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 and temperatures are supported at the moment, voltages aren't. 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. Temperature Monitoring ---------------------- The PC87427 relies on external sensors (following the SensorPath standard), so the resolution and range depend on the type of sensor connected. The integer part can be 8-bit or 9-bit, and can be signed or not. I couldn't find a way to figure out the external sensor data temperature format, so user-space adjustment (typically by a factor 2) may be required.