Re: [PATCH 1/3] dt-bindings: iio: adc: add support for AD5940

From: Jonathan Cameron
Date: Sun Nov 10 2019 - 11:26:18 EST

On Fri, 8 Nov 2019 21:09:44 +0800
Song Qiang <songqiang1304521@xxxxxxxxx> wrote:

> Add yaml devicetree description file and a header file for
> helping configure positive and negtive input of AD5940.
>
> Signed-off-by: Song Qiang <songqiang1304521@xxxxxxxxx>
Ouch. This is a very complex device, so I'm guessing this is the tip
of the iceberg when it comes to the eventual binding.
For reference of others this has a similarly complex DAC and
TIA + some excitation voltage generators (DDS).

Anyhow, a few comments inline but I'll definitely be looking for
a dt maintainer input on this one.

Thanks,

Jonathan

> ---
> .../bindings/iio/adc/adi,ad5940.yaml | 240 ++++++++++++++++++
> include/dt-bindings/iio/adc/adi,ad5940.h | 52 ++++
> 2 files changed, 292 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad5940.yaml
> create mode 100644 include/dt-bindings/iio/adc/adi,ad5940.h
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad5940.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad5940.yaml
> new file mode 100644
> index 000000000000..f7f034fdd8ec
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad5940.yaml
> @@ -0,0 +1,240 @@
> +# SPDX-License-Identifier: GPL-2.0
For new bindings, preference is to include a dual license
(GPL-2.0-only OR BSD-2-Clause)

If Analog is fine doing this that would be great.

> +# Copyright 2019 Analog Devices Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/bindings/iio/adc/adi,ad5940.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD5940 Device Tree Bindings
> +
> +maintainers:
> + - Song Qiang <songqiang1304521@xxxxxxxxx>
> +
> +description: |
> + Analog Devices AD5940 High Precision, Impedance, and Electrochemical Front End.
> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD5940.pdf
> +
> +properties:
> + compatible:
> + enum:
> + - adi,ad5940
> +
> + reg:
> + maxItems: 1
> +
> + vref-supply:
> + description:
> + The regulator to be used to supply the reference voltage.
> + maxItems: 1

It's worth taking a look at similar patch reviews to pick up on things
that are common issues. Rob has pointed out a few times recently that
vref-supply can only ever have one item, so no need for maxItems.

> +
> + adi,interrupt-io:
> + description:
> + Output GPIO index of interrupt controller of AD5940.
> + maxItems: 1

I'm fairly sure an enum can only have one entry so don't think this is
needed.

> + allOf:
> + - $ref: /schemas/types.yaml#/definitions/uint32
> + - enum: [0, 3, 6, 7]
> +
> + '#address-cells':
> + const: 1
> +
> + '#size-cells':
> + const: 0
> +
> +required:
> + - compatible
> + - reg
> + - interrupts
> + - adi,interrupt-io
> +
> +patternProperties:
> + # 'channel@0-255'

Really? That is a lot of channels. Superficially it looks like a much
smaller number of possibilities from the datasheet.

