Qualcomm's QPNP PMIC Voltage ADC Arbiter QPNP 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 Required properties: - compatible : should be "qcom,qpnp-vadc" for Voltage ADC device driver and "qcom,qpnp-vadc-hc" for VADC_HC voltage ADC device driver. - reg : offset and length of the PMIC Aribter register map. - address-cells : Must be one. - size-cells : Must be zero. - interrupts : The USR bank peripheral VADC interrupt. - interrupt-names : Should contain "eoc-int-en-set" for EOC, "high-thr-en-set" for high threshold interrupts and "low-thr-en-set" for low threshold interrupts. High and low threshold interrupts are to be enabled if VADC_USR needs to support recurring measurement. - qcom,adc-bit-resolution : Bit resolution of the ADC. - qcom,adc-vdd-reference : Voltage reference used by the ADC. Channel nodes NOTE: Atleast one Channel node is required. Optional properties: - qcom,vadc-poll-eoc: Use polling instead of interrupts for End of Conversion completion. - qcom,pmic-revid : Phandle pointing to the revision peripheral node. Use it to query the PMIC type and revision for applying the appropriate temperature compensation parameters. -qcom,vadc-meas-int-mode : Enable VADC_USR to handle requests to perform recurring measurements for any one supported channel along with supporting single conversion requests. - qcom,vadc-recalib-check: Add this property to check if recalibration required due to inaccuracy. - qcom,vadc-thermal-node : If present a thermal node is created and the channel is registered as part of the thermal sysfs which allows clients to use the thermal framework to set temperature thresholds and receive notification when the temperature crosses a set threshold, read temperature and enable/set trip types supported by the thermal framework. - hkadc_ldo-supply : Add this property if VADC needs to perform a Software Vote for the HKADC. - hkadc_ok-supply : Add this property if the VADC needs to perform a Software vote for the HKADC VREG_OK. - qcom,cal-val : Add this property for VADC_HC voltage ADC device to select from the following unsigned int. If the property is not present the default calibration value of using the timer value is chosen. 0 : The calibration values used for measurement are from a timer. 1 : Forces a fresh measurement for calibration values at the same time measurement is taken. Client required property: - qcom,-vadc : The phandle to the corresponding vadc device. The consumer name passed to the driver when calling qpnp_get_vadc() is used to associate the client with the corresponding device. Required properties: - label : Channel name used for sysfs entry. - reg : AMUX channel number. - qcom,decimation : Sampling rate to use for the individual channel measurement. Select from following unsigned int for Voltage ADC device. 0 : 512 1 : 1K 2 : 2K 3 : 4K Select from following unsigned int for VADC_HC voltage ADC device. 0 : 256 1 : 512 2 : 1024 - qcom,pre-div-channel-scaling : Pre-div used for the channel before the signal is being measured. Some of the AMUX channels support dividing the signal from a predetermined ratio. The configuration for this node is to know the pre-determined ratio and use it for post scaling. Select from the following unsinged int. 0 : {1, 1} 1 : {1, 3} 2 : {1, 4} 3 : {1, 6} 4 : {1, 20} 5 : {1, 8} 6 : {10, 81} 7 : {1, 10} - qcom,calibration-type : Reference voltage to use for channel calibration. Channel calibration is dependendent on the channel. Certain channels like XO_THERM, BATT_THERM use ratiometric calibration. Most other channels fall under absolute calibration. Select from the following strings. "absolute" : Uses the 625mv and 1.25V reference channels. "ratiometric" : Uses the reference Voltage/GND for calibration. - qcom,scale-function : Scaling function used to convert raw ADC code to units specific to a given channel. Select from the following unsigned int. 0 : Default scaling to convert raw adc code to voltage. 1 : Conversion to temperature based on btm parameters. 2 : Returns result in degC for 100k pull-up. 3 : Returns current across 0.1 ohm resistor. 4 : Returns XO thermistor voltage in degree's Centigrade. 5 : Returns result in degC for 150k pull-up. 9 : Conversion to temperature based on -15~55 allowable battery charging tempeature setting for btm parameters. - qcom,hw-settle-time : Settling period for the channel before ADC read. Select from the following unsigned int. 0 : 0us 1 : 100us 2 : 200us 3 : 300us 4 : 400us 5 : 500us 6 : 600us 7 : 700us 8 : 800us 9 : 900us 0xa : 1ms 0xb : 2ms 0xc : 4ms 0xd : 6ms 0xe : 8ms 0xf : 10ms - qcom,fast-avg-setup : Average 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) Select from the following unsigned int for Voltage ADC device. 0 : 1 1 : 2 2 : 4 3 : 8 4 : 16 5 : 32 6 : 64 7 : 128 8 : 256 Select from the following unsigned int for VADC_HC ADC device. 0 : 1 1 : 2 2 : 4 3 : 8 4 : 16 Example: /* Main Node */ qcom,vadc@3100 { compatible = "qcom,qpnp-vadc"; reg = <0x3100 0x100>; #address-cells = <1>; #size-cells = <0>; interrupts = <0x0 0x31 0x0>; interrupt-names = "eoc-int-en-set"; qcom,adc-bit-resolution = <15>; qcom,adc-vdd-reference = <1800>; /* Channel Node */ chan@0 { label = "usb_in"; reg = <0>; qcom,decimation = <0>; qcom,pre-div-channel-scaling = <4>; qcom,calibration-type = "absolute"; qcom,scale-function = <0>; qcom,hw-settle-time = <0>; qcom,fast-avg-setup = <0>; }; }; Client device example: /* Add to the clients node that needs the VADC channel A/D */ client_node { qcom,client-vadc = <&pm8941_vadc>; }; /* Clients have an option of measuring an analog signal through an MPP. MPP block is not part of the VADC block but is an individual PMIC block that has an option to support clients to configure an MPP as an analog input which can be routed through one of the VADC pre-mux inputs. Here is an example of how to configure an MPP as an analog input */ /* Configure MPP4 as an Analog input to AMUX8 and read from channel 0x23 */ /* MPP DT configuration in the platform DT file*/ mpp@a300 { /* MPP 4 */ qcom,mode = <4>; /* AIN input */ qcom,invert = <1>; /* Enable MPP */ qcom,ain-route = <3>; /* AMUX 8 */ qcom,master-en = <1>; qcom,src-sel = <0>; /* Function constant */ }; /* VADC Channel configuration */ chan@23 { label = "mpp4_div3"; reg = <0x23>; qcom,decimation = <0>; qcom,pre-div-channel-scaling = <1>; qcom,calibration-type = "absolute"; qcom,scale-function = <0>; qcom,hw-settle-time = <0>; qcom,fast-avg-setup = <0>; };