Re: [PATCH v2 1/2] dt-bindings: adc: provide max34408/9 device tree binding document

[Ivan Mikhaylov]

On Sat, 2023-09-30 at 10:37 +0100, Conor Dooley wrote:
> Hey,
> 
> On Fri, Sep 29, 2023 at 11:08:43PM +0300, Ivan Mikhaylov wrote:
> > The hardware binding for i2c current monitoring device with
> > overcurrent
> > control.
> > 
> > Signed-off-by: Ivan Mikhaylov <fr0st61te@xxxxxxxxx>
> > ---
> >  .../bindings/iio/adc/maxim,max34408.yaml      | 101
> > ++++++++++++++++++
> >  1 file changed, 101 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
> > 
> > diff --git
> > a/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
> > b/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
> > new file mode 100644
> > index 000000000000..cdf89fa4c80e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
> > @@ -0,0 +1,101 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/iio/adc/maxim,max34408.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Two- and four-channel current monitors with overcurrent
> > control
> > +
> > +maintainers:
> > +  - Ivan Mikhaylov <fr0st61te@xxxxxxxxx>
> > +
> > +description: |
> > +  The MAX34408/MAX34409 are two- and four-channel current monitors
> > that are
> > +  configured and monitored with a standard I2C/SMBus serial
> > interface. Each
> > +  unidirectional current sensor offers precision high-side
> > operation with a
> > +  low full-scale sense voltage. The devices automatically sequence
> > through
> > +  two or four channels and collect the current-sense samples and
> > average them
> > +  to reduce the effect of impulse noise. The raw ADC samples are
> > compared to
> > +  user-programmable digital thresholds to indicate overcurrent
> > conditions.
> > +  Overcurrent conditions trigger a hardware output to provide an
> > immediate
> > +  indication to shut down any necessary external circuitry.
> > +
> > +  Specifications about the devices can be found at:
> > + 
> > https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - maxim,max34408
> > +      - maxim,max34409
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  maxim,input1-rsense-val-micro-ohms:
> > +    description:
> > +      Adjust the Rsense value to monitor higher or lower current
> > levels for
> > +      input 1.
> > +    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000,
> > 500000]
> > +    default: 1000
> > +
> > +  maxim,input2-rsense-val-micro-ohms:
> > +    description:
> > +      Adjust the Rsense value to monitor higher or lower current
> > levels for
> > +      input 2.
> > +    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000,
> > 500000]
> > +    default: 1000
> > +
> > +  maxim,input3-rsense-val-micro-ohms:
> > +    description:
> > +      Adjust the Rsense value to monitor higher or lower current
> > levels for
> > +      input 3.
> > +    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000,
> > 500000]
> > +    default: 1000
> > +
> > +  maxim,input4-rsense-val-micro-ohms:
> > +    description:
> > +      Adjust the Rsense value to monitor higher or lower current
> > levels for
> > +      input 4.
> > +    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000,
> > 500000]
> > +    default: 1000
> 
> Having 4 almost identical properties makes it seem like this should
> have
> some channel nodes, each containing an rsense-micro-ohms type
> property.

Conor, I'll look through.

> 
> > +
> > +  maxim,shtdn:
> > +    description:
> > +      Shutdown Output. Open-drain output. This output transitions
> > to high impedance
> > +      when any of the digital comparator thresholds are exceeded
> > as long as the ENA
> > +      pin is high.
> > +    type: boolean
> 
> I don't understand what this property is used for. The description
> here,
> and below for "ena", read like they are the descriptions in the
> datasheet for the pin, rather than how to use the property.
> 
> The drivers don't appear to contain users either - what is the point
> of
> these properties?

ena and shtdn physical pins of hardware, in the previous version
Jonathan asked about adding them into yaml even if it's not used in
code. should I do it in some other way?

> 
> > +
> > +  maxim,ena:
> > +    description:
> > +      SHTDN Enable Input. CMOS digital input. Connect to GND to
> > clear the latch and
> > +      unconditionally deassert (force low) the SHTDN output and
> > reset the shutdown
> > +      delay. Connect to VDD to enable normal latch operation of
> > the SHTDN output.
> > +    type: boolean
> > +
> > +  supply-vdd: true
> 
> As pointed out by the bot, this is not correct. You need to use a
> -supply affix, not a supply-prefix.

Oops.

Thanks.