| Kernel driver pc87427 | 
 | ===================== | 
 |  | 
 | Supported chips: | 
 |   * National Semiconductor PC87427 | 
 |     Prefix: 'pc87427' | 
 |     Addresses scanned: none, address read from Super I/O config space | 
 |     Datasheet: http://www.winbond.com.tw/E-WINBONDHTM/partner/apc_007.html | 
 |  | 
 | Author: Jean Delvare <khali@linux-fr.org> | 
 |  | 
 | Thanks to Amir Habibi at Candelis for setting up a test system, and to | 
 | Michael Kress for testing several iterations of this driver. | 
 |  | 
 |  | 
 | Description | 
 | ----------- | 
 |  | 
 | The National Semiconductor Super I/O chip includes complete hardware | 
 | monitoring capabilities. It can monitor up to 18 voltages, 8 fans and | 
 | 6 temperature sensors. Only the fans are supported at the moment. | 
 |  | 
 | This chip also has fan controlling features, which are not yet supported | 
 | by this driver either. | 
 |  | 
 | The driver assumes that no more than one chip is present, which seems | 
 | reasonable. | 
 |  | 
 |  | 
 | Fan Monitoring | 
 | -------------- | 
 |  | 
 | Fan rotation speeds are reported as 14-bit values from a gated clock | 
 | signal. Speeds down to 83 RPM can be measured. | 
 |  | 
 | An alarm is triggered if the rotation speed drops below a programmable | 
 | limit. Another alarm is triggered if the speed is too low to to be measured | 
 | (including stalled or missing fan). |