From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The VBATTB controllers 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 oscillator or
an external clock device.

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 oscillator 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 clock IDs for the VBATTB controller.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- none; this patch is new

 include/dt-bindings/clock/r9a08g045-vbattb.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 include/dt-bindings/clock/r9a08g045-vbattb.h

diff --git a/include/dt-bindings/clock/r9a08g045-vbattb.h b/include/dt-bindings/clock/r9a08g045-vbattb.h
new file mode 100644
index 000000000000..67774eafad06
--- /dev/null
+++ b/include/dt-bindings/clock/r9a08g045-vbattb.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+ *
+ * Copyright (C) 2024 Renesas Electronics Corp.
+ */
+#ifndef __DT_BINDINGS_CLOCK_R9A08G045_VBATTB_H__
+#define __DT_BINDINGS_CLOCK_R9A08G045_VBATTB_H__
+
+#define VBATTB_XC		0
+#define VBATTB_XBYP		1
+#define VBATTB_MUX		2
+#define VBATTB_VBATTCLK		3
+
+#endif /* __DT_BINDINGS_CLOCK_R9A08G045_VBATTB_H__ */
-- 
2.39.2

Hi Claudiu,

Thanks for your patch!

On Fri, Aug 30, 2024 at 3:02 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> The VBATTB controllers controls the clock for the RTC on the Renesas

controller

> 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 oscillator or

Please drop "oscillator". An external crystal is used with the internal
crystal oscillator.

> an external clock device.
>
> 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 oscillator is connected as input for the VBATTB,

Please drop "oscillator".

>   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 clock IDs for the VBATTB controller.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---
>
> Changes in v3:
> - none; this patch is new

> --- /dev/null
> +++ b/include/dt-bindings/clock/r9a08g045-vbattb.h

renesas,r9a08g045-vbattb.h

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

On Fri, Aug 30, 2024 at 04:02:08PM +0300, Claudiu wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> 
> The VBATTB controllers 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 oscillator or
> an external clock device.
> 
> 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 oscillator 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 clock IDs for the VBATTB controller.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---
> 
> Changes in v3:
> - none; this patch is new
> 
>  include/dt-bindings/clock/r9a08g045-vbattb.h | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>  create mode 100644 include/dt-bindings/clock/r9a08g045-vbattb.h

Squash this into the previous patch. It is part of the binding.

Rob