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

[Cyril Brulebois]

Uwe Kleine-König <uwe at 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 at 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 at 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 at 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 at 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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