On Fri, Dec 18, 2020 at 02:59:00PM -0800, Randy Dunlap wrote:
> On 12/1/20 2:34 PM, mgross@xxxxxxxxxxxxxxx wrote:
> > From: Srikanth Thokala <srikanth.thokala@xxxxxxxxx>
> >
> > Provide overview of XLink PCIe driver implementation
> >
> > Cc: linux-doc@xxxxxxxxxxxxxxx
> > Reviewed-by: Mark Gross <mgross@xxxxxxxxxxxxxxx>
> > Signed-off-by: Srikanth Thokala <srikanth.thokala@xxxxxxxxx>
> > ---
> > Documentation/vpu/index.rst | 1 +
> > Documentation/vpu/xlink-pcie.rst | 91 ++++++++++++++++++++++++++++++++
> > 2 files changed, 92 insertions(+)
> > create mode 100644 Documentation/vpu/xlink-pcie.rst
> >
>
> Hi--
>
> For document, chapter, section, etc., headings, please read & use
> Documentation/doc-guide/sphinx.rst:
>
> * Please stick to this order of heading adornments:
>
> 1. ``=`` with overline for document title::
>
> ==============
> Document title
> ==============
>
> 2. ``=`` for chapters::
>
> Chapters
> ========
>
> 3. ``-`` for sections::
>
> Section
> -------
>
> 4. ``~`` for subsections::
>
> Subsection
> ~~~~~~~~~~
Thanks for the help! I'm new to the sphix markup language and appreciate your
advice. I'll reread that doc-guide.
We'll address the issues on our next posting once the marge window closes.
thanks again for the reviews!
--mark
>
> > diff --git a/Documentation/vpu/xlink-pcie.rst b/Documentation/vpu/xlink-pcie.rst
> > new file mode 100644
> > index 000000000000..bc64b566989d
> > --- /dev/null
> > +++ b/Documentation/vpu/xlink-pcie.rst
> > @@ -0,0 +1,91 @@
> > +.. SPDX-License-Identifier: GPL-2.0-only
> > +
> > +Kernel driver: xlink-pcie driver
> > +================================
> > +Supported chips:
> > + * Intel Edge.AI Computer Vision platforms: Keem Bay
> > + Suffix: Bay
> > + Slave address: 6240
> > + Datasheet: Publicly available at Intel
> > +
> > +Author: Srikanth Thokala Srikanth.Thokala@xxxxxxxxx
> > +
> > +-------------
> > +Introduction:
>
> No colon at end of chapter/section headings.
>
> > +-------------
> > +The xlink-pcie driver in linux-5.4 provides transport layer implementation for
>
> Linux 5.4 (?)
>
> > +the data transfers to support xlink protocol subsystem communication with the
>
> Xlink
>
> > +peer device. i.e, between remote host system and the local Keem Bay device.
>
> device, i.e., between the remote host system and
>
> > +
> > +The Keem Bay device is an ARM based SOC that includes a vision processing
>
> ARM-based
>
> > +unit (VPU) and deep learning, neural network core in the hardware.
> > +The xlink-pcie driver exports a functional device endpoint to the Keem Bay device
> > +and supports two-way communication with peer device.
>
> with the peer device.
>
> > +
> > +------------------------
> > +High-level architecture:
> > +------------------------
> > +Remote Host: IA CPU
> > +Local Host: ARM CPU (Keem Bay)::
> > +
> > + +------------------------------------------------------------------------+
> > + | Remote Host IA CPU | | Local Host ARM CPU (Keem Bay) | |
> > + +==================================+=+===============================+===+
> > + | User App | | User App | |
> > + +----------------------------------+-+-------------------------------+---+
> > + | XLink UAPI | | XLink UAPI | |
> > + +----------------------------------+-+-------------------------------+---+
> > + | XLink Core | | XLink Core | |
> > + +----------------------------------+-+-------------------------------+---+
> > + | XLink PCIe | | XLink PCIe | |
> > + +----------------------------------+-+-------------------------------+---+
> > + | XLink-PCIe Remote Host driver | | XLink-PCIe Local Host driver | |
> > + +----------------------------------+-+-------------------------------+---+
> > + |-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:|:|:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:|
> > + +----------------------------------+-+-------------------------------+---+
> > + | PCIe Host Controller | | PCIe Device Controller | HW|
> > + +----------------------------------+-+-------------------------------+---+
> > + ^ ^
> > + | |
> > + |------------- PCIe x2 Link -----------------|
> > +
> > +This XLink PCIe driver comprises of two variants:
> > +* Local Host driver
> > +
> > + * Intended for ARM CPU
> > + * It is based on PCI Endpoint Framework
> > + * Driver path: {tree}/drivers/misc/xlink-pcie/local_host
> > +
> > +* Remote Host driver
> > +
> > + * Intended for IA CPU
> > + * It is a PCIe endpoint driver
> > + * Driver path: {tree}/drivers/misc/xlink-pcie/remote_host
> > +
> > +XLink PCIe communication between local host and remote host is achieved through
> > +ring buffer management and MSI/Doorbell interrupts.
> > +
> > +The xlink-pcie driver subsystem registers Keem Bay device as an endpoint driver
>
> registers the
>
> > +and provides standard linux pcie sysfs interface, # /sys/bus/pci/devices/xxxx:xx:xx.0/
>
> Linux PCIe
>
> > +
> > +
> > +-------------------------
> > +XLink protocol subsystem:
>
> No colon at end.
>
> > +-------------------------
> > +xlink is an abstracted control and communication subsystem based on channel
>
> Xlink
>
> > +identification. It is intended to support VPU technology both at SoC level as
> > +well as at IP level, over multiple interfaces.
> > +
> > +- The xlink subsystem abstracts several types of communication channels
>
> Xlink
>
> > + underneath, allowing the usage of different interfaces with the
> > + same function call interface.
> > +- The Communication channels are full-duplex protocol channels allowing
> > + concurrent bidirectional communication.
> > +- The xlink subsystem also supports control operations to VPU either
>
> Xlink
>
> > + from standalone local system or from remote system based on communication
> > + interface underneath.
> > +- The xlink subsystem supports following communication interfaces:
>
> Xlink supports the following
>
>
> > + * USB CDC
> > + * Gigabit Ethernet
> > + * PCIe
> > + * IPC
> >
>
>
> cheers.
> --
> ~Randy
>
