From: Muni Sekhar <munisekharrms@gmail.com>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: tglx@linutronix.de, LKML <linux-kernel@vger.kernel.org>,
kernelnewbies <kernelnewbies@kernelnewbies.org>
Subject: Re: Time: new clocksource
Date: Mon, 6 Dec 2021 11:30:21 +0530 [thread overview]
Message-ID: <CAHhAz+iEQTtfxXB8sNEL4WxFjUZo5LYTo4EVyH0mT2=NH3VaUA@mail.gmail.com> (raw)
In-Reply-To: <fe9dbf81-e060-36ab-b769-215af3d65ba7@linaro.org>
On Sat, Dec 4, 2021 at 3:18 AM Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
>
> Hi Sekhar,
>
> On 03/12/2021 17:50, Muni Sekhar wrote:
> > Hi All,
> >
> > We have a Digital PLL with 64 bit timer counter hardware and the
> > counter is accessible from the CPU over the PCIe bus.
> >
> > Is it possible to add this timer counter hardware as new clocksource
> > driver? To do this, can someone please point me to the existing
> > reference source code(or patch) for this task.
>
> You can refer to the drivers located in drivers/clocksource
I don't see the option in menuconfig to build the clocksource driver
as a loadable kernel module, for example CONFIG_X86_PM_TIMER=m instead
of CONFIG_X86_PM_TIMER=y.
So a clocksource driver should always be part of the kernel built-in
module? If so, what's the reason for that?
>
> git annotate on one of the driver can give you the initial commit where
> recent submissions explain the timer internals.
>
> > Suppose if it is possible to add a new clocksource driver for this
> > hardware then does any userspace get_timestamp* API would get the time
> > from this new hardware?
>
> It should if the timer is selected as the clocksource
>
>
> --
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>
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--
Thanks,
Sekhar
next prev parent reply other threads:[~2021-12-06 6:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-03 16:50 Time: new clocksource Muni Sekhar
2021-12-03 21:48 ` Daniel Lezcano
2021-12-06 6:00 ` Muni Sekhar [this message]
2021-12-06 6:29 ` Daniel Lezcano
2021-12-06 7:00 ` Muni Sekhar
2021-12-07 7:33 ` Muni Sekhar
2021-12-08 9:10 ` Valdis Klētnieks
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