Re: [PATCH v3 05/12] dt-bindings: rtc: renesas,rzg3s-rtc: Document the Renesas RTCA-3 IP

Geert Uytterhoeven
2024-10-10T09:29:39Z

Hi Claudiu,

On Fri, Aug 30, 2024 at 3:02 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> Document the RTC IP (RTCA-3) available on the Renesas RZ/G3S SoC.
> The RTC IP available on Renesas RZ/V2H is almost identical with the
> one found on Renesas RZ/G3S (it misses the time capture functionality
> which is not yet implemented on proposed driver). For this, added also a
> generic compatible that will be used at the moment as fallback for both
> RZ/G3S and RZ/V2H.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---
>
> Changes in v3:
> - added RTC bus clock, reset and power-domain; it has been detected
> by reverse engineering that RTC and VBATTB clock, reset and power
> domain are shared; HW manual doesn't mention it
> - updated example with these and with assigned-clock properties
> needed to configure the VBATTCLK MUX with proper parent
> - updated example section with dt-bindings/clock/r9a08g045-cpg.h
> and dt-bindings/clock/r9a08g045-vbattb.h includes
> - for all these, dropped Conor's Rb tag

Thanks for the update!

Sorry for chiming in late, but this RTCA-3 block seems to be a
derivative of the RTC blocks found on older SuperH SoCs, and on RZ/A1
and RZ/A2 ARM SoCs. Differences are found in (lack of)
100/1000-year-count parts and the Year Alarm Enable Register, and in
some control register bits.

The SuperH and RZ/A1 variant is supported by drivers/rtc/rtc-sh.c;
DT bindings for the latter are found in
Documentation/devicetree/bindings/rtc/renesas,sh-rtc.yaml.

(My first guess was that RTC-A1 is used on RZ/A1, RTC-A2 on RZ/A2,
and RTC-A3 on RZ/A3, but apparently RZ/A3UL does not have an RTC...
Oh well, at least it is used on later RZ series SoCs...)

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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