Commit | Line | Data |
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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 | |
125ff808 JD |
5 | through the sysfs interface. Since lm-sensors 3.0.0, libsensors is |
6 | completely chip-independent. It assumes that all the kernel drivers | |
7 | implement the standard sysfs interface described in this document. | |
8 | This makes adding or updating support for any given chip very easy, as | |
9 | libsensors, and applications using it, do not need to be modified. | |
10 | This is a major improvement compared to lm-sensors 2. | |
1da177e4 LT |
11 | |
12 | Note that motherboards vary widely in the connections to sensor chips. | |
13 | There is no standard that ensures, for example, that the second | |
14 | temperature sensor is connected to the CPU, or that the second fan is on | |
15 | the CPU. Also, some values reported by the chips need some computation | |
16 | before they make full sense. For example, most chips can only measure | |
17 | voltages between 0 and +4V. Other voltages are scaled back into that | |
18 | range using external resistors. Since the values of these resistors | |
19 | can change from motherboard to motherboard, the conversions cannot be | |
20 | hard coded into the driver and have to be done in user space. | |
21 | ||
740e06a8 | 22 | For this reason, even if we aim at a chip-independent libsensors, it will |
1da177e4 LT |
23 | still require a configuration file (e.g. /etc/sensors.conf) for proper |
24 | values conversion, labeling of inputs and hiding of unused inputs. | |
25 | ||
26 | An alternative method that some programs use is to access the sysfs | |
27 | files directly. This document briefly describes the standards that the | |
28 | drivers follow, so that an application program can scan for entries and | |
29 | access this data in a simple and consistent way. That said, such programs | |
30 | will have to implement conversion, labeling and hiding of inputs. For | |
31 | this reason, it is still not recommended to bypass the library. | |
32 | ||
1da177e4 | 33 | Each chip gets its own directory in the sysfs /sys/devices tree. To |
740e06a8 JD |
34 | find all sensor chips, it is easier to follow the device symlinks from |
35 | /sys/class/hwmon/hwmon*. | |
1da177e4 | 36 | |
125ff808 JD |
37 | Up to lm-sensors 3.0.0, libsensors looks for hardware monitoring attributes |
38 | in the "physical" device directory. Since lm-sensors 3.0.1, attributes found | |
39 | in the hwmon "class" device directory are also supported. Complex drivers | |
40 | (e.g. drivers for multifunction chips) may want to use this possibility to | |
41 | avoid namespace pollution. The only drawback will be that older versions of | |
42 | libsensors won't support the driver in question. | |
43 | ||
740e06a8 | 44 | All sysfs values are fixed point numbers. |
1da177e4 LT |
45 | |
46 | There is only one value per file, unlike the older /proc specification. | |
47 | The common scheme for files naming is: <type><number>_<item>. Usual | |
48 | types for sensor chips are "in" (voltage), "temp" (temperature) and | |
49 | "fan" (fan). Usual items are "input" (measured value), "max" (high | |
50 | threshold, "min" (low threshold). Numbering usually starts from 1, | |
51 | except for voltages which start from 0 (because most data sheets use | |
52 | this). A number is always used for elements that can be present more | |
53 | than once, even if there is a single element of the given type on the | |
54 | specific chip. Other files do not refer to a specific element, so | |
55 | they have a simple name, and no number. | |
56 | ||
57 | Alarms are direct indications read from the chips. The drivers do NOT | |
58 | make comparisons of readings to thresholds. This allows violations | |
