Re: [PATCH v3 1/2] dt-bindings: iio: dac: Add AD5529R

[Janani Sunil <jan.sun97@gmail.com>]

On 5/26/26 15:11, Rodrigo Alencar wrote:
> On 26/05/19 05:42PM, Janani Sunil wrote:
>> Devicetree bindings for AD5529R 16 channel 12/16 bit high voltage,
>> buffered voltage output digital-to-analog converter (DAC) with an
>> integrated precision reference.
> ...
> Probably others may comment on that, but...
>
> This parent node may support device addressing for multi-device support through
> those ID pins. I suppose that each device may have its own power supplies or
> other resources like the toggle pins or reset and enable.
>
> That way I suppose that an example would look like...
>
>> +
>> +patternProperties:
>> +  "^channel@([0-9]|1[0-5])$":
>> +    type: object
>> +    description: Child nodes for individual channel configuration
>> +
>> +    properties:
>> +      reg:
>> +        description: Channel number.
>> +        minimum: 0
>> +        maximum: 15
>> +
>> +      adi,output-range-microvolt:
>> +        description: |
>> +          Output voltage range for this channel as [min, max] in microvolts.
>> +          If not specified, defaults to 0V to 5V range.
>> +        oneOf:
>> +          - items:
>> +              - const: 0
>> +              - enum: [5000000, 10000000, 20000000, 40000000]
>> +          - items:
>> +              - const: -5000000
>> +              - const: 5000000
>> +          - items:
>> +              - const: -10000000
>> +              - const: 10000000
>> +          - items:
>> +              - const: -15000000
>> +              - const: 15000000
>> +          - items:
>> +              - const: -20000000
>> +              - const: 20000000
>> +
>> +    required:
>> +      - reg
>> +
>> +    additionalProperties: false
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - vdd-supply
>> +  - avdd-supply
>> +  - hvdd-supply
>> +
>> +dependencies:
>> +  spi-cpha: [ spi-cpol ]
>> +  spi-cpol: [ spi-cpha ]
>> +
>> +allOf:
>> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
>> +
>> +unevaluatedProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/gpio/gpio.h>
>> +
>> +    spi {
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +
>> +        dac@0 {
>> +            compatible = "adi,ad5529r-16";
>> +            reg = <0>;
>> +            spi-max-frequency = <25000000>;
>> +
>> +            vdd-supply = <&vdd_regulator>;
>> +            avdd-supply = <&avdd_regulator>;
>> +            hvdd-supply = <&hvdd_regulator>;
>> +            hvss-supply = <&hvss_regulator>;
>> +
>> +            reset-gpios = <&gpio0 87 GPIO_ACTIVE_LOW>;
>> +
>> +            #address-cells = <1>;
>> +            #size-cells = <0>;
>> +
>> +            channel@0 {
>> +                reg = <0>;
>> +                adi,output-range-microvolt = <0 5000000>;
>> +            };
>> +
>> +            channel@1 {
>> +                reg = <1>;
>> +                adi,output-range-microvolt = <(-10000000) 10000000>;
>> +            };
>> +
>> +            channel@2 {
>> +                reg = <2>;
>> +                adi,output-range-microvolt = <0 40000000>;
>> +            };
>> +        };
>> +    };
> ...
>
> 	spi {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
>
> 		multi-dac@0 {
> 			compatible = "adi,ad5529r-16";
> 			reg = <0>;
> 			spi-max-frequency = <25000000>;
>
> 			#address-cells = <1>;
> 			#size-cells = <0>;
>
> 			dac@0 {
> 				reg = <0>;
> 				vdd-supply = <&vdd_regulator>;
> 				avdd-supply = <&avdd_regulator>;
> 				hvdd-supply = <&hvdd_regulator>;
> 				hvss-supply = <&hvss_regulator>;
>
> 				reset-gpios = <&gpio0 87 GPIO_ACTIVE_LOW>;
>
> 				#address-cells = <1>;
> 				#size-cells = <0>;
>
> 				channel@0 {
> 					reg = <0>;
> 					adi,output-range-microvolt = <0 5000000>;
> 				};
>
> 				channel@1 {
> 					reg = <1>;
> 					adi,output-range-microvolt = <(-10000000) 10000000>;
> 				};
>
> 				channel@2 {
> 					reg = <2>;
> 					adi,output-range-microvolt = <0 40000000>;
> 				};
> 			}
>
> 			dac@1 {
> 				reg = <1>;
> 				vdd-supply = <&vdd_regulator>;
> 				avdd-supply = <&avdd_regulator>;
> 				hvdd-supply = <&hvdd_regulator>;
> 				hvss-supply = <&hvss_regulator>;
>
> 				reset-gpios = <&gpio0 88 GPIO_ACTIVE_LOW>;
>
> 				#address-cells = <1>;
> 				#size-cells = <0>;
>
> 				channel@0 {
> 					reg = <0>;
> 					adi,output-range-microvolt = <0 5000000>;
> 				};
>
> 				channel@1 {
> 					reg = <1>;
> 					adi,output-range-microvolt = <(-10000000) 10000000>;
> 				};
> 			}
> 		};
> 	};
>
> then you might need something like:
>
> 	patternProperties:
> 		"^dac@[0-3]$":
>
> and put most of the things under this node pattern.
>
> So the main driver that you're putting together might need to handle up to four instances.
> Even if your current driver cannot handle this, the dt-bindings might need cover that.
>
> Need to double check if each dac node needs a separate compatible, so you would maybe populate
> a platform data to be shared with the child nodes, which would be a separate driver.
> (not sure if it would make sense to mix and match ad5529r-16 and ad5529r-12).

Hi Rodrigo,

Thank you for looking at this.

For now, I would prefer to keep the binding scoped to a single AD5529R device instance. The current
hardware/use case we have only needs one device node and the driver is written around that model as well.
While the device addressing pins could allow multi-device topology, we do not have an actual platform using
that configuration at the moment, so I would prefer not to introduce an extra parent/child binding structure
speculatively without a validating use case.

Best Regards,
Janani Sunil