HID: uhid: report to user-space whether reports are numbered

This makes UHID_START include a "dev_flags" field that describes details
of the hid-device in the kernel. The first flags we introduce describe
whether a given report-type uses numbered reports. This is useful for
transport layers that force report-numbers and therefore might have to
prefix kernel-provided HID-messages with the report-number.

Currently, only HoG needs this and the spec only talks about "global
report numbers". That is, it's a global boolean not a per-type boolean.
However, given the quirks we already have in kernel-space, a per-type
value seems much more appropriate.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c
index 1951148..f6ec5ea 100644
--- a/drivers/hid/uhid.c
+++ b/drivers/hid/uhid.c
@@ -92,8 +92,27 @@
 static int uhid_hid_start(struct hid_device *hid)
 {
 	struct uhid_device *uhid = hid->driver_data;
+	struct uhid_event *ev;
+	unsigned long flags;
 
-	return uhid_queue_event(uhid, UHID_START);
+	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
+	if (!ev)
+		return -ENOMEM;
+
+	ev->type = UHID_START;
+
+	if (hid->report_enum[HID_FEATURE_REPORT].numbered)
+		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS;
+	if (hid->report_enum[HID_OUTPUT_REPORT].numbered)
+		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS;
+	if (hid->report_enum[HID_INPUT_REPORT].numbered)
+		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS;
+
+	spin_lock_irqsave(&uhid->qlock, flags);
+	uhid_queue(uhid, ev);
+	spin_unlock_irqrestore(&uhid->qlock, flags);
+
+	return 0;
 }
 
 static void uhid_hid_stop(struct hid_device *hid)