diff mbox series

[02/12] dt-bindings: clock: renesas,rzg3s-vbattb-clk: Document the VBATTB clock driver

Message ID 20240614071932.1014067-3-claudiu.beznea.uj@bp.renesas.com (mailing list archive)
State Changes Requested, archived
Headers show
Series Add RTC support for the Renesas RZ/G3S SoC | expand

Commit Message

claudiu beznea June 14, 2024, 7:19 a.m. UTC
From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that feeds
the RTC and the tamper detector. Add documentation for the VBATTB clock
driver.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---
 .../clock/renesas,rzg3s-vbattb-clk.yaml       | 90 +++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml

Comments

Conor Dooley June 15, 2024, 12:17 p.m. UTC | #1
On Fri, Jun 14, 2024 at 10:19:22AM +0300, Claudiu wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> 
> The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that feeds
> the RTC and the tamper detector. Add documentation for the VBATTB clock
> driver.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---
>  .../clock/renesas,rzg3s-vbattb-clk.yaml       | 90 +++++++++++++++++++
>  1 file changed, 90 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> 
> diff --git a/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> new file mode 100644
> index 000000000000..ef52a0c0f874
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> @@ -0,0 +1,90 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/clock/renesas,rzg3s-vbattb-clk.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Renesas VBATTB clock
> +
> +maintainers:
> +  - Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> +
> +description:
> +  Renesas VBATTB module is an always on powered module (backed by battery) which
> +  generates a clock (VBATTCLK). This clocks feeds the RTC and the tamper detector
> +  modules.
> +
> +properties:
> +  compatible:
> +    const: renesas,rzg3s-vbattb-clk
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    items:
> +      - description: VBATTB module clock
> +      - description: VBATTB input xtal
> +
> +  clock-names:
> +    items:
> +      - const: bclk
> +      - const: vbattb_xtal
> +
> +  '#clock-cells':
> +    const: 0
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  renesas,vbattb-load-nanofarads:
> +    description: load capacitance of the on board xtal
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [ 4000, 7000, 9000, 12500 ]
> +
> +  renesas,vbattb-osc-bypass:
> +    description: set when external clock is connected to RTXOUT pin
> +    type: boolean

When you say "external clock", is that an input or an output?
Krzysztof Kozlowski June 16, 2024, 7:38 a.m. UTC | #2
On 14/06/2024 09:19, Claudiu wrote:
> +    #include <dt-bindings/clock/r9a08g045-cpg.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    vbattb: vbattb@1005c000 {
> +        compatible = "renesas,rzg3s-vbattb", "syscon", "simple-mfd";
> +        reg = <0x1005c000 0x1000>;
> +        ranges = <0 0 0x1005c000 0 0x1000>;
> +        interrupts = <GIC_SPI 43 IRQ_TYPE_LEVEL_HIGH>;
> +        interrupt-names = "tampdi";
> +        clocks = <&cpg CPG_MOD R9A08G045_VBAT_BCLK>;
> +        clock-names = "bclk";
> +        power-domains = <&cpg>;
> +        resets = <&cpg R9A08G045_VBAT_BRESETN>;
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +        status = "disabled";

Drop.

And keep only one complete example, instead of two. See other complex
devices as example.


