diff options
Diffstat (limited to 'Documentation/i2c/chips/lm78')
| -rw-r--r-- | Documentation/i2c/chips/lm78 | 82 |
1 files changed, 0 insertions, 82 deletions
diff --git a/Documentation/i2c/chips/lm78 b/Documentation/i2c/chips/lm78 deleted file mode 100644 index 357086ed7f64..000000000000 --- a/Documentation/i2c/chips/lm78 +++ /dev/null @@ -1,82 +0,0 @@ -Kernel driver lm78 -================== - -Supported chips: - * National Semiconductor LM78 - Prefix: 'lm78' - Addresses scanned: I2C 0x20 - 0x2f, ISA 0x290 (8 I/O ports) - Datasheet: Publicly available at the National Semiconductor website - http://www.national.com/ - * National Semiconductor LM78-J - Prefix: 'lm78-j' - Addresses scanned: I2C 0x20 - 0x2f, ISA 0x290 (8 I/O ports) - Datasheet: Publicly available at the National Semiconductor website - http://www.national.com/ - * National Semiconductor LM79 - Prefix: 'lm79' - Addresses scanned: I2C 0x20 - 0x2f, ISA 0x290 (8 I/O ports) - Datasheet: Publicly available at the National Semiconductor website - http://www.national.com/ - -Author: Frodo Looijaard <frodol@dds.nl> - -Description ------------ - -This driver implements support for the National Semiconductor LM78, LM78-J -and LM79. They are described as 'Microprocessor System Hardware Monitors'. - -There is almost no difference between the three supported chips. Functionally, -the LM78 and LM78-J are exactly identical. The LM79 has one more VID line, -which is used to report the lower voltages newer Pentium processors use. -From here on, LM7* means either of these three types. - -The LM7* implements one temperature sensor, three fan rotation speed sensors, -seven voltage sensors, VID lines, alarms, and some miscellaneous stuff. - -Temperatures are measured in degrees Celsius. An alarm is triggered once -when the Overtemperature Shutdown limit is crossed; it is triggered again -as soon as it drops below the Hysteresis value. A more useful behavior -can be found by setting the Hysteresis value to +127 degrees Celsius; in -this case, alarms are issued during all the time when the actual temperature -is above the Overtemperature Shutdown value. Measurements are guaranteed -between -55 and +125 degrees, with 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 4.08 volts, with a resolution -of 0.016 volt. - -The VID lines encode the core voltage value: the voltage level your processor -should work with. This is hardcoded by the mainboard and/or processor itself. -It is a value in volts. When it is unconnected, you will often find the -value 3.50 V here. - -In addition to the alarms described above, there are a couple of additional -ones. There is a BTI alarm, which gets triggered when an external chip has -crossed its limits. Usually, this is connected to all LM75 chips; if at -least one crosses its limits, this bit gets set. The CHAS alarm triggers -if your computer case is open. The FIFO alarms should never trigger; it -indicates an internal error. The SMI_IN alarm indicates some other chip -has triggered an SMI interrupt. As we do not use SMI interrupts at all, -this condition usually indicates there is a problem with some other -device. - -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 1.5 seconds since the last update). This means that you can easily -miss once-only alarms. - -The LM7* only updates its values each 1.5 seconds; reading it more often -will do no harm, but will return 'old' values. |