[PATCH v3] ARM: dts: bcm2711-rpi-cm4-io: Add rtc on a pinctrl-muxed i2c bus

[Uwe Kleine-König]

The cm4-io board comes with an PCF85063. Add it to the device tree to make
it usable. The i2c0 bus can use two different pinmux settings to use
different pins. To keep the bus appearing on the usual pin pair (gpio0 +
gpio1) use a pinctrl-muxed setting as the vendor dts does.

Note that if you modified the dts before to add devices to the i2c bus
appearing on pins gpio0 + gpio1 (either directly in the dts or using an
overlay), you have to put these into the i2c at 0 node introduced here now.

Reviewed-by: Maxime Ripard <maxime at cerno.tech>
Signed-off-by: Uwe Kleine-König <uwe at kleine-koenig.org>
---
Hello,

changes since v2 (20211216212948.nrfmm4jpbhoknfr5 at pengutronix.de):

 - add Maxime's R-b tag
 - change the commit log wording to say vendor dts instead of upstream
   dts
 - Add a paragraph to the commit log about breakage this commits
   introduces.

Best regards
Uwe

 arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts | 35 ++++++++++++++++++++++++
 1 file changed, 35 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..5ddad146b541 100644
--- a/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-cm4-io.dts
@@ -18,6 +18,41 @@ led-pwr {
 			linux,default-trigger = "default-on";
 		};
 	};
+
+	i2c0mux {
+		compatible = "i2c-mux-pinctrl";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		i2c-parent = <&i2c0>;
+
+		pinctrl-names = "i2c0", "i2c0-vc";
+		pinctrl-0 = <&i2c0_gpio0>;
+		pinctrl-1 = <&i2c0_gpio44>;
+
+		i2c at 0 {
+			reg = <0>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+		};
+
+		i2c at 1 {
+			reg = <1>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			rtc at 51 {
+				/* Attention: An alarm resets the machine */
+				compatible = "nxp,pcf85063";
+				reg = <0x51>;
+			};
+		};
+	};
+};
+
+&i2c0 {
+	/delete-property/ pinctrl-names;
+	/delete-property/ pinctrl-0;
 };
 
 &ddc0 {

base-commit: fc74e0a40e4f9fd0468e34045b0c45bba11dcbb2
-- 
2.34.1