Re: [PATCH v4 3/5] dt-bindings: iio: dac: Add adi,ltc2664.yaml

[Conor Dooley]

On Wed, Jun 19, 2024 at 02:49:02PM +0800, Kim Seer Paller wrote:
> Add documentation for ltc2664.
> 
> Co-developed-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
> Signed-off-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
> Signed-off-by: Kim Seer Paller <kimseer.paller@xxxxxxxxxx>
> ---
>  .../bindings/iio/dac/adi,ltc2664.yaml         | 167 ++++++++++++++++++
>  MAINTAINERS                                   |   8 +
>  2 files changed, 175 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/dac/adi,ltc2664.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ltc2664.yaml b/Documentation/devicetree/bindings/iio/dac/adi,ltc2664.yaml
> new file mode 100644
> index 000000000000..be37700e3b1f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/adi,ltc2664.yaml
> @@ -0,0 +1,167 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/dac/adi,ltc2664.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices LTC2664 DAC
> +
> +maintainers:
> +  - Michael Hennerich <michael.hennerich@xxxxxxxxxx>
> +  - Kim Seer Paller <kimseer.paller@xxxxxxxxxx>
> +
> +description: |
> +  Analog Devices LTC2664 4 channel, 12-/16-Bit, +-10V DAC
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/2664fa.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ltc2664
> +
> +  reg:
> +    maxItems: 1
> +
> +  spi-max-frequency:
> +    maximum: 50000000
> +
> +  vcc-supply:
> +    description: Analog Supply Voltage Input.
> +
> +  v-pos-supply:
> +    description: Positive Supply Voltage Input.
> +
> +  v-neg-supply:
> +    description: Negative Supply Voltage Input.
> +
> +  iovcc-supply:
> +    description: Digital Input/Output Supply Voltage.
> +
> +  ref-supply:
> +    description:
> +      Reference Input/Output. The voltage at the REF pin sets the full-scale
> +      range of all channels. If not provided the internal reference is used and
> +      also provided on the VREF pin.
> +
> +  reset-gpios:
> +    description:
> +      Active-low Asynchronous Clear Input. A logic low at this level-triggered
> +      input clears the part to the reset code and range determined by the
> +      hardwired option chosen using the MSPAN pins. The control registers are
> +      cleared to zero.
> +    maxItems: 1
> +
> +  adi,manual-span-operation-config:
> +    description:
> +      This property must mimic the MSPAN pin configurations. By tying the MSPAN
> +      pins (MSP2, MSP1 and MSP0) to GND and/or VCC, any output range can be
> +      hardware-configured with different mid-scale or zero-scale reset options.
> +      The hardware configuration is latched during power on reset for proper
> +      operation.
> +        0 - MPS2=GND, MPS1=GND, MSP0=GND (+-10V, reset to 0V)
> +        1 - MPS2=GND, MPS1=GND, MSP0=VCC (+-5V, reset to 0V)
> +        2 - MPS2=GND, MPS1=VCC, MSP0=GND (+-2.5V, reset to 0V)
> +        3 - MPS2=GND, MPS1=VCC, MSP0=VCC (0V to 10, reset to 0V)
> +        4 - MPS2=VCC, MPS1=GND, MSP0=GND (0V to 10V, reset to 5V)
> +        5 - MPS2=VCC, MPS1=GND, MSP0=VCC (0V to 5V, reset to 0V)
> +        6 - MPS2=VCC, MPS1=VCC, MSP0=GND (0V to 5V, reset to 2.5V)
> +        7 - MPS2=VCC, MPS1=VCC, MSP0=VCC (0V to 5V, reset to 0V, enables SoftSpan)
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [0, 1, 2, 3, 4, 5, 6, 7]

Can you explain why this property is required, when below there's one
that sets the ranges in microvolts? Isn't the only new information that
this provides the reset values (in a few cases that it is not 0).
What am I missing?

> +    default: 7
> +
> +  io-channels:
> +    description:
> +      ADC channel to monitor voltages and temperature at the MUXOUT pin.
> +    maxItems: 1
> +
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +patternProperties:
> +  "^channel@[0-3]$":
> +    type: object
> +    additionalProperties: false
> +
> +    properties:
> +      reg:
> +        description: The channel number representing the DAC output channel.
> +        maximum: 3
> +
> +      adi,toggle-mode:
> +        description:
> +          Set the channel as a toggle enabled channel. Toggle operation enables
> +          fast switching of a DAC output between two different DAC codes without
> +          any SPI transaction.
> +        type: boolean
> +
> +      adi,output-range-microvolt:
> +        description: Specify the channel output full scale range.
> +        oneOf:
> +          - items:
> +              - const: 0
> +              - enum: [5000000, 10000000]
> +          - items:
> +              - const: -5000000
> +              - const: 5000000
> +          - items:
> +              - const: -10000000
> +              - const: 10000000
> +          - items:
> +              - const: -2500000
> +              - const: 2500000
> +
> +    required:
> +      - reg
> +      - adi,output-range-microvolt
> +
> +required:
> +  - compatible
> +  - reg
> +  - spi-max-frequency
> +  - vcc-supply
> +  - iovcc-supply
> +  - v-pos-supply
> +  - v-neg-supply
> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        dac@0 {
> +            compatible = "adi,ltc2664";
> +            reg = <0>;
> +            spi-max-frequency = <10000000>;
> +
> +            vcc-supply = <&vcc>;
> +            iovcc-supply = <&vcc>;
> +            ref-supply = <&vref>;
> +            v-pos-supply = <&vpos>;
> +            v-neg-supply = <&vneg>;
> +
> +            io-channels = <&adc 0>;
> +
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +            channel@0 {
> +                    reg = <0>;
> +                    adi,toggle-mode;
> +                    adi,output-range-microvolt = <(-10000000) 10000000>;
> +            };
> +
> +            channel@1 {
> +                    reg = <1>;
> +                    adi,output-range-microvolt = <0 10000000>;
> +            };
> +        };
> +    };
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index be590c462d91..849800d9cbf7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13074,6 +13074,14 @@ S:	Maintained
>  F:	Documentation/devicetree/bindings/iio/dac/lltc,ltc1660.yaml
>  F:	drivers/iio/dac/ltc1660.c
>  
> +LTC2664 IIO DAC DRIVER
> +M:	Michael Hennerich <michael.hennerich@xxxxxxxxxx>
> +M:	Kim Seer Paller <kimseer.paller@xxxxxxxxxx>
> +L:	linux-iio@xxxxxxxxxxxxxxx
> +S:	Supported
> +W:	https://ez.analog.com/linux-software-drivers
> +F:	Documentation/devicetree/bindings/iio/dac/adi,ltc2664.yaml
> +
>  LTC2688 IIO DAC DRIVER
>  M:	Nuno Sá <nuno.sa@xxxxxxxxxx>
>  L:	linux-iio@xxxxxxxxxxxxxxx
> -- 
> 2.34.1
>

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