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k8temp: Add documentation 

k8temp: Add documentation

Add promised documentation for the k8temp driver.

Signed-off-by: Rudolf Marek <r.marek@sh.cvut.cz>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Rudolf Marek 2006-09-24 20:50:57 +02:00 committed by Greg Kroah-Hartman
parent 360b9ab220
commit ef4c4fdb28
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Kernel driver k8temp
====================
Supported chips:
* AMD K8 CPU
Prefix: 'k8temp'
Addresses scanned: PCI space
Datasheet: http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/32559.pdf
Author: Rudolf Marek
Contact: Rudolf Marek <r.marek@sh.cvut.cz>
Description
-----------
This driver permits reading temperature sensor(s) embedded inside AMD K8 CPUs.
Official documentation says that it works from revision F of K8 core, but
in fact it seems to be implemented for all revisions of K8 except the first
two revisions (SH-B0 and SH-B3).
There can be up to four temperature sensors inside single CPU. The driver
will auto-detect the sensors and will display only temperatures from
implemented sensors.
Mapping of /sys files is as follows:
temp1_input - temperature of Core 0 and "place" 0
temp2_input - temperature of Core 0 and "place" 1
temp3_input - temperature of Core 1 and "place" 0
temp4_input - temperature of Core 1 and "place" 1
Temperatures are measured in degrees Celsius and measurement resolution is
1 degree C. It is expected that future CPU will have better resolution. The
temperature is updated once a second. Valid temperatures are from -49 to
206 degrees C.
Temperature known as TCaseMax was specified for processors up to revision E.
This temperature is defined as temperature between heat-spreader and CPU
case, so the internal CPU temperature supplied by this driver can be higher.
There is no easy way how to measure the temperature which will correlate
with TCaseMax temperature.
For newer revisions of CPU (rev F, socket AM2) there is a mathematically
computed temperature called TControl, which must be lower than TControlMax.
The relationship is following:
temp1_input - TjOffset*2 < TControlMax,
TjOffset is not yet exported by the driver, TControlMax is usually
70 degrees C. The rule of the thumb -> CPU temperature should not cross
60 degrees C too much.