Best regards,
Krzysztof
claudiu beznea June 17, 2024, 7:02 a.m. UTC | #3
On 15.06.2024 15:17, Conor Dooley wrote:
> On Fri, Jun 14, 2024 at 10:19:22AM +0300, Claudiu wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>
>> The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that feeds
>> the RTC and the tamper detector. Add documentation for the VBATTB clock
>> driver.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>> ---
>>  .../clock/renesas,rzg3s-vbattb-clk.yaml       | 90 +++++++++++++++++++
>>  1 file changed, 90 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>> new file mode 100644
>> index 000000000000..ef52a0c0f874
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>> @@ -0,0 +1,90 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/clock/renesas,rzg3s-vbattb-clk.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Renesas VBATTB clock
>> +
>> +maintainers:
>> +  - Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>> +
>> +description:
>> +  Renesas VBATTB module is an always on powered module (backed by battery) which
>> +  generates a clock (VBATTCLK). This clocks feeds the RTC and the tamper detector
>> +  modules.
>> +
>> +properties:
>> +  compatible:
>> +    const: renesas,rzg3s-vbattb-clk
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    items:
>> +      - description: VBATTB module clock
>> +      - description: VBATTB input xtal
>> +
>> +  clock-names:
>> +    items:
>> +      - const: bclk
>> +      - const: vbattb_xtal
>> +
>> +  '#clock-cells':
>> +    const: 0
>> +
>> +  power-domains:
>> +    maxItems: 1
>> +
>> +  renesas,vbattb-load-nanofarads:
>> +    description: load capacitance of the on board xtal
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [ 4000, 7000, 9000, 12500 ]
>> +
>> +  renesas,vbattb-osc-bypass:
>> +    description: set when external clock is connected to RTXOUT pin
>> +    type: boolean
> 
> When you say "external clock", is that an input or an output?

I took that statement from the HW manual. As of the HW manual [1], table
42.2, that would be an input.

[1]
https://www.renesas.com/us/en/products/microcontrollers-microprocessors/rz-mpus/rzg3s-general-purpose-microprocessors-single-core-arm-cortex-a55-11-ghz-cpu-and-dual-core-cortex-m33-250
claudiu beznea June 17, 2024, 7:34 a.m. UTC | #4
On 16.06.2024 10:38, Krzysztof Kozlowski wrote:
> On 14/06/2024 09:19, Claudiu wrote:
>> +    #include <dt-bindings/clock/r9a08g045-cpg.h>
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +
>> +    vbattb: vbattb@1005c000 {
>> +        compatible = "renesas,rzg3s-vbattb", "syscon", "simple-mfd";
>> +        reg = <0x1005c000 0x1000>;
>> +        ranges = <0 0 0x1005c000 0 0x1000>;
>> +        interrupts = <GIC_SPI 43 IRQ_TYPE_LEVEL_HIGH>;
>> +        interrupt-names = "tampdi";
>> +        clocks = <&cpg CPG_MOD R9A08G045_VBAT_BCLK>;
>> +        clock-names = "bclk";
>> +        power-domains = <&cpg>;
>> +        resets = <&cpg R9A08G045_VBAT_BRESETN>;
>> +        #address-cells = <2>;
>> +        #size-cells = <2>;
>> +        status = "disabled";
> 
> Drop.

OK.

> 
> And keep only one complete example, instead of two. See other complex
> devices as example.
Do you have in mind an example that you can point me to?

