Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 809 insertions, 0 deletions

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+Naming and data format standards for sysfs files
+------------------------------------------------
+
+The libsensors library offers an interface to the raw sensors data
+through the sysfs interface. Since lm-sensors 3.0.0, libsensors is
+completely chip-independent. It assumes that all the kernel drivers
+implement the standard sysfs interface described in this document.
+This makes adding or updating support for any given chip very easy, as
+libsensors, and applications using it, do not need to be modified.
+This is a major improvement compared to lm-sensors 2.
+
+Note that motherboards vary widely in the connections to sensor chips.
+There is no standard that ensures, for example, that the second
+temperature sensor is connected to the CPU, or that the second fan is on
+the CPU. Also, some values reported by the chips need some computation
+before they make full sense. For example, most chips can only measure
+voltages between 0 and +4V. Other voltages are scaled back into that
+range using external resistors. Since the values of these resistors
+can change from motherboard to motherboard, the conversions cannot be
+hard coded into the driver and have to be done in user space.
+
+For this reason, even if we aim at a chip-independent libsensors, it will
+still require a configuration file (e.g. /etc/sensors.conf) for proper
+values conversion, labeling of inputs and hiding of unused inputs.
+
+An alternative method that some programs use is to access the sysfs
+files directly. This document briefly describes the standards that the
+drivers follow, so that an application program can scan for entries and
+access this data in a simple and consistent way. That said, such programs
+will have to implement conversion, labeling and hiding of inputs. For
+this reason, it is still not recommended to bypass the library.
+
+Each chip gets its own directory in the sysfs /sys/devices tree.  To
+find all sensor chips, it is easier to follow the device symlinks from
+/sys/class/hwmon/hwmon*.
+
+Up to lm-sensors 3.0.0, libsensors looks for hardware monitoring attributes
+in the "physical" device directory. Since lm-sensors 3.0.1, attributes found
+in the hwmon "class" device directory are also supported. Complex drivers
+(e.g. drivers for multifunction chips) may want to use this possibility to
+avoid namespace pollution. The only drawback will be that older versions of
+libsensors won't support the driver in question.
+
+All sysfs values are fixed point numbers.
+
+There is only one value per file, unlike the older /proc specification.
+The common scheme for files naming is: <type><number>_<item>. Usual
+types for sensor chips are "in" (voltage), "temp" (temperature) and
+"fan" (fan). Usual items are "input" (measured value), "max" (high
+threshold, "min" (low threshold). Numbering usually starts from 1,
+except for voltages which start from 0 (because most data sheets use
+this). A number is always used for elements that can be present more
+than once, even if there is a single element of the given type on the
+specific chip. Other files do not refer to a specific element, so
+they have a simple name, and no number.
+
+Alarms are direct indications read from the chips. The drivers do NOT
+make comparisons of readings to thresholds. This allows violations
+between readings to be caught and alarmed. The exact definition of an
+alarm (for example, whether a threshold must be met or must be exceeded
+to cause an alarm) is chip-dependent.
+
+When setting values of hwmon sysfs attributes, the string representation of
+the desired value must be written, note that strings which are not a number
+are interpreted as 0! For more on how written strings are interpreted see the
+"sysfs attribute writes interpretation" section at the end of this file.
+
+-------------------------------------------------------------------------
+
+[0-*]	denotes any positive number starting from 0
+[1-*]	denotes any positive number starting from 1
+RO	read only value
+WO	write only value
+RW	read/write value
+
+Read/write values may be read-only for some chips, depending on the
+hardware implementation.
+
+All entries (except name) are optional, and should only be created in a
+given driver if the chip has the feature.
+
+
+*********************
+* Global attributes *
+*********************
+
+name		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
+
+update_interval	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.
+
+
+************
+* Voltages *
+************
+
+in[0-*]_min	Voltage min value.
+		Unit: millivolt
+		RW
+		
+in[0-*]_lcrit	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.
+
+in[0-*]_max	Voltage max value.
+		Unit: millivolt
+		RW
+		
+in[0-*]_crit	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.