> + "^channel@([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$":
> + type: object
> + description: |
> + Represents the external channels which are connected to the ADC.
> + See Documentation/devicetree/bindings/iio/adc/adc.txt.
> + properties:
> + reg:
> + description:
> + Index of this channel, must be starting from 0.
> + maxItems: 1
> +
> + diff-channels:
> + description:
> + Positive input and negtive input of the ADC buffer of this channel.
> + Input candidates are defined in include/dt-bindings/iio/adc/adi,ad5940.h.
> + minItems: 2
> + maxItems: 2
> + items:
> + - description: Positive input channel
> + - enum:
> + - AD5940_ADC_INPUTP_EXCITATION
> + - AD5940_ADC_INPUTP_FLOATING
> + - AD5940_ADC_INPUTP_HSTIA
> + - AD5940_ADC_INPUTP_LPTIA_LP
> + - AD5940_ADC_INPUTP_AIN0
> + - AD5940_ADC_INPUTP_AIN1
> + - AD5940_ADC_INPUTP_AIN2
> + - AD5940_ADC_INPUTP_AIN3
> + - AD5940_ADC_INPUTP_AVDD_2
> + - AD5940_ADC_INPUTP_DVDD_2
> + - AD5940_ADC_INPUTP_AVDD_REG_2
> + - AD5940_ADC_INPUTP_TEMP
> + - AD5940_ADC_INPUTP_VBIAS_CAP
> + - AD5940_ADC_INPUTP_DE0
> + - AD5940_ADC_INPUTP_SE0
> + - AD5940_ADC_INPUTP_VREF_2V5_2
> + - AD5940_ADC_INPUTP_VREF_1V82
> + - AD5940_ADC_INPUTP_P_TEMP_N
> + - AD5940_ADC_INPUTP_AIN4
> + - AD5940_ADC_INPUTP_AIN6
> + - AD5940_ADC_INPUTP_VZERO
> + - AD5940_ADC_INPUTP_VBIAS0
> + - AD5940_ADC_INPUTP_VCE0
> + - AD5940_ADC_INPUTP_VRE0
> + - AD5940_ADC_INPUTP_VCE0_2
> + - AD5940_ADC_INPUTP_LPTIA
> + - AD5940_ADC_INPUTP_AGND_REF
> +
> + - description: Negtive input channel
> + - enum:
> + # Negtive input candidates
> + - AD5940_ADC_INPUTN_FLOATING
> + - AD5940_ADC_INPUTN_HSTIA
> + - AD5940_ADC_INPUTN_LPTIA
> + - AD5940_ADC_INPUTN_AIN0
> + - AD5940_ADC_INPUTN_AIN1
> + - AD5940_ADC_INPUTN_AIN2
> + - AD5940_ADC_INPUTN_AIN3
> + - AD5940_ADC_INPUTN_VBIAS_CA8
> + - AD5940_ADC_INPUTN_TEMP_N
> + - AD5940_ADC_INPUTN_AIN4
> + - AD5940_ADC_INPUTN_AIN6
> + - AD5940_ADC_INPUTN_VZERO
> + - AD5940_ADC_INPUTN_VBIAS0
> + - AD5940_ADC_INPUTN_EXCITATION
> +
> + channel-name:
> + description:
> + Any string format name you would like to assign to this channel.
> + maxItems: 1
> +
> + required:
> + - reg
> + - diff-channels
> + - channel-name
> +
> +examples:
> + - |
> + ad5940: ad5940@0 {
> + compatible = "adi,ad5940";
> + reg = <0>;
> + spi-max-frequency = <16000000>;
> + vref-supply = <&adc_vref>;
> + interrupt-parent = <&gpio>;
> + interrupts = <24 2>;
> +
> + adi,interrupt-io = <0>;
> +
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + channel@0 {
> + reg = <0>;
> + diff-channels = <AD5940_ADC_INPUTP_VCE0
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "Vce-Vbias";
> + };
> +
> + channel@1 {
> + reg = <1>;
> + diff-channels = <AD5940_ADC_INPUTP_VRE0
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "Vre-Vbias";
> + };
> +
> + channel@2 {
> + reg = <2>;
> + diff-channels = <AD5940_ADC_INPUTP_SE0
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "Vse-Vbias";
> + };
> +
> + channel@3 {
> + reg = <3>;
> + diff-channels = <AD5940_ADC_INPUTP_DE0
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "Vde-Vbias";
> + };
> +
> + channel@4 {
> + reg = <4>;
> + diff-channels = <AD5940_ADC_INPUTP_AIN0
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "ain0-Vbias";
> + };
> +
> + channel@5 {
> + reg = <5>;
> + diff-channels = <AD5940_ADC_INPUTP_AIN1
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "ain1-Vbias";
