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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Tue, 21 Jul 2020 22:50:08 +0200
Message-ID: <CAK8P3a2cP2JpWO4PumaRENcOSj8pLwvJfTe6uP9QtRY8eGi_fA@mail.gmail.com>
Subject: Re: [PATCH] [PATCH] Firmware security information in SYSFS
To:     Daniel Gutson <daniel@eclypsium.com>
Cc:     Derek Kiernan <derek.kiernan@xilinx.com>,
        Tudor Ambarus <tudor.ambarus@microchip.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Richard Hughes <hughsient@gmail.com>,
        Alex Bazhaniuk <alex@eclypsium.com>
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On Mon, Jul 20, 2020 at 9:49 PM Daniel Gutson <daniel@eclypsium.com> wrote:
> On Fri, Jul 17, 2020 at 12:39 PM Arnd Bergmann <arnd@arndb.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