linux-kernel - RE: [RFC PATCH 00/13] Switchtec NTB Support

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Message-ID: <000001d2e6a7$dfc719a0$9f554ce0$@dell.com>
Date:   Fri, 16 Jun 2017 09:53:01 -0400
From:   "Allen Hubbe" <Allen.Hubbe@...l.com>
To:     "'Logan Gunthorpe'" <logang@...tatee.com>,
        <linux-ntb@...glegroups.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Cc:     "'Jon Mason'" <jdmason@...zu.us>,
        "'Dave Jiang'" <dave.jiang@...el.com>,
        "'Bjorn Helgaas'" <bhelgaas@...gle.com>,
        "'Greg Kroah-Hartman'" <gregkh@...uxfoundation.org>,
        "'Kurt Schwemmer'" <kurt.schwemmer@...rosemi.com>,
        "'Stephen Bates'" <sbates@...thlin.com>,
        "'Serge Semin'" <fancer.lancer@...il.com>,
        <Sergey.Semin@...latforms.ru>
Subject: RE: [RFC PATCH 00/13] Switchtec NTB Support

From: Logan Gunthorpe
> Hi,
> 
> This patchset implements Non-Transparent Bridge (NTB) support for the
> Microsemi Switchtec series of switches. We're looking for some
> review from the community at this point but hope to get it upstreamed
> for v4.14.
> 
> Switchtec NTB support is configured over the same function and bar
> as the management endpoint. Thus, the new driver hooks into the
> management driver which we had merged in v4.12. We use the class
> interface API to register an NTB device for every switchtec device
> which supports NTB (not all do).
> 
> The Switchtec hardware supports doorbells, memory windows and messages.
> Seeing there is no native scratchpad support, 128 spads are emulated
> through the use of a pre-setup memory window. The switch has 64
> doorbells which are shared between the two partitions and a
> configurable set of memory windows. While the hardware supports more
> than 2 partitions, this driver only supports the first two seeing
> the current NTB API only supports two hosts.

See what is staged in https://github.com/jonmason/ntb.git ntb-next, with the addition of multi-peer support by Serge.  It would be good at this stage to understand whether the api changes there would also support the Switchtec driver, and what if anything must change, or be planned to change, to support the Switchtec driver.

Thanks for providing the patch set for the Switchtec driver.  My first impression is that it is a good patch set.  Only to be included, it needs to be reconciled with the api changes in ntb-next.  I will follow up with a more detailed review of patches in this series, but sending this now as I don't want to delay your review of ntb-next.

> 
> The driver has been tested with ntb_netdev and fully passes the
> ntb_test script.
> 
> This patchset is based off of v4.12-rc5 and can be found in this
> git repo:
> 
> https://github.com/sbates130272/linux-p2pmem.git switchtec_ntb
> 
> Thanks,
> 
> Logan
> 
> 
> Logan Gunthorpe (13):
>   switchtec: move structure definitions into a common header
>   switchtec: export class symbol for use in upper layer driver
>   switchtec: add ntb hardware register definitions
>   switchtec: add link event notifier block
>   switchtec_ntb: introduce initial ntb driver
>   switchtec_ntb: initialize hardware for memory windows
>   switchtec_ntb: initialize hardware for doorbells and messages
>   switchtec_ntb: add skeleton ntb driver
>   switchtec_ntb: add link management
>   switchtec_ntb: implement doorbell registers
>   switchtec_ntb: implement scratchpad registers
>   switchtec_ntb: add memory window support
>   switchtec_ntb: update switchtec documentation with notes for ntb
> 
>  Documentation/switchtec.txt         |   12 +
>  MAINTAINERS                         |    2 +
>  drivers/ntb/hw/Kconfig              |    1 +
>  drivers/ntb/hw/Makefile             |    1 +
>  drivers/ntb/hw/mscc/Kconfig         |    9 +
>  drivers/ntb/hw/mscc/Makefile        |    1 +
>  drivers/ntb/hw/mscc/switchtec_ntb.c | 1144 +++++++++++++++++++++++++++++++++++
>  drivers/pci/switch/switchtec.c      |  319 ++--------
>  include/linux/ntb.h                 |    3 +
>  include/linux/switchtec.h           |  365 +++++++++++
>  10 files changed, 1601 insertions(+), 256 deletions(-)
>  create mode 100644 drivers/ntb/hw/mscc/Kconfig
>  create mode 100644 drivers/ntb/hw/mscc/Makefile
>  create mode 100644 drivers/ntb/hw/mscc/switchtec_ntb.c
>  create mode 100644 include/linux/switchtec.h
> 
> --
> 2.11.0