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1Kernel driver lm802==================3 4Supported chips:5 6 * National Semiconductor LM807 8 Prefix: 'lm80'9 10 Addresses scanned: I2C 0x28 - 0x2f11 12 Datasheet: Publicly available at the National Semiconductor website13 14 http://www.national.com/15 16 * National Semiconductor LM9608017 18 Prefix: 'lm96080'19 20 Addresses scanned: I2C 0x28 - 0x2f21 22 Datasheet: Publicly available at the National Semiconductor website23 24 http://www.national.com/25 26 27Authors:28 - Frodo Looijaard <frodol@dds.nl>,29 - Philip Edelbrock <phil@netroedge.com>30 31Description32-----------33 34This driver implements support for the National Semiconductor LM80.35It is described as a 'Serial Interface ACPI-Compatible Microprocessor36System Hardware Monitor'. The LM96080 is a more recent incarnation,37it is pin and register compatible, with a few additional features not38yet supported by the driver.39 40The LM80 implements one temperature sensor, two fan rotation speed sensors,41seven voltage sensors, alarms, and some miscellaneous stuff.42 43Temperatures are measured in degrees Celsius. There are two sets of limits44which operate independently. When the HOT Temperature Limit is crossed,45this will cause an alarm that will be reasserted until the temperature46drops below the HOT Hysteresis. The Overtemperature Shutdown (OS) limits47should work in the same way (but this must be checked; the datasheet48is unclear about this). Measurements are guaranteed between -55 and49+125 degrees. The current temperature measurement has a resolution of500.0625 degrees; the limits have a resolution of 1 degree.51 52Fan rotation speeds are reported in RPM (rotations per minute). An alarm is53triggered if the rotation speed has dropped below a programmable limit. Fan54readings can be divided by a programmable divider (1, 2, 4 or 8) to give55the readings more range or accuracy. Not all RPM values can accurately be56represented, so some rounding is done. With a divider of 2, the lowest57representable value is around 2600 RPM.58 59Voltage sensors (also known as IN sensors) report their values in volts.60An alarm is triggered if the voltage has crossed a programmable minimum61or maximum limit. Note that minimum in this case always means 'closest to62zero'; this is important for negative voltage measurements. All voltage63inputs can measure voltages between 0 and 2.55 volts, with a resolution64of 0.01 volt.65 66If an alarm triggers, it will remain triggered until the hardware register67is read at least once. This means that the cause for the alarm may68already have disappeared! Note that in the current implementation, all69hardware registers are read whenever any data is read (unless it is less70than 2.0 seconds since the last update). This means that you can easily71miss once-only alarms.72 73The LM80 only updates its values each 1.5 seconds; reading it more often74will do no harm, but will return 'old' values.75