dacboard/tree/boot/overlays/mmc_spi_cs1.dts

/dts-v1/;
/plugin/;

/ {
   compatible = "brcm,bcm2835", "brcm,bcm2836", "brcm,bcm2708", "brcm,bcm2709";

   fragment@0 {
      target = <&spi0>;
      frag0: __overlay__ {
         status = "okay";
         sd1 {
                reg = <1>;
                status = "okay";
                compatible = "spi,mmc_spi";
                voltage-ranges = <3000 3600>;
                spi-max-frequency = <16000000>;
         };
      };
   };
};