> + };
> +
> + channel@6 {
> + reg = <6>;
> + diff-channels = <AD5940_ADC_INPUTP_AIN2
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "ain2-Vbias";
> + };
> +
> + channel@7 {
> + reg = <7>;
> + diff-channels = <AD5940_ADC_INPUTP_AIN3
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "ain3-Vbias";
> + };
> +
> + channel@8 {
> + reg = <8>;
> + diff-channels = <AD5940_ADC_INPUTP_AIN4
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "ain4-Vbias";
> + };
> +
> + channel@9 {
> + reg = <9>;
> + diff-channels = <AD5940_ADC_INPUTP_AIN6
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "ain6-Vbias";
> + };
> +
> + channel@10 {
> + reg = <10>;
> + diff-channels = <AD5940_ADC_INPUTP_LPTIA_LP
> + AD5940_ADC_INPUTN_LPTIA>;
> + channel-name = "Low power TIA DC";
> + };
> +
> + channel@11 {
> + reg = <11>;
> + diff-channels = <AD5940_ADC_INPUTP_LPTIA
> + AD5940_ADC_INPUTN_LPTIA>;
> + channel-name = "Low power TIA AC";
> + };
> +
> + channel@12 {
> + reg = <12>;
> + diff-channels = <AD5940_ADC_INPUTP_HSTIA
> + AD5940_ADC_INPUTN_HSTIA>;
> + channel-name = "High Speed TIA";
> + };
> +
> + channel@13 {
> + reg = <13>;
> + diff-channels = <AD5940_ADC_INPUTP_TEMP
> + AD5940_ADC_INPUTN_VBIAS0>;
> + channel-name = "Temperature";
> + };
> + };
> diff --git a/include/dt-bindings/iio/adc/adi,ad5940.h b/include/dt-bindings/iio/adc/adi,ad5940.h
> new file mode 100644
> index 000000000000..c17826f2f654
> --- /dev/null
> +++ b/include/dt-bindings/iio/adc/adi,ad5940.h
> @@ -0,0 +1,52 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * This header provides constants for configuring the AD5940 AFE
> + */
> +
> +#ifndef _DT_BINDINGS_IIO_ADC_AD5940_H
> +#define _DT_BINDINGS_IIO_ADC_AD5940_H
> +
> +#define AD5940_ADC_INPUTN_FLOATING 0
> +#define AD5940_ADC_INPUTN_HSTIA 1
> +#define AD5940_ADC_INPUTN_LPTIA 2
> +#define AD5940_ADC_INPUTN_AIN0 4
> +#define AD5940_ADC_INPUTN_AIN1 5
> +#define AD5940_ADC_INPUTN_AIN2 6
> +#define AD5940_ADC_INPUTN_AIN3 7
> +#define AD5940_ADC_INPUTN_VBIAS_CA8 10
> +#define AD5940_ADC_INPUTN_TEMP_N 11
> +#define AD5940_ADC_INPUTN_AIN4 12
> +#define AD5940_ADC_INPUTN_AIN6 14
> +#define AD5940_ADC_INPUTN_VZERO 16
> +#define AD5940_ADC_INPUTN_VBIAS0 17
> +#define AD5940_ADC_INPUTN_EXCITATION 20
> +
> +#define AD5940_ADC_INPUTP_FLOATING 0
> +#define AD5940_ADC_INPUTP_HSTIA 1
> +#define AD5940_ADC_INPUTP_LPTIA_LP 2
> +#define AD5940_ADC_INPUTP_AIN0 4
> +#define AD5940_ADC_INPUTP_AIN1 5
> +#define AD5940_ADC_INPUTP_AIN2 6
> +#define AD5940_ADC_INPUTP_AIN3 7
> +#define AD5940_ADC_INPUTP_AVDD_2 8
> +#define AD5940_ADC_INPUTP_DVDD_2 9
> +#define AD5940_ADC_INPUTP_AVDD_REG_2 10
> +#define AD5940_ADC_INPUTP_TEMP 11
> +#define AD5940_ADC_INPUTP_VBIAS_CAP 12
> +#define AD5940_ADC_INPUTP_DE0 13
> +#define AD5940_ADC_INPUTP_SE0 14
> +#define AD5940_ADC_INPUTP_VREF_2V5_2 16
> +#define AD5940_ADC_INPUTP_VREF_1V82 18
> +#define AD5940_ADC_INPUTP_P_TEMP_N 19
> +#define AD5940_ADC_INPUTP_AIN4 20
> +#define AD5940_ADC_INPUTP_AIN6 22
> +#define AD5940_ADC_INPUTP_VZERO 23
> +#define AD5940_ADC_INPUTP_VBIAS0 24
> +#define AD5940_ADC_INPUTP_VCE0 25
> +#define AD5940_ADC_INPUTP_VRE0 26
> +#define AD5940_ADC_INPUTP_VCE0_2 31
> +#define AD5940_ADC_INPUTP_LPTIA 33
> +#define AD5940_ADC_INPUTP_AGND_REF 35
> +#define AD5940_ADC_INPUTP_EXCITATION 36
> +
> +#endif /* _DT_BINDINGS_IIO_ADC_AD5940 */