diff --git a/sw/devicetree/redpitaya_puzzlefw.dts b/sw/devicetree/redpitaya_puzzlefw.dts
index 83b5415..2966586 100644
--- a/sw/devicetree/redpitaya_puzzlefw.dts
+++ b/sw/devicetree/redpitaya_puzzlefw.dts
@@ -169,6 +169,21 @@
 	status = "okay";
 	is-decoded-cs = <0>;
 	num-cs = <3>;
+
+	// The SPI ports of both ADC chips on the Red Pitaya 4-input board
+	// are connected, via the FPGA, to the PS SPI0 master.
+	adca@0 {
+		// We use a fake compatible string to work around
+		// a limitation in the Linux spidev driver.
+		compatible = "rohm,dh2228fv";
+		reg = <0>;
+		spi-max-frequency = <4000000>;
+	};
+	adcb@1 {
+		compatible = "rohm,dh2228fv";
+		reg = <1>;
+		spi-max-frequency = <4000000>;
+	};
 };
 
 &spi1 {