Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/usb/mtu3/mtu3_debug.h b/drivers/usb/mtu3/mtu3_debug.h
new file mode 100644
index 0000000..e96a692
--- /dev/null
+++ b/drivers/usb/mtu3/mtu3_debug.h
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * mtu3_debug.h - debug header
+ *
+ * Copyright (C) 2019 MediaTek Inc.
+ *
+ * Author: Chunfeng Yun <chunfeng.yun@mediatek.com>
+ */
+
+#ifndef __MTU3_DEBUG_H__
+#define __MTU3_DEBUG_H__
+
+#include <linux/debugfs.h>
+
+#define MTU3_DEBUGFS_NAME_LEN 32
+
+struct mtu3_regset {
+	char name[MTU3_DEBUGFS_NAME_LEN];
+	struct debugfs_regset32 regset;
+	size_t nregs;
+};
+
+struct mtu3_file_map {
+	const char *name;
+	int (*show)(struct seq_file *s, void *unused);
+};
+
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+void ssusb_dev_debugfs_init(struct ssusb_mtk *ssusb);
+void ssusb_dr_debugfs_init(struct ssusb_mtk *ssusb);
+void ssusb_debugfs_create_root(struct ssusb_mtk *ssusb);
+void ssusb_debugfs_remove_root(struct ssusb_mtk *ssusb);
+
+#else
+static inline void ssusb_dev_debugfs_init(struct ssusb_mtk *ssusb) {}
+static inline void ssusb_dr_debugfs_init(struct ssusb_mtk *ssusb) {}
+static inline void ssusb_debugfs_create_root(struct ssusb_mtk *ssusb) {}
+static inline void ssusb_debugfs_remove_root(struct ssusb_mtk *ssusb) {}
+
+#endif /* CONFIG_DEBUG_FS */
+
+#if IS_ENABLED(CONFIG_TRACING)
+void mtu3_dbg_trace(struct device *dev, const char *fmt, ...);
+
+#else
+static inline void mtu3_dbg_trace(struct device *dev, const char *fmt, ...) {}
+
+#endif /* CONFIG_TRACING */
+
+#endif /* __MTU3_DEBUG_H__ */