projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| ba224e2c JD |
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 | |
| 6aa693b8 | 8 | Datasheet: No longer available |
| ba224e2c JD |
9 | |
| 10 | Author: Jean Delvare <[email protected]> | |
| 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 | |
| 008e5f33 JD |
21 | 6 temperature sensors. Only the fans and temperatures are supported at |
| 22 | the moment, voltages aren't. | |
| ba224e2c | 23 | |
| 328716bc JD |
24 | This chip also has fan controlling features (up to 4 PWM outputs), |
| 25 | which are partly supported by this driver. | |
| ba224e2c JD |
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 | |
| fd589a8f | 38 | limit. Another alarm is triggered if the speed is too low to be measured |
| ba224e2c | 39 | (including stalled or missing fan). |
| 328716bc JD |
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. | |
| 008e5f33 JD |
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. |