1Qualcomm's PM8xxx voltage XOADC 2 3The Qualcomm PM8xxx PMICs contain a HK/XO ADC (Housekeeping/Crystal 4oscillator ADC) encompassing PM8018, PM8038, PM8058 and PM8921. 5 6Required properties: 7 8- compatible: should be one of: 9 "qcom,pm8018-adc" 10 "qcom,pm8038-adc" 11 "qcom,pm8058-adc" 12 "qcom,pm8921-adc" 13 14- reg: should contain the ADC base address in the PMIC, typically 15 0x197. 16 17- xoadc-ref-supply: should reference a regulator that can supply 18 a reference voltage on demand. The reference voltage may vary 19 with PMIC variant but is typically something like 2.2 or 1.8V. 20 21The following required properties are standard for IO channels, see 22iio-bindings.txt for more details, but notice that this particular 23ADC has a special addressing scheme that require two cells for 24identifying each ADC channel: 25 26- #address-cells: should be set to <2>, the first cell is the 27 prescaler (on PM8058) or premux (on PM8921) with two valid bits 28 so legal values are 0x00, 0x01 or 0x02. The second cell 29 is the main analog mux setting (0x00..0x0f). The combination 30 of prescaler/premux and analog mux uniquely addresses a hardware 31 channel on all systems. 32 33- #size-cells: should be set to <0> 34 35- #io-channel-cells: should be set to <2>, again the cells are 36 precaler or premux followed by the analog muxing line. 37 38- interrupts: should refer to the parent PMIC interrupt controller 39 and reference the proper ADC interrupt. 40 41Required subnodes: 42 43The ADC channels are configured as subnodes of the ADC. 44 45Since some of them are used for calibrating the ADC, these nodes are 46compulsory: 47 48adc-channel@c { 49 reg = <0x00 0x0c>; 50}; 51 52adc-channel@d { 53 reg = <0x00 0x0d>; 54}; 55 56adc-channel@f { 57 reg = <0x00 0x0f>; 58}; 59 60These three nodes are used for absolute and ratiometric calibration 61and only need to have these reg values: they are by hardware definition 621:1 ratio converters that sample 625, 1250 and 0 milliV and create 63an interpolation calibration for all other ADCs. 64 65Optional subnodes: any channels other than channels [0x00 0x0c], 66[0x00 0x0d] and [0x00 0x0f] are optional. 67 68Required channel node properties: 69 70- reg: should contain the hardware channel number in the range 71 0 .. 0xff (8 bits). 72 73Optional channel node properties: 74 75- qcom,decimation: 76 Value type: <u32> 77 Definition: This parameter is used to decrease the ADC sampling rate. 78 Quicker measurements can be made by reducing the decimation ratio. 79 Valid values are 512, 1024, 2048, 4096. 80 If the property is not found, a default value of 512 will be used. 81 82- qcom,ratiometric: 83 Value type: <u32> 84 Definition: Channel calibration type. If this property is specified 85 VADC will use a special voltage references for channel 86 calibration. The available references are specified in the 87 as a u32 value setting (see below) and it is compulsory 88 to also specify this reference if ratiometric calibration 89 is selected. 90 91 If the property is not found, the channel will be 92 calibrated with the 0.625V and 1.25V reference channels, also 93 known as an absolute calibration. 94 The reference voltage pairs when using ratiometric calibration: 95 0 = XO_IN/XOADC_GND 96 1 = PMIC_IN/XOADC_GND 97 2 = PMIC_IN/BMS_CSP 98 3 (invalid) 99 4 = XOADC_GND/XOADC_GND 100 5 = XOADC_VREF/XOADC_GND 101 102Example: 103 104xoadc: xoadc@197 { 105 compatible = "qcom,pm8058-adc"; 106 reg = <0x197>; 107 interrupts-extended = <&pm8058 76 IRQ_TYPE_EDGE_RISING>; 108 #address-cells = <2>; 109 #size-cells = <0>; 110 #io-channel-cells = <2>; 111 112 vcoin: adc-channel@0 { 113 reg = <0x00 0x00>; 114 }; 115 vbat: adc-channel@1 { 116 reg = <0x00 0x01>; 117 }; 118 dcin: adc-channel@2 { 119 reg = <0x00 0x02>; 120 }; 121 ichg: adc-channel@3 { 122 reg = <0x00 0x03>; 123 }; 124 vph_pwr: adc-channel@4 { 125 reg = <0x00 0x04>; 126 }; 127 usb_vbus: adc-channel@a { 128 reg = <0x00 0x0a>; 129 }; 130 die_temp: adc-channel@b { 131 reg = <0x00 0x0b>; 132 }; 133 ref_625mv: adc-channel@c { 134 reg = <0x00 0x0c>; 135 }; 136 ref_1250mv: adc-channel@d { 137 reg = <0x00 0x0d>; 138 }; 139 ref_325mv: adc-channel@e { 140 reg = <0x00 0x0e>; 141 }; 142 ref_muxoff: adc-channel@f { 143 reg = <0x00 0x0f>; 144 }; 145}; 146 147/* IIO client node */ 148iio-hwmon { 149 compatible = "iio-hwmon"; 150 io-channels = <&xoadc 0x00 0x01>, /* Battery */ 151 <&xoadc 0x00 0x02>, /* DC in (charger) */ 152 <&xoadc 0x00 0x04>, /* VPH the main system voltage */ 153 <&xoadc 0x00 0x0b>, /* Die temperature */ 154 <&xoadc 0x00 0x0c>, /* Reference voltage 1.25V */ 155 <&xoadc 0x00 0x0d>, /* Reference voltage 0.625V */ 156 <&xoadc 0x00 0x0e>; /* Reference voltage 0.325V */ 157}; 158