On 27/05/2024 20:48, Conor Dooley wrote: > On Mon, May 27, 2024 at 08:02:34PM +0300, Dumitru Ceclan via B4 Relay wrote: >> From: Dumitru Ceclan <dumitru.ceclan@xxxxxxxxxx> >> >> Add support for: AD4111, AD4112, AD4114, AD4115, AD4116. >> >> AD411x family ADCs support a VCOM pin, dedicated for single-ended usage. >> AD4111/AD4112 support current channels, usage is implemented by >> specifying channel reg values bigger than 15. >> >> Signed-off-by: Dumitru Ceclan <dumitru.ceclan@xxxxxxxxxx> >> --- >> .../devicetree/bindings/iio/adc/adi,ad7173.yaml | 122 ++++++++++++++++++++- >> 1 file changed, 120 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml >> index ea6cfcd0aff4..5b1af382dad3 100644 >> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml >> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml >> @@ -19,7 +19,18 @@ description: | >> primarily for measurement of signals close to DC but also delivers >> outstanding performance with input bandwidths out to ~10kHz. >> >> + Analog Devices AD411x ADC's: >> + The AD411X family encompasses a series of low power, low noise, 24-bit, >> + sigma-delta analog-to-digital converters that offer a versatile range of >> + specifications. They integrate an analog front end suitable for processing >> + fully differential/single-ended and bipolar voltage inputs. >> + >> Datasheets for supported chips: >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4111.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4112.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4114.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4115.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4116.pdf >> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7172-2.pdf >> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7172-4.pdf >> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7173-8.pdf >> @@ -31,6 +42,11 @@ description: | >> properties: >> compatible: >> enum: >> + - adi,ad4111 >> + - adi,ad4112 >> + - adi,ad4114 >> + - adi,ad4115 >> + - adi,ad4116 >> - adi,ad7172-2 >> - adi,ad7172-4 >> - adi,ad7173-8 >> @@ -129,10 +145,36 @@ patternProperties: >> maximum: 15 >> >> diff-channels: >> + description: | >> + For using current channels specify select the current inputs >> + and enable the adi,current-channel property. >> + >> + Family AD411x supports a dedicated VINCOM voltage input. >> + To select it set the second channel to 16. >> + (VIN2, VINCOM) -> diff-channels = <2 16> >> + >> + There are special values that can be selected besides the voltage >> + analog inputs: >> + 21: REF+ >> + 22: REF− >> + Supported only by AD7172-2, AD7172-4, AD7175-2, AD7175-8, AD7177-2: >> + 19: ((AVDD1 − AVSS)/5)+ >> + 20: ((AVDD1 − AVSS)/5)− >> + >> items: >> minimum: 0 >> maximum: 31 >> >> + single-channel: >> + description: | >> + Models AD4111 and AD4112 support single-ended current channels. >> + To select the desired current input, specify the desired input pair: >> + (IIN2+, IIN2−) -> single-channel = <2> >> + >> + items: >> + minimum: 1 >> + maximum: 16 >> + >> adi,reference-select: >> description: | >> Select the reference source to use when converting on >> @@ -154,9 +196,26 @@ patternProperties: >> - avdd >> default: refout-avss >> >> + adi,current-channel: >> + description: | >> + Signal that the selected inputs are current channels. >> + Only available on AD4111 and AD4112. >> + type: boolean >> + >> + adi,channel-type: >> + description: >> + Used to differentiate between different channel types as the device >> + register configurations are the same for all usage types. >> + Both pseudo-differential and single-ended channels will use the >> + single-ended specifier. >> + $ref: /schemas/types.yaml#/definitions/string >> + enum: >> + - single-ended >> + - differential >> + default: differential > > I dunno if my brain just ain't workin' right today, or if this is not > sufficiently explained, but why is this property needed? You've got > diff-channels and single-channels already, why can you not infer the > information you need from them? What should software do with this > information? > Additionally, "pseudo-differential" is not explained in this binding. > In previous thread we arrived to the conclusion single-ended and pseudo-differential channels should be marked with the flag "differential=false" in the IIO channel struct. This cannot really be inferred as any input pair could be used in that manner and the only difference would be in external wiring. Single-channels cannot be used to define such a channel as two voltage inputs need to be selected. Also, we are already using single-channel to define the current channels. As for explaining the pseudo-differential, should it be explained? A voltage channel within the context of these families is actually differential(as there are always two inputs selected). The single-ended and pseudo-diff use case is actually wiring up a constant voltage to the selected negative input. I did not consider that this should be described, as there is no need for an attribute to describe it. > Also, what does "the device register configurations are the same for > all uses types" mean? The description here implies that you'd be reading > the registers to determine the configuration, but as far as I understand > it's the job of drivers to actually configure devices. > The only way I could interpret this that makes sense to me is that you're > trying to say that the device doesn't have registers that allow you to > do runtime configuration detection - but that's the norm and I would not > call it out here. No, I meant that the same register configuration will be set for both fully differential and single-ended. The user will set diff-channels = <0, 1>, bipolar(or not) and then they can wire whatever to those pins: - a differential signal - AVSS to 1 and a single-ended signal to 0 - AVSS+offset to 1 and a single-ended signal to 0 (which is called pseudo-differential in some datasheets) All these cases will look the same in terms of configuration > > Thanks, > Conor.
