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authorJean Delvare <khali@linux-fr.org>2008-02-23 04:57:53 -0500
committerMark M. Hoffman <mhoffman@lightlink.com>2008-06-19 06:50:31 -0400
commit125ff8087fca28e922e7ad6e082efcf04fe2f0f4 (patch)
tree1bbe653c5542fa7cd2d7303c177fc6a54fae5bfd /Documentation
parented4ec814e45ae8b1596aea0a29b92f6c3614acaa (diff)
hwmon: Update the sysfs interface documentation
* Document the characteristics of libsensors 3.0.0 and 3.0.1. * The sysfs interface is no longer subject to changes. Signed-off-by: Jean Delvare <khali@linux-fr.org> Acked-by: Juerg Haefliger <juergh at gmail.com> Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/hwmon/sysfs-interface33
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
4The libsensors library offers an interface to the raw sensors data 4The libsensors library offers an interface to the raw sensors data
5through the sysfs interface. See libsensors documentation and source for 5through the sysfs interface. Since lm-sensors 3.0.0, libsensors is
6further information. As of writing this document, libsensors 6completely chip-independent. It assumes that all the kernel drivers
7(from lm_sensors 2.8.3) is heavily chip-dependent. Adding or updating 7implement the standard sysfs interface described in this document.
8support for any given chip requires modifying the library's code. 8This makes adding or updating support for any given chip very easy, as
9This is because libsensors was written for the procfs interface 9libsensors, and applications using it, do not need to be modified.
10older kernel modules were using, which wasn't standardized enough. 10This is a major improvement compared to lm-sensors 2.
11Recent versions of libsensors (from lm_sensors 2.8.2 and later) have
12support for the sysfs interface, though.
13
14The new sysfs interface was designed to be as chip-independent as
15possible.
16 11
17Note that motherboards vary widely in the connections to sensor chips. 12Note that motherboards vary widely in the connections to sensor chips.
18There is no standard that ensures, for example, that the second 13There 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
35will have to implement conversion, labeling and hiding of inputs. For 30will have to implement conversion, labeling and hiding of inputs. For
36this reason, it is still not recommended to bypass the library. 31this reason, it is still not recommended to bypass the library.
37 32
38If you are developing a userspace application please send us feedback on
39this standard.
40
41Note that this standard isn't completely established yet, so it is subject
42to changes. If you are writing a new hardware monitoring driver those
43features can't seem to fit in this interface, please contact us with your
44extension proposal. Keep in mind that backward compatibility must be
45preserved.
46
47Each chip gets its own directory in the sysfs /sys/devices tree. To 33Each chip gets its own directory in the sysfs /sys/devices tree. To
48find all sensor chips, it is easier to follow the device symlinks from 34find all sensor chips, it is easier to follow the device symlinks from
49/sys/class/hwmon/hwmon*. 35/sys/class/hwmon/hwmon*.
50 36
37Up to lm-sensors 3.0.0, libsensors looks for hardware monitoring attributes
38in the "physical" device directory. Since lm-sensors 3.0.1, attributes found
39in the hwmon "class" device directory are also supported. Complex drivers
40(e.g. drivers for multifunction chips) may want to use this possibility to
41avoid namespace pollution. The only drawback will be that older versions of
42libsensors won't support the driver in question.
43
51All sysfs values are fixed point numbers. 44All sysfs values are fixed point numbers.
52 45
53There is only one value per file, unlike the older /proc specification. 46There is only one value per file, unlike the older /proc specification.