Re: [PATCH 07/10] dt-bindings:iio:adc:maxim,max1027: Pull out to separate binding doc.

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 1 Nov 2020 20:33:04 +0000
Jonathan Cameron <jic23@kernel.org> wrote:

> On Sun, 1 Nov 2020 14:25:57 +0100
> Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> > Hi Jonathan,
> > 
> > Jonathan Cameron <jic23@kernel.org> wrote on Sat, 31 Oct 2020 18:12:39
> > +0000:
> >   
> > > From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > 
> > > The afe/voltage-divider.yaml example uses this device with 2 properties
> > > not provided by trivial-devices.yaml (spi-max-frequency and #io-channel-cells)
> > > 
> > > Solve that by creating a more specific binding doc.    
> > 
> > I don't know #io-channel-cells but spi-max-frequency is very common and
> > is related to the fact that this device is a SPI device (hence, a SPI
> > subnode), IMHO it has nothing to do with trivial-devices.yaml
> > description.  
> 
> There may be some logic to adding spi-max-frequency to the allowed properties
> of devices listed in trivial-devices.  Right now it's not there so you will
> get warnings if you check a dts file that has it in for bindings described
> by that file.  I've been lazy here, but ideally we also want to document
> a maximum for this property.  In this case, it should be 10000000 (10MHz).
> I'll add that to this binding either in v2, or whilst applying.
> 
> The io-channel-cells, is specific to devices proving analog channel measurement
> services that other bindings can make use of.  (typically ADCs and DACs).
> Currently only applies to IIO bindings for ADCs and DACs.
> It specifies how many parameters are needed as part of the phandle to identify
> a channel.
> 
> Given most of trivial devices don't fall into that category, we need to do
> a separate binding where it's known to be used anyway.
> 
> As a side note.. I just noticed these devices have reference voltage pins.
> At somepoint (not necessarily now) we should look at adding appropriate regulator
> bindings.

Applied with the addition of 10000000 maximum for spi-max-frequency.

thanks,

Jonathan

> 
> Jonathan
> 
> >   
> > > 
> > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > Cc: Miquel Raynal <miquel.raynal@bootlin.com>
> > > Cc: Philippe Reynes <tremyfr@yahoo.fr>
> > > ---
> > >  .../bindings/iio/adc/maxim,max1027.yaml       | 64 +++++++++++++++++++
> > >  .../devicetree/bindings/trivial-devices.yaml  | 12 ----
> > >  2 files changed, 64 insertions(+), 12 deletions(-)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/iio/adc/maxim,max1027.yaml b/Documentation/devicetree/bindings/iio/adc/maxim,max1027.yaml
> > > new file mode 100644
> > > index 000000000000..09e853c50c76
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/iio/adc/maxim,max1027.yaml
> > > @@ -0,0 +1,64 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/iio/adc/maxim,max1027.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Maxim MAX1027 and similar ADCs
> > > +
> > > +maintainers:
> > > +  - Miquel Raynal <miquel.raynal@bootlin.com>
> > > +  - Philippe Reynes <tremyfr@yahoo.fr>
> > > +
> > > +description: |
> > > +  300ks/s SPI ADCs with temperature sensors.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +        # 10-bit 8 channels
> > > +      - maxim,max1027
> > > +        # 10-bit 12 channels
> > > +      - maxim,max1029
> > > +        # 10-bit 16 channels
> > > +      - maxim,max1031
> > > +         # 12-bit 8 channels
> > > +      - maxim,max1227
> > > +         # 12-bit 12 channels
> > > +      - maxim,max1229
> > > +         # 12-bit 16 channels
> > > +      - maxim,max1231
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  spi-max-frequency: true
> > > +
> > > +  "#io-channel-cells":
> > > +    const: 1
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    #include <dt-bindings/interrupt-controller/irq.h>
> > > +    spi {
> > > +       #address-cells = <1>;
> > > +       #size-cells = <0>;
> > > +        maxadc: adc@0 {
> > > +            compatible = "maxim,max1027";
> > > +            reg = <0>;
> > > +            #io-channel-cells = <1>;
> > > +            interrupt-parent = <&gpio5>;
> > > +            interrupts = <15 IRQ_TYPE_EDGE_RISING>;
> > > +            spi-max-frequency = <1000000>;
> > > +        };
> > > +    };
> > > +...
> > > diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
> > > index d154ea97e30d..185e09e61e16 100644
> > > --- a/Documentation/devicetree/bindings/trivial-devices.yaml
> > > +++ b/Documentation/devicetree/bindings/trivial-devices.yaml
> > > @@ -108,18 +108,6 @@ properties:
> > >            - isil,isl68137
> > >              # 5 Bit Programmable, Pulse-Width Modulator
> > >            - maxim,ds1050
> > > -            # 10-bit 8 channels 300ks/s SPI ADC with temperature sensor
> > > -          - maxim,max1027
> > > -            # 10-bit 12 channels 300ks/s SPI ADC with temperature sensor
> > > -          - maxim,max1029
> > > -            # 10-bit 16 channels 300ks/s SPI ADC with temperature sensor
> > > -          - maxim,max1031
> > > -            # 12-bit 8 channels 300ks/s SPI ADC with temperature sensor
> > > -          - maxim,max1227
> > > -            # 12-bit 12 channels 300ks/s SPI ADC with temperature sensor
> > > -          - maxim,max1229
> > > -            # 12-bit 16 channels 300ks/s SPI ADC with temperature sensor
> > > -          - maxim,max1231
> > >              # Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
> > >            - maxim,max1237
> > >              # PECI-to-I2C translator for PECI-to-SMBus/I2C protocol conversion    
> > 
> > Thanks,
> > Miquèl  
>