59 | between readings to be caught and alarmed. The exact definition of an | |
60 | alarm (for example, whether a threshold must be met or must be exceeded | |
61 | to cause an alarm) is chip-dependent. | |
62 | ||
2ed42633 HG |
63 | When setting values of hwmon sysfs attributes, the string representation of |
64 | the desired value must be written, note that strings which are not a number | |
65 | are interpreted as 0! For more on how written strings are interpreted see the | |
66 | "sysfs attribute writes interpretation" section at the end of this file. | |
1da177e4 LT |
67 | |
68 | ------------------------------------------------------------------------- | |
69 | ||
057bc350 RM |
70 | [0-*] denotes any positive number starting from 0 |
71 | [1-*] denotes any positive number starting from 1 | |
72 | RO read only value | |
cd4e96c5 | 73 | WO write only value |
057bc350 RM |
74 | RW read/write value |
75 | ||
76 | Read/write values may be read-only for some chips, depending on the | |
77 | hardware implementation. | |
78 | ||
176544dc JD |
79 | All entries (except name) are optional, and should only be created in a |
80 | given driver if the chip has the feature. | |
81 | ||
82 | ||
d2b847d4 IS |
83 | ********************* |
84 | * Global attributes * | |
85 | ********************* | |
176544dc JD |
86 | |
87 | name The chip name. | |
88 | This should be a short, lowercase string, not containing | |
89 | spaces nor dashes, representing the chip name. This is | |
90 | the only mandatory attribute. | |
91 | I2C devices get this attribute created automatically. | |
92 | RO | |
93 | ||
d2b847d4 IS |
94 | update_rate The rate at which the chip will update readings. |
95 | Unit: millisecond | |
96 | RW | |
97 | Some devices have a variable update rate. This attribute | |
98 | can be used to change the update rate to the desired | |
99 | frequency. | |
100 | ||
740e06a8 | 101 | |
1da177e4 LT |
102 | ************ |
103 | * Voltages * | |
104 | ************ | |
105 | ||
057bc350 | 106 | in[0-*]_min Voltage min value. |
1da177e4 | 107 | Unit: millivolt |
057bc350 | 108 | RW |
1da177e4 | 109 | |
f46fc8cd GR |
110 | in[0-*]_lcrit Voltage critical min value. |
111 | Unit: millivolt | |
112 | RW | |
113 | If voltage drops to or below this limit, the system may | |
114 | take drastic action such as power down or reset. At the very | |
115 | least, it should report a fault. | |
116 | ||
057bc350 | 117 | in[0-*]_max Voltage max value. |
1da177e4 | 118 | Unit: millivolt |
057bc350 | 119 | RW |
1da177e4 | 120 | |
f46fc8cd GR |
121 | in[0-*]_crit Voltage critical max value. |
122 | Unit: millivolt | |
123 | RW | |
124 | If voltage reaches or exceeds this limit, the system may | |
125 | take drastic action such as power down or reset. At the very | |
126 | least, it should report a fault. | |
127 | ||
057bc350 | 128 | in[0-*]_input Voltage input value. |
1da177e4 | 129 | Unit: millivolt |
057bc350 RM |
130 | RO |
131 | Voltage measured on the chip pin. | |
1da177e4 LT |
132 | Actual voltage depends on the scaling resistors on the |
133 | motherboard, as recommended in the chip datasheet. | |
134 | This varies by chip and by motherboard. | |
135 | Because of this variation, values are generally NOT scaled | |
136 | by the chip driver, and must be done by the application. | |
137 | However, some drivers (notably lm87 and via686a) | |
057bc350 | 138 | do scale, because of internal resistors built into a chip. |
176544dc JD |
139 | These drivers will output the actual voltage. Rule of |
140 | thumb: drivers should report the voltage values at the | |
141 | "pins" of the chip. | |
142 | ||
143 | in[0-*]_label Suggested voltage channel label. | |
144 | Text string | |
145 | Should only be created if the driver has hints about what | |
146 | this voltage channel is being used for, and user-space | |
