[PATCH v3 1/2] arm64: dts: allwinner: h616: orangepi-zero2w: add 24-pin expansion overlay

[Vladimir]

The optional 24-pin expansion board carries two buttons on LRADC channel 0
and an IR receiver.  Keep them out of the base board .dts: with the board
detached the LRADC input and the IR receiver pin are not driven and float,
which can produce phantom key presses and interrupt storms.

Provide them as a devicetree overlay instead, following the existing
sun8i-orangepi-zero-interface-board.dtso approach.

Tested on: OrangePi Zero 2W (Allwinner H618) with the 24-pin expansion board.

Signed-off-by: Vladimir <anykey196 at gmail.com>
---
 arch/arm64/boot/dts/allwinner/Makefile        |  2 +
 .../sun50i-h618-orangepi-zero2w-24pin.dtso    | 42 +++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 arch/arm64/boot/dts/allwinner/sun50i-h618-orangepi-zero2w-24pin.dtso

diff --git a/arch/arm64/boot/dts/allwinner/Makefile b/arch/arm64/boot/dts/allwinner/Makefile
index d1f768dd646..e4576030276 100644
--- a/arch/arm64/boot/dts/allwinner/Makefile
+++ b/arch/arm64/boot/dts/allwinner/Makefile
@@ -57,6 +57,8 @@ dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h616-orangepi-zero2.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h616-x96-mate.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h618-longanpi-3h.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h618-orangepi-zero2w.dtb
+dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h618-orangepi-zero2w-24pin.dtb
+sun50i-h618-orangepi-zero2w-24pin-dtbs := sun50i-h618-orangepi-zero2w.dtb sun50i-h618-orangepi-zero2w-24pin.dtbo
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h618-orangepi-zero3.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h618-transpeed-8k618-t.dtb
 dtb-$(CONFIG_ARCH_SUNXI) += sun50i-h618-yuzukihd-chameleon.dtb
diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h618-orangepi-zero2w-24pin.dtso b/arch/arm64/boot/dts/allwinner/sun50i-h618-orangepi-zero2w-24pin.dtso
new file mode 100644
index 00000000000..2d7e98e4b66
--- /dev/null
+++ b/arch/arm64/boot/dts/allwinner/sun50i-h618-orangepi-zero2w-24pin.dtso
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: (GPL-2.0-or-later OR X11)
+/*
+ * Device tree overlay for the Orange Pi Zero 2W 24-pin expansion board.
+ *
+ * The expansion board provides two buttons wired to LRADC channel 0 and an
+ * IR receiver.  These are only present when the board is attached, so they
+ * are deliberately kept out of the base .dts: on a bare board the LRADC
+ * input and the IR receiver pin are not driven and float, which can cause
+ * phantom key presses and interrupt storms.
+ *
+ * Apply on top of:
+ *   arch/arm64/boot/dts/allwinner/sun50i-h618-orangepi-zero2w.dts
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/input/input.h>
+
+&lradc {
+	vref-supply = <&reg_vcc3v3>;
+	status = "okay";
+	wakeup-source;
+
+	button-1000 {
+		label = "KEY_1";
+		linux,code = <KEY_1>;
+		channel = <0>;
+		voltage = <1000000>;
+	};
+
+	button-1600 {
+		label = "KEY_ENTER";
+		linux,code = <KEY_ENTER>;
+		channel = <0>;
+		voltage = <1600000>;
+	};
+};
+
+&ir {
+	status = "okay";
+};
-- 
2.55.0.windows.3