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Diffstat (limited to 'Documentation/hwmon/sysfs-interface')
| -rw-r--r-- | Documentation/hwmon/sysfs-interface | 713 |
1 files changed, 598 insertions, 115 deletions
diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface index 764cdc5480e..2cc95ad4660 100644 --- a/Documentation/hwmon/sysfs-interface +++ b/Documentation/hwmon/sysfs-interface @@ -2,17 +2,12 @@ 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. +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 @@ -24,7 +19,7 @@ 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 +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. @@ -35,19 +30,18 @@ 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/ +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. To get the true value of some -of the values, you should divide by the specified value. +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 @@ -66,96 +60,216 @@ 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 + spaces nor dashes, representing the chip name. This 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[0-8]_min Voltage min value. +in[0-*]_min Voltage min value. Unit: millivolt - Read/Write + RW -in[0-8]_max Voltage max value. +in[0-*]_lcrit Voltage critical min value. Unit: millivolt - Read/Write + 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[0-8]_input Voltage input value. +in[0-*]_crit Voltage critical max value. Unit: millivolt - Read only + 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, 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. + 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 + +cpu[0-*]_vid CPU core reference voltage. Unit: millivolt - Read only. + RO Not always correct. vrm Voltage Regulator Module version number. - Read only. - Two digit number, first is major version, second is - minor version. + 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[1-3]_min Fan minimum value +fan[1-*]_min Fan minimum value Unit: revolution/min (RPM) - Read/Write. + RW -fan[1-3]_input Fan input value. +fan[1-*]_max Fan maximum value Unit: revolution/min (RPM) - Read only. + Only rarely supported by the hardware. + RW -fan[1-3]_div Fan divisor. +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 + +Also see the Alarms section for status flags associated with fans. + + ******* * PWM * ******* -pwm[1-3] Pulse width modulation fan control. +pwm[1-*] Pulse width modulation fan control. Integer value in the range 0 to 255 - Read/Write + RW 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-*]_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 @@ -163,8 +277,7 @@ 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 + RW temp[1-*]_auto_point[1-*]_pwm temp[1-*]_auto_point[1-*]_temp @@ -172,85 +285,389 @@ 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[1-3]_type Sensor type selection. - Integers 1, 2, 3 or thermistor Beta value (3435) - Read/Write. - 1: PII/Celeron Diode +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[1-4]_max Temperature max value. - Unit: millidegree Celcius - Read/Write value. +temp[1-*]_max Temperature max value. + Unit: millidegree Celsius (or millivolt, see below) + RW -temp[1-3]_min Temperature min value. - Unit: millidegree Celcius - Read/Write value. +temp[1-*]_min Temperature min value. + Unit: millidegree Celsius + RW -temp[1-3]_max_hyst +temp[1-*]_max_hyst Temperature hysteresis value for max limit. - Unit: millidegree Celcius + Unit: millidegree Celsius Must be reported as an absolute temperature, NOT a delta from the max value. - Read/Write value. + RW -temp[1-4]_input Temperature input value. - Unit: millidegree Celcius - Read only value. +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[1-4]_crit Temperature critical value, typically greater than +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 Celcius - Read/Write value. + Unit: millidegree Celsius + RW -temp[1-2]_crit_hyst +temp[1-*]_crit_hyst Temperature hysteresis value for critical limit. - Unit: millidegree Celcius + 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. - 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. +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 + +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 * ************ -Note that no known chip provides current measurements as of writing, -so this part is theoretical, so to say. +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-n]_max Current max value +curr[1-*]_crit Current critical high value. Unit: milliampere - Read/Write. + RW -curr[1-n]_min Current min value. +curr[1-*]_input Current input value Unit: milliampere - Read/Write. + RO -curr[1-n]_input Current input value +curr[1-*]_average + Average current use Unit: milliampere - Read only. + 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 + +Also see the Alarms section for status flags associated with currents. ********* -* Other * +* 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 + +Also see the Alarms section for status flags associated with power readings. + +********** +* Energy * +********** + +energy[1-*]_input Cumulative energy use + Unit: microJoule + RO + + +************ +* Humidity * +************ + +humidity[1-*]_input Humidity + Unit: milli-percent (per cent mille, pcm) + RO + + +********** +* 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. - Read only. + RO Integer representation of one to four bytes. A '1' bit means an alarm. Chips should be programmed for 'comparator' mode so that @@ -258,20 +675,86 @@ alarms Alarm bitmask. 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. + 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_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. - -pec Enable or disable PEC (SMBus only) - Read/Write + 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 */ |