HID: ll_driver: Extend the interface with idle requests

Some drivers send the idle command directly to underlying device,
creating an unwanted dependency on the underlying transport layer.
This patch adds hid_hw_idle() to the interface, thereby removing
usbhid from the lion share of the drivers.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 420466b..effcd3d 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -1253,6 +1253,20 @@
 	}
 }
 
+static int usbhid_idle(struct hid_device *hid, int report, int idle,
+		int reqtype)
+{
+	struct usb_device *dev = hid_to_usb_dev(hid);
+	struct usb_interface *intf = to_usb_interface(hid->dev.parent);
+	struct usb_host_interface *interface = intf->cur_altsetting;
+	int ifnum = interface->desc.bInterfaceNumber;
+
+	if (reqtype != HID_REQ_SET_IDLE)
+		return -EINVAL;
+
+	return hid_set_idle(dev, ifnum, report, idle);
+}
+
 static struct hid_ll_driver usb_hid_driver = {
 	.parse = usbhid_parse,
 	.start = usbhid_start,
@@ -1263,6 +1277,7 @@
 	.hidinput_input_event = usb_hidinput_input_event,
 	.request = usbhid_request,
 	.wait = usbhid_wait_io,
+	.idle = usbhid_idle,
 };
 
 static int usbhid_probe(struct usb_interface *intf, const struct usb_device_id *id)