+static LIST_HEAD(wakeup_sources);
+
+/**
+ * wakeup_source_create - Create a struct wakeup_source object.
+ * @name: Name of the new wakeup source.
+ */
+struct wakeup_source *wakeup_source_create(const char *name)
+{
+ struct wakeup_source *ws;
+
+ ws = kzalloc(sizeof(*ws), GFP_KERNEL);
+ if (!ws)
+ return NULL;
+
+ spin_lock_init(&ws->lock);
+ if (name)
+ ws->name = kstrdup(name, GFP_KERNEL);
+
+ return ws;
+}
+EXPORT_SYMBOL_GPL(wakeup_source_create);
+
+/**
+ * wakeup_source_destroy - Destroy a struct wakeup_source object.
+ * @ws: Wakeup source to destroy.
+ */
+void wakeup_source_destroy(struct wakeup_source *ws)
+{
+ if (!ws)
+ return;
+
+ spin_lock_irq(&ws->lock);
+ while (ws->active) {
+ spin_unlock_irq(&ws->lock);
+
+ schedule_timeout_interruptible(msecs_to_jiffies(TIMEOUT));
+
+ spin_lock_irq(&ws->lock);
+ }
+ spin_unlock_irq(&ws->lock);
+
+ kfree(ws->name);
+ kfree(ws);
+}
+EXPORT_SYMBOL_GPL(wakeup_source_destroy);
+
+/**
+ * wakeup_source_add - Add given object to the list of wakeup sources.
+ * @ws: Wakeup source object to add to the list.
+ */
+void wakeup_source_add(struct wakeup_source *ws)
+{
+ if (WARN_ON(!ws))
+ return;
+
+ setup_timer(&ws->timer, pm_wakeup_timer_fn, (unsigned long)ws);
+ ws->active = false;
+
+ spin_lock_irq(&events_lock);
+ list_add_rcu(&ws->entry, &wakeup_sources);
+ spin_unlock_irq(&events_lock);
+ synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(wakeup_source_add);
+
+/**
+ * wakeup_source_remove - Remove given object from the wakeup sources list.
+ * @ws: Wakeup source object to remove from the list.
+ */
+void wakeup_source_remove(struct wakeup_source *ws)
+{
+ if (WARN_ON(!ws))
+ return;
+
+ spin_lock_irq(&events_lock);
+ list_del_rcu(&ws->entry);
+ spin_unlock_irq(&events_lock);
+ synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(wakeup_source_remove);
+
+/**
+ * wakeup_source_register - Create wakeup source and add it to the list.
+ * @name: Name of the wakeup source to register.
+ */
+struct wakeup_source *wakeup_source_register(const char *name)
+{
+ struct wakeup_source *ws;
+
+ ws = wakeup_source_create(name);
+ if (ws)
+ wakeup_source_add(ws);
+
+ return ws;
+}
+EXPORT_SYMBOL_GPL(wakeup_source_register);
+
+/**
+ * wakeup_source_unregister - Remove wakeup source from the list and remove it.
+ * @ws: Wakeup source object to unregister.
+ */
+void wakeup_source_unregister(struct wakeup_source *ws)
+{
+ wakeup_source_remove(ws);
+ wakeup_source_destroy(ws);
+}
+EXPORT_SYMBOL_GPL(wakeup_source_unregister);
+
+/**
+ * device_wakeup_attach - Attach a wakeup source object to a device object.
+ * @dev: Device to handle.
+ * @ws: Wakeup source object to attach to @dev.
+ *
+ * This causes @dev to be treated as a wakeup device.
+ */
+static int device_wakeup_attach(struct device *dev, struct wakeup_source *ws)
+{
+ spin_lock_irq(&dev->power.lock);
+ if (dev->power.wakeup) {
+ spin_unlock_irq(&dev->power.lock);
+ return -EEXIST;
+ }
+ dev->power.wakeup = ws;
+ spin_unlock_irq(&dev->power.lock);
+ return 0;
+}
+
+/**
+ * device_wakeup_enable - Enable given device to be a wakeup source.
+ * @dev: Device to handle.
+ *
+ * Create a wakeup source object, register it and attach it to @dev.
+ */
+int device_wakeup_enable(struct device *dev)
+{
+ struct wakeup_source *ws;
+ int ret;
+
+ if (!dev || !dev->power.can_wakeup)
+ return -EINVAL;
+
+ ws = wakeup_source_register(dev_name(dev));
+ if (!ws)
+ return -ENOMEM;
+
+ ret = device_wakeup_attach(dev, ws);
+ if (ret)
+ wakeup_source_unregister(ws);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(device_wakeup_enable);
+
+/**
+ * device_wakeup_detach - Detach a device's wakeup source object from it.
+ * @dev: Device to detach the wakeup source object from.
+ *
+ * After it returns, @dev will not be treated as a wakeup device any more.
+ */
+static struct wakeup_source *device_wakeup_detach(struct device *dev)
+{
+ struct wakeup_source *ws;
+
+ spin_lock_irq(&dev->power.lock);
+ ws = dev->power.wakeup;
+ dev->power.wakeup = NULL;
+ spin_unlock_irq(&dev->power.lock);
+ return ws;
+}
+
+/**
+ * device_wakeup_disable - Do not regard a device as a wakeup source any more.
+ * @dev: Device to handle.
+ *
+ * Detach the @dev's wakeup source object from it, unregister this wakeup source
+ * object and destroy it.
+ */
+int device_wakeup_disable(struct device *dev)
+{
+ struct wakeup_source *ws;
+
+ if (!dev || !dev->power.can_wakeup)
+ return -EINVAL;
+
+ ws = device_wakeup_detach(dev);
+ if (ws)
+ wakeup_source_unregister(ws);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(device_wakeup_disable);
+
+/**
+ * device_init_wakeup - Device wakeup initialization.
+ * @dev: Device to handle.
+ * @enable: Whether or not to enable @dev as a wakeup device.
+ *
+ * By default, most devices should leave wakeup disabled. The exceptions are
+ * devices that everyone expects to be wakeup sources: keyboards, power buttons,
+ * possibly network interfaces, etc.
+ */
+int device_init_wakeup(struct device *dev, bool enable)
+{
+ int ret = 0;
+
+ if (enable) {
+ device_set_wakeup_capable(dev, true);
+ ret = device_wakeup_enable(dev);
+ } else {
+ device_set_wakeup_capable(dev, false);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(device_init_wakeup);
+
+/**
+ * device_set_wakeup_enable - Enable or disable a device to wake up the system.
+ * @dev: Device to handle.
+ */
+int device_set_wakeup_enable(struct device *dev, bool enable)
+{
+ if (!dev || !dev->power.can_wakeup)
+ return -EINVAL;
+
+ return enable ? device_wakeup_enable(dev) : device_wakeup_disable(dev);
+}
+EXPORT_SYMBOL_GPL(device_set_wakeup_enable);