On 31.10.2024 11:46, Krzysztof Kozlowski wrote: > On 31/10/2024 10:26, Claudiu Beznea wrote: >> Hi, Geert, Krzysztof, >> >> On 31.10.2024 10:43, Geert Uytterhoeven wrote: >>> 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? >> >> On RZ/G3S the RTC counter needs the clock provided by VBATTB. >> >> I'll try with this as a module. > > So it will defer, why would this be a problem? This does not look like No problems with it. I wrongly phrased it. That being said, I'll set CLK_RENESAS_VBATTB as module along with RTC and do the proper adjustments in drivers/clk/renesas/Kconfig. Thank you, Claudiu > critical core component, which would halt the system probe (and even > then systems like Android put everything as modules). > > Best regards, > Krzysztof >