+
+in[0-*]_input	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.
+
+in[0-*]_average
+		Average voltage
+		Unit: millivolt
+		RO
+
+in[0-*]_lowest
+		Historical minimum voltage
+		Unit: millivolt
+		RO
+
+in[0-*]_highest
+		Historical maximum voltage
+		Unit: millivolt
+		RO
+
+in[0-*]_reset_history
+		Reset inX_lowest and inX_highest
+		WO
+
+in_reset_history
+		Reset inX_lowest and inX_highest for all sensors
+		WO
+
+in[0-*]_label	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
+
+in[0-*]_enable
+		Enable or disable the sensors.
+		When disabled the sensor read will return -ENODATA.
+		1: Enable
+		0: Disable
+		RW
+
+cpu[0-*]_vid	CPU core reference voltage.
+		Unit: millivolt
+		RO
+		Not always correct.
+
+vrm		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.
+
+Also see the Alarms section for status flags associated with voltages.
+
+
+********
+* Fans *
+********
+
+fan[1-*]_min	Fan minimum value
+		Unit: revolution/min (RPM)
+		RW
+
+fan[1-*]_max	Fan maximum value
+		Unit: revolution/min (RPM)
+		Only rarely supported by the hardware.
+		RW
+
+fan[1-*]_input	Fan input value.
+		Unit: revolution/min (RPM)
+		RO
+
+fan[1-*]_div	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.
+
+fan[1-*]_pulses	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.
+
+fan[1-*]_target
+		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.
+
+fan[1-*]_label	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
+
+fan[1-*]_enable
+		Enable or disable the sensors.
+		When disabled the sensor read will return -ENODATA.
+		1: Enable
+		0: Disable
+		RW
+
+Also see the Alarms section for status flags associated with fans.
+
+
+*******
+* PWM *
+*******
+
+pwm[1-*]	Pulse width modulation fan control.
+		Integer value in the range 0 to 255
+		RW
+		255 is max or 100%.
+
+pwm[1-*]_enable
+		Fan speed control method:
+		0: no fan speed control (i.e. fan at full speed)
+		1: manual fan speed control enabled (using pwm[1-*])
+		2+: automatic fan speed control enabled
+		Check individual chip documentation files for automatic mode
+		details.
+		RW
+
+pwm[1-*]_mode	0: DC mode (direct current)
+		1: PWM mode (pulse-width modulation)
+		RW
+
+pwm[1-*]_freq	Base PWM frequency in Hz.
+		Only possibly available when pwmN_mode is PWM, but not always
+		present even then.
+		RW
+
+pwm[1-*]_auto_channels_temp
+		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
+
+pwm[1-*]_auto_point[1-*]_pwm
+pwm[1-*]_auto_point[1-*]_temp
+pwm[1-*]_auto_point[1-*]_temp_hyst
+		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
+
+temp[1-*]_auto_point[1-*]_pwm
+temp[1-*]_auto_point[1-*]_temp
+temp[1-*]_auto_point[1-*]_temp_hyst
+		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
+
+There is a third case where trip points are associated to both PWM output
+channels and temperature channels: the PWM values are associated to PWM
+output channels while the temperature values are associated to temperature
+channels. In that case, the result is determined by the mapping between
+temperature inputs and PWM outputs. When several temperature inputs are
+mapped to a given PWM output, this leads to several candidate PWM values.
+The actual result is up to the chip, but in general the highest candidate
+value (fastest fan speed) wins.
+
+
+****************
+* Temperatures *
+****************
+
+temp[1-*]_type	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
+
+temp[1-*]_max	Temperature max value.
+		Unit: millidegree Celsius (or millivolt, see below)
+		RW
+
+temp[1-*]_min	Temperature min value.
+		Unit: millidegree Celsius
+		RW
+
+temp[1-*]_max_hyst
+		Temperature hysteresis value for max limit.
+		Unit: millidegree Celsius
+		Must be reported as an absolute temperature, NOT a delta
+		from the max value.
