xref: /openbmc/linux/Documentation/ABI/testing/sysfs-class-hwmon (revision 9a87ffc99ec8eb8d35eed7c4f816d75f5cc9662e)

What:		/sys/class/hwmon/hwmonX/name
Description:
		The chip name.
		This should be a short, lowercase string, not containing
		whitespace, dashes, or the wildcard character '*'.
		This attribute represents the chip name. It is the only
		mandatory attribute.
		I2C devices get this attribute created automatically.

		RO

What:		/sys/class/hwmon/hwmonX/label
Description:
		A descriptive label that allows to uniquely identify a
		device within the system.
		The contents of the label are free-form.

		RO

What:		/sys/class/hwmon/hwmonX/update_interval
Description:
		The interval at which the chip will update readings.
		Unit: millisecond

		RW

		Some devices have a variable update rate or interval.
		This attribute can be used to change it to the desired value.

What:		/sys/class/hwmon/hwmonX/inY_min
Description:
		Voltage min value.

		Unit: millivolt

		RW

What:		/sys/class/hwmon/hwmonX/inY_lcrit
Description:
		Voltage critical min value.

		Unit: millivolt

		RW

		If voltage drops to or below this limit, the system may
		take drastic action such as power down or reset. At the very
		least, it should report a fault.

What:		/sys/class/hwmon/hwmonX/inY_max
Description:
		Voltage max value.

		Unit: millivolt

		RW

What:		/sys/class/hwmon/hwmonX/inY_crit
Description:
		Voltage critical max value.

		Unit: millivolt

		RW

		If voltage reaches or exceeds this limit, the system may
		take drastic action such as power down or reset. At the very
		least, it should report a fault.

What:		/sys/class/hwmon/hwmonX/inY_input
Description:
		Voltage input value.

		Unit: millivolt

		RO

		Voltage measured on the chip pin.

		Actual voltage depends on the scaling resistors on the
		motherboard, as recommended in the chip datasheet.

		This varies by chip and by motherboard.
		Because of this variation, values are generally NOT scaled
		by the chip driver, and must be done by the application.
		However, some drivers (notably lm87 and via686a)
		do scale, because of internal resistors built into a chip.
		These drivers will output the actual voltage. Rule of
		thumb: drivers should report the voltage values at the
		"pins" of the chip.

What:		/sys/class/hwmon/hwmonX/inY_average
Description:
		Average voltage

		Unit: millivolt

		RO

What:		/sys/class/hwmon/hwmonX/inY_lowest
Description:
		Historical minimum voltage

		Unit: millivolt

		RO

What:		/sys/class/hwmon/hwmonX/inY_highest
Description:
		Historical maximum voltage

		Unit: millivolt

		RO

What:		/sys/class/hwmon/hwmonX/inY_reset_history
Description:
		Reset inX_lowest and inX_highest

		WO

What:		/sys/class/hwmon/hwmonX/in_reset_history
Description:
		Reset inX_lowest and inX_highest for all sensors

		WO

What:		/sys/class/hwmon/hwmonX/inY_label
Description:
		Suggested voltage channel label.

		Text string

		Should only be created if the driver has hints about what
		this voltage channel is being used for, and user-space
		doesn't. In all other cases, the label is provided by
		user-space.

		RO

What:		/sys/class/hwmon/hwmonX/inY_enable
Description:
		Enable or disable the sensors.

		When disabled the sensor read will return -ENODATA.

		- 1: Enable
		- 0: Disable

		RW

What:		/sys/class/hwmon/hwmonX/cpuY_vid
Description:
		CPU core reference voltage.

		Unit: millivolt

		RO

		Not always correct.

What:		/sys/class/hwmon/hwmonX/vrm
Description:
		Voltage Regulator Module version number.

		RW (but changing it should no more be necessary)

		Originally the VRM standard version multiplied by 10, but now
		an arbitrary number, as not all standards have a version
		number.

		Affects the way the driver calculates the CPU core reference
		voltage from the vid pins.

