Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/Documentation/networking/device_drivers/wwan/iosm.rst b/Documentation/networking/device_drivers/wwan/iosm.rst
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+.. SPDX-License-Identifier: GPL-2.0-only
+
+.. Copyright (C) 2020-21 Intel Corporation
+
+.. _iosm_driver_doc:
+
+===========================================
+IOSM Driver for Intel M.2 PCIe based Modems
+===========================================
+The IOSM (IPC over Shared Memory) driver is a WWAN PCIe host driver developed
+for linux or chrome platform for data exchange over PCIe interface between
+Host platform & Intel M.2 Modem. The driver exposes interface conforming to the
+MBIM protocol [1]. Any front end application ( eg: Modem Manager) could easily
+manage the MBIM interface to enable data communication towards WWAN.
+
+Basic usage
+===========
+MBIM functions are inactive when unmanaged. The IOSM driver only provides a
+userspace interface MBIM "WWAN PORT" representing MBIM control channel and does
+not play any role in managing the functionality. It is the job of a userspace
+application to detect port enumeration and enable MBIM functionality.
+
+Examples of few such userspace application 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 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 IOSM 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 Driver supports
+upto 8 IP sessions for simultaneous IP communication.
+
+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-name wwan0 type wwan linkid 1
+
+The driver will automatically map the "wwan0-1" network device to MBIM IP
+session 1.
+
+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) devices and connections"
+      - http://www.freedesktop.org/wiki/Software/ModemManager/