Re: [PATCH v2 2/2] DT: iio: vadc: document dt binding

[Jonathan Cameron]

On 13/09/14 00:35, Hartmut Knaack wrote:
> Stanimir Varbanov schrieb, Am 11.09.2014 17:13:
>> Document DT binding for Qualcomm SPMI PMIC voltage ADC
>> driver.
>>
> Still one typo left.
>> Signed-off-by: Stanimir Varbanov <svarbanov@xxxxxxxxxx>
>> Signed-off-by: Ivan T. Ivanov <iivanov@xxxxxxxxxx>
>> ---
>>  .../devicetree/bindings/iio/adc/qcom,spmi-vadc.txt |  123 ++++++++++++++++++++
>>  1 files changed, 123 insertions(+), 0 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
>> new file mode 100644
>> index 0000000..5abb491
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
>> @@ -0,0 +1,123 @@
>> +Qualcomm's SPMI PMIC voltage ADC
>> +
>> +SPMI PMIC voltage ADC (VADC) provides interface to clients to read
>> +voltage. A 15 bit ADC is used for voltage measurements. There are multiple
>> +peripherals to the VADC and the scope of the driver is to provide interface
>> +for the USR peripheral of the VADC.
>> +
>> +VADC node:
>> +
>> +- compatible:
>> +    Usage: required
>> +    Value type: <string>
>> +    Definition: Should contain "qcom,spmi-vadc".
>> +
>> +- reg:
>> +    Usage: required
>> +    Value type: <u32>
>> +    Definition: Base address in the SPMI PMIC register map.
>> +
>> +- address-cells:
>> +    Usage: required
>> +    Value type: <u32>
>> +    Definition: Must be one.
>> +
>> +- size-cells:
>> +    Usage: required
>> +    Value type: <u32>
>> +    Definition: Must be zero.
>> +
>> +- interrupts:
>> +    Usage: required
>> +    Value type: <prop-encoded-array>
>> +    Definition: End of convertion interrupt number.
> Typo: conversion
>> +
>> +- qcom,poll-eoc:
>> +    Usage: optional
>> +    Value type: <empty>
>> +    Definition: Use polling instead of interrupt for end of conversion
>> +            completion.
>> +
>> +Channel node properties:
>> +
>> +- reg:
>> +    Usage: required
>> +    Value type: <u32>
>> +    Definition: AMUX channel number.
>> +            See include/dt-bindings/iio/qcom,spmi-pmic-vadc.h
>> +
>> +- qcom,decimation:
>> +    Usage: optional
>> +    Value type: <u32>
>> +    Definition: Sampling rate to use for the individual channel measurement.
>> +            Quicker measurements can be made by reducing decimation ratio.
>> +            Valid values are 512, 1024, 2048, 4096.
>> +            If property is not found, default value of 512 will be used.
>> +
>> +- qcom,pre-scaling:
>> +    Usage: optional
>> +    Value type: <u32 array>
>> +    Definition: 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.
>> +            <1 1>, <1 3>, <1 4>, <1 6>, <1 20>, <1 8>, <10 81>, <1 10>
>> +            If property is not found default value depending of chip will be used.
>> +
>> +- qcom,ratiometric:
>> +    Usage: optional
>> +    Value type: <empty>
>> +    Definition: Channel calibration type. If this property is specified
>> +            VADC will use the VDD reference(1.8V) and GND for channel
>> +            calibration. If property is not found, channel will be
>> +            calibrated with 625mV and 1.25V reference channels.
>> +
>> +- qcom,hw-settle-time:
>> +    Usage: optional
>> +    Value type: <u32>
>> +    Definition: Time between AMUX getting configured and the ADC starting
>> +            conversion. Delay = 100us * (value) for value < 11, and
>> +            2ms * (value - 10) otherwise.
>> +            Valid values are: 0, 100, 200, 300, 400, 500, 600, 700, 800,
>> +            900 us and 1, 2, 4, 6, 8, 10 ms
>> +            If property is not found, channel will use 0us.
>> +
>> +- qcom,avg-samples:
>> +    Usage: optional
>> +    Value type: <u32>
>> +    Definition: Number of samples to be used for measurement.
>> +            Fast averaging provides the option to obtain a single measurement
>> +            from the ADC that is an average of multiple samples. The value
>> +            selected is 2^(value).
>> +            Valid values are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
>> +            If property is not found, 1 sample will be used.
>> +
>> +NOTE: At least one channel node is required.

Why?  As far as I can see it will register all the channels anyway.  If that is not the intent
you need to build the iio_chan_spec array rather than using a static one.

I'm fine with it providing channels with sensible defaults if they aren't overridden, but then
it should work fine with no channel nodes.

Jonathan


>> +
>> +Example:
>> +	/* VADC node */
>> +	pmic_vadc: vadc@3100 {
>> +		compatible = "qcom,spmi-vadc";
>> +		reg = <0x3100 0x100>;
>> +		interrupts = <0x0 0x31 0x0 IRQ_TYPE_EDGE_RISING>;
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +		#io-channel-cells = <1>;
>> +		io-channel-ranges;
>> +
>> +		/* Channel node */
>> +		usb_id_nopull {
>> +			reg = <VADC_LR_MUX10_USB_ID>;
>> +			qcom,decimation = <512>;
>> +			qcom,ratiometric;
>> +			qcom,hw-settle-time = <200>;
>> +			qcom,avg-samples = <1>;
>> +			qcom,pre-scaling = <1 3>;
>> +		};
>> +	};
>> +
>> +	/* IIO client node */
>> +	usb {
>> +		io-channels = <&pmic_vadc VADC_LR_MUX10_USB_ID>;
>> +		io-channel-names = "vadc";
>> +	};
>>
> 
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