HID: uhid: forward open/close events to user-space

HID core notifies us with *_open/*_close callbacks when there is an actual
user of our device. We forward these to user-space so they can react on
this. This allows user-space to skip I/O unless they receive an OPEN
event. When they receive a CLOSE event they can stop I/O again to save
energy.
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/uhid.c

@@ -97,11 +97,16 @@ static void uhid_hid_stop(struct hid_device *hid)
 
 static int uhid_hid_open(struct hid_device *hid)
 {
-	return 0;
+	struct uhid_device *uhid = hid->driver_data;
+
+	return uhid_queue_event(uhid, UHID_OPEN);
 }
 
 static void uhid_hid_close(struct hid_device *hid)
 {
+	struct uhid_device *uhid = hid->driver_data;
+
+	uhid_queue_event(uhid, UHID_CLOSE);
 }
 
 static int uhid_hid_input(struct input_dev *input, unsigned int type,

include/linux/uhid.h

@@ -27,6 +27,8 @@ enum uhid_event_type {
 	UHID_DESTROY,
 	UHID_START,
 	UHID_STOP,
+	UHID_OPEN,
+	UHID_CLOSE,
 	UHID_INPUT,
 };