1*4882a593SmuzhiyunKernel driver lm80 2*4882a593Smuzhiyun================== 3*4882a593Smuzhiyun 4*4882a593SmuzhiyunSupported chips: 5*4882a593Smuzhiyun 6*4882a593Smuzhiyun * National Semiconductor LM80 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun Prefix: 'lm80' 9*4882a593Smuzhiyun 10*4882a593Smuzhiyun Addresses scanned: I2C 0x28 - 0x2f 11*4882a593Smuzhiyun 12*4882a593Smuzhiyun Datasheet: Publicly available at the National Semiconductor website 13*4882a593Smuzhiyun 14*4882a593Smuzhiyun http://www.national.com/ 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun * National Semiconductor LM96080 17*4882a593Smuzhiyun 18*4882a593Smuzhiyun Prefix: 'lm96080' 19*4882a593Smuzhiyun 20*4882a593Smuzhiyun Addresses scanned: I2C 0x28 - 0x2f 21*4882a593Smuzhiyun 22*4882a593Smuzhiyun Datasheet: Publicly available at the National Semiconductor website 23*4882a593Smuzhiyun 24*4882a593Smuzhiyun http://www.national.com/ 25*4882a593Smuzhiyun 26*4882a593Smuzhiyun 27*4882a593SmuzhiyunAuthors: 28*4882a593Smuzhiyun - Frodo Looijaard <frodol@dds.nl>, 29*4882a593Smuzhiyun - Philip Edelbrock <phil@netroedge.com> 30*4882a593Smuzhiyun 31*4882a593SmuzhiyunDescription 32*4882a593Smuzhiyun----------- 33*4882a593Smuzhiyun 34*4882a593SmuzhiyunThis driver implements support for the National Semiconductor LM80. 35*4882a593SmuzhiyunIt is described as a 'Serial Interface ACPI-Compatible Microprocessor 36*4882a593SmuzhiyunSystem Hardware Monitor'. The LM96080 is a more recent incarnation, 37*4882a593Smuzhiyunit is pin and register compatible, with a few additional features not 38*4882a593Smuzhiyunyet supported by the driver. 39*4882a593Smuzhiyun 40*4882a593SmuzhiyunThe LM80 implements one temperature sensor, two fan rotation speed sensors, 41*4882a593Smuzhiyunseven voltage sensors, alarms, and some miscellaneous stuff. 42*4882a593Smuzhiyun 43*4882a593SmuzhiyunTemperatures are measured in degrees Celsius. There are two sets of limits 44*4882a593Smuzhiyunwhich operate independently. When the HOT Temperature Limit is crossed, 45*4882a593Smuzhiyunthis will cause an alarm that will be reasserted until the temperature 46*4882a593Smuzhiyundrops below the HOT Hysteresis. The Overtemperature Shutdown (OS) limits 47*4882a593Smuzhiyunshould work in the same way (but this must be checked; the datasheet 48*4882a593Smuzhiyunis unclear about this). Measurements are guaranteed between -55 and 49*4882a593Smuzhiyun+125 degrees. The current temperature measurement has a resolution of 50*4882a593Smuzhiyun0.0625 degrees; the limits have a resolution of 1 degree. 51*4882a593Smuzhiyun 52*4882a593SmuzhiyunFan rotation speeds are reported in RPM (rotations per minute). An alarm is 53*4882a593Smuzhiyuntriggered if the rotation speed has dropped below a programmable limit. Fan 54*4882a593Smuzhiyunreadings can be divided by a programmable divider (1, 2, 4 or 8) to give 55*4882a593Smuzhiyunthe readings more range or accuracy. Not all RPM values can accurately be 56*4882a593Smuzhiyunrepresented, so some rounding is done. With a divider of 2, the lowest 57*4882a593Smuzhiyunrepresentable value is around 2600 RPM. 58*4882a593Smuzhiyun 59*4882a593SmuzhiyunVoltage sensors (also known as IN sensors) report their values in volts. 60*4882a593SmuzhiyunAn alarm is triggered if the voltage has crossed a programmable minimum 61*4882a593Smuzhiyunor maximum limit. Note that minimum in this case always means 'closest to 62*4882a593Smuzhiyunzero'; this is important for negative voltage measurements. All voltage 63*4882a593Smuzhiyuninputs can measure voltages between 0 and 2.55 volts, with a resolution 64*4882a593Smuzhiyunof 0.01 volt. 65*4882a593Smuzhiyun 66*4882a593SmuzhiyunIf an alarm triggers, it will remain triggered until the hardware register 67*4882a593Smuzhiyunis read at least once. This means that the cause for the alarm may 68*4882a593Smuzhiyunalready have disappeared! Note that in the current implementation, all 69*4882a593Smuzhiyunhardware registers are read whenever any data is read (unless it is less 70*4882a593Smuzhiyunthan 2.0 seconds since the last update). This means that you can easily 71*4882a593Smuzhiyunmiss once-only alarms. 72*4882a593Smuzhiyun 73*4882a593SmuzhiyunThe LM80 only updates its values each 1.5 seconds; reading it more often 74*4882a593Smuzhiyunwill do no harm, but will return 'old' values. 75