1Qualcomm's SPMI PMIC ADC 2 3- SPMI PMIC voltage ADC (VADC) provides interface to clients to read 4 voltage. The VADC is a 15-bit sigma-delta ADC. 5- SPMI PMIC5 voltage ADC (ADC) provides interface to clients to read 6 voltage. The VADC is a 16-bit sigma-delta ADC. 7 8VADC node: 9 10- compatible: 11 Usage: required 12 Value type: <string> 13 Definition: Should contain "qcom,spmi-vadc". 14 Should contain "qcom,spmi-adc5" for PMIC5 ADC driver. 15 Should contain "qcom,spmi-adc-rev2" for PMIC rev2 ADC driver. 16 Should contain "qcom,pms405-adc" for PMS405 PMIC 17 18- reg: 19 Usage: required 20 Value type: <prop-encoded-array> 21 Definition: VADC base address in the SPMI PMIC register map. 22 23- #address-cells: 24 Usage: required 25 Value type: <u32> 26 Definition: Must be one. Child node 'reg' property should define ADC 27 channel number. 28 29- #size-cells: 30 Usage: required 31 Value type: <u32> 32 Definition: Must be zero. 33 34- #io-channel-cells: 35 Usage: required 36 Value type: <u32> 37 Definition: Must be one. For details about IIO bindings see: 38 Documentation/devicetree/bindings/iio/iio-bindings.txt 39 40- interrupts: 41 Usage: optional 42 Value type: <prop-encoded-array> 43 Definition: End of conversion interrupt. 44 45Channel node properties: 46 47- reg: 48 Usage: required 49 Value type: <u32> 50 Definition: ADC channel number. 51 See include/dt-bindings/iio/qcom,spmi-vadc.h 52 53- label: 54 Usage: required for "qcom,spmi-adc5" and "qcom,spmi-adc-rev2" 55 Value type: <empty> 56 Definition: ADC input of the platform as seen in the schematics. 57 For thermistor inputs connected to generic AMUX or GPIO inputs 58 these can vary across platform for the same pins. Hence select 59 the platform schematics name for this channel. 60 61- qcom,decimation: 62 Usage: optional 63 Value type: <u32> 64 Definition: This parameter is used to decrease ADC sampling rate. 65 Quicker measurements can be made by reducing decimation ratio. 66 - For compatible property "qcom,spmi-vadc", valid values are 67 512, 1024, 2048, 4096. If property is not found, default value 68 of 512 will be used. 69 - For compatible property "qcom,spmi-adc5", valid values are 250, 420 70 and 840. If property is not found, default value of 840 is used. 71 - For compatible property "qcom,spmi-adc-rev2", valid values are 256, 72 512 and 1024. If property is not present, default value is 1024. 73 74- qcom,pre-scaling: 75 Usage: optional 76 Value type: <u32 array> 77 Definition: Used for scaling the channel input signal before the signal is 78 fed to VADC. The configuration for this node is to know the 79 pre-determined ratio and use it for post scaling. Select one from 80 the following options. 81 <1 1>, <1 3>, <1 4>, <1 6>, <1 20>, <1 8>, <10 81>, <1 10> 82 If property is not found default value depending on chip will be used. 83 84- qcom,ratiometric: 85 Usage: optional 86 Value type: <empty> 87 Definition: Channel calibration type. 88 - For compatible property "qcom,spmi-vadc", if this property is 89 specified VADC will use the VDD reference (1.8V) and GND for 90 channel calibration. If property is not found, channel will be 91 calibrated with 0.625V and 1.25V reference channels, also 92 known as absolute calibration. 93 - For compatible property "qcom,spmi-adc5" and "qcom,spmi-adc-rev2", 94 if this property is specified VADC will use the VDD reference 95 (1.875V) and GND for channel calibration. If property is not found, 96 channel will be calibrated with 0V and 1.25V reference channels, 97 also known as absolute calibration. 98 99- qcom,hw-settle-time: 100 Usage: optional 101 Value type: <u32> 102 Definition: Time between AMUX getting configured and the ADC starting 103 conversion. The 'hw_settle_time' is an index used from valid values 104 and programmed in hardware to achieve the hardware settling delay. 105 - For compatible property "qcom,spmi-vadc" and "qcom,spmi-adc-rev2", 106 Delay = 100us * (hw_settle_time) for hw_settle_time < 11, 107 and 2ms * (hw_settle_time - 10) otherwise. 108 Valid values are: 0, 100, 200, 300, 400, 500, 600, 700, 800, 109 900 us and 1, 2, 4, 6, 8, 10 ms. 110 If property is not found, channel will use 0us. 111 - For compatible property "qcom,spmi-adc5", delay = 15us for 112 value 0, 100us * (value) for values < 11, 113 and 2ms * (value - 10) otherwise. 114 Valid values are: 15, 100, 200, 300, 400, 500, 600, 700, 800, 115 900 us and 1, 2, 4, 6, 8, 10 ms 116 Certain controller digital versions have valid values of 117 15, 100, 200, 300, 400, 500, 600, 700, 1, 2, 4, 8, 16, 32, 64, 128 ms 118 If property is not found, channel will use 15us. 119 120- qcom,avg-samples: 121 Usage: optional 122 Value type: <u32> 123 Definition: Number of samples to be used for measurement. 124 Averaging provides the option to obtain a single measurement 125 from the ADC that is an average of multiple samples. The value 126 selected is 2^(value). 127 - For compatible property "qcom,spmi-vadc", valid values 128 are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 129 If property is not found, 1 sample will be used. 130 - For compatible property "qcom,spmi-adc5" and "qcom,spmi-adc-rev2", 131 valid values are: 1, 2, 4, 8, 16 132 If property is not found, 1 sample will be used. 133 134NOTE: 135 136For compatible property "qcom,spmi-vadc" following channels, also known as 137reference point channels, are used for result calibration and their channel 138configuration nodes should be defined: 139VADC_REF_625MV and/or VADC_SPARE1(based on PMIC version) VADC_REF_1250MV, 140VADC_GND_REF and VADC_VDD_VADC. 141 142Example: 143 144#include <dt-bindings/iio/qcom,spmi-vadc.h> 145#include <linux/irq.h> 146/* ... */ 147 148 /* VADC node */ 149 pmic_vadc: vadc@3100 { 150 compatible = "qcom,spmi-vadc"; 151 reg = <0x3100>; 152 interrupts = <0x0 0x31 0x0 IRQ_TYPE_EDGE_RISING>; 153 #address-cells = <1>; 154 #size-cells = <0>; 155 #io-channel-cells = <1>; 156 io-channel-ranges; 157 158 /* Channel node */ 159 adc-chan@VADC_LR_MUX10_USB_ID { 160 reg = <VADC_LR_MUX10_USB_ID>; 161 qcom,decimation = <512>; 162 qcom,ratiometric; 163 qcom,hw-settle-time = <200>; 164 qcom,avg-samples = <1>; 165 qcom,pre-scaling = <1 3>; 166 }; 167 }; 168 169 /* IIO client node */ 170 usb { 171 io-channels = <&pmic_vadc VADC_LR_MUX10_USB_ID>; 172 io-channel-names = "vadc"; 173 }; 174