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cubelinux-kernel/Documentation/hwmon/max31785.rst
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Greg Kroah-Hartman 598cf27219 Linux 6.19.3
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com>
Tested-by: Peter Schneider <pschneider1968@googlemail.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Tested-by: Brett A C Sheffield <bacs@librecast.net>
Tested-by: Mark Brown <broonie@kernel.org>
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Tested-by: Ronald Warsow <rwarsow@gmx.de>
Tested-by: Justin M. Forbes <jforbes@fedoraproject.org>
Tested-by: Ron Economos <re@w6rz.net>
Tested-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-02-19 16:33:27 +01:00

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Kernel driver max31785
======================
Supported chips:
* Maxim MAX31785, MAX31785A
Prefix: 'max31785' or 'max31785a'
Addresses scanned: -
Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/max31785.pdf
Author: Andrew Jeffery <andrew@aj.id.au>
Description
-----------
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
======================= =======================================================