328716bc16
Add initial support for PWM outputs of the PC87427 Super-I/O chip. Only mode change and manual fan speed control are supported. Automatic mode configuration isn't supported, and won't be until at least one board is known, which makes uses of the PWM outputs. Signed-off-by: Jean Delvare <khali@linux-fr.org> Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
48 lines
1.4 KiB
Plaintext
48 lines
1.4 KiB
Plaintext
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 <khali@linux-fr.org>
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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 are supported at the moment.
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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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