HID: add hid_hw_open/close/power() handlers

Instead of exposing the guts of hid->ll_driver relationship to HID
sub-drivers provide these helpers to encapsulate the details.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/linux/hid.h b/include/linux/hid.h
index bb0f56f..e2af195 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -820,6 +820,49 @@
 	hdev->ll_driver->stop(hdev);
 }
 
+/**
+ * hid_hw_open - signal underlaying HW to start delivering events
+ *
+ * @hdev: hid device
+ *
+ * Tell underlying HW to start delivering events from the device.
+ * This function should be called sometime after successful call
+ * to hid_hiw_start().
+ */
+static inline int __must_check hid_hw_open(struct hid_device *hdev)
+{
+	return hdev->ll_driver->open(hdev);
+}
+
+/**
+ * hid_hw_close - signal underlaying HW to stop delivering events
+ *
+ * @hdev: hid device
+ *
+ * This function indicates that we are not interested in the events
+ * from this device anymore. Delivery of events may or may not stop,
+ * depending on the number of users still outstanding.
+ */
+static inline void hid_hw_close(struct hid_device *hdev)
+{
+	hdev->ll_driver->close(hdev);
+}
+
+/**
+ * hid_hw_power - requests underlying HW to go into given power mode
+ *
+ * @hdev: hid device
+ * @level: requested power level (one of %PM_HINT_* defines)
+ *
+ * This function requests underlying hardware to enter requested power
+ * mode.
+ */
+
+static inline int hid_hw_power(struct hid_device *hdev, int level)
+{
+	return hdev->ll_driver->power ? hdev->ll_driver->power(hdev, level) : 0;
+}
+
 void hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,
 		int interrupt);