usb: musb: add tracepoints support for debugging

To avoid printk() overhead while debugging, this patch implements the
foundation of tracepoints logging for musb driver to make debug
easier.

Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/musb/musb_trace.c b/drivers/usb/musb/musb_trace.c
new file mode 100644
index 0000000..70973d9
--- /dev/null
+++ b/drivers/usb/musb/musb_trace.c
@@ -0,0 +1,33 @@
+/*
+ * musb_trace.c - MUSB Controller Trace Support
+ *
+ * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Author: Bin Liu <b-liu@ti.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define CREATE_TRACE_POINTS
+#include "musb_trace.h"
+
+void musb_dbg(struct musb *musb, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	trace_musb_log(musb, &vaf);
+
+	va_end(args);
+}