[PATCH] ARM: dts: bcm2711-rpi-cm4-io: Add rtc on i2c0

[PATCH] ARM: dts: bcm2711-rpi-cm4-io: Add rtc on i2c0

[Uwe Kleine-König]

The cm4-io board comes with an PCF85063. Add it to the device tree to make
it usable.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
---
 arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
index 19600b629be5..1b67ad65e228 100644
--- a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
@@ -20,6 +20,17 @@ led-pwr {
 	};
 };
 
+&i2c0 {
+	pinctrl-0 = <&i2c0_gpio44>;
+	status = "okay";
+
+	rtc@51 {
+		/* Attention: An alarm resets the machine */
+		compatible = "nxp,pcf85063";
+		reg = <0x51>;
+	};
+};
+
 &ddc0 {
 	status = "okay";
 };

base-commit: 8ab774587903771821b59471cc723bba6d893942
-- 
2.30.2


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Re: [PATCH] ARM: dts: bcm2711-rpi-cm4-io: Add rtc on i2c0

[Cyril Brulebois]

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Uwe Kleine-König <uwe@kleine-koenig.org> (2021-11-22):
> The cm4-io board comes with an PCF85063. Add it to the device tree to make
> it usable.
> 
> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
> ---
>  arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> index 19600b629be5..1b67ad65e228 100644
> --- a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> +++ b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> @@ -20,6 +20,17 @@ led-pwr {
>  	};
>  };
>  
> +&i2c0 {
> +	pinctrl-0 = <&i2c0_gpio44>;
> +	status = "okay";
> +
> +	rtc@51 {
> +		/* Attention: An alarm resets the machine */
> +		compatible = "nxp,pcf85063";
> +		reg = <0x51>;
> +	};
> +};
> +
>  &ddc0 {
>  	status = "okay";
>  };
> 
> base-commit: 8ab774587903771821b59471cc723bba6d893942

I had come up with the pinctrl-0 setting on my own, making sure i2c0 was
visible in userland (via i2c-2; i2c-0 and i2c-1 being the internal ones,
for HDMI outputs), and I toyed with rtc@51 via an overlay to enable the
RTC automatically (instead of toying with new_device under /sys/class).
My next step was checking whether having both i2c0 wired properly and
the RTC enabled made sense for mainline, and apparently Uwe agrees. :)

This patch looks good to me, and seems to work fine:

Tested-by: Cyril Brulebois <cyril@debamax.com>


Checking arch/arm64/boot/dts/broadcom/.bcm2711-rpi-cm4-io.dtb.dts.tmp,
it looks like i2c0 was already getting enabled anyway, but wired to
i2c0_gpio0 instead:

    &i2c0 {
     pinctrl-names = "default";
     pinctrl-0 = <&i2c0_gpio0>;
     status = "okay";
     clock-frequency = <100000>;
    };


Cheers,
-- 
Cyril Brulebois -- Debian Consultant @ DEBAMAX -- https://debamax.com/

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Re: [PATCH] ARM: dts: bcm2711-rpi-cm4-io: Add rtc on i2c0

[Dave Stevenson]

Hi

On Mon, 22 Nov 2021 at 15:27, Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
>
> The cm4-io board comes with an PCF85063. Add it to the device tree to make
> it usable.
>
> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
> ---
>  arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> index 19600b629be5..1b67ad65e228 100644
> --- a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> +++ b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> @@ -20,6 +20,17 @@ led-pwr {
>         };
>  };
>
> +&i2c0 {
> +       pinctrl-0 = <&i2c0_gpio44>;

This will break the assumption that most users will make that i2c0 is
on GPIOs 0&1 (pins 27&28 on the 40 pin header). This is the case on
all other Pi variants, so having it different on the CM4IO is going to
catch some out.

You can use the i2c-mux-pinctrl module to expose both pin mappings of
the BSC0 peripheral as separate I2C buses, which is what the
downstream device tree does.

  Dave

> +       status = "okay";
> +
> +       rtc@51 {
> +               /* Attention: An alarm resets the machine */
> +               compatible = "nxp,pcf85063";
> +               reg = <0x51>;
> +       };
> +};
> +
>  &ddc0 {
>         status = "okay";
>  };
>
> base-commit: 8ab774587903771821b59471cc723bba6d893942
> --
> 2.30.2
>
>
> _______________________________________________
> linux-rpi-kernel mailing list
> linux-rpi-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rpi-kernel

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Re: [PATCH] ARM: dts: bcm2711-rpi-cm4-io: Add rtc on i2c0

[nicolas saenz julienne]

+ Stephan, feel free to chime in.

On Mon, 2021-11-22 at 16:33 +0000, Dave Stevenson wrote:
> Hi
> 
> On Mon, 22 Nov 2021 at 15:27, Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
> > 
> > The cm4-io board comes with an PCF85063. Add it to the device tree to make
> > it usable.
> > 
> > Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
> > ---
> >  arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> > index 19600b629be5..1b67ad65e228 100644
> > --- a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> > +++ b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
> > @@ -20,6 +20,17 @@ led-pwr {
> >         };
> >  };
> > 
> > +&i2c0 {
> > +       pinctrl-0 = <&i2c0_gpio44>;
> 
> This will break the assumption that most users will make that i2c0 is
> on GPIOs 0&1 (pins 27&28 on the 40 pin header). This is the case on
> all other Pi variants, so having it different on the CM4IO is going to
> catch some out.
> 
> You can use the i2c-mux-pinctrl module to expose both pin mappings of
> the BSC0 peripheral as separate I2C buses, which is what the
> downstream device tree does.

+1

I think it can be done without breaking anything as long as we enable
CONFIG_I2C_MUX_PINCTRL in arm64's defconfig.

Regards,
Nicolas

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Re: [PATCH] ARM: dts: bcm2711-rpi-cm4-io: Add rtc on i2c0

[Stefan Wahren]

Hi,

Am 30.11.21 um 13:02 schrieb nicolas saenz julienne:
> + Stephan, feel free to chime in.
>
> On Mon, 2021-11-22 at 16:33 +0000, Dave Stevenson wrote:
>> Hi
>>
>> On Mon, 22 Nov 2021 at 15:27, Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
>>> The cm4-io board comes with an PCF85063. Add it to the device tree to make
>>> it usable.
>>>
>>> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
>>> ---
>>>  arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts | 11 +++++++++++
>>>  1 file changed, 11 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
>>> index 19600b629be5..1b67ad65e228 100644
>>> --- a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
>>> +++ b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
>>> @@ -20,6 +20,17 @@ led-pwr {
>>>         };
>>>  };
>>>
>>> +&i2c0 {
>>> +       pinctrl-0 = <&i2c0_gpio44>;
>> This will break the assumption that most users will make that i2c0 is
>> on GPIOs 0&1 (pins 27&28 on the 40 pin header). This is the case on
>> all other Pi variants, so having it different on the CM4IO is going to
>> catch some out.
>>
>> You can use the i2c-mux-pinctrl module to expose both pin mappings of
>> the BSC0 peripheral as separate I2C buses, which is what the
>> downstream device tree does.
> +1
>
> I think it can be done without breaking anything as long as we enable
> CONFIG_I2C_MUX_PINCTRL in arm64's defconfig.

i didn't test Dave's suggestion, but it sounds like the better approach
to me. Even this results in more changes ...

Thanks

>
> Regards,
> Nicolas


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