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authorIngo Molnar <mingo@elte.hu>2008-06-25 14:16:51 +0400
committerIngo Molnar <mingo@elte.hu>2008-06-25 14:16:51 +0400
commitd02859ecb321c8c0f74cb9bbe3f51a59e58822b0 (patch)
tree05dd5bdc55081c0a90bf0afc35c07d0d6e25d015 /Documentation/hwmon/sysfs-interface
parenta987b16cc6123af2c9414032701bab5f73c54c89 (diff)
parent543cf4cb3fe6f6cae3651ba918b9c56200b257d0 (diff)
downloadlinux-d02859ecb321c8c0f74cb9bbe3f51a59e58822b0.tar.xz
Merge commit 'v2.6.26-rc8' into x86/xen
Conflicts: arch/x86/xen/enlighten.c arch/x86/xen/mmu.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/hwmon/sysfs-interface')
-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.