On 5/29/24 8:38 AM, Ceclan, Dumitru wrote: > On 28/05/2024 20:52, Conor Dooley wrote: >> On Tue, May 28, 2024 at 03:16:07PM +0300, Ceclan, Dumitru wrote: >>> 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. >> >> If I understand correctly, the property could be simplified to a flag >> then, since it's only the pseudo differential mode that you cannot be >> sure of? >> You know when you're single-ended based on single-channel, so the >> additional info you need is only in the pseudo-differential case. >> > Yes, it could just be a boolean flag. The only thing I have against > that is the awkwardness of having both diff-channels and > differential=false within a channel definition. > > No, there is no uncertainty regarding pseudo-differential, it's > basically single-ended. > > We cannot use single-channel for voltage channels, two voltage > inputs need to be specified. And again, single-channel will be > used here for the current channels. Instead of using diff-channels for single-ended/pseudo-differential plus a property that says "actually not differential" could we just add a second common-mode-channel property to specify the second input pin that is connected to the common mode voltage source? Just to make sure I'm understanding, single-ended means common mode voltage is 0V (or AVSS for this chip, I guess) and pseudo-differential means the common mode voltage is something else other than that. In other words, single-ended is just a special case of pseudo-differential. So effectively, no difference that we need to describe? So something like this could work? /* a fully differential voltage input channel */ channel@0 { reg = <0>; bipolar; diff-channels = <0 1>; /* VIN0 is +, VIN1 is - */ adi,reference-select = "vref"; }; /* a single-ended voltage input channel */ channel@1 { reg = <1>; /* no bipolar since common mode is 0V */ single-channel = <2>; /* VIN2 is input */ common-mode-channel = <3>; /* VIN3 connected to 0V */ }; /* a pseudo-differential voltage input channel */ channel@2 { reg = <2>; bipolar; /* since common mode is not 0V */ single-channel = <4>; /* VIN4 is input */ common-mode-channel = <5>; /* VIN5 connected to Vref / 2 */ adi,reference-select = "vref"; }; /* a current input channel */ channel@3 { reg = <3>; bipolar; /* 0 is not the same pin as channel@0 because of * the adi,current-channel flag */ single-channel = <0>; /* using IIN0+ and IIN0- pins */ adi,current-channel; }; If we really wanted to go all the way, we could also think about adding a common-mode-supply property in each channel node to with a common-mode-channel property to describe the voltage source that the pin is connected to.
