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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-01-24 12:49:59 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-01-24 12:49:59 +0100
commit836aedb1414d4724b2ec68dd19810960c593720c (patch)
tree4f826283e16638ba521f5d31b021d79166cfde99 /Documentation/ABI
parentcf860be639d86ed77af179c925085ae0721ae602 (diff)
downloadlinux-836aedb1414d4724b2ec68dd19810960c593720c.tar.gz
ACPI / PM: Expose power states of ACPI devices to user space
Make it possible to retrieve the current power state of a device with ACPI power management from user space via sysfs by adding two new attributes, power_state and real_power_state, to the sysfs directory associated with the struct acpi_device object representing the device's ACPI node. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-devices-power_state20
-rw-r--r--Documentation/ABI/testing/sysfs-devices-real_power_state23
2 files changed, 43 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-power_state b/Documentation/ABI/testing/sysfs-devices-power_state
new file mode 100644
index 00000000000..7ad9546748f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-power_state
@@ -0,0 +1,20 @@
+What: /sys/devices/.../power_state
+Date: January 2013
+Contact: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+ The /sys/devices/.../power_state attribute is only present for
+ device objects representing ACPI device nodes that provide power
+ management methods.
+
+ If present, it contains a string representing the current ACPI
+ power state of the given device node. Its possible values,
+ "D0", "D1", "D2", "D3hot", and "D3cold", reflect the power state
+ names defined by the ACPI specification (ACPI 4 and above).
+
+ If the device node uses shared ACPI power resources, this state
+ determines a list of power resources required not to be turned
+ off. However, some power resources needed by the device node in
+ higher-power (lower-number) states may also be ON because of
+ some other devices using them at the moment.
+
+ This attribute is read-only.
diff --git a/Documentation/ABI/testing/sysfs-devices-real_power_state b/Documentation/ABI/testing/sysfs-devices-real_power_state
new file mode 100644
index 00000000000..8b3527c82a7
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-real_power_state
@@ -0,0 +1,23 @@
+What: /sys/devices/.../real_power_state
+Date: January 2013
+Contact: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+ The /sys/devices/.../real_power_state attribute is only present
+ for device objects representing ACPI device nodes that provide
+ power management methods and use ACPI power resources for power
+ management.
+
+ If present, it contains a string representing the real ACPI
+ power state of the given device node as returned by the _PSC
+ control method or inferred from the configuration of power
+ resources. Its possible values, "D0", "D1", "D2", "D3hot", and
+ "D3cold", reflect the power state names defined by the ACPI
+ specification (ACPI 4 and above).
+
+ In some situations the value of this attribute may be different
+ from the value of the /sys/devices/.../power_state attribute for
+ the same device object. If that happens, some shared power
+ resources used by the device node are only ON because of some
+ other devices using them at the moment.
+
+ This attribute is read-only.