Thank you,
Claudiu Beznea

> 
> 
> Best regards,
> Krzysztof
>
Conor Dooley June 17, 2024, 3:19 p.m. UTC | #5
On Mon, Jun 17, 2024 at 10:02:47AM +0300, claudiu beznea wrote:
> 
> 
> On 15.06.2024 15:17, Conor Dooley wrote:
> > On Fri, Jun 14, 2024 at 10:19:22AM +0300, Claudiu wrote:
> >> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >>
> >> The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that feeds
> >> the RTC and the tamper detector. Add documentation for the VBATTB clock
> >> driver.
> >>
> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >> ---
> >>  .../clock/renesas,rzg3s-vbattb-clk.yaml       | 90 +++++++++++++++++++
> >>  1 file changed, 90 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> >>
> >> diff --git a/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> >> new file mode 100644
> >> index 000000000000..ef52a0c0f874
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> >> @@ -0,0 +1,90 @@
> >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/clock/renesas,rzg3s-vbattb-clk.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: Renesas VBATTB clock
> >> +
> >> +maintainers:
> >> +  - Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >> +
> >> +description:
> >> +  Renesas VBATTB module is an always on powered module (backed by battery) which
> >> +  generates a clock (VBATTCLK). This clocks feeds the RTC and the tamper detector
> >> +  modules.
> >> +
> >> +properties:
> >> +  compatible:
> >> +    const: renesas,rzg3s-vbattb-clk
> >> +
> >> +  reg:
> >> +    maxItems: 1
> >> +
> >> +  clocks:
> >> +    items:
> >> +      - description: VBATTB module clock
> >> +      - description: VBATTB input xtal
> >> +
> >> +  clock-names:
> >> +    items:
> >> +      - const: bclk
> >> +      - const: vbattb_xtal
> >> +
> >> +  '#clock-cells':
> >> +    const: 0
> >> +
> >> +  power-domains:
> >> +    maxItems: 1
> >> +
> >> +  renesas,vbattb-load-nanofarads:
> >> +    description: load capacitance of the on board xtal
> >> +    $ref: /schemas/types.yaml#/definitions/uint32
> >> +    enum: [ 4000, 7000, 9000, 12500 ]
> >> +
> >> +  renesas,vbattb-osc-bypass:
> >> +    description: set when external clock is connected to RTXOUT pin
> >> +    type: boolean
> > 
> > When you say "external clock", is that an input or an output?
> 
> I took that statement from the HW manual. As of the HW manual [1], table
> 42.2, that would be an input.

Forgive me for not wanting to open the zip etc and find the information
in the document, but why do you need an extra property? Is it not
something you can determine from the clocks/clock-names properties?
It sounds like an additional clock from your description, is it actually
different way to provide the second clock you mention above?

> 
> [1]
> https://www.renesas.com/us/en/products/microcontrollers-microprocessors/rz-mpus/rzg3s-general-purpose-microprocessors-single-core-arm-cortex-a55-11-ghz-cpu-and-dual-core-cortex-m33-250
>
claudiu beznea June 18, 2024, 7:34 a.m. UTC | #6
On 17.06.2024 18:19, Conor Dooley wrote:
> On Mon, Jun 17, 2024 at 10:02:47AM +0300, claudiu beznea wrote:
>>
>>
>> On 15.06.2024 15:17, Conor Dooley wrote:
>>> On Fri, Jun 14, 2024 at 10:19:22AM +0300, Claudiu wrote:
>>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>
>>>> The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that feeds
>>>> the RTC and the tamper detector. Add documentation for the VBATTB clock
>>>> driver.
>>>>
>>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>> ---
>>>>  .../clock/renesas,rzg3s-vbattb-clk.yaml       | 90 +++++++++++++++++++
>>>>  1 file changed, 90 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>>>> new file mode 100644
>>>> index 000000000000..ef52a0c0f874
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>>>> @@ -0,0 +1,90 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/clock/renesas,rzg3s-vbattb-clk.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: Renesas VBATTB clock
>>>> +
>>>> +maintainers:
>>>> +  - Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>> +
>>>> +description:
>>>> +  Renesas VBATTB module is an always on powered module (backed by battery) which
>>>> +  generates a clock (VBATTCLK). This clocks feeds the RTC and the tamper detector
>>>> +  modules.
>>>> +
>>>> +properties:
>>>> +  compatible:
>>>> +    const: renesas,rzg3s-vbattb-clk
>>>> +
>>>> +  reg:
>>>> +    maxItems: 1
>>>> +
>>>> +  clocks:
>>>> +    items:
>>>> +      - description: VBATTB module clock
>>>> +      - description: VBATTB input xtal
>>>> +
>>>> +  clock-names:
>>>> +    items:
>>>> +      - const: bclk
>>>> +      - const: vbattb_xtal
>>>> +
>>>> +  '#clock-cells':
>>>> +    const: 0
>>>> +
>>>> +  power-domains:
>>>> +    maxItems: 1
>>>> +
>>>> +  renesas,vbattb-load-nanofarads:
>>>> +    description: load capacitance of the on board xtal
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    enum: [ 4000, 7000, 9000, 12500 ]
>>>> +
>>>> +  renesas,vbattb-osc-bypass:
>>>> +    description: set when external clock is connected to RTXOUT pin
>>>> +    type: boolean
>>>
>>> When you say "external clock", is that an input or an output?
>>
>> I took that statement from the HW manual. As of the HW manual [1], table
>> 42.2, that would be an input.
> 
> Forgive me for not wanting to open the zip etc and find the information
> in the document, but why do you need an extra property? Is it not
> something you can determine from the clocks/clock-names properties?

