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

From: Jonathan Cameron
Date: Sun May 26 2019 - 13:53:32 EST

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On Fri, 24 May 2019 21:28:02 -0300
Renato Lui Geh <renatogeh@xxxxxxxxx> wrote:

> 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?
Correct. If you 'require' a regulator you actually have to use
the optional form and then check if you got one. Otherwise you get
a stub and only find out later that you can't read it's current
value.

Jonathan

> >
> >>
> >> > +
> >> > +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
> >
> >> > + };
> >>
> >>

Next message: Paolo Bonzini: "Re: [GIT PULL] KVM changes for Linux 5.2-rc2"
Previous message: Jonathan Cameron: "Re: [PATCH v2 2/3] iio: common: cros_ec_sensors: add sysfs attribute for frequencies"
In reply to: Renato Lui Geh: "Re: [PATCH] dt-bindings: iio: adc: add adi,ad7780.yaml binding"
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