Kernel driver max34440

Supported chips:

Author: Guenter Roeck <>


This driver supports hardware monitoring for Maxim MAX34440 PMBus 6-Channel Power-Supply Manager, MAX34441 PMBus 5-Channel Power-Supply Manager and Intelligent Fan Controller, and MAX34446 PMBus Power-Supply Data Logger. It also supports the MAX34451, MAX34460, and MAX34461 PMBus Voltage Monitor & Sequencers. The MAX34451 supports monitoring voltage or current of 12 channels based on GIN pins. The MAX34460 supports 12 voltage channels, and the MAX34461 supports 16 voltage channels.

The driver is a client driver to the core PMBus driver. Please see Documentation/hwmon/pmbus.rst for details on PMBus client drivers.

Usage Notes

This driver does not auto-detect devices. You will have to instantiate the devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for details.

For MAX34446, the value of the currX_crit attribute determines if current or voltage measurement is enabled for a given channel. Voltage measurement is enabled if currX_crit is set to 0; current measurement is enabled if the attribute is set to a positive value. Power measurement is only enabled if channel 1 (3) is configured for voltage measurement, and channel 2 (4) is configured for current measurement.

Platform data support

The driver supports standard PMBus driver platform data.

Sysfs entries

The following attributes are supported. Limits are read-write; all other attributes are read-only.


in[1-6]_label “vout[1-6]”.
in[1-6]_input Measured voltage. From READ_VOUT register.
in[1-6]_min Minimum Voltage. From VOUT_UV_WARN_LIMIT register.
in[1-6]_max Maximum voltage. From VOUT_OV_WARN_LIMIT register.
in[1-6]_lcrit Critical minimum Voltage. VOUT_UV_FAULT_LIMIT register.
in[1-6]_crit Critical maximum voltage. From VOUT_OV_FAULT_LIMIT register.
in[1-6]_min_alarm Voltage low alarm. From VOLTAGE_UV_WARNING status.
in[1-6]_max_alarm Voltage high alarm. From VOLTAGE_OV_WARNING status.
in[1-6]_lcrit_alarm Voltage critical low alarm. From VOLTAGE_UV_FAULT status.
in[1-6]_crit_alarm Voltage critical high alarm. From VOLTAGE_OV_FAULT status.
in[1-6]_lowest Historical minimum voltage.
in[1-6]_highest Historical maximum voltage.
in[1-6]_reset_history Write any value to reset history.


MAX34446 only supports in[1-4].


curr[1-6]_label “iout[1-6]”.
curr[1-6]_input Measured current. From READ_IOUT register.
curr[1-6]_max Maximum current. From IOUT_OC_WARN_LIMIT register.
curr[1-6]_crit Critical maximum current. From IOUT_OC_FAULT_LIMIT register.
curr[1-6]_max_alarm Current high alarm. From IOUT_OC_WARNING status.
curr[1-6]_crit_alarm Current critical high alarm. From IOUT_OC_FAULT status.
curr[1-4]_average Historical average current (MAX34446/34451 only).
curr[1-6]_highest Historical maximum current.
curr[1-6]_reset_history Write any value to reset history.


  • in6 and curr6 attributes only exist for MAX34440.
  • MAX34446 only supports curr[1-4].


power[1,3]_label “pout[1,3]”
power[1,3]_input Measured power.
power[1,3]_average Historical average power.
power[1,3]_highest Historical maximum power.


Power attributes only exist for MAX34446.


temp[1-8]_input Measured temperatures. From READ_TEMPERATURE_1 register. temp1 is the chip’s internal temperature. temp2..temp5 are remote I2C temperature sensors. For MAX34441, temp6 is a remote thermal-diode sensor. For MAX34440, temp6..8 are remote I2C temperature sensors.
temp[1-8]_max Maximum temperature. From OT_WARN_LIMIT register.
temp[1-8]_crit Critical high temperature. From OT_FAULT_LIMIT register.
temp[1-8]_max_alarm Temperature high alarm.
temp[1-8]_crit_alarm Temperature critical high alarm.
temp[1-8]_average Historical average temperature (MAX34446 only).
temp[1-8]_highest Historical maximum temperature.
temp[1-8]_reset_history Write any value to reset history.


  • temp7 and temp8 attributes only exist for MAX34440.
  • MAX34446 only supports temp[1-3].


  • MAX34451 supports attribute groups in[1-16] (or curr[1-16] based on input pins) and temp[1-5].
  • MAX34460 supports attribute groups in[1-12] and temp[1-5].
  • MAX34461 supports attribute groups in[1-16] and temp[1-5].