Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | Naming and data format standards for sysfs files |
2 | ------------------------------------------------ | |
3 | ||
4 | The libsensors library offers an interface to the raw sensors data | |
5 | through the sysfs interface. See libsensors documentation and source for | |
6 | more further information. As of writing this document, libsensors | |
7 | (from lm_sensors 2.8.3) is heavily chip-dependant. Adding or updating | |
8 | support for any given chip requires modifying the library's code. | |
9 | This is because libsensors was written for the procfs interface | |
10 | older kernel modules were using, which wasn't standardized enough. | |
11 | Recent versions of libsensors (from lm_sensors 2.8.2 and later) have | |
12 | support for the sysfs interface, though. | |
13 | ||
14 | The new sysfs interface was designed to be as chip-independant as | |
15 | possible. | |
16 | ||
17 | Note that motherboards vary widely in the connections to sensor chips. | |
18 | There is no standard that ensures, for example, that the second | |
19 | temperature sensor is connected to the CPU, or that the second fan is on | |
20 | the CPU. Also, some values reported by the chips need some computation | |
21 | before they make full sense. For example, most chips can only measure | |
22 | voltages between 0 and +4V. Other voltages are scaled back into that | |
23 | range using external resistors. Since the values of these resistors | |
24 | can change from motherboard to motherboard, the conversions cannot be | |
25 | hard coded into the driver and have to be done in user space. | |
26 | ||
27 | For this reason, even if we aim at a chip-independant libsensors, it will | |
28 | still require a configuration file (e.g. /etc/sensors.conf) for proper | |
29 | values conversion, labeling of inputs and hiding of unused inputs. | |
30 | ||
31 | An alternative method that some programs use is to access the sysfs | |
32 | files directly. This document briefly describes the standards that the | |
33 | drivers follow, so that an application program can scan for entries and | |
34 | access this data in a simple and consistent way. That said, such programs | |
35 | will have to implement conversion, labeling and hiding of inputs. For | |
36 | this reason, it is still not recommended to bypass the library. | |
37 | ||
38 | If you are developing a userspace application please send us feedback on | |
39 | this standard. | |
40 | ||
41 | Note that this standard isn't completely established yet, so it is subject | |
42 | to changes, even important ones. One more reason to use the library instead | |
43 | of accessing sysfs files directly. | |
44 | ||
45 | Each chip gets its own directory in the sysfs /sys/devices tree. To | |
46 | find all sensor chips, it is easier to follow the symlinks from | |
47 | /sys/i2c/devices/ | |
48 | ||
49 | All sysfs values are fixed point numbers. To get the true value of some | |
50 | of the values, you should divide by the specified value. | |
51 | ||
52 | There is only one value per file, unlike the older /proc specification. | |
53 | The common scheme for files naming is: <type><number>_<item>. Usual | |
54 | types for sensor chips are "in" (voltage), "temp" (temperature) and | |
55 | "fan" (fan). Usual items are "input" (measured value), "max" (high | |
56 | threshold, "min" (low threshold). Numbering usually starts from 1, | |
57 | except for voltages which start from 0 (because most data sheets use | |
58 | this). A number is always used for elements that can be present more | |
59 | than once, even if there is a single element of the given type on the | |
60 | specific chip. Other files do not refer to a specific element, so | |
61 | they have a simple name, and no number. | |
62 | ||
63 | Alarms are direct indications read from the chips. The drivers do NOT | |
64 | make comparisons of readings to thresholds. This allows violations | |
