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>

drivers/usb/musb/musb_trace.h

@@ -0,0 +1,54 @@
+/*
+ * musb_trace.h - 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.
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM musb
+
+#if !defined(__MUSB_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __MUSB_TRACE_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+#include "musb_core.h"
+
+#define MUSB_MSG_MAX   500
+
+TRACE_EVENT(musb_log,
+	TP_PROTO(struct musb *musb, struct va_format *vaf),
+	TP_ARGS(musb, vaf),
+	TP_STRUCT__entry(
+		__string(name, dev_name(musb->controller))
+		__dynamic_array(char, msg, MUSB_MSG_MAX)
+	),
+	TP_fast_assign(
+		__assign_str(name, dev_name(musb->controller));
+		vsnprintf(__get_str(msg), MUSB_MSG_MAX, vaf->fmt, *vaf->va);
+	),
+	TP_printk("%s: %s", __get_str(name), __get_str(msg))
+);
+
+#endif /* __MUSB_TRACE_H */
+
+/* this part has to be here */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE musb_trace
+
+#include <trace/define_trace.h>