1*4882a593SmuzhiyunKernel driver adc128d818 2*4882a593Smuzhiyun======================== 3*4882a593Smuzhiyun 4*4882a593SmuzhiyunSupported chips: 5*4882a593Smuzhiyun 6*4882a593Smuzhiyun * Texas Instruments ADC818D818 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun Prefix: 'adc818d818' 9*4882a593Smuzhiyun 10*4882a593Smuzhiyun Addresses scanned: I2C 0x1d, 0x1e, 0x1f, 0x2d, 0x2e, 0x2f 11*4882a593Smuzhiyun 12*4882a593Smuzhiyun Datasheet: Publicly available at the TI website https://www.ti.com/ 13*4882a593Smuzhiyun 14*4882a593SmuzhiyunAuthor: Guenter Roeck 15*4882a593Smuzhiyun 16*4882a593SmuzhiyunDescription 17*4882a593Smuzhiyun----------- 18*4882a593Smuzhiyun 19*4882a593SmuzhiyunThis driver implements support for the Texas Instruments ADC128D818. 20*4882a593SmuzhiyunIt is described as 'ADC System Monitor with Temperature Sensor'. 21*4882a593Smuzhiyun 22*4882a593SmuzhiyunThe ADC128D818 implements one temperature sensor and seven voltage sensors. 23*4882a593Smuzhiyun 24*4882a593SmuzhiyunTemperatures are measured in degrees Celsius. There is one set of limits. 25*4882a593SmuzhiyunWhen the HOT Temperature Limit is crossed, this will cause an alarm that will 26*4882a593Smuzhiyunbe reasserted until the temperature drops below the HOT Hysteresis. 27*4882a593SmuzhiyunMeasurements are guaranteed between -55 and +125 degrees. The temperature 28*4882a593Smuzhiyunmeasurement has a resolution of 0.5 degrees; the limits have a resolution 29*4882a593Smuzhiyunof 1 degree. 30*4882a593Smuzhiyun 31*4882a593SmuzhiyunVoltage sensors (also known as IN sensors) report their values in volts. 32*4882a593SmuzhiyunAn alarm is triggered if the voltage has crossed a programmable minimum 33*4882a593Smuzhiyunor maximum limit. Note that minimum in this case always means 'closest to 34*4882a593Smuzhiyunzero'; this is important for negative voltage measurements. All voltage 35*4882a593Smuzhiyuninputs can measure voltages between 0 and 2.55 volts, with a resolution 36*4882a593Smuzhiyunof 0.625 mV. 37*4882a593Smuzhiyun 38*4882a593SmuzhiyunIf an alarm triggers, it will remain triggered until the hardware register 39*4882a593Smuzhiyunis read at least once. This means that the cause for the alarm may 40*4882a593Smuzhiyunalready have disappeared by the time the alarm is read. The driver 41*4882a593Smuzhiyuncaches the alarm status for each sensor until it is at least reported 42*4882a593Smuzhiyunonce, to ensure that alarms are reported to user space. 43*4882a593Smuzhiyun 44*4882a593SmuzhiyunThe ADC128D818 only updates its values approximately once per second; 45*4882a593Smuzhiyunreading it more often will do no harm, but will return 'old' values. 46*4882a593Smuzhiyun 47*4882a593SmuzhiyunIn addition to the scanned address list, the chip can also be configured for 48*4882a593Smuzhiyunaddresses 0x35 to 0x37. Those addresses are not scanned. You have to instantiate 49*4882a593Smuzhiyunthe driver explicitly if the chip is configured for any of those addresses in 50*4882a593Smuzhiyunyour system. 51