It can't be determined from clocks/clock-names as of my understanding. It
depends on the type of the input clock (crystal oscillator or external
hardware device generating the clock).

> It sounds like an additional clock from your description, is it actually
> different way to provide the second clock you mention above?

This is the block diagram (see [1], only picture this time) of the module
controlling the clock. Please open it, it helps in understanding what I'll
explain above.

The VBATTB blocks controlling the VBATTBCLK are:
- 32KHz-clock oscillator
- the mux controlled by BKSCCR.SOSEL
- the gate who's input is the mux output and XOSCCR.OUTEN

To the 32 KHz-clock oscillator block could be connected:
1/ either a crystal oscillator in which case it will be connected to both
RTXIN and RTXOUT pins (the direction of RTXOUT is wrong in this picture for
this case)
2/ or a device (like [2]) generating a clock which has a single output and,
from my understanding and experience with devices like this, only RTXIN is
needed, RTXOUT is connected to the ground; for this case the 32KHz-clock
oscillator block from [1] need to be bypassed in which case the newly
introduced property will be used; this will select the XBYP on the mux.

Thank you,
Claudiu Beznea

[1] https://pasteboard.co/QYsCvhfQlX6n.png
[2]
https://ro.mouser.com/datasheet/2/268/DSC1001_3_4_1_8V_3_3V_Low_Power_Precision_CMOS_Osc-3314582.pdf

> 
>>
>> [1]
>> https://www.renesas.com/us/en/products/microcontrollers-microprocessors/rz-mpus/rzg3s-general-purpose-microprocessors-single-core-arm-cortex-a55-11-ghz-cpu-and-dual-core-cortex-m33-250
>>
Geert Uytterhoeven June 18, 2024, 7:56 a.m. UTC | #7
Hi Claudiu,

On Tue, Jun 18, 2024 at 9:34 AM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
> On 17.06.2024 18:19, Conor Dooley wrote:
> > On Mon, Jun 17, 2024 at 10:02:47AM +0300, claudiu beznea wrote:
> >> On 15.06.2024 15:17, Conor Dooley wrote:
> >>> On Fri, Jun 14, 2024 at 10:19:22AM +0300, Claudiu wrote:
> >>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >>>>
> >>>> The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that feeds
> >>>> the RTC and the tamper detector. Add documentation for the VBATTB clock
> >>>> driver.
> >>>>
> >>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >>>> ---
> >>>>  .../clock/renesas,rzg3s-vbattb-clk.yaml       | 90 +++++++++++++++++++
> >>>>  1 file changed, 90 insertions(+)
> >>>>  create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> >>>>
> >>>> diff --git a/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> >>>> new file mode 100644
> >>>> index 000000000000..ef52a0c0f874
> >>>> --- /dev/null
> >>>> +++ b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
> >>>> +  renesas,vbattb-osc-bypass:
> >>>> +    description: set when external clock is connected to RTXOUT pin

FTR, this contradicts the explanation below, which states the external
clock oscillator is connected to RTXIN.

