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Date: Mon, 19 Dec 2016 12:02:02 -0500
From: Keith Busch <keith.busch@intel.com>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Jonathan Corbet <corbet@lwn.net>,
        "David S. Miller" <davem@davemloft.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Emil Velikov <emil.l.velikov@gmail.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Guenter Roeck <linux@roeck-us.net>, linux-doc@vger.kernel.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvme@lists.infradead.org,
        Stephen Bates <stephen.bates@microsemi.com>,
        Kurt Schwemmer <kurt.schwemmer@microsemi.com>
Subject: Re: [RFC 1/1] MicroSemi Switchtec management interface driver
Message-ID: <20161219170201.GA1043@localhost.localdomain>
References: <1481994562-9283-1-git-send-email-logang@deltatee.com>
 <1481994562-9283-2-git-send-email-logang@deltatee.com>
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On Sat, Dec 17, 2016 at 10:09:22AM -0700, Logan Gunthorpe wrote:
> Microsemi's "Switchtec" line of PCI switch devices is already
> supported by the kernel with standard PCI switch drivers. However, the
> Switchtec device advertises a special management endpoint which
> enables some additional functionality. This includes:
> 
>  * Packet and Byte Counters
>  * Firmware Upgrades
>  * Event and Error logs
>  * Querying port link status
>  * Custom user firmware commands
> 
> This patch introduces the switchtec kernel module which provides
> pci driver that exposes a char device. The char device provides
> userspace access to this interface through read, write and (optionally)
> poll calls. Currently no ioctls have been implemented but a couple
> may be added in a later revision.
> 
> A short text file is provided which documents the switchtec driver
> and outlines the semantics of using the char device.

Some of this would be simplified if you use the managed device API's:
devm_request_irq, pcim_enable_device, pcim_iomap, etc...