mode 100644 index 000000000000..dd5b731957ca --- /dev/null +++ b/Documentation/networking/device_drivers/wwan/t7xx.rst @@ -0,0 +1,120 @@ +.. 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 diff --git a/MAINTAINERS b/MAINTAINERS index cbf21e11deb7..0ea12c2b53f3 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12488,6 +12488,17 @@ S: Maintained F: drivers/net/dsa/mt7530.* F: net/dsa/tag_mtk.c +MEDIATEK T7XX 5G WWAN MODEM DRIVER +M: Chandrashekar Devegowda +M: Intel Corporation +R: Chiranjeevi Rapolu +R: Liu Haijun +R: M Chetan Kumar +R: Ricardo Martinez +L: netdev@vger.kernel.org +S: Supported +F: drivers/net/wwan/t7xx/ + MEDIATEK USB3 DRD IP DRIVER M: Chunfeng Yun L: linux-usb@vger.kernel.org