The X-Powers AXP20X and AXP22X PMICs have multiple ADCs. They expose the
battery voltage, battery charge and discharge currents, AC-in and VBUS
voltages and currents, 2 GPIOs muxable in ADC mode and PMIC temperature.

This adds the device tree binding documentation for the X-Powers AXP20X
and AXP22X PMICs ADCs.

Signed-off-by: Quentin Schulz <redacted>
---
 .../devicetree/bindings/iio/adc/axp20x_adc.txt     | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/axp20x_adc.txt

diff --git a/Documentation/devicetree/bindings/iio/adc/axp20x_adc.txt b/Documentation/devicetree/bindings/iio/adc/axp20x_adc.txt
new file mode 100644
index 0000000..1b60065
--- /dev/null
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@@ -0,0 +1,24 @@
+X-Powers AXP20X and AXP22X PMIC Analog to Digital Converter (ADC)
+
+The X-Powers AXP20X and AXP22X PMICs have multiple ADCs. They expose the
+battery voltage, battery charge and discharge currents, AC-in and VBUS
+voltages and currents, 2 GPIOs muxable in ADC mode and PMIC temperature.
+
+The AXP22X PMICs do not have all ADCs of the AXP20X though.
+
+Required properties:
+ - compatible, one of:
+			"x-powers,axp209-adc"
+			"x-powers,axp221-adc"
+ - #io-channel-cells = <1>;
+
+This is a subnode of the AXP20X PMIC.
+
+Example:
+
+&axp209 {
+	axp209_adc: axp209_adc {