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
2.9 KiB
74 lines
2.9 KiB
20 years ago
|
Kernel driver lm87
|
||
|
|
==================
|
||
|
|
|
||
|
|
Supported chips:
|
||
|
|
* National Semiconductor LM87
|
||
|
|
Prefix: 'lm87'
|
||
|
|
Addresses scanned: I2C 0x2c - 0x2f
|
||
|
|
Datasheet: http://www.national.com/pf/LM/LM87.html
|
||
|
|
|
||
|
|
Authors:
|
||
|
|
Frodo Looijaard <frodol@dds.nl>,
|
||
|
|
Philip Edelbrock <phil@netroedge.com>,
|
||
|
|
Mark Studebaker <mdsxyz123@yahoo.com>,
|
||
|
|
Stephen Rousset <stephen.rousset@rocketlogix.com>,
|
||
|
|
Dan Eaton <dan.eaton@rocketlogix.com>,
|
||
|
|
Jean Delvare <khali@linux-fr.org>,
|
||
|
|
Original 2.6 port Jeff Oliver
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
This driver implements support for the National Semiconductor LM87.
|
||
|
|
|
||
|
|
The LM87 implements up to three temperature sensors, up to two fan
|
||
|
|
rotation speed sensors, up to seven voltage sensors, alarms, and some
|
||
|
|
miscellaneous stuff.
|
||
|
|
|
||
|
|
Temperatures are measured in degrees Celsius. Each input has a high
|
||
|
|
and low alarm settings. A high limit produces an alarm when the value
|
||
|
|
goes above it, and an alarm is also produced when the value goes below
|
||
|
|
the low limit.
|
||
|
|
|
||
|
|
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.
|
||
|
|
|
||
|
|
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 1.0 seconds since the last update). This means that you can easily
|
||
|
|
miss once-only alarms.
|
||
|
|
|
||
|
|
The lm87 driver only updates its values each 1.0 seconds; reading it more
|
||
|
|
often will do no harm, but will return 'old' values.
|
||
|
|
|
||
|
|
|
||
|
|
Hardware Configurations
|
||
|
|
-----------------------
|
||
|
|
|
||
|
|
The LM87 has four pins which can serve one of two possible functions,
|
||
|
|
depending on the hardware configuration.
|
||
|
|
|
||
|
|
Some functions share pins, so not all functions are available at the same
|
||
|
|
time. Which are depends on the hardware setup. This driver assumes that
|
||
|
|
the BIOS configured the chip correctly. In that respect, it differs from
|
||
|
|
the original driver (from lm_sensors for Linux 2.4), which would force the
|
||
|
|
LM87 to an arbitrary, compile-time chosen mode, regardless of the actual
|
||
|
|
chipset wiring.
|
||
|
|
|
||
|
|
For reference, here is the list of exclusive functions:
|
||
|
|
- in0+in5 (default) or temp3
|
||
|
|
- fan1 (default) or in6
|
||
|
|
- fan2 (default) or in7
|
||
|
|
- VID lines (default) or IRQ lines (not handled by this driver)
|