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Commit | Line | Data |
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1 | Kernel driver pc87427 | |
2 | ===================== | |
3 | ||
4 | Supported chips: | |
5 | * National Semiconductor PC87427 | |
6 | Prefix: 'pc87427' | |
7 | Addresses scanned: none, address read from Super I/O config space | |
8 | Datasheet: No longer available | |
9 | ||
10 | Author: Jean Delvare <jdelvare@suse.de> | |
11 | ||
12 | Thanks to Amir Habibi at Candelis for setting up a test system, and to | |
13 | Michael Kress for testing several iterations of this driver. | |
14 | ||
15 | ||
16 | Description | |
17 | ----------- | |
18 | ||
19 | The National Semiconductor Super I/O chip includes complete hardware | |
20 | monitoring capabilities. It can monitor up to 18 voltages, 8 fans and | |
21 | 6 temperature sensors. Only the fans and temperatures are supported at | |
22 | the moment, voltages aren't. | |
23 | ||
24 | This chip also has fan controlling features (up to 4 PWM outputs), | |
25 | which are partly supported by this driver. | |
26 | ||
27 | The driver assumes that no more than one chip is present, which seems | |
28 | reasonable. | |
29 | ||
30 | ||
31 | Fan Monitoring | |
32 | -------------- | |
33 | ||
34 | Fan rotation speeds are reported as 14-bit values from a gated clock | |
35 | signal. Speeds down to 83 RPM can be measured. | |
36 | ||
37 | An alarm is triggered if the rotation speed drops below a programmable | |
38 | limit. Another alarm is triggered if the speed is too low to be measured | |
39 | (including stalled or missing fan). | |
40 | ||
41 | ||
42 | Fan Speed Control | |
43 | ----------------- | |
44 | ||
45 | Fan speed can be controlled by PWM outputs. There are 4 possible modes: | |
46 | always off, always on, manual and automatic. The latter isn't supported | |
47 | by the driver: you can only return to that mode if it was the original | |
48 | setting, and the configuration interface is missing. | |
49 | ||
50 | ||
51 | Temperature Monitoring | |
52 | ---------------------- | |
53 | ||
54 | The PC87427 relies on external sensors (following the SensorPath | |
55 | standard), so the resolution and range depend on the type of sensor | |
56 | connected. The integer part can be 8-bit or 9-bit, and can be signed or | |
57 | not. I couldn't find a way to figure out the external sensor data | |
58 | temperature format, so user-space adjustment (typically by a factor 2) | |
59 | may be required. |