1Kernel driver da9052 2==================== 3 4Supported chips: 5 6 * Dialog Semiconductors DA9052-BC and DA9053-AA/Bx PMICs 7 8 Prefix: 'da9052' 9 10 Datasheet: Datasheet is not publicly available. 11 12Authors: David Dajun Chen <dchen@diasemi.com> 13 14Description 15----------- 16 17The DA9052/53 provides an Analogue to Digital Converter (ADC) with 10 bits 18resolution and track and hold circuitry combined with an analogue input 19multiplexer. The analogue input multiplexer will allow conversion of up to 10 20different inputs. The track and hold circuit ensures stable input voltages at 21the input of the ADC during the conversion. 22 23The ADC is used to measure the following inputs: 24 25========= =================================================================== 26Channel 0 VDDOUT - measurement of the system voltage 27Channel 1 ICH - internal battery charger current measurement 28Channel 2 TBAT - output from the battery NTC 29Channel 3 VBAT - measurement of the battery voltage 30Channel 4 ADC_IN4 - high impedance input (0 - 2.5V) 31Channel 5 ADC_IN5 - high impedance input (0 - 2.5V) 32Channel 6 ADC_IN6 - high impedance input (0 - 2.5V) 33Channel 7 XY - TSI interface to measure the X and Y voltage of the touch 34 screen resistive potentiometers 35Channel 8 Internal Tjunc. - sense (internal temp. sensor) 36Channel 9 VBBAT - measurement of the backup battery voltage 37========= =================================================================== 38 39By using sysfs attributes we can measure the system voltage VDDOUT, the battery 40charging current ICH, battery temperature TBAT, battery junction temperature 41TJUNC, battery voltage VBAT and the back up battery voltage VBBAT. 42 43Voltage Monitoring 44------------------ 45 46Voltages are sampled by a 10 bit ADC. 47 48The battery voltage is calculated as: 49 50 Milli volt = ((ADC value * 1000) / 512) + 2500 51 52The backup battery voltage is calculated as: 53 54 Milli volt = (ADC value * 2500) / 512; 55 56The voltages on ADC channels 4, 5 and 6 are calculated as: 57 58 Milli volt = (ADC value * 2500) / 1023 59 60Temperature Monitoring 61---------------------- 62 63Temperatures are sampled by a 10 bit ADC. Junction and battery temperatures 64are monitored by the ADC channels. 65 66The junction temperature is calculated: 67 68 Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8 69 70The junction temperature attribute is supported by the driver. 71 72The battery temperature is calculated: 73 74 Degree Celsius = 1 / (t1 + 1/298) - 273 75 76where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255)) 77 78Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively. 79