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-rw-r--r-- | Documentation/hwmon/sysfs-interface | 33 |
1 files changed, 13 insertions, 20 deletions
diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface index f4a8ebc1ef1a..2d845730d4e0 100644 --- a/Documentation/hwmon/sysfs-interface +++ b/Documentation/hwmon/sysfs-interface | |||
@@ -2,17 +2,12 @@ Naming and data format standards for sysfs files | |||
2 | ------------------------------------------------ | 2 | ------------------------------------------------ |
3 | 3 | ||
4 | The libsensors library offers an interface to the raw sensors data | 4 | The libsensors library offers an interface to the raw sensors data |
5 | through the sysfs interface. See libsensors documentation and source for | 5 | through the sysfs interface. Since lm-sensors 3.0.0, libsensors is |
6 | further information. As of writing this document, libsensors | 6 | completely chip-independent. It assumes that all the kernel drivers |
7 | (from lm_sensors 2.8.3) is heavily chip-dependent. Adding or updating | 7 | implement the standard sysfs interface described in this document. |
8 | support for any given chip requires modifying the library's code. | 8 | This makes adding or updating support for any given chip very easy, as |
9 | This is because libsensors was written for the procfs interface | 9 | libsensors, and applications using it, do not need to be modified. |
10 | older kernel modules were using, which wasn't standardized enough. | 10 | This is a major improvement compared to lm-sensors 2. |
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-independent as | ||
15 | possible. | ||
16 | 11 | ||
17 | Note that motherboards vary widely in the connections to sensor chips. | 12 | Note that motherboards vary widely in the connections to sensor chips. |
18 | There is no standard that ensures, for example, that the second | 13 | There is no standard that ensures, for example, that the second |
@@ -35,19 +30,17 @@ 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 | 30 | will have to implement conversion, labeling and hiding of inputs. For |
36 | this reason, it is still not recommended to bypass the library. | 31 | this reason, it is still not recommended to bypass the library. |
37 | 32 | ||
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. If you are writing a new hardware monitoring driver those | ||
43 | features can't seem to fit in this interface, please contact us with your | ||
44 | extension proposal. Keep in mind that backward compatibility must be | ||
45 | preserved. | ||
46 | |||
47 | Each chip gets its own directory in the sysfs /sys/devices tree. To | 33 | Each chip gets its own directory in the sysfs /sys/devices tree. To |
48 | find all sensor chips, it is easier to follow the device symlinks from | 34 | find all sensor chips, it is easier to follow the device symlinks from |
49 | /sys/class/hwmon/hwmon*. | 35 | /sys/class/hwmon/hwmon*. |
50 | 36 | ||
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 | |||
51 | All sysfs values are fixed point numbers. | 44 | All sysfs values are fixed point numbers. |
52 | 45 | ||
53 | There is only one value per file, unlike the older /proc specification. | 46 | There is only one value per file, unlike the older /proc specification. |