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Diffstat (limited to 'kernel/Documentation/hwmon/da9052')
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diff --git a/kernel/Documentation/hwmon/da9052 b/kernel/Documentation/hwmon/da9052 new file mode 100644 index 000000000..5bc51346b --- /dev/null +++ b/kernel/Documentation/hwmon/da9052 @@ -0,0 +1,61 @@ +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. |