+		RW
+
+temp[1-*]_min_hyst
+		Temperature hysteresis value for min limit.
+		Unit: millidegree Celsius
+		Must be reported as an absolute temperature, NOT a delta
+		from the min value.
+		RW
+
+temp[1-*]_input Temperature input value.
+		Unit: millidegree Celsius
+		RO
+
+temp[1-*]_crit	Temperature critical max value, typically greater than
+		corresponding temp_max values.
+		Unit: millidegree Celsius
+		RW
+
+temp[1-*]_crit_hyst
+		Temperature hysteresis value for critical limit.
+		Unit: millidegree Celsius
+		Must be reported as an absolute temperature, NOT a delta
+		from the critical value.
+		RW
+
+temp[1-*]_emergency
+		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
+
+temp[1-*]_emergency_hyst
+		Temperature hysteresis value for emergency limit.
+		Unit: millidegree Celsius
+		Must be reported as an absolute temperature, NOT a delta
+		from the emergency value.
+		RW
+
+temp[1-*]_lcrit	Temperature critical min value, typically lower than
+		corresponding temp_min values.
+		Unit: millidegree Celsius
+		RW
+
+temp[1-*]_lcrit_hyst
+		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
+
+temp[1-*]_offset
+		Temperature offset which is added to the temperature reading
+		by the chip.
+		Unit: millidegree Celsius
+		Read/Write value.
+
+temp[1-*]_label	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
+
+temp[1-*]_lowest
+		Historical minimum temperature
+		Unit: millidegree Celsius
+		RO
+
+temp[1-*]_highest
+		Historical maximum temperature
+		Unit: millidegree Celsius
+		RO
+
+temp[1-*]_reset_history
+		Reset temp_lowest and temp_highest
+		WO
+
+temp_reset_history
+		Reset temp_lowest and temp_highest for all sensors
+		WO
+
+temp[1-*]_enable
+		Enable or disable the sensors.
+		When disabled the sensor read will return -ENODATA.
+		1: Enable
+		0: Disable
+		RW
+
+Some chips measure temperature using external thermistors and an ADC, and
+report the temperature measurement as a voltage. Converting this voltage
+back to a temperature (or the other way around for limits) requires
+mathematical functions not available in the kernel, so the conversion
+must occur in user space. For these chips, all temp* files described
+above should contain values expressed in millivolt instead of millidegree
+Celsius. In other words, such temperature channels are handled as voltage
+channels by the driver.
+
+Also see the Alarms section for status flags associated with temperatures.
+
+
+************
+* Currents *
+************
+
+curr[1-*]_max	Current max value
+		Unit: milliampere
+		RW
+
+curr[1-*]_min	Current min value.
+		Unit: milliampere
+		RW
+
+curr[1-*]_lcrit	Current critical low value
+		Unit: milliampere
+		RW
+
+curr[1-*]_crit	Current critical high value.
+		Unit: milliampere
+		RW
+
+curr[1-*]_input	Current input value
+		Unit: milliampere
+		RO
+
+curr[1-*]_average
+		Average current use
+		Unit: milliampere
+		RO
+
+curr[1-*]_lowest
+		Historical minimum current
+		Unit: milliampere
+		RO
+
+curr[1-*]_highest
+		Historical maximum current
+		Unit: milliampere
+		RO
+
+curr[1-*]_reset_history
+		Reset currX_lowest and currX_highest
+		WO
+
+curr_reset_history
+		Reset currX_lowest and currX_highest for all sensors
+		WO
+
+curr[1-*]_enable
+		Enable or disable the sensors.
+		When disabled the sensor read will return -ENODATA.
+		1: Enable
+		0: Disable
+		RW
+
+Also see the Alarms section for status flags associated with currents.
+
+*********
+* Power *
+*********
+
+power[1-*]_average		Average power use
+				Unit: microWatt
+				RO
+
+power[1-*]_average_interval	Power use averaging interval.  A poll
+				notification is sent to this file if the
+				hardware changes the averaging interval.
