projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / blame
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|---|---|---|
| ef4c4fdb RM |
1 | Kernel driver k8temp |
| 2 | ==================== | |
| 3 | ||
| 4 | Supported 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 | ||
| 10 | Author: Rudolf Marek | |
| 11 | Contact: Rudolf Marek <r.marek@sh.cvut.cz> | |
| 12 | ||
| 13 | Description | |
| 14 | ----------- | |
| 15 | ||
| 16 | This driver permits reading temperature sensor(s) embedded inside AMD K8 CPUs. | |
| 17 | Official documentation says that it works from revision F of K8 core, but | |
| 18 | in fact it seems to be implemented for all revisions of K8 except the first | |
| 19 | two revisions (SH-B0 and SH-B3). | |
| 20 | ||
| 21 | There can be up to four temperature sensors inside single CPU. The driver | |
| 22 | will auto-detect the sensors and will display only temperatures from | |
| 23 | implemented sensors. | |
| 24 | ||
| 25 | Mapping of /sys files is as follows: | |
| 26 | ||
| 27 | temp1_input - temperature of Core 0 and "place" 0 | |
| 28 | temp2_input - temperature of Core 0 and "place" 1 | |
| 29 | temp3_input - temperature of Core 1 and "place" 0 | |
| 30 | temp4_input - temperature of Core 1 and "place" 1 | |
| 31 | ||
| 32 | Temperatures are measured in degrees Celsius and measurement resolution is | |
| 33 | 1 degree C. It is expected that future CPU will have better resolution. The | |
| 34 | temperature is updated once a second. Valid temperatures are from -49 to | |
| 35 | 206 degrees C. | |
| 36 | ||
| 37 | Temperature known as TCaseMax was specified for processors up to revision E. | |
| 38 | This temperature is defined as temperature between heat-spreader and CPU | |
| 39 | case, so the internal CPU temperature supplied by this driver can be higher. | |
| 40 | There is no easy way how to measure the temperature which will correlate | |
| 41 | with TCaseMax temperature. | |
| 42 | ||
| 43 | For newer revisions of CPU (rev F, socket AM2) there is a mathematically | |
| 44 | computed temperature called TControl, which must be lower than TControlMax. | |
| 45 | ||
| 46 | The relationship is following: | |
| 47 | ||
| 48 | temp1_input - TjOffset*2 < TControlMax, | |
| 49 | ||
| 50 | TjOffset is not yet exported by the driver, TControlMax is usually | |
| 51 | 70 degrees C. The rule of the thumb -> CPU temperature should not cross | |
| 52 | 60 degrees C too much. |