ADC not ready for SAMD21

[cperkulator]

I'm just digging into this a bit but I'm try to set up analogs on a custom board using an ATSAMD21G part.

reduced DTS:

  zephyr,user {
	  io-channels = <&adc 0>;
  };
  
  &adc {
	  #address-cells = <1>;
	  #size-cells = <0>;
      status = "okay";
  
	  channel@0 {
		  reg = <0>;
		  zephyr,gain = "ADC_GAIN_1";
		  zephyr,reference = "ADC_REF_INTERNAL";
		  zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
		  zephyr,resolution = <12>;
		  zephyr,input-positive = <0>;
          status = "okay";
	  };
  };

Through some debugging I've found that the adc_sam0_init function calls pinctrl_lookup_state which returns -ENOENT and causes everything to break? Any suggestions for what to look into?