Re: [PATCH v3 2/2] DT: iio: vadc: document dt binding

Jonathan Cameron
2014-09-27T09:43:46Z

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";
> + };
>