Hi Amit,
On 4/3/2020 5:34 PM, Amit Kucheria wrote:
+required:
+ - compatible
+ - reg
+ - '#address-cells'
+ - '#size-cells'
+ - '#io-channel-cells'
+
+patternProperties:
+ "^[a-z0-9-_@]$":
+ type: object
+ description: |
+ Represents the external channels which are connected to the ADC.
+ For compatible property "qcom,spmi-vadc" following channels, also known as
+ reference point channels, are used for result calibration and their channel
+ configuration nodes should be defined:
+ VADC_REF_625MV and/or VADC_SPARE1(based on PMIC version) VADC_REF_1250MV,
+ VADC_GND_REF and VADC_VDD_VADC.
Instead of this note for "qcom,spmi-vadc", you can enforce this
through checks in YAML grammar.
A simple example can be found in
Documentation/devicetree/bindings/thermal/qcom-tsens.yaml. Look for
the if, then, else clause which determines how many interrupts need to
be defined.
I have gone through tsens and other examples, but I'm not able to get a
way to apply this kind of constraint, on what child nodes should be present.
In this case, the constraint would have to be that for compatible
property "qcom,spmi-vadc", there should be at least four child nodes and
those four should have their "reg" property fixed to the channel values
mentioned above. I can see how to apply constraints on a single property
like interrupts in tsens, but I'm not sure if there is a way to specify
a lower limit to the number of child nodes or something like "there
should be at least one child node with value 0x9 for its "reg"
property". I could not find any examples with constraints placed on
number of occurrences of a child node.
Can you please share an example of such a constraint if you are aware of
any or suggest some way by which this kind of constraint can be specified?
+
+ properties:
+ reg:
+ description: |
+ ADC channel number.
+ See include/dt-bindings/iio/qcom,spmi-vadc.h
+
+ label:
+ description: |
+ ADC input of the platform as seen in the schematics.
+ For thermistor inputs connected to generic AMUX or GPIO inputs
+ these can vary across platform for the same pins. Hence select
+ the platform schematics name for this channel. It is required
+ for "qcom,spmi-adc5" and "qcom,spmi-adc-rev2".
+ allOf:
+ - $ref: /schemas/types.yaml#/definitions/string
You shouldn't need allOf here.
Just a "$ref: /schemas/types.yaml#/definitions/string" should be fine.
And move it above the description.
Same for all the uses of allOf below.
I'll make the change in the next post.
+ qcom,decimation:
+ description: |
+ This parameter is used to decrease ADC sampling rate.
+ Quicker measurements can be made by reducing decimation ratio.
+ - For compatible property "qcom,spmi-vadc", valid values are
+ 512, 1024, 2048, 4096. If property is not found, default value
+ of 512 will be used.
+ - For compatible property "qcom,spmi-adc5", valid values are 250, 420
+ and 840. If property is not found, default value of 840 is used.
+ - For compatible property "qcom,spmi-adc-rev2", valid values are 256,
+ 512 and 1024. If property is not present, default value is 1024.
+ allOf:
+ - $ref: /schemas/types.yaml#/definitions/uint32
+
As pointed out by Jonathon, please enforce these by keying off the
compatible property.
I'll do this for all properties for which it's applicable in the next post.
+ qcom,pre-scaling:
+ description: |
+ Used for scaling the channel input signal before the signal is
+ fed to VADC. The configuration for this node is to know the
+ pre-determined ratio and use it for post scaling. Select one from
+ the following options.
Please improve this description from the old binding. Does <1 3> mean
the signal is scaled 3x or 1/3x?
<1 3> means it is scaled down to 1/3rd of actual value. I'll add to the
description in the next post.
+ <1 1>, <1 3>, <1 4>, <1 6>, <1 20>, <1 8>, <10 81>, <1 10>
+ If property is not found default value depending on chip will be used.
+ allOf:
+ - $ref: /schemas/types.yaml#/definitions/uint32
+
