64 lines
1.9 KiB
ReStructuredText
64 lines
1.9 KiB
ReStructuredText
Kernel driver pc87427
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=====================
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Supported chips:
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* National Semiconductor PC87427
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Prefix: 'pc87427'
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Addresses scanned: none, address read from Super I/O config space
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Datasheet: No longer available
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Author: Jean Delvare <jdelvare@suse.de>
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Thanks to Amir Habibi at Candelis for setting up a test system, and to
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Michael Kress for testing several iterations of this driver.
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Description
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-----------
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The National Semiconductor Super I/O chip includes complete hardware
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monitoring capabilities. It can monitor up to 18 voltages, 8 fans and
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6 temperature sensors. Only the fans and temperatures are supported at
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the moment, voltages aren't.
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This chip also has fan controlling features (up to 4 PWM outputs),
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which are partly supported by this driver.
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The driver assumes that no more than one chip is present, which seems
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reasonable.
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Fan Monitoring
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--------------
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Fan rotation speeds are reported as 14-bit values from a gated clock
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signal. Speeds down to 83 RPM can be measured.
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An alarm is triggered if the rotation speed drops below a programmable
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limit. Another alarm is triggered if the speed is too low to be measured
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(including stalled or missing fan).
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Fan Speed Control
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-----------------
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Fan speed can be controlled by PWM outputs. There are 4 possible modes:
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always off, always on, manual and automatic. The latter isn't supported
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by the driver: you can only return to that mode if it was the original
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setting, and the configuration interface is missing.
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Temperature Monitoring
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----------------------
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The PC87427 relies on external sensors (following the SensorPath
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standard), so the resolution and range depend on the type of sensor
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connected. The integer part can be 8-bit or 9-bit, and can be signed or
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not. I couldn't find a way to figure out the external sensor data
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temperature format, so user-space adjustment (typically by a factor 2)
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may be required.
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