ACPI / PM: Expose current status of ACPI power resources

Since ACPI power resources are going to be used more extensively on
new hardware platforms, it becomes necessary for user space (powertop
in particular) to observe some properties of those resources for
diagnostics purposes.

For this reason, expose the current status of each ACPI power
resource to user space via sysfs by adding a new resource_in_use
attribute to the sysfs directory representing the given power
resource.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-resource_in_use b/Documentation/ABI/testing/sysfs-devices-resource_in_use
new file mode 100644
index 000000000000..b4a3bc5922a3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-resource_in_use
@@ -0,0 +1,12 @@
+What:           /sys/devices/.../resource_in_use
+Date:           January 2013
+Contact:        Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+                The /sys/devices/.../resource_in_use attribute is only present
+                for device objects representing ACPI power resources.
+
+                If present, it contains a number (0 or 1) representing the
+                current status of the given power resource (0 means that the
+                resource is not in use and therefore it has been turned off).
+
+                This attribute is read-only.