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    SubjectRe: [PATCH v3 2/2] DT: iio: vadc: document dt binding
    On 24/09/14 13:56, Stanimir Varbanov wrote:
    > Document DT binding for Qualcomm SPMI PMIC voltage ADC
    > driver.
    >
    > Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
    > Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
    Ideally I'd like a device tree maintainer to take a look at this
    as it's non trivial. Right now we have just missed this cycle anyway so there
    is now plenty of time.

    Jonathan
    > ---
    > .../devicetree/bindings/iio/adc/qcom,spmi-vadc.txt | 130 ++++++++++++++++++++
    > 1 files changed, 130 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..fa30300
    > --- /dev/null
    > +++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
    > @@ -0,0 +1,130 @@
    > +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: optional
    > + Value type: <prop-encoded-array>
    > + Definition: End of conversion interrupt number. If this property does
    > + not exist polling will be used instead.
    > +
    > +- interrupt-names:
    > + Usage: optional
    > + Value type: <string>
    > + Definition: Should contain the interrupt name "eoc" (end of conversion).
    > +
    > +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.
    > + Otherwise the absolute calibration will be used.
    > +
    > +- 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 reference channel nodes are required. The reference channels
    > + might be different depending on PMIC version.
    > + Reference channels per type of calibration are:
    > + - absolute
    > + (VADC_REF_625MV or VADC_SPARE1) and VADC_REF_1250MV
    > + - ratiomatric
    > + VADC_GND_REF and VADC_VDD_VADC
    > +
    > +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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