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M Chetan Kumar says: ==================== net: iosm: PCIe Driver for Intel M.2 Modem The IOSM (IPC over Shared Memory) driver is a PCIe host driver implemented 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. Any front end application ( eg: Modem Manager) could easily manage the MBIM interface to enable data communication towards WWAN. Intel M.2 modem uses 2 BAR regions. The first region is dedicated to Doorbell register for IRQs and the second region is used as scratchpad area for book keeping modem execution stage details along with host system shared memory region context details. The upper edge of the driver exposes the control and data channels for user space application interaction. At lower edge these data and control channels are associated to pipes. The pipes are lowest level interfaces used over PCIe as a logical channel for message exchange. A single channel maps to UL and DL pipe and are initialized on device open. On UL path, driver copies application sent data to SKBs associate it with transfer descriptor and puts it on to ring buffer for DMA transfer. Once information has been updated in shared memory region, host gives a Doorbell to modem to perform DMA and modem uses MSI to communicate back to host. For receiving data in DL path, SKBs are pre-allocated during pipe open and transfer descriptors are given to modem for DMA transfer. The driver exposes two types of ports, namely "wwan0mbim0", a char device node which is used for MBIM control operation and "wwan0-x",(x = 0,1,2..7) network interfaces for IP data communication. 1) MBIM Control Interface: This node exposes an interface between modem and application using char device exposed by "IOSM" driver to establish and manage the MBIM data communication with PCIe based Intel M.2 Modems. 2) MBIM Data Interface: 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. This applies on top of WWAN core rtnetlink series posted here: https://lore.kernel.org/netdev/1623486057-13075-1-git-send-email-loic.poulain@linaro.org/ Also driver has been compiled and tested on top of netdev net-next tree. https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/ ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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| kernel | ||
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| net | ||
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| usr | ||
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| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.