What:		/sys/class/hwmon/hwmonX/inY_rated_min
Description:
		Minimum rated voltage.

		Unit: millivolt

		RO

What:		/sys/class/hwmon/hwmonX/inY_rated_max
Description:
		Maximum rated voltage.

		Unit: millivolt

		RO

What:		/sys/class/hwmon/hwmonX/fanY_min
Description:
		Fan minimum value

		Unit: revolution/min (RPM)

		RW

What:		/sys/class/hwmon/hwmonX/fanY_max
Description:
		Fan maximum value

		Unit: revolution/min (RPM)

		Only rarely supported by the hardware.
		RW

What:		/sys/class/hwmon/hwmonX/fanY_input
Description:
		Fan input value.

		Unit: revolution/min (RPM)

		RO

What:		/sys/class/hwmon/hwmonX/fanY_div
Description:
		Fan divisor.

		Integer value in powers of two (1, 2, 4, 8, 16, 32, 64, 128).

		RW

		Some chips only support values 1, 2, 4 and 8.
		Note that this is actually an internal clock divisor, which
		affects the measurable speed range, not the read value.

What:		/sys/class/hwmon/hwmonX/fanY_pulses
Description:
		Number of tachometer pulses per fan revolution.

		Integer value, typically between 1 and 4.

		RW

		This value is a characteristic of the fan connected to the
		device's input, so it has to be set in accordance with the fan
		model.

		Should only be created if the chip has a register to configure
		the number of pulses. In the absence of such a register (and
		thus attribute) the value assumed by all devices is 2 pulses
		per fan revolution.

What:		/sys/class/hwmon/hwmonX/fanY_target
Description:
		Desired fan speed

		Unit: revolution/min (RPM)

		RW

		Only makes sense if the chip supports closed-loop fan speed
		control based on the measured fan speed.

What:		/sys/class/hwmon/hwmonX/fanY_label
Description:
		Suggested fan channel label.

		Text string

		Should only be created if the driver has hints about what
		this fan channel is being used for, and user-space doesn't.
		In all other cases, the label is provided by user-space.

		RO

What:		/sys/class/hwmon/hwmonX/fanY_enable
Description:
		Enable or disable the sensors.

		When disabled the sensor read will return -ENODATA.

		- 1: Enable
		- 0: Disable

		RW

What:		/sys/class/hwmon/hwmonX/fanY_fault
Description:
		Reports if a fan has reported failure.

		- 1: Failed
		- 0: Ok

		RO

What:		/sys/class/hwmon/hwmonX/pwmY
Description:
		Pulse width modulation fan control.

		Integer value in the range 0 to 255

		RW

		255 is max or 100%.

What:		/sys/class/hwmon/hwmonX/pwmY_enable
Description:
		Fan speed control method:

		- 0: no fan speed control (i.e. fan at full speed)
		- 1: manual fan speed control enabled (using `pwmY`)
		- 2+: automatic fan speed control enabled

		Check individual chip documentation files for automatic mode
		details.

		RW

What:		/sys/class/hwmon/hwmonX/pwmY_mode
Description:
		- 0: DC mode (direct current)
		- 1: PWM mode (pulse-width modulation)

		RW

What:		/sys/class/hwmon/hwmonX/pwmY_freq
Description:
		Base PWM frequency in Hz.

		Only possibly available when pwmN_mode is PWM, but not always
		present even then.

		RW

What:		/sys/class/hwmon/hwmonX/pwmY_auto_channels_temp
Description:
		Select which temperature channels affect this PWM output in
		auto mode.

		Bitfield, 1 is temp1, 2 is temp2, 4 is temp3 etc...
		Which values are possible depend on the chip used.

		RW

What:		/sys/class/hwmon/hwmonX/pwmY_auto_pointZ_pwm
What:		/sys/class/hwmon/hwmonX/pwmY_auto_pointZ_temp
What:		/sys/class/hwmon/hwmonX/pwmY_auto_pointZ_temp_hyst
Description:
		Define the PWM vs temperature curve.

