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diff --git a/Documentation/i2c/sysfs-interface b/Documentation/i2c/sysfs-interface deleted file mode 100644 index 346400519d0..00000000000 --- a/Documentation/i2c/sysfs-interface +++ /dev/null @@ -1,274 +0,0 @@ -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. |