4 files changed, 41 insertions, 1 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.
diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index 3f16dd4db23e..946720a4db57 100644
--- a/drivers/acpi/power.c
+++ b/drivers/acpi/power.c
@@ -87,6 +87,12 @@ static DEFINE_MUTEX(power_resource_list_lock);
                              Power Resource Management
    -------------------------------------------------------------------------- */
 
+static inline
+struct acpi_power_resource *to_power_resource(struct acpi_device *device)
+{
+        return container_of(device, struct acpi_power_resource, device);
+}
+
 static struct acpi_power_resource *acpi_power_get_context(acpi_handle handle)
 {
         struct acpi_device *device;
@@ -94,7 +100,7 @@ static struct acpi_power_resource *acpi_power_get_context(acpi_handle handle)
         if (acpi_bus_get_device(handle, &device))
                 return NULL;
 
-        return container_of(device, struct acpi_power_resource, device);
+        return to_power_resource(device);
 }
 
 static int acpi_power_resources_list_add(acpi_handle handle,
@@ -678,6 +684,21 @@ static void acpi_release_power_resource(struct device *dev)
         kfree(resource);
 }
 
+static ssize_t acpi_power_in_use_show(struct device *dev,
+                                      struct device_attribute *attr,
+                                      char *buf) {
+        struct acpi_power_resource *resource;
+
+        resource = to_power_resource(to_acpi_device(dev));
+        return sprintf(buf, "%u\n", !!resource->ref_count);
+}
+static DEVICE_ATTR(resource_in_use, 0444, acpi_power_in_use_show, NULL);
+
+static void acpi_power_sysfs_remove(struct acpi_device *device)
+{
+        device_remove_file(&device->dev, &dev_attr_resource_in_use);
+}
+
 int acpi_add_power_resource(acpi_handle handle)
 {
         struct acpi_power_resource *resource;
@@ -725,6 +746,9 @@ int acpi_add_power_resource(acpi_handle handle)
         if (result)
                 goto err;
 
+        if (!device_create_file(&device->dev, &dev_attr_resource_in_use))
+                device->remove = acpi_power_sysfs_remove;
+
         mutex_lock(&power_resource_list_lock);
         list_add(&resource->list_node, &acpi_power_resource_list);
         mutex_unlock(&power_resource_list_lock);
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 9761d589f3f5..9801837876b7 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -791,6 +791,9 @@ static void acpi_device_unregister(struct acpi_device *device)
 
         acpi_power_add_remove_device(device, false);
         acpi_device_remove_files(device);
+        if (device->remove)
+                device->remove(device);
+
         device_del(&device->dev);
         /*
          * Drop the reference counts of all power resources the device depends
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index fca1b9cb27d9..aef56a9f4e70 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -280,6 +280,7 @@ struct acpi_device {
         struct mutex physical_node_lock;
         DECLARE_BITMAP(physical_node_id_bitmap, ACPI_MAX_PHYSICAL_NODE);
         struct list_head power_dependent;
+        void (*remove)(struct acpi_device *);
 };
 
 static inline void *acpi_driver_data(struct acpi_device *d)