65 | between readings to be caught and alarmed. The exact definition of an | |
66 | alarm (for example, whether a threshold must be met or must be exceeded | |
67 | to cause an alarm) is chip-dependent. | |
68 | ||
69 | ||
70 | ------------------------------------------------------------------------- | |
71 | ||
72 | ************ | |
73 | * Voltages * | |
74 | ************ | |
75 | ||
76 | in[0-8]_min Voltage min value. | |
77 | Unit: millivolt | |
78 | Read/Write | |
79 | ||
80 | in[0-8]_max Voltage max value. | |
81 | Unit: millivolt | |
82 | Read/Write | |
83 | ||
84 | in[0-8]_input Voltage input value. | |
85 | Unit: millivolt | |
86 | Read only | |
87 | Actual voltage depends on the scaling resistors on the | |
88 | motherboard, as recommended in the chip datasheet. | |
89 | This varies by chip and by motherboard. | |
90 | Because of this variation, values are generally NOT scaled | |
91 | by the chip driver, and must be done by the application. | |
92 | However, some drivers (notably lm87 and via686a) | |
93 | do scale, with various degrees of success. | |
94 | These drivers will output the actual voltage. | |
95 | ||
96 | Typical usage: | |
97 | in0_* CPU #1 voltage (not scaled) | |
98 | in1_* CPU #2 voltage (not scaled) | |
99 | in2_* 3.3V nominal (not scaled) | |
100 | in3_* 5.0V nominal (scaled) | |
101 | in4_* 12.0V nominal (scaled) | |
102 | in5_* -12.0V nominal (scaled) | |
103 | in6_* -5.0V nominal (scaled) | |
104 | in7_* varies | |
105 | in8_* varies | |
106 | ||
107 | cpu[0-1]_vid CPU core reference voltage. | |
108 | Unit: millivolt | |
109 | Read only. | |
110 | Not always correct. | |
111 | ||
112 | vrm Voltage Regulator Module version number. | |
113 | Read only. | |
114 | Two digit number, first is major version, second is | |
115 | minor version. | |
116 | Affects the way the driver calculates the CPU core reference | |
117 | voltage from the vid pins. | |
118 | ||
119 | ||
120 | ******** | |
121 | * Fans * | |
122 | ******** | |
123 | ||
124 | fan[1-3]_min Fan minimum value | |
125 | Unit: revolution/min (RPM) | |
126 | Read/Write. | |
127 | ||
128 | fan[1-3]_input Fan input value. | |
129 | Unit: revolution/min (RPM) | |
130 | Read only. | |
131 | ||
132 | fan[1-3]_div Fan divisor. | |
133 | Integer value in powers of two (1, 2, 4, 8, 16, 32, 64, 128). | |
134 | Some chips only support values 1, 2, 4 and 8. | |
135 | Note that this is actually an internal clock divisor, which | |
136 | affects the measurable speed range, not the read value. | |
137 | ||
138 | ******* | |
139 | * PWM * | |
140 | ******* | |
141 | ||
142 | pwm[1-3] Pulse width modulation fan control. | |
143 | Integer value in the range 0 to 255 | |
144 | Read/Write | |
145 | 255 is max or 100%. | |
146 | ||
147 | pwm[1-3]_enable | |
148 | Switch PWM on and off. | |
149 | Not always present even if fan*_pwm is. | |
150 | 0 to turn off | |
151 | 1 to turn on in manual mode | |
152 | 2 to turn on in automatic mode | |
153 | Read/Write | |
154 | ||
155 | pwm[1-*]_auto_channels_temp | |
156 | Select which temperature channels affect this PWM output in | |
157 | auto mode. Bitfield, 1 is temp1, 2 is temp2, 4 is temp3 etc... | |
158 | Which values are possible depend on the chip used. | |
159 | ||
160 | pwm[1-*]_auto_point[1-*]_pwm | |
161 | pwm[1-*]_auto_point[1-*]_temp | |
162 | pwm[1-*]_auto_point[1-*]_temp_hyst | |
163 | Define the PWM vs temperature curve. Number of trip points is | |
164 | chip-dependent. Use this for chips which associate trip points | |
165 | to PWM output channels. | |
166 | ||
167 | OR | |
168 | ||
169 | temp[1-*]_auto_point[1-*]_pwm | |
170 | temp[1-*]_auto_point[1-*]_temp | |
171 | temp[1-*]_auto_point[1-*]_temp_hyst | |
172 | Define the PWM vs temperature curve. Number of trip points is | |
173 | chip-dependent. Use this for chips which associate trip points | |
174 | to temperature channels. | |
175 | ||
176 | ||
177 | **************** | |
178 | * Temperatures * | |
179 | **************** | |
180 | ||
181 | temp[1-3]_type Sensor type selection. | |
