IOMUX routing configuration can be found in the following kernel device tree source files:
arch/arm64/boot/dts/congatec/imx8qm-cgtsmx8.dtsi
arch/arm64/boot/dts/congatec/imx8qm-cgtqmx8.dtsi
arch/arm64/boot/dts/congatec/imx8qm-cgtsx8x.dtsi
arch/arm64/boot/dts/congatec/imx8qm-cgtqx8x.dtsi