Re: [PATCH v2 2/2] dt-bindings: iio: adc: devicetree bindings for texas instruments ads7142

Jonathan Cameron
2021-05-16T09:56:19Z

On Sun, 16 May 2021 07:31:05 +0000
Jozsef Horvath <info@ministro.hu> wrote:

> This is a device tree schema for iio driver for
> Texas Instruments ADS7142 dual-channel, programmable sensor monitor.
>
> Datasheet: https://www.ti.com/lit/ds/symlink/ads7142.pdf
>
> Signed-off-by: Jozsef Horvath <info@ministro.hu>

Hi József,

A few comments inline.

thanks,

Jonathan
> ---
>
> changes v1
> - Redundant parameters (ti,threshold-rising, etc.)
> are removed
> - Supply name changed(vref -> avdd)
> - Added dvdd supply
> - All the properties are removed with prefix "ti,"
> changes v2
> - "ti,prealert-count" parameter added, just for completeness.
> ---
> .../bindings/iio/adc/ti,ads7142.yaml | 110 ++++++++++++++++++
> 1 file changed, 110 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,ads7142.yaml
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads7142.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads7142.yaml
> new file mode 100644
> index 000000000000..6e52079c68f7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads7142.yaml
> @@ -0,0 +1,110 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/iio/adc/ti,ads7142.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +
> +title: Texas Instruments ADS7142 adc driver device tree bindings

ADC

> +
> +maintainers:
> + - József Horváth <info@ministro.hu>
> +
> +description: |
> + This document is for describing the required device tree parameters
> + for ads7142 adc

ADC

> + The required parameters for proper operation are described below.
> +
> + Datasheet: https://www.ti.com/lit/ds/symlink/ads7142.pdf
> +
> +properties:
> + compatible:
> + const: ti,ads7142
> +
> + reg:
> + maxItems: 1
> +
> + interrupts:
> + description: |
> + The BUSY/PDY pin is used as interrupt line

RDY ?

> + in autonomous monitoring mode.
> + maxItems: 1
> +
> + avdd-supply:
> + description: Regulator for the reference voltage
> +
> + dvdd-supply: true
> +
> + "#address-cells":
> + const: 1
> +
> + "#size-cells":
> + const: 0
> +
> + "#io-channel-cells":
> + const: 1
> +
> + ti,prealert-count:
> + description: |
> + Sets the Pre-Alert Event Count for both,
> + high and low comparators, for both the channels.

Interesting. Why is this a device tree property rather than something
we want to configure from userspace? Looks like it would map to _period
after scaling by the sampling frequency.

https://elixir.bootlin.com/linux/latest/source/Documentation/ABI/testing/sysfs-bus-iio#L1003

> + $ref: /schemas/types.yaml#/definitions/uint32
> + maximum: 15
> + minimum: 0
> +
> +patternProperties:
> + "^channel@[0-1]$":
> + $ref: "adc.yaml"
> + type: object
> + description: |
> + Represents the external channels which are connected to the ADC.
> + properties:
> + reg:
> + description: |
> + The channel number.
> + items:
> + minimum: 0
> + maximum: 1

enum: [0 1]
is a more compact way of putting this IIRC.

> +
> + required:
> + - reg
> +
> + additionalProperties: false
> +
> +required:
> + - compatible
> + - "#io-channel-cells"
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + i2c {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + adc@1f {
> + compatible = "ti,ads7142";
> + reg = <0x1f>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + #io-channel-cells = <1>;
> +
> + avdd-supply = <&vdd_3v3_reg>;
> + dvdd-supply = <&vdd_1v8_reg>;
> +
> + interrupt-parent = <&gpio>;
> + interrupts = <7 2>;
> +
> + ti,prealert-count = <4>;
> +
> + channel@0 {
> + reg = <0>;
> + };
> +
> + channel@1 {
> + reg = <1>;
> + };
> + };
> + };
> +...
> +