mirror of
https://github.com/torvalds/linux.git
synced 2024-11-27 06:31:52 +00:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
275 lines
8.6 KiB
Plaintext
275 lines
8.6 KiB
Plaintext
Naming and data format standards for sysfs files
|
|
------------------------------------------------
|
|
|
|
The libsensors library offers an interface to the raw sensors data
|
|
through the sysfs interface. See libsensors documentation and source for
|
|
more further information. As of writing this document, libsensors
|
|
(from lm_sensors 2.8.3) is heavily chip-dependant. Adding or updating
|
|
support for any given chip requires modifying the library's code.
|
|
This is because libsensors was written for the procfs interface
|
|
older kernel modules were using, which wasn't standardized enough.
|
|
Recent versions of libsensors (from lm_sensors 2.8.2 and later) have
|
|
support for the sysfs interface, though.
|
|
|
|
The new sysfs interface was designed to be as chip-independant as
|
|
possible.
|
|
|
|
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-independant 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.
|
|
|
|
If you are developing a userspace application please send us feedback on
|
|
this standard.
|
|
|
|
Note that this standard isn't completely established yet, so it is subject
|
|
to changes, even important ones. One more reason to use the library instead
|
|
of accessing sysfs files directly.
|
|
|
|
Each chip gets its own directory in the sysfs /sys/devices tree. To
|
|
find all sensor chips, it is easier to follow the symlinks from
|
|
/sys/i2c/devices/
|
|
|
|
All sysfs values are fixed point numbers. To get the true value of some
|
|
of the values, you should divide by the specified value.
|
|
|
|
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.
|
|
|
|
|
|
-------------------------------------------------------------------------
|
|
|
|
************
|
|
* Voltages *
|
|
************
|
|
|
|
in[0-8]_min Voltage min value.
|
|
Unit: millivolt
|
|
Read/Write
|
|
|
|
in[0-8]_max Voltage max value.
|
|
Unit: millivolt
|
|
Read/Write
|
|
|
|
in[0-8]_input Voltage input value.
|
|
Unit: millivolt
|
|
Read only
|
|
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, with various degrees of success.
|
|
These drivers will output the actual voltage.
|
|
|
|
Typical usage:
|
|
in0_* CPU #1 voltage (not scaled)
|
|
in1_* CPU #2 voltage (not scaled)
|
|
in2_* 3.3V nominal (not scaled)
|
|
in3_* 5.0V nominal (scaled)
|
|
in4_* 12.0V nominal (scaled)
|
|
in5_* -12.0V nominal (scaled)
|
|
in6_* -5.0V nominal (scaled)
|
|
in7_* varies
|
|
in8_* varies
|
|
|
|
cpu[0-1]_vid CPU core reference voltage.
|
|
Unit: millivolt
|
|
Read only.
|
|
Not always correct.
|
|
|
|
vrm Voltage Regulator Module version number.
|
|
Read only.
|
|
Two digit number, first is major version, second is
|
|
minor version.
|
|
Affects the way the driver calculates the CPU core reference
|
|
voltage from the vid pins.
|
|
|
|
|
|
********
|
|
* Fans *
|
|
********
|
|
|
|
fan[1-3]_min Fan minimum value
|
|
Unit: revolution/min (RPM)
|
|
Read/Write.
|
|
|
|
fan[1-3]_input Fan input value.
|
|
Unit: revolution/min (RPM)
|
|
Read only.
|
|
|
|
fan[1-3]_div Fan divisor.
|
|
Integer value in powers of two (1, 2, 4, 8, 16, 32, 64, 128).
|
|
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.
|
|
|
|
*******
|
|
* PWM *
|
|
*******
|
|
|
|
pwm[1-3] Pulse width modulation fan control.
|
|
Integer value in the range 0 to 255
|
|
Read/Write
|
|
255 is max or 100%.
|
|
|
|
pwm[1-3]_enable
|
|
Switch PWM on and off.
|
|
Not always present even if fan*_pwm is.
|
|
0 to turn off
|
|
1 to turn on in manual mode
|
|
2 to turn on in automatic mode
|
|
Read/Write
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
OR
|
|
|
|
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.
|
|
|
|
|
|
****************
|
|
* Temperatures *
|
|
****************
|
|
|
|
temp[1-3]_type Sensor type selection.
|
|
Integers 1, 2, 3 or thermistor Beta value (3435)
|
|
Read/Write.
|
|
1: PII/Celeron Diode
|
|
2: 3904 transistor
|
|
3: thermal diode
|
|
Not all types are supported by all chips
|
|
|
|
temp[1-4]_max Temperature max value.
|
|
Unit: millidegree Celcius
|
|
Read/Write value.
|
|
|
|
temp[1-3]_min Temperature min value.
|
|
Unit: millidegree Celcius
|
|
Read/Write value.
|
|
|
|
temp[1-3]_max_hyst
|
|
Temperature hysteresis value for max limit.
|
|
Unit: millidegree Celcius
|
|
Must be reported as an absolute temperature, NOT a delta
|
|
from the max value.
|
|
Read/Write value.
|
|
|
|
temp[1-4]_input Temperature input value.
|
|
Unit: millidegree Celcius
|
|
Read only value.
|
|
|
|
temp[1-4]_crit Temperature critical value, typically greater than
|
|
corresponding temp_max values.
|
|
Unit: millidegree Celcius
|
|
Read/Write value.
|
|
|
|
temp[1-2]_crit_hyst
|
|
Temperature hysteresis value for critical limit.
|
|
Unit: millidegree Celcius
|
|
Must be reported as an absolute temperature, NOT a delta
|
|
from the critical value.
|
|
Read/Write value.
|
|
|
|
If there are multiple temperature sensors, temp1_* is
|
|
generally the sensor inside the chip itself,
|
|
reported as "motherboard temperature". temp2_* to
|
|
temp4_* are generally sensors external to the chip
|
|
itself, for example the thermal diode inside the CPU or
|
|
a thermistor nearby.
|
|
|
|
|
|
************
|
|
* Currents *
|
|
************
|
|
|
|
Note that no known chip provides current measurements as of writing,
|
|
so this part is theoretical, so to say.
|
|
|
|
curr[1-n]_max Current max value
|
|
Unit: milliampere
|
|
Read/Write.
|
|
|
|
curr[1-n]_min Current min value.
|
|
Unit: milliampere
|
|
Read/Write.
|
|
|
|
curr[1-n]_input Current input value
|
|
Unit: milliampere
|
|
Read only.
|
|
|
|
|
|
*********
|
|
* Other *
|
|
*********
|
|
|
|
alarms Alarm bitmask.
|
|
Read only.
|
|
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.
|
|
Bits are defined in kernel/include/sensors.h.
|
|
|
|
beep_enable Beep/interrupt enable
|
|
0 to disable.
|
|
1 to enable.
|
|
Read/Write
|
|
|
|
beep_mask Bitmask for beep.
|
|
Same format as 'alarms' with the same bit locations.
|
|
Read/Write
|
|
|
|
eeprom Raw EEPROM data in binary form.
|
|
Read only.
|