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>
> ---
>
> Changes in v5:
> - collected tags
>
> Changes in v4:
> - dropped oscillator from patch description
> - s/on-board/internal in patch description
> - updated dt-binding included file name in the driver as it has been
> renamed to include/dt-bindings/clock/renesas,r9a08g045-vbattb.h
> - dropped the "_BIT" from driver macros
> - used "quartz-load-femtofarads" dt property instead of adding a new one
> - register the "vbattclk" as critical clock as this feeds the RTC counter
> logic and it needs to stay on from the moment the RTC is configured;
> along with it, added a comment to express this.
>
> Changes in v3:
> - updated patch description
> - dropped dependency on MFD_RENESAS_VBATTB as now there is no
> driver built under this flag
> - dropped include/clk.h
> - added pm_runtime and reset control support
> - updated register offsets
> - registered 4 clocks: xc, xbyp, mux, vbattclk using generic
> clock drivers
> - added MODULE_DEVICE_TABLE()
>
> Changes in v2:
> - updated patch description
> - added vendor name in Kconfig flag
> - used cleanup.h lock helpers
> - dropped the MFD code
> - updated registers offsets
> - added vbattb_clk_update_bits() and used it where possible
> - added vbattb_clk_need_bypass() to detect the bypass setup necessity
> - changed the compatible and driver names
>
>
> drivers/clk/renesas/Kconfig | 4 +
> drivers/clk/renesas/Makefile | 1 +
> drivers/clk/renesas/clk-vbattb.c | 205 +++++++++++++++++++++++++++++++
> 3 files changed, 210 insertions(+)
> create mode 100644 drivers/clk/renesas/clk-vbattb.c
>
> diff --git a/drivers/clk/renesas/Kconfig b/drivers/clk/renesas/Kconfig
> index 76791a1c50ac..4e835a3f1ab4 100644
> --- 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
> + select RESET_CONTROLLER
> +
...
> +
> +static const struct of_device_id vbattb_clk_match[] = {
> + { .compatible = "renesas,r9a08g045-vbattb" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, vbattb_clk_match);
> +
> +static struct platform_driver vbattb_clk_driver = {
> + .driver = {
> + .name = "renesas-vbattb-clk",
> + .of_match_table = vbattb_clk_match,
> + },
> + .probe = vbattb_clk_probe,
> +};
> +module_platform_driver(vbattb_clk_driver);
That's a module, isn't it?
> +
> +MODULE_DESCRIPTION("Renesas VBATTB Clock Driver");
> +MODULE_AUTHOR("Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> --
> 2.39.2
>
