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authorRudolf Marek <r.marek@sh.cvut.cz>2006-09-24 14:50:57 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2006-09-28 18:31:14 -0400
commitef4c4fdb2809c84c2ed8f037ae7c96cc03992569 (patch)
tree3f370d63afef990567ff0dbaec812c3f06bad3b8 /Documentation/hwmon
parent360b9ab220aedaf346380fc2344729d9acc3b075 (diff)
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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1Kernel driver k8temp
2====================
3
4Supported chips:
5 * AMD K8 CPU
6 Prefix: 'k8temp'
7 Addresses scanned: PCI space
8 Datasheet: http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/32559.pdf
9
10Author: Rudolf Marek
11Contact: Rudolf Marek <r.marek@sh.cvut.cz>
12
13Description
14-----------
15
16This driver permits reading temperature sensor(s) embedded inside AMD K8 CPUs.
17Official documentation says that it works from revision F of K8 core, but
18in fact it seems to be implemented for all revisions of K8 except the first
19two revisions (SH-B0 and SH-B3).
20
21There can be up to four temperature sensors inside single CPU. The driver
22will auto-detect the sensors and will display only temperatures from
23implemented sensors.
24
25Mapping of /sys files is as follows:
26
27temp1_input - temperature of Core 0 and "place" 0
28temp2_input - temperature of Core 0 and "place" 1
29temp3_input - temperature of Core 1 and "place" 0
30temp4_input - temperature of Core 1 and "place" 1
31
32Temperatures are measured in degrees Celsius and measurement resolution is
331 degree C. It is expected that future CPU will have better resolution. The
34temperature is updated once a second. Valid temperatures are from -49 to
35206 degrees C.
36
37Temperature known as TCaseMax was specified for processors up to revision E.
38This temperature is defined as temperature between heat-spreader and CPU
39case, so the internal CPU temperature supplied by this driver can be higher.
40There is no easy way how to measure the temperature which will correlate
41with TCaseMax temperature.
42
43For newer revisions of CPU (rev F, socket AM2) there is a mathematically
44computed temperature called TControl, which must be lower than TControlMax.
45
46The relationship is following:
47
48temp1_input - TjOffset*2 < TControlMax,
49
50TjOffset is not yet exported by the driver, TControlMax is usually
5170 degrees C. The rule of the thumb -> CPU temperature should not cross
5260 degrees C too much.