netdev - RE: [PATCH V2 00/16] net: iosm: PCIe Driver for Intel M.2 Modem

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Date:   Thu, 6 May 2021 10:51:12 +0000
From:   "Kumar, M Chetan" <m.chetan.kumar@...el.com>
To:     Aleksander Morgado <aleksander@...ksander.es>,
        Loic Poulain <loic.poulain@...aro.org>
CC:     Network Development <netdev@...r.kernel.org>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "johannes@...solutions.net" <johannes@...solutions.net>,
        "Sudi, Krishna C" <krishna.c.sudi@...el.com>,
        linuxwwan <linuxwwan@...el.com>
Subject: RE: [PATCH V2 00/16] net: iosm: PCIe Driver for Intel M.2 Modem

Hi Aleksander,

> > 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 "wwanctrl", a char
> > device node which is used for MBIM control operation and "INMx",(x =
> > 0,1,2..7) network interfaces for IP data communication.
> 
> Is there any plan to integrate this driver in the new "wwan" subsystem so
> that the character device for MBIM control is exposed in the same format
> (i.e. same name rules and such) as with the MHI driver?
> 
Yes, we are working on it. The next version of driver would have these adaptation to expose MBIM "WWAN Port".

Regards,
Chetan