6 * National Semiconductor PC87427
10 Addresses scanned: none, address read from Super I/O config space
12 Datasheet: No longer available
14 Author: Jean Delvare <jdelvare@suse.de>
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.
23 The National Semiconductor Super I/O chip includes complete hardware
24 monitoring capabilities. It can monitor up to 18 voltages, 8 fans and
25 6 temperature sensors. Only the fans and temperatures are supported at
26 the moment, voltages aren't.
28 This chip also has fan controlling features (up to 4 PWM outputs),
29 which are partly supported by this driver.
31 The driver assumes that no more than one chip is present, which seems
38 Fan rotation speeds are reported as 14-bit values from a gated clock
39 signal. Speeds down to 83 RPM can be measured.
41 An alarm is triggered if the rotation speed drops below a programmable
42 limit. Another alarm is triggered if the speed is too low to be measured
43 (including stalled or missing fan).
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.
55 Temperature Monitoring
56 ----------------------
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)