linux-kernel - Re: [PATCH] [PATCH] Firmware security information in SYSFS

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Date:   Tue, 21 Jul 2020 22:50:08 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Daniel Gutson <daniel@...ypsium.com>
Cc:     Derek Kiernan <derek.kiernan@...inx.com>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Richard Hughes <hughsient@...il.com>,
        Alex Bazhaniuk <alex@...ypsium.com>
Subject: Re: [PATCH] [PATCH] Firmware security information in SYSFS

On Mon, Jul 20, 2020 at 9:49 PM Daniel Gutson <daniel@...ypsium.com> wrote:
> On Fri, Jul 17, 2020 at 12:39 PM Arnd Bergmann <arnd@...db.de> wrote:
>>
>> My impression was that the state of the registers you read would
>> be the same if you read them multiple times, at least until you
>> reboot and the firmware has a chance to change them.
>
>
> That's not always the case, for example for the SMI count.
> Another example is WPD, a driver (such as the intel-spi for instance) can change its value if it is unlocked.
> But many others don't change so it might be a good idea to add another function to the API to register constant values.

Ok, if the value can change, then I suppose you can pass a pointer to the
'struct class_attribute' or 'struct file_operations' with the appropriate
'show' callbacks, this should be easier than creating another callback
abstraction.

For values that can not change, passing the value should be easier.

       Arnd