[PATCH v2 7/7] arm64: dts: freescale: imx8mm-verdin: Add Cortex-M4F UART_4 overlay

From: Ernest Van Hoecke

Date: Fri Jul 24 2026 - 12:39:16 EST


From: Ernest Van Hoecke <ernest.vanhoecke@xxxxxxxxxxx>

Verdin UART_4 can be assigned to Cortex-M4F firmware. Add an overlay
that marks the UART as reserved so Linux does not claim the port.

The overlay is also combined with the Verdin iMX8M Mini Development
Board device tree to provide a ready-to-use DTB for the WiFi SoM
variant.

Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@xxxxxxxxxxx>
---
arch/arm64/boot/dts/freescale/Makefile | 3 +++
arch/arm64/boot/dts/freescale/imx8mm-verdin-uart4-mcu.dtso | 14 ++++++++++++++
2 files changed, 17 insertions(+)

diff --git a/arch/arm64/boot/dts/freescale/Makefile b/arch/arm64/boot/dts/freescale/Makefile
index fe261d7bdab5..95ae85ab4adf 100644
--- a/arch/arm64/boot/dts/freescale/Makefile
+++ b/arch/arm64/boot/dts/freescale/Makefile
@@ -192,6 +192,7 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-nonwifi-yavia.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-nonwifi-zinnia.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-panel-cap-touch-10inch-dsi.dtbo
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-panel-cap-touch-7inch-dsi.dtbo
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-uart4-mcu.dtbo
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dahlia-dsi-to-hdmi.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dahlia-panel-cap-touch-10inch-dsi.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dahlia.dtb
@@ -199,6 +200,7 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dev-dsi-to-hdmi.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dev-dsi-to-lvds-panel-cap-touch-10inch.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dev-nau8822-btl.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dev-panel-cap-touch-7inch-dsi.dtb
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dev-uart4-mcu.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-dev.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-ivy.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-verdin-wifi-mallow.dtb
@@ -220,6 +222,7 @@ imx8mm-verdin-wifi-dev-dsi-to-lvds-panel-cap-touch-10inch-dtbs := imx8mm-verdin-
imx8mm-verdin-wifi-dev-nau8822-btl-dtbs := imx8mm-verdin-wifi-dev.dtb imx8mm-verdin-dev-nau8822-btl.dtbo
imx8mm-verdin-wifi-dev-panel-cap-touch-7inch-dsi-dtbs := imx8mm-verdin-wifi-dev.dtb \
imx8mm-verdin-panel-cap-touch-7inch-dsi.dtbo
+imx8mm-verdin-wifi-dev-uart4-mcu-dtbs := imx8mm-verdin-wifi-dev.dtb imx8mm-verdin-uart4-mcu.dtbo
imx8mm-verdin-wifi-yavia-dsi-to-hdmi-dtbs := imx8mm-verdin-wifi-yavia.dtb imx8mm-verdin-dsi-to-hdmi.dtbo

imx8mm-tqma8mqml-mba8mx-lvds-g133han01-dtbs += imx8mm-tqma8mqml-mba8mx.dtb imx8mm-tqma8mqml-mba8mx-lvds-g133han01.dtbo
diff --git a/arch/arm64/boot/dts/freescale/imx8mm-verdin-uart4-mcu.dtso b/arch/arm64/boot/dts/freescale/imx8mm-verdin-uart4-mcu.dtso
new file mode 100644
index 000000000000..8dbecffe9e7b
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8mm-verdin-uart4-mcu.dtso
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+/*
+ * Copyright (c) Toradex
+ *
+ * Verdin iMX8M Mini UART_4 for Cortex-M4F
+ */
+
+/dts-v1/;
+/plugin/;
+
+/* Verdin UART_4 */
+&uart4 {
+ status = "reserved";
+};

--
2.43.0