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>

drivers/hid/usbhid/hid-core.c

@@ -1253,6 +1253,20 @@ static void usbhid_request(struct hid_device *hid, struct hid_report *rep, int r
 	}
 }
 
+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 @@ static struct hid_ll_driver usb_hid_driver = {
 	.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)

include/linux/hid.h

@@ -664,6 +664,7 @@ struct hid_driver {
  *	   shouldn't allocate anything to not leak memory
  * @request: send report request to device (e.g. feature report)
  * @wait: wait for buffered io to complete (send/recv reports)
+ * @idle: send idle request to device
  */
 struct hid_ll_driver {
 	int (*start)(struct hid_device *hdev);
@@ -683,6 +684,7 @@ struct hid_ll_driver {
 			struct hid_report *report, int reqtype);
 
 	int (*wait)(struct hid_device *hdev);
+	int (*idle)(struct hid_device *hdev, int report, int idle, int reqtype);
 
 };
 
@@ -906,6 +908,23 @@ static inline void hid_hw_request(struct hid_device *hdev,
 		hdev->ll_driver->request(hdev, report, reqtype);
 }
 
+/**
+ * hid_hw_idle - send idle request to device
+ *
+ * @hdev: hid device
+ * @report: report to control
+ * @idle: idle state
+ * @reqtype: hid request type
+ */
+static inline int hid_hw_idle(struct hid_device *hdev, int report, int idle,
+		int reqtype)
+{
+	if (hdev->ll_driver->idle)
+		return hdev->ll_driver->idle(hdev, report, idle, reqtype);
+
+	return 0;
+}
+
 /**
  * hid_hw_wait - wait for buffered io to complete
  *