Hi Krzysztof,
On Thu, Oct 31, 2024 at 8:48 AM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
> On Wed, Oct 30, 2024 at 01:01:13PM +0200, Claudiu wrote:
> > From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >
> > The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that is used
> > by the RTC. The input to the VBATTB could be a 32KHz crystal
> > or an external clock device.
> >
> > The HW block diagram for the clock generator is as follows:
> >
> > +----------+ XC `\
> > RTXIN --->| |----->| \ +----+ VBATTCLK
> > | 32K clock| | |----->|gate|----------->
> > | osc | XBYP | | +----+
> > RTXOUT --->| |----->| /
> > +----------+ ,
> >
> > After discussions w/ Stephen Boyd the clock tree associated with this
> > hardware block was exported in Linux as:
> >
> > vbattb-xtal
> > xbyp
> > xc
> > mux
> > vbattbclk
> >
> > where:
> > - input-xtal is the input clock (connected to RTXIN, RTXOUT pins)
> > - xc, xbyp are mux inputs
> > - mux is the internal mux
> > - vbattclk is the gate clock that feeds in the end the RTC
> >
> > to allow selecting the input of the MUX though assigned-clock DT
> > properties, using the already existing clock drivers and avoid adding
> > other DT properties. If the crystal is connected on RTXIN,
> > RTXOUT pins the XC will be selected as mux input. If an external clock
> > device is connected on RTXIN, RTXOUT pins the XBYP will be selected as
> > mux input.
> >
> > The load capacitance of the internal crystal can be configured
> > with renesas,vbattb-load-nanofarads DT property.
> >
> > Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> > --- a/drivers/clk/renesas/Kconfig
> > +++ b/drivers/clk/renesas/Kconfig
> > @@ -237,6 +237,10 @@ config CLK_RZV2H
> > bool "RZ/V2H(P) family clock support" if COMPILE_TEST
> > select RESET_CONTROLLER
> >
> > +config CLK_RENESAS_VBATTB
> > + bool "Renesas VBATTB clock controller"
>
> tristate
Good point.
However, does it work as a module, or would that break the RTC?
And this is missing
depends on ARCH_RENESAS || COMPILE_TEST
which I can add while applying.
>
> > + select RESET_CONTROLLER
> > +
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
