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ba224e2c JD |
1 | Kernel driver pc87427 |
2 | ===================== | |
3 | ||
4 | Supported chips: | |
b04f2f7d | 5 | |
ba224e2c | 6 | * National Semiconductor PC87427 |
b04f2f7d | 7 | |
ba224e2c | 8 | Prefix: 'pc87427' |
b04f2f7d | 9 | |
ba224e2c | 10 | Addresses scanned: none, address read from Super I/O config space |
b04f2f7d | 11 | |
6aa693b8 | 12 | Datasheet: No longer available |
ba224e2c | 13 | |
7c81c60f | 14 | Author: Jean Delvare <jdelvare@suse.de> |
ba224e2c JD |
15 | |
16 | Thanks to Amir Habibi at Candelis for setting up a test system, and to | |
17 | Michael Kress for testing several iterations of this driver. | |
18 | ||
19 | ||
20 | Description | |
21 | ----------- | |
22 | ||
23 | The National Semiconductor Super I/O chip includes complete hardware | |
24 | monitoring capabilities. It can monitor up to 18 voltages, 8 fans and | |
008e5f33 JD |
25 | 6 temperature sensors. Only the fans and temperatures are supported at |
26 | the moment, voltages aren't. | |
ba224e2c | 27 | |
328716bc JD |
28 | This chip also has fan controlling features (up to 4 PWM outputs), |
29 | which are partly supported by this driver. | |
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30 | |
31 | The driver assumes that no more than one chip is present, which seems | |
32 | reasonable. | |
33 | ||
34 | ||
35 | Fan Monitoring | |
36 | -------------- | |
37 | ||
38 | Fan rotation speeds are reported as 14-bit values from a gated clock | |
39 | signal. Speeds down to 83 RPM can be measured. | |
40 | ||
41 | An alarm is triggered if the rotation speed drops below a programmable | |
fd589a8f | 42 | limit. Another alarm is triggered if the speed is too low to be measured |
ba224e2c | 43 | (including stalled or missing fan). |
328716bc JD |
44 | |
45 | ||
46 | Fan Speed Control | |
47 | ----------------- | |
48 | ||
49 | Fan speed can be controlled by PWM outputs. There are 4 possible modes: | |
50 | always off, always on, manual and automatic. The latter isn't supported | |
51 | by the driver: you can only return to that mode if it was the original | |
52 | setting, and the configuration interface is missing. | |
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53 | |
54 | ||
55 | Temperature Monitoring | |
56 | ---------------------- | |
57 | ||
58 | The PC87427 relies on external sensors (following the SensorPath | |
59 | standard), so the resolution and range depend on the type of sensor | |
60 | connected. The integer part can be 8-bit or 9-bit, and can be signed or | |
61 | not. I couldn't find a way to figure out the external sensor data | |
62 | temperature format, so user-space adjustment (typically by a factor 2) | |
63 | may be required. |