On Mon, Dec 6, 2021 at 11:59 AM Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> wrote: > > On 06/12/2021 07:00, Muni Sekhar wrote: > > On Sat, Dec 4, 2021 at 3:18 AM Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> 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? For built-in module we need to compile the whole kernel, but we are currently using the kernel via linux-image-4.15.0-54-generic.deb file installation. > > > >> 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 > > > > > > > > > -- > <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 -- Thanks, Sekhar _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