e53004e2 | 182 | Integers 1 to 4 or thermistor Beta value (typically 3435) |
1da177e4 LT |
183 | Read/Write. |
184 | 1: PII/Celeron Diode | |
185 | 2: 3904 transistor | |
186 | 3: thermal diode | |
e53004e2 | 187 | 4: thermistor (default/unknown Beta) |
1da177e4 LT |
188 | Not all types are supported by all chips |
189 | ||
190 | temp[1-4]_max Temperature max value. | |
191 | Unit: millidegree Celcius | |
192 | Read/Write value. | |
193 | ||
194 | temp[1-3]_min Temperature min value. | |
195 | Unit: millidegree Celcius | |
196 | Read/Write value. | |
197 | ||
198 | temp[1-3]_max_hyst | |
199 | Temperature hysteresis value for max limit. | |
200 | Unit: millidegree Celcius | |
201 | Must be reported as an absolute temperature, NOT a delta | |
202 | from the max value. | |
203 | Read/Write value. | |
204 | ||
205 | temp[1-4]_input Temperature input value. | |
206 | Unit: millidegree Celcius | |
207 | Read only value. | |
208 | ||
209 | temp[1-4]_crit Temperature critical value, typically greater than | |
210 | corresponding temp_max values. | |
211 | Unit: millidegree Celcius | |
212 | Read/Write value. | |
213 | ||
214 | temp[1-2]_crit_hyst | |
215 | Temperature hysteresis value for critical limit. | |
216 | Unit: millidegree Celcius | |
217 | Must be reported as an absolute temperature, NOT a delta | |
218 | from the critical value. | |
219 | Read/Write value. | |
220 | ||
221 | If there are multiple temperature sensors, temp1_* is | |
222 | generally the sensor inside the chip itself, | |
223 | reported as "motherboard temperature". temp2_* to | |
224 | temp4_* are generally sensors external to the chip | |
225 | itself, for example the thermal diode inside the CPU or | |
226 | a thermistor nearby. | |
227 | ||
228 | ||
229 | ************ | |
230 | * Currents * | |
231 | ************ | |
232 | ||
233 | Note that no known chip provides current measurements as of writing, | |
234 | so this part is theoretical, so to say. | |
235 | ||
236 | curr[1-n]_max Current max value | |
237 | Unit: milliampere | |
238 | Read/Write. | |
239 | ||
240 | curr[1-n]_min Current min value. | |
241 | Unit: milliampere | |
242 | Read/Write. | |
243 | ||
244 | curr[1-n]_input Current input value | |
245 | Unit: milliampere | |
246 | Read only. | |
247 | ||
248 | ||
249 | ********* | |
250 | * Other * | |
251 | ********* | |
252 | ||
253 | alarms Alarm bitmask. | |
254 | Read only. | |
255 | Integer representation of one to four bytes. | |
256 | A '1' bit means an alarm. | |
257 | Chips should be programmed for 'comparator' mode so that | |
258 | the alarm will 'come back' after you read the register | |
259 | if it is still valid. | |
260 | Generally a direct representation of a chip's internal | |
261 | alarm registers; there is no standard for the position | |
262 | of individual bits. | |
263 | Bits are defined in kernel/include/sensors.h. | |
264 | ||
e53004e2 JD |
265 | alarms_in Alarm bitmask relative to in (voltage) channels |
266 | Read only | |
267 | A '1' bit means an alarm, LSB corresponds to in0 and so on | |
268 | Prefered to 'alarms' for newer chips | |
269 | ||
270 | alarms_fan Alarm bitmask relative to fan channels | |
271 | Read only | |
272 | A '1' bit means an alarm, LSB corresponds to fan1 and so on | |
273 | Prefered to 'alarms' for newer chips | |
274 | ||
275 | alarms_temp Alarm bitmask relative to temp (temperature) channels | |
276 | Read only | |
277 | A '1' bit means an alarm, LSB corresponds to temp1 and so on | |
278 | Prefered to 'alarms' for newer chips | |
279 | ||
1da177e4 LT |
280 | beep_enable Beep/interrupt enable |
281 | 0 to disable. | |
282 | 1 to enable. | |
283 | Read/Write | |
284 | ||
285 | beep_mask Bitmask for beep. | |
286 | Same format as 'alarms' with the same bit locations. | |
287 | Read/Write | |
288 | ||
289 | eeprom Raw EEPROM data in binary form. | |
290 | Read only. | |
c3df5806 JD |
291 | |
292 | pec Enable or disable PEC (SMBus only) | |
293 | Read/Write |