> >>>> +    type: boolean
> >>>
> >>> When you say "external clock", is that an input or an output?
> >>
> >> I took that statement from the HW manual. As of the HW manual [1], table
> >> 42.2, that would be an input.
> >
> > Forgive me for not wanting to open the zip etc and find the information
> > in the document, but why do you need an extra property? Is it not
> > something you can determine from the clocks/clock-names properties?
>
> It can't be determined from clocks/clock-names as of my understanding. It
> depends on the type of the input clock (crystal oscillator or external
> hardware device generating the clock).
>
> > It sounds like an additional clock from your description, is it actually
> > different way to provide the second clock you mention above?
>
> This is the block diagram (see [1], only picture this time) of the module
> controlling the clock. Please open it, it helps in understanding what I'll
> explain above.
>
> The VBATTB blocks controlling the VBATTBCLK are:
> - 32KHz-clock oscillator
> - the mux controlled by BKSCCR.SOSEL
> - the gate who's input is the mux output and XOSCCR.OUTEN
>
> To the 32 KHz-clock oscillator block could be connected:
> 1/ either a crystal oscillator in which case it will be connected to both
> RTXIN and RTXOUT pins (the direction of RTXOUT is wrong in this picture for
> this case)
> 2/ or a device (like [2]) generating a clock which has a single output and,
> from my understanding and experience with devices like this, only RTXIN is
> needed, RTXOUT is connected to the ground; for this case the 32KHz-clock
> oscillator block from [1] need to be bypassed in which case the newly
> introduced property will be used; this will select the XBYP on the mux.

Sounds similar to the RAA215300 PMIC, which includes an ISL1208-derived
RTC, where this was handled using two different clock names:
https://elixir.bootlin.com/linux/v6.10-rc1/source/Documentation/devicetree/bindings/regulator/renesas,raa215300.yaml#L49
https://elixir.bootlin.com/linux/v6.10-rc1/source/drivers/rtc/rtc-isl1208.c#L869

Gr{oetje,eeting}s,

                        Geert
claudiu beznea June 18, 2024, 8:11 a.m. UTC | #8
Hi, Geert,

On 18.06.2024 10:56, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Tue, Jun 18, 2024 at 9:34 AM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
>> On 17.06.2024 18:19, Conor Dooley wrote:
>>> On Mon, Jun 17, 2024 at 10:02:47AM +0300, claudiu beznea wrote:
>>>> On 15.06.2024 15:17, Conor Dooley wrote:
>>>>> On Fri, Jun 14, 2024 at 10:19:22AM +0300, Claudiu wrote:
>>>>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>>>
>>>>>> The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that feeds
>>>>>> the RTC and the tamper detector. Add documentation for the VBATTB clock
>>>>>> driver.
>>>>>>
>>>>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>>> ---
>>>>>>  .../clock/renesas,rzg3s-vbattb-clk.yaml       | 90 +++++++++++++++++++
>>>>>>  1 file changed, 90 insertions(+)
>>>>>>  create mode 100644 Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>>>>>> new file mode 100644
>>>>>> index 000000000000..ef52a0c0f874
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
>>>>>> +  renesas,vbattb-osc-bypass:
>>>>>> +    description: set when external clock is connected to RTXOUT pin
> 
> FTR, this contradicts the explanation below, which states the external
> clock oscillator is connected to RTXIN.

I agree.

