linux-kernel - Re: [PATCH v3] Watchdog: New module for ITE 5632 watchdog

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Message-Id: <a91ff3fa-5c0f-4302-9f98-6cbb254e747c@app.fastmail.com>
Date: Thu, 29 Feb 2024 14:15:38 -0500
From: "Mark Pearson" <mpearson@...ebb.ca>
To: "Guenter Roeck" <linux@...ck-us.net>, "David Ober" <dober6023@...il.com>,
 wim@...ux-watchdog.org
Cc: linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
 "David Ober" <dober@...ovo.com>
Subject: Re: [PATCH v3] Watchdog: New module for ITE 5632 watchdog


On Thu, Feb 29, 2024, at 1:47 PM, Guenter Roeck wrote:
> On 2/29/24 10:12, Mark Pearson wrote:
> [ ... ]
>
>>> Is it necessary to treat this differently than, say,
>>> drivers/hwmon/it87.c and drivers/watchdog/it87_wdt.c ?
>>> Those work together nicely because most of the address space is
>>> separate; access through Super-IO registers
>>> is limited enough that it can be shared by using request_muxed_region()
>>> in both drivers.
>>>
>>> I'll have to look deeper into NCT6692D (and NCT6686, for that matter),
>>> to see if those require mfd drivers.
>>> I'll also need to get the datasheets for those chips and confirm that
>>> they really need different watchdog
>>> drivers to start with.
>>>
>> Ack - I'll look at those and see. Quick look at the watchdog driver and it looks possible but I need to check the details more carefully.
>> Afraid I can't share the datasheet as I don't have permission to release it. How much of a blocker is that for you?
>> 
>
> I do have the datasheet for the NCT6683 EC space. I'll need to check if
> it matches the code submitted for the NCT6686 watchdog.
>
> For NCT6692D, I asked Nuvoton if they can share the datasheet.
> Given that it is some kind of security controller chip, it may well be
> that Lenovo has an NDA with Nuvoton which prevents them from sharing
> the datasheet. We'll see.
>
> Undocumented ITE chips are simply not supportable. No matter what, someone
> will have to step up as maintainer for those chips.
>
Ack, but given the ITE chip is for our platform, are we as the submitter not on the hook for maintaining it - especially if we're making so it's only usable on the Lenovo platform? 
I'd expect myself or David to need to respond to any issues.

Looking at the it87 driver - it looks like the main thing is the request/release of the region when doing a superio_enter/exit, which we are missing and would be needed. Can definitely do that in our version, instead of the MFD, if that is preferred.

I haven't gone and looked back at the NCT devices again. Need to do that.

Thanks
Mark