[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 at 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 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>;
> 
> 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