| 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 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". |
| - 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. |
| |
| Client required property: |
| - qcom,<consumer name>-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. |
| 0 : 512 |
| 1 : 1K |
| 2 : 2K |
| 3 : 4K |
| - 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} |
| - 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. |
| 0 : 1 |
| 1 : 2 |
| 2 : 4 |
| 3 : 8 |
| 4 : 16 |
| 5 : 32 |
| 6 : 64 |
| 7 : 128 |
| 8 : 256 |
| |
| 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>; |
| }; |