forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
74 lines
2.8 KiB
74 lines
2.8 KiB
Kernel driver lm80 |
|
================== |
|
|
|
Supported chips: |
|
|
|
* National Semiconductor LM80 |
|
|
|
Prefix: 'lm80' |
|
|
|
Addresses scanned: I2C 0x28 - 0x2f |
|
|
|
Datasheet: Publicly available at the National Semiconductor website |
|
|
|
http://www.national.com/ |
|
|
|
* National Semiconductor LM96080 |
|
|
|
Prefix: 'lm96080' |
|
|
|
Addresses scanned: I2C 0x28 - 0x2f |
|
|
|
Datasheet: Publicly available at the National Semiconductor website |
|
|
|
http://www.national.com/ |
|
|
|
|
|
Authors: |
|
- Frodo Looijaard <[email protected]>, |
|
- Philip Edelbrock <[email protected]> |
|
|
|
Description |
|
----------- |
|
|
|
This driver implements support for the National Semiconductor LM80. |
|
It is described as a 'Serial Interface ACPI-Compatible Microprocessor |
|
System Hardware Monitor'. The LM96080 is a more recent incarnation, |
|
it is pin and register compatible, with a few additional features not |
|
yet supported by the driver. |
|
|
|
The LM80 implements one temperature sensor, two fan rotation speed sensors, |
|
seven voltage sensors, alarms, and some miscellaneous stuff. |
|
|
|
Temperatures are measured in degrees Celsius. There are two sets of limits |
|
which operate independently. When the HOT Temperature Limit is crossed, |
|
this will cause an alarm that will be reasserted until the temperature |
|
drops below the HOT Hysteresis. The Overtemperature Shutdown (OS) limits |
|
should work in the same way (but this must be checked; the datasheet |
|
is unclear about this). Measurements are guaranteed between -55 and |
|
+125 degrees. The current temperature measurement has a resolution of |
|
0.0625 degrees; the limits have a resolution of 1 degree. |
|
|
|
Fan rotation speeds are reported in RPM (rotations per minute). An alarm is |
|
triggered if the rotation speed has dropped below a programmable limit. Fan |
|
readings can be divided by a programmable divider (1, 2, 4 or 8) to give |
|
the readings more range or accuracy. Not all RPM values can accurately be |
|
represented, so some rounding is done. With a divider of 2, the lowest |
|
representable value is around 2600 RPM. |
|
|
|
Voltage sensors (also known as IN sensors) report their values in volts. |
|
An alarm is triggered if the voltage has crossed a programmable minimum |
|
or maximum limit. Note that minimum in this case always means 'closest to |
|
zero'; this is important for negative voltage measurements. All voltage |
|
inputs can measure voltages between 0 and 2.55 volts, with a resolution |
|
of 0.01 volt. |
|
|
|
If an alarm triggers, it will remain triggered until the hardware register |
|
is read at least once. This means that the cause for the alarm may |
|
already have disappeared! Note that in the current implementation, all |
|
hardware registers are read whenever any data is read (unless it is less |
|
than 2.0 seconds since the last update). This means that you can easily |
|
miss once-only alarms. |
|
|
|
The LM80 only updates its values each 1.5 seconds; reading it more often |
|
will do no harm, but will return 'old' values.
|
|
|