Re: [PATCH] dt-bindings: iio: adc: add adi,ad7780.yaml binding

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Hi Jonathan, Alex,

Thanks for the review. Some comments inline.

Thanks,
Renato

On 05/20, Ardelean, Alexandru wrote:
On Sun, 2019-05-19 at 12:32 +0100, Jonathan Cameron wrote:
[External]


On Sat, 18 May 2019 19:41:12 -0300
Renato Lui Geh <renatogeh@xxxxxxxxx> wrote:

> This patch adds a YAML binding for the Analog Devices AD7780/1 and
> AD7170/1 analog-to-digital converters.
>
> Signed-off-by: Renato Lui Geh <renatogeh@xxxxxxxxx>

One comment inline.  I'll also be needing an ack from Analog on this,
preferably Michael's.

Thanks,

Jonathan
> ---
>  .../bindings/iio/adc/adi,ad7780.txt           | 48 -----------
>  .../bindings/iio/adc/adi,ad7780.yaml          | 85 +++++++++++++++++++

You should also update the MAINTAINERS file.
Maybe in a following patch.
It looks like there is not entry in there, so maybe you need to add a new
one.

Something like:


ANALOG DEVICES INC AD7780 DRIVER
M:      Michael Hennerich <Michael.Hennerich@xxxxxxxxxx>
M:      Renato Lui Geh <renatogeh@xxxxxxxxx>
L:      linux-iio@xxxxxxxxxxxxxxx
W:      http://ez.analog.com/community/linux-device-drivers
S:      Supported
F:      drivers/iio/adc/ad7780.c
F:      Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml

This should be after this block
ANALOG DEVICES INC AD7768-1 DRIVER

Note that I added you as a co-maintainer.
If you want, you do not need to add that line.

>  2 files changed, 85 insertions(+), 48 deletions(-)
>  delete mode 100644
> Documentation/devicetree/bindings/iio/adc/adi,ad7780.txt
>  create mode 100644
> Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7780.txt
> b/Documentation/devicetree/bindings/iio/adc/adi,ad7780.txt
> deleted file mode 100644
> index 440e52555349..000000000000
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7780.txt
> +++ /dev/null
> @@ -1,48 +0,0 @@
> -* Analog Devices AD7170/AD7171/AD7780/AD7781
> -
> -Data sheets:
> -
> -- AD7170:
> -     *
> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7170.pdf
> -- AD7171:
> -     *
> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7171.pdf
> -- AD7780:
> -     *
> https://www.analog.com/media/en/technical-documentation/data-sheets/ad7780.pdf
> -- AD7781:
> -     *
> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7781.pdf
> -
> -Required properties:
> -
> -- compatible: should be one of
> -     * "adi,ad7170"
> -     * "adi,ad7171"
> -     * "adi,ad7780"
> -     * "adi,ad7781"
> -- reg: spi chip select number for the device
> -- vref-supply: the regulator supply for the ADC reference voltage
> -
> -Optional properties:
> -
> -- powerdown-gpios:  must be the device tree identifier of the PDRST
> pin. If
> -                 specified, it will be asserted during driver probe.
> As the
> -                 line is active high, it should be marked
> GPIO_ACTIVE_HIGH.
> -- adi,gain-gpios:   must be the device tree identifier of the GAIN
> pin. Only for
> -                 the ad778x chips. If specified, it will be asserted
> during
> -                 driver probe. As the line is active low, it should be
> marked
> -                 GPIO_ACTIVE_LOW.
> -- adi,filter-gpios: must be the device tree identifier of the FILTER
> pin. Only
> -                 for the ad778x chips. If specified, it will be
> asserted
> -                 during driver probe. As the line is active low, it
> should be
> -                 marked GPIO_ACTIVE_LOW.
> -
> -Example:
> -
> -adc@0 {
> -     compatible =  "adi,ad7780";
> -     reg =         <0>;
> -     vref-supply = <&vdd_supply>
> -
> -     powerdown-gpios  = <&gpio 12 GPIO_ACTIVE_HIGH>;
> -     adi,gain-gpios   = <&gpio  5 GPIO_ACTIVE_LOW>;
> -     adi,filter-gpios = <&gpio 15 GPIO_ACTIVE_LOW>;
> -};
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml
> b/Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml
> new file mode 100644
> index 000000000000..931bc4f8ec04
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml
> @@ -0,0 +1,85 @@
> +# SPDX-License-Identifier: GPL-2.0
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/adi,ad7780.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD7170/AD7171/AD7780/AD7781 analog to digital
> converters
> +
> +maintainers:
> +  - Michael Hennerich <michael.hennerich@xxxxxxxxxx>
> +
> +description: |
> +  The ad7780 is a sigma-delta analog to digital converter. This driver
> provides
> +  reading voltage values and status bits from both the ad778x and
> ad717x series.
> +  Its interface also allows writing on the FILTER and GAIN GPIO pins
> on the
> +  ad778x.
> +
> +  Specifications on the converters can be found at:
> +    AD7170:
> +
> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7170.pdf
> +    AD7171:
> +
> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7171.pdf
> +    AD7780:
> +
> https://www.analog.com/media/en/technical-documentation/data-sheets/ad7780.pdf
> +    AD7781:
> +
> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7781.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ad7170
> +      - adi,ad7171
> +      - adi,ad7780
> +      - adi,ad7781
> +
> +  reg:
> +    description:
> +      Chip select number for the device