> 
>>>>>> +    type: boolean
>>>>>
>>>>> When you say "external clock", is that an input or an output?
>>>>
>>>> I took that statement from the HW manual. As of the HW manual [1], table
>>>> 42.2, that would be an input.
>>>
>>> Forgive me for not wanting to open the zip etc and find the information
>>> in the document, but why do you need an extra property? Is it not
>>> something you can determine from the clocks/clock-names properties?
>>
>> It can't be determined from clocks/clock-names as of my understanding. It
>> depends on the type of the input clock (crystal oscillator or external
>> hardware device generating the clock).
>>
>>> It sounds like an additional clock from your description, is it actually
>>> different way to provide the second clock you mention above?
>>
>> This is the block diagram (see [1], only picture this time) of the module
>> controlling the clock. Please open it, it helps in understanding what I'll
>> explain above.
>>
>> The VBATTB blocks controlling the VBATTBCLK are:
>> - 32KHz-clock oscillator
>> - the mux controlled by BKSCCR.SOSEL
>> - the gate who's input is the mux output and XOSCCR.OUTEN
>>
>> To the 32 KHz-clock oscillator block could be connected:
>> 1/ either a crystal oscillator in which case it will be connected to both
>> RTXIN and RTXOUT pins (the direction of RTXOUT is wrong in this picture for
>> this case)
>> 2/ or a device (like [2]) generating a clock which has a single output and,
>> from my understanding and experience with devices like this, only RTXIN is
>> needed, RTXOUT is connected to the ground; for this case the 32KHz-clock
>> oscillator block from [1] need to be bypassed in which case the newly
>> introduced property will be used; this will select the XBYP on the mux.
> 
> Sounds similar to the RAA215300 PMIC, which includes an ISL1208-derived
> RTC, where this was handled using two different clock names:
> https://elixir.bootlin.com/linux/v6.10-rc1/source/Documentation/devicetree/bindings/regulator/renesas,raa215300.yaml#L49
> https://elixir.bootlin.com/linux/v6.10-rc1/source/drivers/rtc/rtc-isl1208.c#L869

Yes, seem similar. I wasn't aware of this approach. I'll switch to it.

Thank  you,
Claudiu Beznea

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
>
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
new file mode 100644
index 000000000000..ef52a0c0f874
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/renesas,rzg3s-vbattb-clk.yaml
@@ -0,0 +1,90 @@ 
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/renesas,rzg3s-vbattb-clk.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas VBATTB clock
+
+maintainers:
+  - Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
+
+description:
+  Renesas VBATTB module is an always on powered module (backed by battery) which
+  generates a clock (VBATTCLK). This clocks feeds the RTC and the tamper detector
+  modules.
+
+properties:
+  compatible:
+    const: renesas,rzg3s-vbattb-clk
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: VBATTB module clock
+      - description: VBATTB input xtal
+
+  clock-names:
+    items:
+      - const: bclk
+      - const: vbattb_xtal
+
+  '#clock-cells':
+    const: 0
+
+  power-domains:
+    maxItems: 1
+
+  renesas,vbattb-load-nanofarads:
+    description: load capacitance of the on board xtal
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [ 4000, 7000, 9000, 12500 ]
+
+  renesas,vbattb-osc-bypass:
+    description: set when external clock is connected to RTXOUT pin
+    type: boolean
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - power-domains
+  - '#clock-cells'
+  - renesas,vbattb-load-nanofarads
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/r9a08g045-cpg.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    vbattb: vbattb@1005c000 {
+        compatible = "renesas,rzg3s-vbattb", "syscon", "simple-mfd";
+        reg = <0x1005c000 0x1000>;
+        ranges = <0 0 0x1005c000 0 0x1000>;
+        interrupts = <GIC_SPI 43 IRQ_TYPE_LEVEL_HIGH>;
+        interrupt-names = "tampdi";
+        clocks = <&cpg CPG_MOD R9A08G045_VBAT_BCLK>;
+        clock-names = "bclk";
+        power-domains = <&cpg>;
+        resets = <&cpg R9A08G045_VBAT_BRESETN>;
+        #address-cells = <2>;
+        #size-cells = <2>;
+        status = "disabled";
+
+        vbattclk: clock-controller@1c {
+            compatible = "renesas,rzg3s-vbattb-clk";
+            reg = <0 0x1c 0 0x10>;
+            clocks = <&cpg CPG_MOD R9A08G045_VBAT_BCLK>, <&vbattb_xtal>;
+            clock-names = "bclk", "vbattb_xtal";
+            #clock-cells = <0>;
+            power-domains = <&cpg>;
+            status = "disabled";
+        };
+    };
+
+...