Kernel driver pc87427 ===================== Supported chips: * National Semiconductor PC87427 Prefix: 'pc87427' Addresses scanned: none, address read from Super I/O config space Datasheet: No longer available Author: Jean Delvare 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 (up to 4 PWM outputs), which are partly supported by this driver. 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 be measured (including stalled or missing fan). Fan Speed Control ----------------- Fan speed can be controlled by PWM outputs. There are 4 possible modes: always off, always on, manual and automatic. The latter isn't supported by the driver: you can only return to that mode if it was the original setting, and the configuration interface is missing.