No need to add a description.
This is pretty standard.

> +    maxItems: 1
> +
> +  vref-supply:
> +    description:
> +      The regulator supply for the ADC reference voltage
> +    maxItems: 1
> +

As I see in the driver, it's not vref-supply, it's avdd-supply.

You're absolutely right. Shouldn't have mindlessly copied
from the txt, even though the txt's was also my fault.

By the way, a quick look at ad7170 and ad7780's datasheets
shows that the 7170 uses VDD, and the 7780, AVDD. Are they
equivalent?

> +  powerdown-gpios:
> +    description:
> +      Must be the device tree identifier of the PDRST pin. If
> +      specified, it will be asserted during driver probe. As the
> +      line is active high, it should be marked GPIO_ACTIVE_HIGH.
> +    maxItems: 1
> +
> +  adi,gain-gpios:
> +    description:
> +      Must be the device tree identifier of the GAIN pin. Only for
> +      the ad778x chips. If specified, it will be asserted during
> +      driver probe. As the line is active low, it should be marked
> +      GPIO_ACTIVE_LOW.
> +    maxItems: 1
> +
> +  adi,filter-gpios:
> +    description:
> +      Must be the device tree identifier of the FILTER pin. Only
> +      for the ad778x chips. If specified, it will be asserted
> +      during driver probe. As the line is active low, it should be
> +      marked GPIO_ACTIVE_LOW.
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - vref-supply

Is that actually true?  I'd imagine it'll use a stub regulator if
it isn't supplied.

Hmm, I also think this can be omitted as required.
devm_regulator_get() is used.
devm_regulator_get_exclusive() would be needed to make this required.

I see. So the difference between devm_regulator_get and
devm_regulator_get_optional is that the former uses a stub
when the requested reg isn't supplied, and the latter
doesn't?


> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    adc@0 {

The adc@0 block should be included in a spi block.

So, something like

spi0 {
    adc@0 {
           compatible =  "adi,ad7780";
           reg =         <0>;
           avdd-supply = <&vdd_supply>

           powerdown-gpios  = <&gpio 12 GPIO_ACTIVE_HIGH>;
           adi,gain-gpios   = <&gpio  5 GPIO_ACTIVE_LOW>;
           adi,filter-gpios = <&gpio 15 GPIO_ACTIVE_LOW>;
    };
};

I know this wasn't the case before, but it should be (from what I recall).

> +      compatible =  "adi,ad7780";
> +      reg = <0>;
> +      vref-supply = <&vdd_supply>;
> +
> +      powerdown-gpios  = <&gpio0 12 GPIO_ACTIVE_HIGH>;
> +      adi,gain-gpios   = <&gpio1  5 GPIO_ACTIVE_LOW>;
> +      adi,filter-gpios = <&gpio2 15 GPIO_ACTIVE_LOW>;

Rest looks good.

Thanks
Alex

> +    };


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