HID: make .raw_request mandatory

SET_REPORT and GET_REPORT are mandatory in the HID specification.
Make the corresponding API in hid-core mandatory too, which removes the
need to test against it in some various places.

Signed-off-by: Benjamin Tissoires <[e-mail]>
Reviewed-by: David Herrmann <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

Documentation/hid/hid-transport.txt

···
                        int reqtype)
    Same as ->request() but provides the report as raw buffer. This request shall
    be synchronous. A transport driver must not use ->wait() to complete such
-   requests.
+   requests. This request is mandatory and hid core will reject the device if
+   it is missing.
 
  - int (*output_report) (struct hid_device *hdev, __u8 *buf, size_t len)
    Send raw output report via intr channel. Used by some HID device drivers

drivers/hid/hid-core.c

···
 	int ret;
 	int len;
 
-	if (!hid->ll_driver->raw_request)
-		return;
-
 	buf = hid_alloc_report_buf(report, GFP_KERNEL);
 	if (!buf)
 		return;
···
 	 * wait for coming driver */
 	if (hid_ignore(hdev))
 		return -ENODEV;
+
+	/*
+	 * Check for the mandatory transport channel.
+	 */
+	 if (!hdev->ll_driver->raw_request) {
+		hid_err(hdev, "transport driver missing .raw_request()\n");
+		return -EINVAL;
+	 }
 
 	/*
 	 * Read the device report descriptor once and use as template

drivers/hid/hid-input.c

···
 	}
 
 	input_set_drvdata(input_dev, hid);
-	if (hid->ll_driver->request || hid->ll_driver->output_report ||
-	    hid->ll_driver->raw_request)
-		input_dev->event = hidinput_input_event;
+	input_dev->event = hidinput_input_event;
 	input_dev->open = hidinput_open;
 	input_dev->close = hidinput_close;
 	input_dev->setkeycode = hidinput_setkeycode;

include/linux/hid.h

···
 	if (len < 1 || len > HID_MAX_BUFFER_SIZE || !buf)
 		return -EINVAL;
 
-	if (hdev->ll_driver->raw_request)
-		return hdev->ll_driver->raw_request(hdev, reportnum, buf, len,
+	return hdev->ll_driver->raw_request(hdev, reportnum, buf, len,
 						    rtype, reqtype);
-
-	return -ENOSYS;
 }
 
 /**