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Diffstat (limited to 'Documentation/devicetree/bindings/iio/adc/qcom,pm8xxx-xoadc.txt')
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diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,pm8xxx-xoadc.txt b/Documentation/devicetree/bindings/iio/adc/qcom,pm8xxx-xoadc.txt new file mode 100644 index 000000000..3ae061277 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/adc/qcom,pm8xxx-xoadc.txt @@ -0,0 +1,157 @@ +Qualcomm's PM8xxx voltage XOADC + +The Qualcomm PM8xxx PMICs contain a HK/XO ADC (Housekeeping/Crystal +oscillator ADC) encompassing PM8018, PM8038, PM8058 and PM8921. + +Required properties: + +- compatible: should be one of: + "qcom,pm8018-adc" + "qcom,pm8038-adc" + "qcom,pm8058-adc" + "qcom,pm8921-adc" + +- reg: should contain the ADC base address in the PMIC, typically + 0x197. + +- xoadc-ref-supply: should reference a regulator that can supply + a reference voltage on demand. The reference voltage may vary + with PMIC variant but is typically something like 2.2 or 1.8V. + +The following required properties are standard for IO channels, see +iio-bindings.txt for more details, but notice that this particular +ADC has a special addressing scheme that require two cells for +identifying each ADC channel: + +- #address-cells: should be set to <2>, the first cell is the + prescaler (on PM8058) or premux (on PM8921) with two valid bits + so legal values are 0x00, 0x01 or 0x02. The second cell + is the main analog mux setting (0x00..0x0f). The combination + of prescaler/premux and analog mux uniquely addresses a hardware + channel on all systems. + +- #size-cells: should be set to <0> + +- #io-channel-cells: should be set to <2>, again the cells are + precaler or premux followed by the analog muxing line. + +- interrupts: should refer to the parent PMIC interrupt controller + and reference the proper ADC interrupt. + +Required subnodes: + +The ADC channels are configured as subnodes of the ADC. + +Since some of them are used for calibrating the ADC, these nodes are +compulsory: + +adc-channel@c { + reg = <0x00 0x0c>; +}; + +adc-channel@d { + reg = <0x00 0x0d>; +}; + +adc-channel@f { + reg = <0x00 0x0f>; +}; + +These three nodes are used for absolute and ratiometric calibration +and only need to have these reg values: they are by hardware definition +1:1 ratio converters that sample 625, 1250 and 0 milliV and create +an interpolation calibration for all other ADCs. + +Optional subnodes: any channels other than channels [0x00 0x0c], +[0x00 0x0d] and [0x00 0x0f] are optional. + +Required channel node properties: + +- reg: should contain the hardware channel number in the range + 0 .. 0xff (8 bits). + +Optional channel node properties: + +- qcom,decimation: + Value type: <u32> + Definition: This parameter is used to decrease the ADC sampling rate. + Quicker measurements can be made by reducing the decimation ratio. + Valid values are 512, 1024, 2048, 4096. + If the property is not found, a default value of 512 will be used. + +- qcom,ratiometric: + Value type: <u32> + Definition: Channel calibration type. If this property is specified + VADC will use a special voltage references for channel + calibration. The available references are specified in the + as a u32 value setting (see below) and it is compulsory + to also specify this reference if ratiometric calibration + is selected. + + If the property is not found, the channel will be + calibrated with the 0.625V and 1.25V reference channels, also + known as an absolute calibration. + The reference voltage pairs when using ratiometric calibration: + 0 = XO_IN/XOADC_GND + 1 = PMIC_IN/XOADC_GND + 2 = PMIC_IN/BMS_CSP + 3 (invalid) + 4 = XOADC_GND/XOADC_GND + 5 = XOADC_VREF/XOADC_GND + +Example: + +xoadc: xoadc@197 { + compatible = "qcom,pm8058-adc"; + reg = <0x197>; + interrupts-extended = <&pm8058 76 IRQ_TYPE_EDGE_RISING>; + #address-cells = <2>; + #size-cells = <0>; + #io-channel-cells = <2>; + + vcoin: adc-channel@0 { + reg = <0x00 0x00>; + }; + vbat: adc-channel@1 { + reg = <0x00 0x01>; + }; + dcin: adc-channel@2 { + reg = <0x00 0x02>; + }; + ichg: adc-channel@3 { + reg = <0x00 0x03>; + }; + vph_pwr: adc-channel@4 { + reg = <0x00 0x04>; + }; + usb_vbus: adc-channel@a { + reg = <0x00 0x0a>; + }; + die_temp: adc-channel@b { + reg = <0x00 0x0b>; + }; + ref_625mv: adc-channel@c { + reg = <0x00 0x0c>; + }; + ref_1250mv: adc-channel@d { + reg = <0x00 0x0d>; + }; + ref_325mv: adc-channel@e { + reg = <0x00 0x0e>; + }; + ref_muxoff: adc-channel@f { + reg = <0x00 0x0f>; + }; +}; + +/* IIO client node */ +iio-hwmon { + compatible = "iio-hwmon"; + io-channels = <&xoadc 0x00 0x01>, /* Battery */ + <&xoadc 0x00 0x02>, /* DC in (charger) */ + <&xoadc 0x00 0x04>, /* VPH the main system voltage */ + <&xoadc 0x00 0x0b>, /* Die temperature */ + <&xoadc 0x00 0x0c>, /* Reference voltage 1.25V */ + <&xoadc 0x00 0x0d>, /* Reference voltage 0.625V */ + <&xoadc 0x00 0x0e>; /* Reference voltage 0.325V */ +}; |