> >> + > >> + adi,pin-pairing: > >> + description: | > >> + The input pin pairing for the negative input. This can be: > >> + - REFGND, normally 0V (single-ended) > >> + - COM, normally V_REF/2, see com-supply (pseudo-differential) > >> + - For even numbered pins, the next odd numbered pin (differential) > >> + $ref: /schemas/types.yaml#/definitions/string > >> + enum: [refgnd, com, next] > > > > Next is full on differential, just provide both channels via > > diff-channels. You can constrain the particular combinations in the binding. > > > > Refcnd is normal single ended. Probably want to use the new single-channel > > property for that as we are mixing differential and single ended channels > > so reg is pretty much just an index. > > > > Hmm. For comm we haven't had done a recent binding for a chip with the option > > of pseudo differential that is per channel, they've been whole device only. > > That feels like it will be common enough we need to support it cleanly > > with a 'general' scheme. > > I think we have. :-) > > https://lore.kernel.org/linux-iio/adc6cba9-2e79-475f-9c24-039fe9d3345d@xxxxxxxxxxxx/T/#mcbc1ce3a2541db502bf7870b7ea8574626a46312 > My goldfish like memory strikes again. Had completely forgotten that :) > > > > Problem is I know someone will have a chip with 2 vincom pins and selecting > > between them, so we can't just have pseudo-differential as a boolean and adc.yaml > > > > There are horrible solutions like a magic channel number that changes the > > meaning of diff-channels but that's ugly. > > Maybe pseudo-differential for now and we have to later we add > > pseudo-differential-comm = <0> etc? > > > > I was trying to keep things simple with 1 property instead of 3, but we > can drop adi,pin-pairing and use the standard diff-channels, single-channel > and common-mode-channel properties. Sounds good. > > >> +examples: > >> + - | > >> + #include <dt-bindings/gpio/gpio.h> > >> + > >> + spi { > >> + #address-cells = <1>; > >> + #size-cells = <0>; > >> + > >> + adc@0 { > >> + compatible = "adi,ad4695"; > >> + reg = <0>; > >> + spi-cpol; > >> + spi-cpha; > >> + spi-max-frequency = <80000000>; > >> + avdd-supply = <&supply_2_5V>; > >> + vdd-supply = <&supply_1_8V>; > >> + vio-supply = <&supply_1_2V>; > >> + ref-supply = <&supply_5V>; > >> + reset-gpios = <&gpio 1 GPIO_ACTIVE_LOW>; > >> + > >> + #address-cells = <1>; > >> + #size-cells = <0>; > >> + > > Using the standard adc.yaml properties, these would now be: > > >> + /* Differential channel between IN0 and IN1. */ > >> + channel@0 { > >> + reg = <0>; > > diff-channels = <0>, <1>; > > >> + bipolar; > >> + }; > >> + > >> + /* Single-ended channel between IN2 and REFGND. */ > >> + channel@2 { > >> + reg = <2>; > > single-channel = <2>; > common-mode-channel = <0>; I wonder if we count ground ad default and so don't necessarily specify this? I don't really mind either way though. Maybe just default to 0 works. > > >> + }; > >> + > >> + /* Pseudo-differential channel between IN3 and COM. */ > >> + channel@f { > >> + reg = <3>; > > single-channel = <3>; > common-mode-channel = <1>; > > >> + bipolar; > >> + }; > >> + }; > >> + }; > > > > And I will add a header file with macros for the common mode > channel values. Great Jonathan >
