diff --git a/arch/arm/boot/dts/stm32mp157a-dk1.dts b/arch/arm/boot/dts/stm32mp157a-dk1.dts
index d03d4cd2606ab63457ce136ef8f83e6cf0378268..65ee61b7667adb72c9fdbecafd6f47210751e9a6 100644
--- a/arch/arm/boot/dts/stm32mp157a-dk1.dts
+++ b/arch/arm/boot/dts/stm32mp157a-dk1.dts
@@ -18,6 +18,7 @@
 	aliases {
 		ethernet0 = &ethernet0;
 		serial0 = &uart4;
+		serial1 = &usart3;
 	};
 
 	chosen {
diff --git a/arch/arm/boot/dts/stm32mp157c-dk2.dts b/arch/arm/boot/dts/stm32mp157c-dk2.dts
index 9a8a26710ac1c90313aaee5fa68aa6a4d2f771c8..fb690a817e28da299457707f580bc8b80556c347 100644
--- a/arch/arm/boot/dts/stm32mp157c-dk2.dts
+++ b/arch/arm/boot/dts/stm32mp157c-dk2.dts
@@ -19,6 +19,7 @@
 	aliases {
 		ethernet0 = &ethernet0;
 		serial0 = &uart4;
+		serial1 = &usart3;
 	};
 
 	chosen {
diff --git a/arch/arm/boot/dts/stm32mp15xx-dkx.dtsi b/arch/arm/boot/dts/stm32mp15xx-dkx.dtsi
index dd5cef55d3edbec5dcddcc57de4b01361867ffbf..c562e181c2b1c98e09c028c647993f149d931a58 100644
--- a/arch/arm/boot/dts/stm32mp15xx-dkx.dtsi
+++ b/arch/arm/boot/dts/stm32mp15xx-dkx.dtsi
@@ -591,6 +591,15 @@
 	status = "okay";
 };
 
+&usart3 {
+	pinctrl-names = "default", "sleep", "idle";
+	pinctrl-0 = <&usart3_pins_c>;
+	pinctrl-1 = <&usart3_sleep_pins_c>;
+	pinctrl-2 = <&usart3_idle_pins_c>;
+	uart-has-rtscts;
+	status = "disabled";
+};
+
 &usbh_ehci {
 	phys = <&usbphyc_port0>;
 	status = "okay";