114 lines
4.0 KiB
Plaintext
114 lines
4.0 KiB
Plaintext
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Qualcomm's QPNP PMIC current ADC driver
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QPNP PMIC current ADC (IADC) provides interface to clients to read
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current. A 16 bit ADC is used for current measurements. There are multiple
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peripherals to the IADC and the scope of the driver is to provide interface
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for the USR peripheral of the IADC.
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IADC node
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Required properties:
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- compatible : should be "qcom,qpnp-iadc" for Current ADC driver.
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- reg : offset and length of the PMIC Aribter register map.
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- address-cells : Must be one.
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- size-cells : Must be zero.
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- interrupts : The USR bank peripheral IADC interrupt.
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- interrupt-names : Should contain "eoc-int-en-set".
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- qcom,adc-bit-resolution : Bit resolution of the ADC.
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- qcom,adc-vdd-reference : Voltage reference used by the ADC.
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Optional properties:
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- qcom,rsense : Use this property when external rsense should be used
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for current calculation and specify the units in nano-ohms.
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- qcom,iadc-poll-eoc: Use polling instead of interrupts for End of Conversion completion.
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Channel node
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NOTE: Atleast one Channel node is required.
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Required properties:
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- label : Channel name used for sysfs entry.
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- reg : AMUX channel number.
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- qcom,channel-num : Channel number associated to the AMUX input.
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- qcom,decimation : Sampling rate to use for the individual channel measurement.
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Select from the following unsigned int.
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0 : 512
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1 : 1K
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2 : 2K
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3 : 4K
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- qcom,pre-div-channel-scaling : Pre-div used for the channel before the signal
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is being measured.
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- qcom,calibration-type : Calibration point values vary with temperature.
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For improved accuracy fresh gain and offset point values
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can be used for calibration. Reading fresh values for ever
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read affects the reading time. Application can use the historic
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values used from the trim register values.
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Select from the following strings.
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"absolute" : Uses TRIM gain and offset values for calibration.
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"ratiometric" : Calculate the gain and offset calibration value when an ADC
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request is issued.
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- qcom,scale-function : Scaling fuction used to convert raw ADC code to units specific to
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a given channel.
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Select from the following unsigned int.
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0 : Default scaling to convert raw adc code to voltage.
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1 : Conversion to temperature based on btm parameters.
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2 : Returns result in milli degree's Centigrade.
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3 : Returns current across 0.1 ohm resistor.
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4 : Returns XO thermistor voltage in degree's Centigrade.
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- qcom,hw-settle-time : Settling period for the channel before ADC read.
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Select from the following unsigned int.
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0 : 0us
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1 : 100us
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2 : 200us
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3 : 300us
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4 : 400us
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5 : 500us
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6 : 600us
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7 : 700us
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8 : 800us
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9 : 900us
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0xa : 1ms
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0xb : 2ms
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0xc : 4ms
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0xd : 6ms
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0xe : 8ms
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0xf : 10ms
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- qcom,fast-avg-setup : Average number of samples to be used for measurement. Fast averaging
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provides the option to obtain a single measurement from the ADC that
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is an average of multiple samples. The value selected is 2^(value)
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Select from the following unsigned int.
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0 : 1
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1 : 2
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2 : 4
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3 : 8
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4 : 16
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5 : 32
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6 : 64
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7 : 128
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8 : 256
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Example:
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/* Main Node */
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qcom,iadc@3200 {
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compatible = "qcom,qpnp-iadc";
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reg = <0x3200 0x100>;
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#address-cells = <1>;
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#size-cells = <0>;
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interrupts = <0 0x36 0>;
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interrupt-names = "eoc-int-en-set";
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qcom,adc-bit-resolution = <16>;
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qcom,adc-vdd-reference = <1800>;
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qcom,rsense = <1500>;
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/* Channel Node */
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chan@0 = {
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label = "rsense";
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reg = <0>;
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qcom,decimation = <0>;
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qcom,pre-div-channel-scaling = <20>;
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qcom,calibration-type = "fresh";
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qcom,scale-function = <0>;
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qcom,hw-settle-time = <0>;
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qcom,fast-avg-setup = <0>;
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};
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};
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