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diff --git a/Documentation/hwmon/da9052.rst b/Documentation/hwmon/da9052.rst new file mode 100644 index 000000000000..c1c0f1f08904 --- /dev/null +++ b/Documentation/hwmon/da9052.rst @@ -0,0 +1,78 @@ +Kernel driver da9052 +==================== + +Supported chips: + + * Dialog Semiconductors DA9052-BC and DA9053-AA/Bx PMICs + + Prefix: 'da9052' + + Datasheet: Datasheet is not publicly available. + +Authors: David Dajun Chen <dchen@diasemi.com> + +Description +----------- + +The DA9052/53 provides an Analogue to Digital Converter (ADC) with 10 bits +resolution and track and hold circuitry combined with an analogue input +multiplexer. The analogue input multiplexer will allow conversion of up to 10 +different inputs. The track and hold circuit ensures stable input voltages at +the input of the ADC during the conversion. + +The ADC is used to measure the following inputs: + +========= =================================================================== +Channel 0 VDDOUT - measurement of the system voltage +Channel 1 ICH - internal battery charger current measurement +Channel 2 TBAT - output from the battery NTC +Channel 3 VBAT - measurement of the battery voltage +Channel 4 ADC_IN4 - high impedance input (0 - 2.5V) +Channel 5 ADC_IN5 - high impedance input (0 - 2.5V) +Channel 6 ADC_IN6 - high impedance input (0 - 2.5V) +Channel 7 XY - TSI interface to measure the X and Y voltage of the touch + screen resistive potentiometers +Channel 8 Internal Tjunc. - sense (internal temp. sensor) +Channel 9 VBBAT - measurement of the backup battery voltage +========= =================================================================== + +By using sysfs attributes we can measure the system voltage VDDOUT, the battery +charging current ICH, battery temperature TBAT, battery junction temperature +TJUNC, battery voltage VBAT and the back up battery voltage VBBAT. + +Voltage Monitoring +------------------ + +Voltages are sampled by a 10 bit ADC. + +The battery voltage is calculated as: + + Milli volt = ((ADC value * 1000) / 512) + 2500 + +The backup battery voltage is calculated as: + + Milli volt = (ADC value * 2500) / 512; + +The voltages on ADC channels 4, 5 and 6 are calculated as: + + Milli volt = (ADC value * 2500) / 1023 + +Temperature Monitoring +---------------------- + +Temperatures are sampled by a 10 bit ADC. Junction and battery temperatures +are monitored by the ADC channels. + +The junction temperature is calculated: + + Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8 + +The junction temperature attribute is supported by the driver. + +The battery temperature is calculated: + + Degree Celsius = 1 / (t1 + 1/298) - 273 + +where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255)) + +Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively. |