| Jean Delvare | ba224e2 | 2006-12-12 18:18:29 +0100 | [diff] [blame] | 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 |
| Jean Delvare | 6aa693b | 2008-10-17 17:51:17 +0200 | [diff] [blame] | 8 | Datasheet: No longer available |
| Jean Delvare | ba224e2 | 2006-12-12 18:18:29 +0100 | [diff] [blame] | 9 | |
| 10 | Author: Jean Delvare <khali@linux-fr.org> |
| 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 |
| Jean Delvare | 008e5f3 | 2010-08-14 21:08:59 +0200 | [diff] [blame] | 21 | 6 temperature sensors. Only the fans and temperatures are supported at |
| 22 | the moment, voltages aren't. |
| Jean Delvare | ba224e2 | 2006-12-12 18:18:29 +0100 | [diff] [blame] | 23 | |
| Jean Delvare | 328716b | 2010-08-14 21:08:58 +0200 | [diff] [blame] | 24 | This chip also has fan controlling features (up to 4 PWM outputs), |
| 25 | which are partly supported by this driver. |
| Jean Delvare | ba224e2 | 2006-12-12 18:18:29 +0100 | [diff] [blame] | 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 |
| Anand Gadiyar | fd589a8 | 2009-07-16 17:13:03 +0200 | [diff] [blame] | 38 | limit. Another alarm is triggered if the speed is too low to be measured |
| Jean Delvare | ba224e2 | 2006-12-12 18:18:29 +0100 | [diff] [blame] | 39 | (including stalled or missing fan). |
| Jean Delvare | 328716b | 2010-08-14 21:08:58 +0200 | [diff] [blame] | 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. |
| Jean Delvare | 008e5f3 | 2010-08-14 21:08:59 +0200 | [diff] [blame] | 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. |