147 | doesn't. In all other cases, the label is provided by | |
148 | user-space. | |
149 | RO | |
1da177e4 | 150 | |
057bc350 | 151 | cpu[0-*]_vid CPU core reference voltage. |
1da177e4 | 152 | Unit: millivolt |
057bc350 | 153 | RO |
1da177e4 LT |
154 | Not always correct. |
155 | ||
156 | vrm Voltage Regulator Module version number. | |
057bc350 RM |
157 | RW (but changing it should no more be necessary) |
158 | Originally the VRM standard version multiplied by 10, but now | |
159 | an arbitrary number, as not all standards have a version | |
160 | number. | |
1da177e4 LT |
161 | Affects the way the driver calculates the CPU core reference |
162 | voltage from the vid pins. | |
163 | ||
057bc350 RM |
164 | Also see the Alarms section for status flags associated with voltages. |
165 | ||
1da177e4 LT |
166 | |
167 | ******** | |
168 | * Fans * | |
169 | ******** | |
170 | ||
057bc350 | 171 | fan[1-*]_min Fan minimum value |
1da177e4 | 172 | Unit: revolution/min (RPM) |
057bc350 | 173 | RW |
1da177e4 | 174 | |
d54d4624 CE |
175 | fan[1-*]_max Fan maximum value |
176 | Unit: revolution/min (RPM) | |
177 | Only rarely supported by the hardware. | |
178 | RW | |
179 | ||
057bc350 | 180 | fan[1-*]_input Fan input value. |
1da177e4 | 181 | Unit: revolution/min (RPM) |
057bc350 | 182 | RO |
1da177e4 | 183 | |
057bc350 | 184 | fan[1-*]_div Fan divisor. |
1da177e4 | 185 | Integer value in powers of two (1, 2, 4, 8, 16, 32, 64, 128). |
057bc350 | 186 | RW |
1da177e4 LT |
187 | Some chips only support values 1, 2, 4 and 8. |
188 | Note that this is actually an internal clock divisor, which | |
189 | affects the measurable speed range, not the read value. | |
190 | ||
2dbc514a JD |
191 | fan[1-*]_target |
192 | Desired fan speed | |
193 | Unit: revolution/min (RPM) | |
194 | RW | |
195 | Only makes sense if the chip supports closed-loop fan speed | |
196 | control based on the measured fan speed. | |
197 | ||
176544dc JD |
198 | fan[1-*]_label Suggested fan channel label. |
199 | Text string | |
200 | Should only be created if the driver has hints about what | |
201 | this fan channel is being used for, and user-space doesn't. | |
202 | In all other cases, the label is provided by user-space. | |
203 | RO | |
204 | ||
057bc350 RM |
205 | Also see the Alarms section for status flags associated with fans. |
206 | ||
207 | ||
1da177e4 LT |
208 | ******* |
209 | * PWM * | |
210 | ******* | |
211 | ||
057bc350 | 212 | pwm[1-*] Pulse width modulation fan control. |
1da177e4 | 213 | Integer value in the range 0 to 255 |
057bc350 | 214 | RW |
1da177e4 LT |
215 | 255 is max or 100%. |
216 | ||
057bc350 | 217 | pwm[1-*]_enable |
875f25d5 JD |
218 | Fan speed control method: |
219 | 0: no fan speed control (i.e. fan at full speed) | |
220 | 1: manual fan speed control enabled (using pwm[1-*]) | |
221 | 2+: automatic fan speed control enabled | |
f8d0c19a JD |
222 | Check individual chip documentation files for automatic mode |
223 | details. | |
057bc350 RM |
224 | RW |
225 | ||
f8d0c19a JD |
226 | pwm[1-*]_mode 0: DC mode (direct current) |
227 | 1: PWM mode (pulse-width modulation) | |
228 | RW | |
229 | ||
230 | pwm[1-*]_freq Base PWM frequency in Hz. | |
231 | Only possibly available when pwmN_mode is PWM, but not always | |
232 | present even then. | |
057bc350 | 233 | RW |
1da177e4 LT |
234 | |
235 | pwm[1-*]_auto_channels_temp | |
236 | Select which temperature channels affect this PWM output in | |
237 | auto mode. Bitfield, 1 is temp1, 2 is temp2, 4 is temp3 etc... | |
238 | Which values are possible depend on the chip used. | |
057bc350 | 239 | RW |
1da177e4 LT |
240 | |
241 | pwm[1-*]_auto_point[1-*]_pwm | |
242 | pwm[1-*]_auto_point[1-*]_temp | |
243 | pwm[1-*]_auto_point[1-*]_temp_hyst | |
244 | Define the PWM vs temperature curve. Number of trip points is | |