+				Unit: milliseconds
+				RW
+
+power[1-*]_average_interval_max	Maximum power use averaging interval
+				Unit: milliseconds
+				RO
+
+power[1-*]_average_interval_min	Minimum power use averaging interval
+				Unit: milliseconds
+				RO
+
+power[1-*]_average_highest	Historical average maximum power use
+				Unit: microWatt
+				RO
+
+power[1-*]_average_lowest	Historical average minimum power use
+				Unit: microWatt
+				RO
+
+power[1-*]_average_max		A poll notification is sent to
+				power[1-*]_average when power use
+				rises above this value.
+				Unit: microWatt
+				RW
+
+power[1-*]_average_min		A poll notification is sent to
+				power[1-*]_average when power use
+				sinks below this value.
+				Unit: microWatt
+				RW
+
+power[1-*]_input		Instantaneous power use
+				Unit: microWatt
+				RO
+
+power[1-*]_input_highest	Historical maximum power use
+				Unit: microWatt
+				RO
+
+power[1-*]_input_lowest		Historical minimum power use
+				Unit: microWatt
+				RO
+
+power[1-*]_reset_history	Reset input_highest, input_lowest,
+				average_highest and average_lowest.
+				WO
+
+power[1-*]_accuracy		Accuracy of the power meter.
+				Unit: Percent
+				RO
+
+power[1-*]_cap			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
+
+power[1-*]_cap_hyst		Margin of hysteresis built around capping and
+				notification.
+				Unit: microWatt
+				RW
+
+power[1-*]_cap_max		Maximum cap that can be set.
+				Unit: microWatt
+				RO
+
+power[1-*]_cap_min		Minimum cap that can be set.
+				Unit: microWatt
+				RO
+
+power[1-*]_max			Maximum power.
+				Unit: microWatt
+				RW
+
+power[1-*]_crit			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
+
+power[1-*]_enable		Enable or disable the sensors.
+				When disabled the sensor read will return
+				-ENODATA.
+				1: Enable
+				0: Disable
+				RW
+
+Also see the Alarms section for status flags associated with power readings.
+
+**********
+* Energy *
+**********
+
+energy[1-*]_input		Cumulative energy use
+				Unit: microJoule
+				RO
+
+energy[1-*]_enable		Enable or disable the sensors.
+				When disabled the sensor read will return
+				-ENODATA.
+				1: Enable
+				0: Disable
+				RW
+
+************
+* Humidity *
+************
+
+humidity[1-*]_input		Humidity
+				Unit: milli-percent (per cent mille, pcm)
+				RO
+
+
+humidity[1-*]_enable		Enable or disable the sensors
+				When disabled the sensor read will return
+				-ENODATA.
+				1: Enable
+				0: Disable
+				RW
+
+**********
+* Alarms *
+**********
+
+Each channel or limit may have an associated alarm file, containing a
+boolean value. 1 means than an alarm condition exists, 0 means no alarm.
+
+Usually a given chip will either use channel-related alarms, or
+limit-related alarms, not both. The driver should just reflect the hardware
+implementation.
+
+in[0-*]_alarm
+curr[1-*]_alarm
+power[1-*]_alarm
+fan[1-*]_alarm
+temp[1-*]_alarm
+		Channel alarm
+		0: no alarm
+		1: alarm
+		RO
+
+OR
+
+in[0-*]_min_alarm
+in[0-*]_max_alarm
+in[0-*]_lcrit_alarm
+in[0-*]_crit_alarm
+curr[1-*]_min_alarm
+curr[1-*]_max_alarm
+curr[1-*]_lcrit_alarm
+curr[1-*]_crit_alarm
+power[1-*]_cap_alarm
+power[1-*]_max_alarm
+power[1-*]_crit_alarm
+fan[1-*]_min_alarm
+fan[1-*]_max_alarm
+temp[1-*]_min_alarm
+temp[1-*]_max_alarm
+temp[1-*]_lcrit_alarm
+temp[1-*]_crit_alarm
+temp[1-*]_emergency_alarm
+		Limit alarm
+		0: no alarm
+		1: alarm
+		RO
+
+Each input channel may have an associated fault file. This can be used
+to notify open diodes, unconnected fans etc. where the hardware
+supports it. When this boolean has value 1, the measurement for that
+channel should not be trusted.