		Number of trip points is chip-dependent. Use this for chips
		which associate trip points to PWM output channels.

		RW

What:		/sys/class/hwmon/hwmonX/tempY_auto_pointZ_pwm
What:		/sys/class/hwmon/hwmonX/tempY_auto_pointZ_temp
What:		/sys/class/hwmon/hwmonX/tempY_auto_pointZ_temp_hyst
Description:
		Define the PWM vs temperature curve.

		Number of trip points is chip-dependent. Use this for chips
		which associate trip points to temperature channels.

		RW

What:		/sys/class/hwmon/hwmonX/tempY_type
Description:
		Sensor type selection.

		Integers 1 to 6

		RW

		- 1: CPU embedded diode
		- 2: 3904 transistor
		- 3: thermal diode
		- 4: thermistor
		- 5: AMD AMDSI
		- 6: Intel PECI

		Not all types are supported by all chips

What:		/sys/class/hwmon/hwmonX/tempY_max
Description:
		Temperature max value.

		Unit: millidegree Celsius (or millivolt, see below)

		RW

What:		/sys/class/hwmon/hwmonX/tempY_min
Description:
		Temperature min value.

		Unit: millidegree Celsius

		RW

What:		/sys/class/hwmon/hwmonX/tempY_max_hyst
Description:
		Temperature hysteresis value for max limit.

		Unit: millidegree Celsius

		Must be reported as an absolute temperature, NOT a delta
		from the max value.

		RW

What:		/sys/class/hwmon/hwmonX/tempY_min_hyst
Description:
		Temperature hysteresis value for min limit.
		Unit: millidegree Celsius

		Must be reported as an absolute temperature, NOT a delta
		from the min value.

		RW

What:		/sys/class/hwmon/hwmonX/tempY_input
Description:
		Temperature input value.

		Unit: millidegree Celsius

		RO

What:		/sys/class/hwmon/hwmonX/tempY_crit
Description:
		Temperature critical max value, typically greater than
		corresponding temp_max values.

		Unit: millidegree Celsius

		RW

What:		/sys/class/hwmon/hwmonX/tempY_crit_alarm
Description:
		Critical high temperature alarm flag.

		- 0: OK
		- 1: temperature has reached tempY_crit

		RW

		Contrary to regular alarm flags which clear themselves
		automatically when read, this one sticks until cleared by
		the user. This is done by writing 0 to the file. Writing
		other values is unsupported.

What:		/sys/class/hwmon/hwmonX/tempY_crit_hyst
Description:
		Temperature hysteresis value for critical limit.

		Unit: millidegree Celsius

		Must be reported as an absolute temperature, NOT a delta
		from the critical value.

		RW

What:		/sys/class/hwmon/hwmonX/tempY_emergency
Description:
		Temperature emergency max value, for chips supporting more than
		two upper temperature limits. Must be equal or greater than
		corresponding temp_crit values.

		Unit: millidegree Celsius

		RW

What:		/sys/class/hwmon/hwmonX/tempY_emergency_hyst
Description:
		Temperature hysteresis value for emergency limit.

		Unit: millidegree Celsius

		Must be reported as an absolute temperature, NOT a delta
		from the emergency value.

		RW

What:		/sys/class/hwmon/hwmonX/tempY_lcrit
Description:
		Temperature critical min value, typically lower than
		corresponding temp_min values.

		Unit: millidegree Celsius

		RW

What:		/sys/class/hwmon/hwmonX/tempY_lcrit_hyst
Description:
		Temperature hysteresis value for critical min limit.

		Unit: millidegree Celsius

		Must be reported as an absolute temperature, NOT a delta
		from the critical min value.

		RW

What:		/sys/class/hwmon/hwmonX/tempY_offset
Description:
		Temperature offset which is added to the temperature reading
		by the chip.

		Unit: millidegree Celsius

		Read/Write value.

What:		/sys/class/hwmon/hwmonX/tempY_label
Description:
		Suggested temperature channel label.

