0001 Kernel driver pc87427
0002 =====================
0003
0004 Supported chips:
0005
0006 * National Semiconductor PC87427
0007
0008 Prefix: 'pc87427'
0009
0010 Addresses scanned: none, address read from Super I/O config space
0011
0012 Datasheet: No longer available
0013
0014 Author: Jean Delvare <jdelvare@suse.de>
0015
0016 Thanks to Amir Habibi at Candelis for setting up a test system, and to
0017 Michael Kress for testing several iterations of this driver.
0018
0019
0020 Description
0021 -----------
0022
0023 The National Semiconductor Super I/O chip includes complete hardware
0024 monitoring capabilities. It can monitor up to 18 voltages, 8 fans and
0025 6 temperature sensors. Only the fans and temperatures are supported at
0026 the moment, voltages aren't.
0027
0028 This chip also has fan controlling features (up to 4 PWM outputs),
0029 which are partly supported by this driver.
0030
0031 The driver assumes that no more than one chip is present, which seems
0032 reasonable.
0033
0034
0035 Fan Monitoring
0036 --------------
0037
0038 Fan rotation speeds are reported as 14-bit values from a gated clock
0039 signal. Speeds down to 83 RPM can be measured.
0040
0041 An alarm is triggered if the rotation speed drops below a programmable
0042 limit. Another alarm is triggered if the speed is too low to be measured
0043 (including stalled or missing fan).
0044
0045
0046 Fan Speed Control
0047 -----------------
0048
0049 Fan speed can be controlled by PWM outputs. There are 4 possible modes:
0050 always off, always on, manual and automatic. The latter isn't supported
0051 by the driver: you can only return to that mode if it was the original
0052 setting, and the configuration interface is missing.
0053
0054
0055 Temperature Monitoring
0056 ----------------------
0057
0058 The PC87427 relies on external sensors (following the SensorPath
0059 standard), so the resolution and range depend on the type of sensor
0060 connected. The integer part can be 8-bit or 9-bit, and can be signed or
0061 not. I couldn't find a way to figure out the external sensor data
0062 temperature format, so user-space adjustment (typically by a factor 2)
0063 may be required.
