linux-kernel - Re: [PATCH v2 3/3] clocksource: Add clockevent support to NPS400 driver

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Date:   Mon, 31 Oct 2016 10:51:40 -0700
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     Noam Camus <noamca@...lanox.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
CC:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] clocksource: Add clockevent support to NPS400
 driver

Hi Daniel,

On 10/31/2016 10:03 AM, Noam Camus wrote:
>> Oops, wait. Here, arch/arc/kernel/time.c should be moved in drivers/clocksource and consolidated with this driver.
>> >Very likely, CPUHP_AP_ARC_TIMER_STARTING can be used for all ARC timers.
> Indeed the ARC timer driver served as my inspiration but due to HW threads handling they are not the same.
> Moving drivers from arch/arc to driver/clocksource is not my call (Vineet Gupta is the maintainer of ARC)
> And I think they quiet differ now so consolidation gain is not obvious.

Sorry this was on my todo list at low priority. Anyways took a quick look at it now.

The problem is timer code overlaps pure driver land and ARC specific code. e.g.
CONFIG_ARC_HAS_RTC clocksource needs to check whether hardware exists or not. We
currently conveniently check that from cpuinfo populated at boot time. Now either
I need to export that info as a function (which should be done anyways) - but then
define stub for !ARC. Either that or duplicate the detection code here (orig copy
in arc setup.c)

So doing this exercise cleanly would mean exporting much of
arch/arc/include/asm/{arcregs.h, mcip.h} out of ARC into include/soc/arc/*. Isn't
this kind of going back to include/asm-<arch>/* days ?

Honestly I do want to move the driver in the right place but not sure how to do
this cleanly.

Thoughts ?

-Vineet