net: iosm: infrastructure

1) Kconfig & Makefile changes for IOSM Driver compilation.
2) Add IOSM Driver documentation.
3) Modified MAINTAINER file for IOSM Driver addition.

Signed-off-by: M Chetan Kumar <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/device_drivers/index.rst

···
    qlogic/index
    wan/index
    wifi/index
+   wwan/index
 
 .. only::  subproject and html
 

Documentation/networking/device_drivers/wwan/index.rst

···
+.. SPDX-License-Identifier: GPL-2.0-only
+
+WWAN Device Drivers
+===================
+
+Contents:
+
+.. toctree::
+   :maxdepth: 2
+
+   iosm
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`

Documentation/networking/device_drivers/wwan/iosm.rst

···
+.. 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/

MAINTAINERS

···
 S:	Maintained
 F:	drivers/platform/x86/intel-wmi-thunderbolt.c
 
+INTEL WWAN IOSM DRIVER
+M:	M Chetan Kumar <[e-mail]>
+M:	Intel Corporation <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	drivers/net/wwan/iosm/
+
 INTEL(R) TRACE HUB
 M:	Alexander Shishkin <[e-mail]>
 S:	Supported

drivers/net/wwan/Kconfig

···
 	  To compile this driver as a module, choose M here: the module will be
 	  called mhi_wwan_ctrl.
 
+config IOSM
+	tristate "IOSM Driver for Intel M.2 WWAN Device"
+	select WWAN_CORE
+	depends on INTEL_IOMMU
+	help
+	  This driver enables Intel M.2 WWAN Device communication.
+
+	  If you have one of those Intel M.2 WWAN Modules and wish to use it in
+	  Linux say Y/M here.
+
+	  If unsure, say N.
+
 endif # WWAN

drivers/net/wwan/Makefile

···
 obj-$(CONFIG_WWAN_HWSIM) += wwan_hwsim.o
 
 obj-$(CONFIG_MHI_WWAN_CTRL) += mhi_wwan_ctrl.o
+obj-$(CONFIG_IOSM) += iosm/

drivers/net/wwan/iosm/Makefile

···
+# SPDX-License-Identifier: (GPL-2.0-only)
+#
+# Copyright (C) 2020-21 Intel Corporation.
+#
+
+iosm-y = \
+	iosm_ipc_task_queue.o	\
+	iosm_ipc_imem.o			\
+	iosm_ipc_imem_ops.o		\
+	iosm_ipc_mmio.o			\
+	iosm_ipc_port.o			\
+	iosm_ipc_wwan.o			\
+	iosm_ipc_uevent.o		\
+	iosm_ipc_pm.o			\
+	iosm_ipc_pcie.o			\
+	iosm_ipc_irq.o			\
+	iosm_ipc_chnl_cfg.o		\
+	iosm_ipc_protocol.o		\
+	iosm_ipc_protocol_ops.o	\
+	iosm_ipc_mux.o			\
+	iosm_ipc_mux_codec.o
+
+obj-$(CONFIG_IOSM) := iosm.o
+
+# compilation flags
+ccflags-y += -DDEBUG