HID: wiimote: Add write-register helpers

Add helpers to synchronously write registers of the wiimote. This is heavily
used by initialization functions for wiimote peripherals.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-wiimote.c

@@ -39,6 +39,9 @@ struct wiimote_state {
 	struct completion ready;
 	int cmd;
 	__u32 opt;
+
+	/* results of synchronous requests */
+	__u8 cmd_err;
 };
 
 struct wiimote_data {
@@ -394,6 +397,25 @@ static void wiiproto_req_wmem(struct wiimote_data *wdata, bool eeprom,
 	wiimote_queue(wdata, cmd, sizeof(cmd));
 }
 
+/* requries the cmd-mutex to be held */
+static int wiimote_cmd_write(struct wiimote_data *wdata, __u32 offset,
+						const __u8 *wmem, __u8 size)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&wdata->state.lock, flags);
+	wiimote_cmd_set(wdata, WIIPROTO_REQ_WMEM, 0);
+	wiiproto_req_wreg(wdata, offset, wmem, size);
+	spin_unlock_irqrestore(&wdata->state.lock, flags);
+
+	ret = wiimote_cmd_wait(wdata);
+	if (!ret && wdata->state.cmd_err)
+		ret = -EIO;
+
+	return ret;
+}
+
 static enum led_brightness wiimote_leds_get(struct led_classdev *led_dev)
 {
 	struct wiimote_data *wdata;
@@ -635,9 +657,13 @@ static void handler_return(struct wiimote_data *wdata, const __u8 *payload)
 
 	handler_keys(wdata, payload);
 
-	if (err)
+	if (wiimote_cmd_pending(wdata, cmd, 0)) {
+		wdata->state.cmd_err = err;
+		wiimote_cmd_complete(wdata);
+	} else if (err) {
 		hid_warn(wdata->hdev, "Remote error %hhu on req %hhu\n", err,
 									cmd);
+	}
 }
 
 static void handler_drm_KA(struct wiimote_data *wdata, const __u8 *payload)