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authorLinus Torvalds <torvalds@linux-foundation.org>2008-06-21 12:31:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-06-21 12:31:32 -0700
commitbec95aab8c056ab490fe7fa54da822938562443d (patch)
tree597856476547811928a6d053f9e050045c613d38 /Documentation
parent71c2742f5e6348d76ee62085cf0a13e5eff0f00e (diff)
parentbcccc3a28e9cbb44549cde326852c26203a53a56 (diff)
downloadlwn-bec95aab8c056ab490fe7fa54da822938562443d.tar.gz
lwn-bec95aab8c056ab490fe7fa54da822938562443d.zip
Merge branch 'release' of git://lm-sensors.org/kernel/mhoffman/hwmon-2.6
* 'release' of git://lm-sensors.org/kernel/mhoffman/hwmon-2.6: hwmon: (lm75) sensor reading bugfix hwmon: (abituguru3) update driver detection hwmon: (w83791d) new maintainer hwmon: (abituguru3) Identify Abit AW8D board as such hwmon: Update the sysfs interface documentation hwmon: (adt7473) Initialize max_duty_at_overheat before use hwmon: (lm85) Fix function RANGE_TO_REG()
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
------------------------------------------------
The libsensors library offers an interface to the raw sensors data
-through the sysfs interface. See libsensors documentation and source for
-further information. As of writing this document, libsensors
-(from lm_sensors 2.8.3) is heavily chip-dependent. 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-independent 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
@@ -35,19 +30,17 @@ 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. If you are writing a new hardware monitoring driver those
-features can't seem to fit in this interface, please contact us with your
-extension proposal. Keep in mind that backward compatibility must be
-preserved.
-
Each chip gets its own directory in the sysfs /sys/devices tree. To
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.
There is only one value per file, unlike the older /proc specification.