linux-kernel - Re: [PATCH v2 6/7] Watchdog: introduce ARM SBSA watchdog driver

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Date:	Sat, 23 May 2015 22:47:50 +0800
From:	Fu Wei <fu.wei@...aro.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Arnd Bergmann <arnd@...db.de>, Hanjun Guo <hanjun.guo@...aro.org>,
	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	Linaro ACPI Mailman List <linaro-acpi@...ts.linaro.org>,
	linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	Wei Fu <tekkamanninja@...il.com>,
	G Gregory <graeme.gregory@...aro.org>,
	Al Stone <al.stone@...aro.org>,
	Timur Tabi <timur@...eaurora.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	vgandhi@...eaurora.org, wim@...ana.be,
	Jon Masters <jcm@...hat.com>, Leo Duran <leo.duran@....com>,
	Jon Corbet <corbet@....net>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v2 6/7] Watchdog: introduce ARM SBSA watchdog driver

Hi Guenter,


On 22 May 2015 at 23:01, Guenter Roeck <linux@...ck-us.net> wrote:
> On Fri, May 22, 2015 at 04:55:04PM +0200, Arnd Bergmann wrote:
>> On Friday 22 May 2015 22:50:30 Hanjun Guo wrote:
>> > > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> > > index e5e7c55..25a0df1 100644
>> > > --- a/drivers/watchdog/Kconfig
>> > > +++ b/drivers/watchdog/Kconfig
>> > > @@ -152,6 +152,18 @@ config ARM_SP805_WATCHDOG
>> > >         ARM Primecell SP805 Watchdog timer. This will reboot your system when
>> > >         the timeout is reached.
>> > >
>> > > +config ARM_SBSA_WATCHDOG
>> > > +     tristate "ARM SBSA Generic Watchdog"
>> > > +     depends on ARM || ARM64 || COMPILE_TEST
>> >
>> > SBSA is for ARMv8-A based (64-bit) servers, no need to depends on ARM,
>> > and why we depends on COMPILE_TEST?
>> >
>>
>> I think it's a reasonable assumption that someone will sooner or later
>> put that hardware into an ARM32 machine, or run a 32-bit kernel on
>> a chip that has it.
>>
>> While SBSA requires this watchdog device, nothing prevents SoC
>> manufacturers from using the same design in something that is not
>> a server.
>>
> Tricky, though. Since teh driver uses arm specific clock functions,
> I don't think this can compile on a non-arm machine.

yes, According to SBSA spec, the clock source of SBSAwatchdog is
system counter which is a part of arm arch timer.
So I think SBSA watchdog always goes with  ARM.

ARM arch timer has been used on ARM32 and ARM64, so SBSA also can be
used on ARM32.
Just  there is not a ARM32 hardware has that IP core right now.

>
> Guenter



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch
Ph: +86 21 61221326(direct)
Ph: +86 186 2020 4684 (mobile)
Room 1512, Regus One Corporate Avenue,Level 15,
One Corporate Avenue,222 Hubin Road,Huangpu District,
Shanghai,China 200021
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