mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-04 11:56:50 +07:00
ef4c4fdb28
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>
53 lines
1.9 KiB
Plaintext
53 lines
1.9 KiB
Plaintext
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.
|