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The MAX31790 has a tach input enable bit in each fan's configuration register. This is only enabled by the driver if RPM mode is selected, but the driver doesn't provide a way to independently enable tachometer input regardless of the regulator mode. By adding the fanN_enable sysfs files, we can decouple the tach input from the regulator mode. Also update the documentation. Signed-off-by: Justin Ledford <justinledford@google.com> Link: https://lore.kernel.org/r/20220829195930.2521755-1-justinledford@google.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
46 lines
1.5 KiB
ReStructuredText
46 lines
1.5 KiB
ReStructuredText
Kernel driver max31790
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======================
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Supported chips:
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* Maxim MAX31790
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Prefix: 'max31790'
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Addresses scanned: -
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Datasheet: https://pdfserv.maximintegrated.com/en/ds/MAX31790.pdf
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Author: Il Han <corone.il.han@gmail.com>
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Description
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-----------
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This driver implements support for the Maxim MAX31790 chip.
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The MAX31790 controls the speeds of up to six fans using six independent
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PWM outputs. The desired fan speeds (or PWM duty cycles) are written
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through the I2C interface. The outputs drive "4-wire" fans directly,
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or can be used to modulate the fan's power terminals using an external
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pass transistor.
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Tachometer inputs monitor fan tachometer logic outputs for precise (+/-1%)
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monitoring and control of fan RPM as well as detection of fan failure.
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Six pins are dedicated tachometer inputs. Any of the six PWM outputs can
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also be configured to serve as tachometer inputs.
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Sysfs entries
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-------------
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================== === =======================================================
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fan[1-12]_input RO fan tachometer speed in RPM
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fan[1-12]_fault RO fan experienced fault
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fan[1-6]_target RW desired fan speed in RPM
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fan[1-6]_enable RW enable or disable the tachometer input
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pwm[1-6]_enable RW regulator mode, 0=disabled (duty cycle=0%), 1=manual mode, 2=rpm mode
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pwm[1-6] RW read: current pwm duty cycle,
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write: target pwm duty cycle (0-255)
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================== === =======================================================
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