On Wed, Oct 30, 2024 at 01:01:11PM +0200, Claudiu wrote: > From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx> > > The VBATTB IP of the Renesas RZ/G3S SoC controls the clock for RTC, > the tamper detector and a small general usage memory of 128B. > > The VBATTB controller controls the clock for the RTC on the Renesas > RZ/G3S. The HW block diagram for the clock logic is as follows: > > +----------+ XC `\ > RTXIN --->| |----->| \ +----+ VBATTCLK > | 32K clock| | |----->|gate|-----------> > | osc | XBYP | | +----+ > RTXOUT --->| |----->| / > +----------+ ,/ > > One could connect as input to this HW block either a crystal or > an external clock device. This is board specific. > > After discussions w/ Stephen Boyd the clock tree associated with this > hardware block was exported in Linux as: > > input-xtal > xbyp > xc > mux > vbattclk > > 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. > > This allows select the input of the mux based on the type of the > connected input clock: > - if the 32768 crystal is connected as input for the VBATTB, > the input of the mux should be xc > - if an external clock device is connected as input for the VBATTB the > input of the mux should be xbyp > > Add bindings for the VBATTB controller. > > Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx> > --- > > Changes in v5: > - used spaces in the diagram from the patch description > - added "This is board specific" in the board description to emphasize > the usage of the assigned-clocks in the example > - added default for quartz-load-femtofarads > - collected tags Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> Best regards, Krzysztof