245 | chip-dependent. Use this for chips which associate trip points | |
246 | to PWM output channels. | |
057bc350 | 247 | RW |
1da177e4 | 248 | |
1da177e4 LT |
249 | temp[1-*]_auto_point[1-*]_pwm |
250 | temp[1-*]_auto_point[1-*]_temp | |
251 | temp[1-*]_auto_point[1-*]_temp_hyst | |
252 | Define the PWM vs temperature curve. Number of trip points is | |
253 | chip-dependent. Use this for chips which associate trip points | |
254 | to temperature channels. | |
057bc350 | 255 | RW |
1da177e4 | 256 | |
f7290e24 JD |
257 | There is a third case where trip points are associated to both PWM output |
258 | channels and temperature channels: the PWM values are associated to PWM | |
259 | output channels while the temperature values are associated to temperature | |
260 | channels. In that case, the result is determined by the mapping between | |
261 | temperature inputs and PWM outputs. When several temperature inputs are | |
262 | mapped to a given PWM output, this leads to several candidate PWM values. | |
263 | The actual result is up to the chip, but in general the highest candidate | |
264 | value (fastest fan speed) wins. | |
265 | ||
1da177e4 LT |
266 | |
267 | **************** | |
268 | * Temperatures * | |
269 | **************** | |
270 | ||
057bc350 | 271 | temp[1-*]_type Sensor type selection. |
b26f9330 | 272 | Integers 1 to 6 |
057bc350 | 273 | RW |
1da177e4 LT |
274 | 1: PII/Celeron Diode |
275 | 2: 3904 transistor | |
276 | 3: thermal diode | |
b26f9330 | 277 | 4: thermistor |
61db011d RM |
278 | 5: AMD AMDSI |
279 | 6: Intel PECI | |
1da177e4 LT |
280 | Not all types are supported by all chips |
281 | ||
057bc350 | 282 | temp[1-*]_max Temperature max value. |
740e06a8 | 283 | Unit: millidegree Celsius (or millivolt, see below) |
057bc350 | 284 | RW |
1da177e4 | 285 | |
057bc350 | 286 | temp[1-*]_min Temperature min value. |
740e06a8 | 287 | Unit: millidegree Celsius |
057bc350 | 288 | RW |
1da177e4 | 289 | |
057bc350 | 290 | temp[1-*]_max_hyst |
1da177e4 | 291 | Temperature hysteresis value for max limit. |
740e06a8 | 292 | Unit: millidegree Celsius |
1da177e4 LT |
293 | Must be reported as an absolute temperature, NOT a delta |
294 | from the max value. | |
057bc350 | 295 | RW |
1da177e4 | 296 | |
057bc350 | 297 | temp[1-*]_input Temperature input value. |
740e06a8 | 298 | Unit: millidegree Celsius |
057bc350 | 299 | RO |
1da177e4 | 300 | |
f46fc8cd | 301 | temp[1-*]_crit Temperature critical max value, typically greater than |
1da177e4 | 302 | corresponding temp_max values. |
740e06a8 | 303 | Unit: millidegree Celsius |
057bc350 | 304 | RW |
1da177e4 | 305 | |
057bc350 | 306 | temp[1-*]_crit_hyst |
1da177e4 | 307 | Temperature hysteresis value for critical limit. |
740e06a8 | 308 | Unit: millidegree Celsius |
1da177e4 LT |
309 | Must be reported as an absolute temperature, NOT a delta |
310 | from the critical value. | |
057bc350 | 311 | RW |
1da177e4 | 312 | |
f46fc8cd GR |
313 | temp[1-*]_lcrit Temperature critical min value, typically lower than |
314 | corresponding temp_min values. | |
315 | Unit: millidegree Celsius | |
316 | RW | |
317 | ||
176544dc | 318 | temp[1-*]_offset |
59ac8367 HR |
319 | Temperature offset which is added to the temperature reading |
320 | by the chip. | |
321 | Unit: millidegree Celsius | |
322 | Read/Write value. | |
323 | ||
176544dc JD |
324 | temp[1-*]_label Suggested temperature channel label. |
325 | Text string | |
326 | Should only be created if the driver has hints about what | |
327 | this temperature channel is being used for, and user-space | |
328 | doesn't. In all other cases, the label is provided by | |
329 | user-space. | |
330 | RO | |
1da177e4 | 331 | |
cd4e96c5 AP |
332 | temp[1-*]_lowest |
333 | Historical minimum temperature | |
334 | Unit: millidegree Celsius | |
335 | RO | |
336 | ||