		Text string

		Should only be created if the driver has hints about what
		this temperature channel is being used for, and user-space
		doesn't. In all other cases, the label is provided by
		user-space.

		RO

What:		/sys/class/hwmon/hwmonX/tempY_lowest
Description:
		Historical minimum temperature

		Unit: millidegree Celsius

		RO

What:		/sys/class/hwmon/hwmonX/tempY_highest
Description:
		Historical maximum temperature

		Unit: millidegree Celsius

		RO

What:		/sys/class/hwmon/hwmonX/tempY_reset_history
Description:
		Reset temp_lowest and temp_highest

		WO

What:		/sys/class/hwmon/hwmonX/temp_reset_history
Description:
		Reset temp_lowest and temp_highest for all sensors

		WO

What:		/sys/class/hwmon/hwmonX/tempY_enable
Description:
		Enable or disable the sensors.

		When disabled the sensor read will return -ENODATA.

		- 1: Enable
		- 0: Disable

		RW

What:		/sys/class/hwmon/hwmonX/tempY_rated_min
Description:
		Minimum rated temperature.

		Unit: millidegree Celsius

		RO

What:		/sys/class/hwmon/hwmonX/tempY_rated_max
Description:
		Maximum rated temperature.

		Unit: millidegree Celsius

		RO

What:		/sys/class/hwmon/hwmonX/currY_max
Description:
		Current max value

		Unit: milliampere

		RW

What:		/sys/class/hwmon/hwmonX/currY_min
Description:
		Current min value.

		Unit: milliampere

		RW

What:		/sys/class/hwmon/hwmonX/currY_lcrit
Description:
		Current critical low value

		Unit: milliampere

		RW

What:		/sys/class/hwmon/hwmonX/currY_crit
Description:
		Current critical high value.

		Unit: milliampere

		RW

What:		/sys/class/hwmon/hwmonX/currY_input
Description:
		Current input value

		Unit: milliampere

		RO

What:		/sys/class/hwmon/hwmonX/currY_average
Description:
		Average current use

		Unit: milliampere

		RO

What:		/sys/class/hwmon/hwmonX/currY_lowest
Description:
		Historical minimum current

		Unit: milliampere

		RO

What:		/sys/class/hwmon/hwmonX/currY_highest
Description:
		Historical maximum current
		Unit: milliampere
		RO

What:		/sys/class/hwmon/hwmonX/currY_reset_history
Description:
		Reset currX_lowest and currX_highest

		WO

What:		/sys/class/hwmon/hwmonX/curr_reset_history
Description:
		Reset currX_lowest and currX_highest for all sensors

		WO

What:		/sys/class/hwmon/hwmonX/currY_enable
Description:
		Enable or disable the sensors.

		When disabled the sensor read will return -ENODATA.

		- 1: Enable
		- 0: Disable

		RW

What:		/sys/class/hwmon/hwmonX/currY_rated_min
Description:
		Minimum rated current.

		Unit: milliampere

		RO

What:		/sys/class/hwmon/hwmonX/currY_rated_max
Description:
		Maximum rated current.

		Unit: milliampere

		RO

What:		/sys/class/hwmon/hwmonX/powerY_average
Description:
		Average power use

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_average_interval
Description:
		Power use averaging interval.  A poll
		notification is sent to this file if the
		hardware changes the averaging interval.

		Unit: milliseconds

		RW

What:		/sys/class/hwmon/hwmonX/powerY_average_interval_max
Description:
		Maximum power use averaging interval

		Unit: milliseconds

		RO

What:		/sys/class/hwmon/hwmonX/powerY_average_interval_min
Description:
		Minimum power use averaging interval

		Unit: milliseconds

		RO

What:		/sys/class/hwmon/hwmonX/powerY_average_highest
Description:
		Historical average maximum power use

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_average_lowest
Description:
		Historical average minimum power use

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_average_max
Description:
		A poll notification is sent to
		`powerY_average` when power use
		rises above this value.

