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Kernel driver max31785
Supported chips:
* Maxim MAX31785, MAX31785A
Prefix: 'max31785' or 'max31785a'
Addresses scanned: -
Author: Andrew Jeffery <>
The Maxim MAX31785 is a PMBus device providing closed-loop, multi-channel fan
management with temperature and remote voltage sensing. Various fan control
features are provided, including PWM frequency control, temperature hysteresis,
dual tachometer measurements, and fan health monitoring.
For dual-rotor configurations the MAX31785A exposes the second rotor tachometer
readings in attributes fan[5-8]_input. By contrast the MAX31785 only exposes
the slowest rotor measurement, and does so in the fan[1-4]_input attributes.
Usage Notes
This driver does not probe for PMBus devices. You will have to instantiate
devices explicitly.
Sysfs attributes
======================= =======================================================
fan[1-4]_alarm Fan alarm.
fan[1-4]_fault Fan fault.
fan[1-8]_input Fan RPM. On the MAX31785A, inputs 5-8 correspond to the
second rotor of fans 1-4
fan[1-4]_target Fan input target
in[1-6]_crit Critical maximum output voltage
in[1-6]_crit_alarm Output voltage critical high alarm
in[1-6]_input Measured output voltage
in[1-6]_label "vout[18-23]"
in[1-6]_lcrit Critical minimum output voltage
in[1-6]_lcrit_alarm Output voltage critical low alarm
in[1-6]_max Maximum output voltage
in[1-6]_max_alarm Output voltage high alarm
in[1-6]_min Minimum output voltage
in[1-6]_min_alarm Output voltage low alarm
pwm[1-4] Fan target duty cycle (0..255)
pwm[1-4]_enable 0: Full-speed
1: Manual PWM control
2: Automatic PWM (tach-feedback RPM fan-control)
3: Automatic closed-loop (temp-feedback fan-control)
temp[1-11]_crit Critical high temperature
temp[1-11]_crit_alarm Chip temperature critical high alarm
temp[1-11]_input Measured temperature
temp[1-11]_max Maximum temperature
temp[1-11]_max_alarm Chip temperature high alarm
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