337 | temp[1-*]_highest | |
338 | Historical maximum temperature | |
339 | Unit: millidegree Celsius | |
340 | RO | |
341 | ||
342 | temp[1-*]_reset_history | |
343 | Reset temp_lowest and temp_highest | |
344 | WO | |
345 | ||
346 | temp_reset_history | |
347 | Reset temp_lowest and temp_highest for all sensors | |
348 | WO | |
349 | ||
740e06a8 JD |
350 | Some chips measure temperature using external thermistors and an ADC, and |
351 | report the temperature measurement as a voltage. Converting this voltage | |
352 | back to a temperature (or the other way around for limits) requires | |
353 | mathematical functions not available in the kernel, so the conversion | |
354 | must occur in user space. For these chips, all temp* files described | |
355 | above should contain values expressed in millivolt instead of millidegree | |
356 | Celsius. In other words, such temperature channels are handled as voltage | |
357 | channels by the driver. | |
358 | ||
057bc350 RM |
359 | Also see the Alarms section for status flags associated with temperatures. |
360 | ||
1da177e4 LT |
361 | |
362 | ************ | |
363 | * Currents * | |
364 | ************ | |
365 | ||
366 | Note that no known chip provides current measurements as of writing, | |
367 | so this part is theoretical, so to say. | |
368 | ||
057bc350 | 369 | curr[1-*]_max Current max value |
1da177e4 | 370 | Unit: milliampere |
057bc350 | 371 | RW |
1da177e4 | 372 | |
057bc350 | 373 | curr[1-*]_min Current min value. |
1da177e4 | 374 | Unit: milliampere |
057bc350 | 375 | RW |
1da177e4 | 376 | |
057bc350 | 377 | curr[1-*]_input Current input value |
1da177e4 | 378 | Unit: milliampere |
057bc350 | 379 | RO |
1da177e4 | 380 | |
38fb56a2 DW |
381 | ********* |
382 | * Power * | |
383 | ********* | |
384 | ||
385 | power[1-*]_average Average power use | |
386 | Unit: microWatt | |
387 | RO | |
388 | ||
115a57c5 DW |
389 | power[1-*]_average_interval Power use averaging interval. A poll |
390 | notification is sent to this file if the | |
391 | hardware changes the averaging interval. | |
ddedc658 DW |
392 | Unit: milliseconds |
393 | RW | |
394 | ||
115a57c5 DW |
395 | power[1-*]_average_interval_max Maximum power use averaging interval |
396 | Unit: milliseconds | |
397 | RO | |
398 | ||
399 | power[1-*]_average_interval_min Minimum power use averaging interval | |
400 | Unit: milliseconds | |
401 | RO | |
402 | ||
38fb56a2 DW |
403 | power[1-*]_average_highest Historical average maximum power use |
404 | Unit: microWatt | |
405 | RO | |
406 | ||
407 | power[1-*]_average_lowest Historical average minimum power use | |
408 | Unit: microWatt | |
409 | RO | |
410 | ||
115a57c5 DW |
411 | power[1-*]_average_max A poll notification is sent to |
412 | power[1-*]_average when power use | |
413 | rises above this value. | |
414 | Unit: microWatt | |
415 | RW | |
416 | ||
417 | power[1-*]_average_min A poll notification is sent to | |
418 | power[1-*]_average when power use | |
419 | sinks below this value. | |
420 | Unit: microWatt | |
421 | RW | |
422 | ||
38fb56a2 DW |
423 | power[1-*]_input Instantaneous power use |
424 | Unit: microWatt | |
425 | RO | |
426 | ||
427 | power[1-*]_input_highest Historical maximum power use | |
428 | Unit: microWatt | |
429 | RO | |
430 | ||
431 | power[1-*]_input_lowest Historical minimum power use | |
432 | Unit: microWatt | |
433 | RO | |
434 | ||
435 | power[1-*]_reset_history Reset input_highest, input_lowest, | |
436 | average_highest and average_lowest. | |
437 | WO | |
1da177e4 | 438 | |
115a57c5 DW |
439 | power[1-*]_accuracy Accuracy of the power meter. |
440 | Unit: Percent | |
441 | RO | |
442 | ||
443 | power[1-*]_alarm 1 if the system is drawing more power than the | |
444 | cap allows; 0 otherwise. A poll notification is | |
445 | sent to this file when the power use exceeds the | |
