Messages in this thread | | | Subject | Re: Time: new clocksource | From | Daniel Lezcano <> | Date | Mon, 6 Dec 2021 07:29:32 +0100 |
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On 06/12/2021 07:00, Muni Sekhar wrote: > 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?
Yes, that is the case today.
> If so, what's the reason for that?
The timer is a component needed at boot time, so a module version does really not make sense.
So I would return back the question : what is the reason for a module?
>> 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 >> >> >> -- >> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs >> >> Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | >> <http://twitter.com/#!/linaroorg> Twitter | >> <http://www.linaro.org/linaro-blog/> Blog > > >
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