+
+fan[1-*]_fault
+temp[1-*]_fault
+		Input fault condition
+		0: no fault occurred
+		1: fault condition
+		RO
+
+Some chips also offer the possibility to get beeped when an alarm occurs:
+
+beep_enable	Master beep enable
+		0: no beeps
+		1: beeps
+		RW
+
+in[0-*]_beep
+curr[1-*]_beep
+fan[1-*]_beep
+temp[1-*]_beep
+		Channel beep
+		0: disable
+		1: enable
+		RW
+
+In theory, a chip could provide per-limit beep masking, but no such chip
+was seen so far.
+
+Old drivers provided a different, non-standard interface to alarms and
+beeps. These interface files are deprecated, but will be kept around
+for compatibility reasons:
+
+alarms		Alarm bitmask.
+		RO
+		Integer representation of one to four bytes.
+		A '1' bit means an alarm.
+		Chips should be programmed for 'comparator' mode so that
+		the alarm will 'come back' after you read the register
+		if it is still valid.
+		Generally a direct representation of a chip's internal
+		alarm registers; there is no standard for the position
+		of individual bits. For this reason, the use of this
+		interface file for new drivers is discouraged. Use
+		individual *_alarm and *_fault files instead.
+		Bits are defined in kernel/include/sensors.h.
+
+beep_mask	Bitmask for beep.
+		Same format as 'alarms' with the same bit locations,
+		use discouraged for the same reason. Use individual
+		*_beep files instead.
+		RW
+
+
+***********************
+* Intrusion detection *
+***********************
+
+intrusion[0-*]_alarm
+		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.
+
+intrusion[0-*]_beep
+		Chassis intrusion beep
+		0: disable
+		1: enable
+		RW
+
+
+sysfs attribute writes interpretation
+-------------------------------------
+
+hwmon sysfs attributes always contain numbers, so the first thing to do is to
+convert the input to a number, there are 2 ways todo this depending whether
+the number can be negative or not:
+unsigned long u = simple_strtoul(buf, NULL, 10);
+long s = simple_strtol(buf, NULL, 10);
+
+With buf being the buffer with the user input being passed by the kernel.
+Notice that we do not use the second argument of strto[u]l, and thus cannot
+tell when 0 is returned, if this was really 0 or is caused by invalid input.
+This is done deliberately as checking this everywhere would add a lot of
+code to the kernel.
+
+Notice that it is important to always store the converted value in an
+unsigned long or long, so that no wrap around can happen before any further
+checking.
+
+After the input string is converted to an (unsigned) long, the value should be
+checked if its acceptable. Be careful with further conversions on the value
+before checking it for validity, as these conversions could still cause a wrap
+around before the check. For example do not multiply the result, and only
+add/subtract if it has been divided before the add/subtract.
+
+What to do if a value is found to be invalid, depends on the type of the
+sysfs attribute that is being set. If it is a continuous setting like a
+tempX_max or inX_max attribute, then the value should be clamped to its
+limits using clamp_val(value, min_limit, max_limit). If it is not continuous
+like for example a tempX_type, then when an invalid value is written,
+-EINVAL should be returned.
+
+Example1, temp1_max, register is a signed 8 bit value (-128 - 127 degrees):
+
+	long v = simple_strtol(buf, NULL, 10) / 1000;
+	v = clamp_val(v, -128, 127);
+	/* write v to register */
+
+Example2, fan divider setting, valid values 2, 4 and 8:
+
+	unsigned long v = simple_strtoul(buf, NULL, 10);
+
+	switch (v) {
+	case 2: v = 1; break;
+	case 4: v = 2; break;
+	case 8: v = 3; break;
+	default:
+		return -EINVAL;
+	}
+	/* write v to register */