ACPI / PM: Expose lists of device power resources to user space

Since ACPI power resources are going to be used more extensively on
new hardware platforms, it is necessary to allow user space (powertop
in particular) to look at the lists of power resources corresponding
to different power states of devices for diagnostics and control
purposes.

For this reason, for each power state of an ACPI device node using
power resources create a special attribute group under the device
node's directory in sysfs containing links to sysfs directories
representing the power resources in that list.  The names of the
new attribute groups are "power_resources_<state>", where <state>
is the state name i.e. "D0", "D1", "D2", or "D3hot".

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

4 files changed, 55 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-power_resources_D0 b/Documentation/ABI/testing/sysfs-devices-power_resources_D0
new file mode 100644
index 000000000000..73b77a6be196
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-power_resources_D0
@@ -0,0 +1,13 @@
+What:           /sys/devices/.../power_resources_D0/
+Date:           January 2013
+Contact:        Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+                The /sys/devices/.../power_resources_D0/ directory is only
+                present for device objects representing ACPI device nodes that
+                use ACPI power resources for power management.
+
+                If present, it contains symbolic links to device directories
+                representing ACPI power resources that need to be turned on for
+                the given device node to be in ACPI power state D0.  The names
+                of the links are the same as the names of the directories they
+                point to.
diff --git a/Documentation/ABI/testing/sysfs-devices-power_resources_D1 b/Documentation/ABI/testing/sysfs-devices-power_resources_D1
new file mode 100644
index 000000000000..30c20703fb8c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-power_resources_D1
@@ -0,0 +1,14 @@
+What:           /sys/devices/.../power_resources_D1/
+Date:           January 2013
+Contact:        Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+                The /sys/devices/.../power_resources_D1/ directory is only
+                present for device objects representing ACPI device nodes that
+                use ACPI power resources for power management and support ACPI
+                power state D1.
+
+                If present, it contains symbolic links to device directories
+                representing ACPI power resources that need to be turned on for
+                the given device node to be in ACPI power state D1.  The names
+                of the links are the same as the names of the directories they
+                point to.
diff --git a/Documentation/ABI/testing/sysfs-devices-power_resources_D2 b/Documentation/ABI/testing/sysfs-devices-power_resources_D2
new file mode 100644
index 000000000000..fd9d84b421e1
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-power_resources_D2
@@ -0,0 +1,14 @@
+What:           /sys/devices/.../power_resources_D2/
+Date:           January 2013
+Contact:        Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+                The /sys/devices/.../power_resources_D2/ directory is only
+                present for device objects representing ACPI device nodes that
+                use ACPI power resources for power management and support ACPI
+                power state D2.
+
+                If present, it contains symbolic links to device directories
+                representing ACPI power resources that need to be turned on for
+                the given device node to be in ACPI power state D2.  The names
+                of the links are the same as the names of the directories they
+                point to.
diff --git a/Documentation/ABI/testing/sysfs-devices-power_resources_D3hot b/Documentation/ABI/testing/sysfs-devices-power_resources_D3hot
new file mode 100644
index 000000000000..3df32c20addf
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-power_resources_D3hot
@@ -0,0 +1,14 @@
+What:           /sys/devices/.../power_resources_D3hot/
+Date:           January 2013
+Contact:        Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+                The /sys/devices/.../power_resources_D3hot/ directory is only
+                present for device objects representing ACPI device nodes that
+                use ACPI power resources for power management and support ACPI
+                power state D3hot.
+
+                If present, it contains symbolic links to device directories
+                representing ACPI power resources that need to be turned on for
+                the given device node to be in ACPI power state D3hot.  The
+                names of the links are the same as the names of the directories
+                they point to.