Message-ID: <21bebf9d-eb27-5607-b0a9-274c46ef8aa3@intel.com>
Date:   Mon, 27 Feb 2023 14:04:36 -0800
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Subject: Re: [PATCH v1 0/6] PolarFire SoC Auto Update Support
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To:     Conor Dooley <conor.dooley@microchip.com>,
        Xu Yilun <yilun.xu@intel.com>
CC:     Conor Dooley <conor@kernel.org>,
        Daire McNamara <daire.mcnamara@microchip.com>,
        Rob Herring <robh+dt@kernel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
        Moritz Fischer <mdf@kernel.org>, Wu Hao <hao.wu@intel.com>,
        Tom Rix <trix@redhat.com>, <linux-riscv@lists.infradead.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-fpga@vger.kernel.org>
References: <20230217164023.14255-1-conor@kernel.org>
 <Y/ht1eHgtRrLxIhC@yilunxu-OptiPlex-7050> <Y/h1KFGSw13OabYw@wendy>
From:   Russ Weight <russell.h.weight@intel.com>
In-Reply-To: <Y/h1KFGSw13OabYw@wendy>
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Hi Conor,

On 2/24/23 00:28, Conor Dooley wrote:
> On Fri, Feb 24, 2023 at 03:57:09PM +0800, Xu Yilun wrote:
>> On 2023-02-17 at 16:40:17 +0000, Conor Dooley wrote:
>>> This patchset adds support for the "Auto Update" feature on PolarFire
>>> SoC that allows for writing an FPGA bistream to the SPI flash connected
>>> to the system controller.
>> I haven't fully checked the patches yet, just some quick comments:
>>
>> Since this feature is just to R/W the flash, and would not affect the
>> runtime FPGA region, I don't think an FPGA manager is actually needed.
>> Why not just use the MTD uAPI? There is a set of exsiting MTD uAPI &
>> MTD tool if I remember correctly.
> A lack of interest in opening up the system controller to userspace!
> You're right in that the writing of the image can be done that way, and
> while I was testing I used the userspace bits of mtd along the way - but
> for validating that the image we are writing we rely on the system
> controller.
> I'm really not interested in exposing the system controller's
> functionality, especially the bitstream manipulation parts, to userspace
> due to the risk of input validation bugs, so at least that side of
> things should remain in the kernel.
> I suppose I could implement something custom in drivers/soc that does
> the validation only, and push the rest out to userspace. Just seemed
> fitting to do the whole lot in drivers/fpga.
Conor,

In case you haven't already looked at the new firmware-upload
support in the firmware-loader, I'll give you some references
here to see if it fit you needs. This would only support the
write (not the read) but it would allow the controller to do
validation on the write.

The is the cover letter which shows a usage example:
https://lore.kernel.org/lkml/20220421212204.36052-1-russell.h.weight@intel.com/

And this is a pointer to the latest documentation for it:
https://docs.kernel.org/driver-api/firmware/fw_upload.html

The only current user is: drivers/fpga/intel-m10-bmc-sec-update.c

- Russ

>
> Cheers,
> Conor.
>