projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 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. | |
| ba224e2c JD |
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. | |
| 008e5f33 JD |
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. |