		Unit: microWatt

		RW

What:		/sys/class/hwmon/hwmonX/powerY_average_min
Description:
		A poll notification is sent to
		`powerY_average` when power use
		sinks below this value.

		Unit: microWatt

		RW

What:		/sys/class/hwmon/hwmonX/powerY_input
Description:
		Instantaneous power use

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_input_highest
Description:
		Historical maximum power use

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_input_lowest
Description:
		Historical minimum power use

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_reset_history
Description:
		Reset input_highest, input_lowest,
		average_highest and average_lowest.

		WO

What:		/sys/class/hwmon/hwmonX/powerY_accuracy
Description:
		Accuracy of the power meter.

		Unit: Percent

		RO

What:		/sys/class/hwmon/hwmonX/powerY_cap
Description:
		If power use rises above this limit, the
		system should take action to reduce power use.
		A poll notification is sent to this file if the
		cap is changed by the hardware.  The `*_cap`
		files only appear if the cap is known to be
		enforced by hardware.

		Unit: microWatt

		RW

What:		/sys/class/hwmon/hwmonX/powerY_cap_hyst
Description:
		Margin of hysteresis built around capping and
		notification.

		Unit: microWatt

		RW

What:		/sys/class/hwmon/hwmonX/powerY_cap_max
Description:
		Maximum cap that can be set.

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_cap_min
Description:
		Minimum cap that can be set.

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_max
Description:
		Maximum power.

		Unit: microWatt

		RW

What:		/sys/class/hwmon/hwmonX/powerY_crit
Description:
		Critical maximum power.

		If power rises to or above this limit, the
		system is expected take drastic action to reduce
		power consumption, such as a system shutdown or
		a forced powerdown of some devices.

		Unit: microWatt

		RW

What:		/sys/class/hwmon/hwmonX/powerY_enable
Description:
		Enable or disable the sensors.

		When disabled the sensor read will return
		-ENODATA.

		- 1: Enable
		- 0: Disable

		RW

What:		/sys/class/hwmon/hwmonX/powerY_rated_min
Description:
		Minimum rated power.

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/powerY_rated_max
Description:
		Maximum rated power.

		Unit: microWatt

		RO

What:		/sys/class/hwmon/hwmonX/energyY_input
Description:
		Cumulative energy use

		Unit: microJoule

		RO

What:		/sys/class/hwmon/hwmonX/energyY_enable
Description:
		Enable or disable the sensors.

		When disabled the sensor read will return
		-ENODATA.

		- 1: Enable
		- 0: Disable

		RW

What:		/sys/class/hwmon/hwmonX/humidityY_input
Description:
		Humidity

		Unit: milli-percent (per cent mille, pcm)

		RO


What:		/sys/class/hwmon/hwmonX/humidityY_enable
Description:
		Enable or disable the sensors

		When disabled the sensor read will return
		-ENODATA.

		- 1: Enable
		- 0: Disable

		RW

What:		/sys/class/hwmon/hwmonX/humidityY_rated_min
Description:
		Minimum rated humidity.

		Unit: milli-percent (per cent mille, pcm)

		RO

What:		/sys/class/hwmon/hwmonX/humidityY_rated_max
Description:
		Maximum rated humidity.

		Unit: milli-percent (per cent mille, pcm)

		RO


What:		/sys/class/hwmon/hwmonX/intrusionY_alarm
Description:
		Chassis intrusion detection

		- 0: OK
		- 1: intrusion detected

		RW

		Contrary to regular alarm flags which clear themselves
		automatically when read, this one sticks until cleared by
		the user. This is done by writing 0 to the file. Writing
		other values is unsupported.

What:		/sys/class/hwmon/hwmonX/intrusionY_beep
Description:
		Chassis intrusion beep

		- 0: disable
		- 1: enable

		RW

What:		/sys/class/hwmon/hwmonX/device/pec
Description:
		PEC support on I2C devices

		- 0, off, n: disable
		- 1, on, y: enable

		RW