Bluetooth: mediatek: add gpio pin to reset bt

Support the platform Bluetooth to be reset by hardware pin,
when a Bluetooth exception occurs, attempt to reset the
Bluetooth module using the hardware reset pin, as this
method is generally more stable and reliable than a
software reset. If the hardware reset pin is not specified
in the device tree, fall back to the existing software
reset mechanism to ensure backward compatibility.

Co-developed: Sean Wang <[e-mail]>
Co-developed: Hao Qin <[e-mail]>
Co-developed: Chris Lu <[e-mail]>
Signed-off-by: Zhangchao Zhang <[e-mail]>
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Signed-off-by: Luiz Augusto von Dentz <[e-mail]>

drivers/bluetooth/btusb.c

···
 	btusb_stop_traffic(data);
 	usb_kill_anchored_urbs(&data->tx_anchor);
 
+	/* Toggle the hard reset line. The MediaTek device is going to
+	 * yank itself off the USB and then replug. The cleanup is handled
+	 * correctly on the way out (standard USB disconnect), and the new
+	 * device is detected cleanly and bound to the driver again like
+	 * it should be.
+	 */
+	if (data->reset_gpio) {
+		gpiod_set_value_cansleep(data->reset_gpio, 1);
+		msleep(200);
+		gpiod_set_value_cansleep(data->reset_gpio, 0);
+		return 0;
+	}
+
 	err = btmtk_usb_subsys_reset(hdev, btmtk_data->dev_id);
 
 	usb_queue_reset_device(data->intf);