446 | cap. This file only appears if the cap is known | |
447 | to be enforced by hardware. | |
448 | RO | |
449 | ||
450 | power[1-*]_cap If power use rises above this limit, the | |
451 | system should take action to reduce power use. | |
452 | A poll notification is sent to this file if the | |
453 | cap is changed by the hardware. The *_cap | |
454 | files only appear if the cap is known to be | |
455 | enforced by hardware. | |
456 | Unit: microWatt | |
457 | RW | |
458 | ||
459 | power[1-*]_cap_hyst Margin of hysteresis built around capping and | |
460 | notification. | |
461 | Unit: microWatt | |
462 | RW | |
463 | ||
464 | power[1-*]_cap_max Maximum cap that can be set. | |
465 | Unit: microWatt | |
466 | RO | |
467 | ||
468 | power[1-*]_cap_min Minimum cap that can be set. | |
469 | Unit: microWatt | |
470 | RO | |
471 | ||
ddedc658 DW |
472 | ********** |
473 | * Energy * | |
474 | ********** | |
475 | ||
476 | energy[1-*]_input Cumulative energy use | |
477 | Unit: microJoule | |
478 | RO | |
479 | ||
ec199209 | 480 | |
400b48ec JD |
481 | ********** |
482 | * Alarms * | |
483 | ********** | |
484 | ||
485 | Each channel or limit may have an associated alarm file, containing a | |
486 | boolean value. 1 means than an alarm condition exists, 0 means no alarm. | |
487 | ||
488 | Usually a given chip will either use channel-related alarms, or | |
489 | limit-related alarms, not both. The driver should just reflect the hardware | |
490 | implementation. | |
491 | ||
057bc350 RM |
492 | in[0-*]_alarm |
493 | fan[1-*]_alarm | |
494 | temp[1-*]_alarm | |
400b48ec | 495 | Channel alarm |
057bc350 RM |
496 | 0: no alarm |
497 | 1: alarm | |
498 | RO | |
400b48ec JD |
499 | |
500 | OR | |
501 | ||
057bc350 RM |
502 | in[0-*]_min_alarm |
503 | in[0-*]_max_alarm | |
504 | fan[1-*]_min_alarm | |
d54d4624 | 505 | fan[1-*]_max_alarm |
057bc350 RM |
506 | temp[1-*]_min_alarm |
507 | temp[1-*]_max_alarm | |
508 | temp[1-*]_crit_alarm | |
400b48ec | 509 | Limit alarm |
057bc350 RM |
510 | 0: no alarm |
511 | 1: alarm | |
512 | RO | |
400b48ec JD |
513 | |
514 | Each input channel may have an associated fault file. This can be used | |
515 | to notify open diodes, unconnected fans etc. where the hardware | |
516 | supports it. When this boolean has value 1, the measurement for that | |
517 | channel should not be trusted. | |
518 | ||
7817a39e JD |
519 | in[0-*]_fault |
520 | fan[1-*]_fault | |
521 | temp[1-*]_fault | |
400b48ec | 522 | Input fault condition |
057bc350 RM |
523 | 0: no fault occured |
524 | 1: fault condition | |
525 | RO | |
400b48ec JD |
526 | |
527 | Some chips also offer the possibility to get beeped when an alarm occurs: | |
528 | ||
529 | beep_enable Master beep enable | |
057bc350 RM |
530 | 0: no beeps |
531 | 1: beeps | |
532 | RW | |
400b48ec | 533 | |
057bc350 RM |
534 | in[0-*]_beep |
535 | fan[1-*]_beep | |
536 | temp[1-*]_beep | |
400b48ec | 537 | Channel beep |
057bc350 RM |
538 | 0: disable |
539 | 1: enable | |
540 | RW | |
400b48ec JD |
541 | |
542 | In theory, a chip could provide per-limit beep masking, but no such chip | |
543 | was seen so far. | |
544 | ||
545 | Old drivers provided a different, non-standard interface to alarms and | |
546 | beeps. These interface files are deprecated, but will be kept around | |
547 | for compatibility reasons: | |
1da177e4 LT |
548 | |
549 | alarms Alarm bitmask. | |
057bc350 | 550 | RO |
1da177e4 LT |
551 | Integer representation of one to four bytes. |
552 | A '1' bit means an alarm. | |
553 | Chips should be programmed for 'comparator' mode so that | |
554 | the alarm will 'come back' after you read the register | |
555 | if it is still valid. | |
556 | Generally a direct representation of a chip's internal | |
557 | alarm registers; there is no standard for the position | |
400b48ec JD |
558 | of individual bits. For this reason, the use of this |
559 | interface file for new drivers is discouraged. Use | |
560 | individual *_alarm and *_fault files instead. | |
1da177e4 LT |
561 | Bits are defined in kernel/include/sensors.h. |
562 | ||
1da177e4 | 563 | beep_mask Bitmask for beep. |
400b48ec JD |
564 | Same format as 'alarms' with the same bit locations, |
565 | use discouraged for the same reason. Use individual | |
566 | *_beep files instead. | |
057bc350 | 567 | RW |
2ed42633 HG |
568 | |
569 | ||
ec199209 JD |
570 | *********************** |
571 | * Intrusion detection * | |
572 | *********************** | |
573 | ||
574 | intrusion[0-*]_alarm | |
575 | Chassis intrusion detection | |
576 | 0: OK | |
577 | 1: intrusion detected | |
578 | RW | |
579 | Contrary to regular alarm flags which clear themselves | |
580 | automatically when read, this one sticks until cleared by | |
581 | the user. This is done by writing 0 to the file. Writing | |
582 | other values is unsupported. | |
583 | ||
584 | intrusion[0-*]_beep | |
585 | Chassis intrusion beep | |
586 | 0: disable | |
587 | 1: enable | |
588 | RW | |
589 | ||
590 | ||
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591 | sysfs attribute writes interpretation |
592 | ------------------------------------- | |
593 | ||
594 | hwmon sysfs attributes always contain numbers, so the first thing to do is to | |
595 | convert the input to a number, there are 2 ways todo this depending whether | |
596 | the number can be negative or not: | |
597 | unsigned long u = simple_strtoul(buf, NULL, 10); | |
598 | long s = simple_strtol(buf, NULL, 10); | |
599 | ||
600 | With buf being the buffer with the user input being passed by the kernel. | |
601 | Notice that we do not use the second argument of strto[u]l, and thus cannot | |
602 | tell when 0 is returned, if this was really 0 or is caused by invalid input. | |
603 | This is done deliberately as checking this everywhere would add a lot of | |
604 | code to the kernel. | |
605 | ||
606 | Notice that it is important to always store the converted value in an | |
607 | unsigned long or long, so that no wrap around can happen before any further | |
608 | checking. | |
609 | ||
610 | After the input string is converted to an (unsigned) long, the value should be | |
611 | checked if its acceptable. Be careful with further conversions on the value | |
612 | before checking it for validity, as these conversions could still cause a wrap | |
613 | around before the check. For example do not multiply the result, and only | |
614 | add/subtract if it has been divided before the add/subtract. | |
615 | ||
616 | What to do if a value is found to be invalid, depends on the type of the | |
617 | sysfs attribute that is being set. If it is a continuous setting like a | |
618 | tempX_max or inX_max attribute, then the value should be clamped to its | |
619 | limits using SENSORS_LIMIT(value, min_limit, max_limit). If it is not | |
620 | continuous like for example a tempX_type, then when an invalid value is | |
621 | written, -EINVAL should be returned. | |
622 | ||
623 | Example1, temp1_max, register is a signed 8 bit value (-128 - 127 degrees): | |
5fbea518 JD |
624 | |
625 | long v = simple_strtol(buf, NULL, 10) / 1000; | |
626 | v = SENSORS_LIMIT(v, -128, 127); | |
627 | /* write v to register */ | |
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628 | |
629 | Example2, fan divider setting, valid values 2, 4 and 8: | |
5fbea518 JD |
630 | |
631 | unsigned long v = simple_strtoul(buf, NULL, 10); | |
632 | ||
633 | switch (v) { | |
634 | case 2: v = 1; break; | |
635 | case 4: v = 2; break; | |
636 | case 8: v = 3; break; | |
637 | default: | |
638 | return -EINVAL; | |
639 | } | |
640 | /* write v to register */ |