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/Makefile

@@ -2,9 +2,12 @@
 # for USB OTG silicon based on Mentor Graphics INVENTRA designs
 #
 
+# define_trace.h needs to know how to find our header
+CFLAGS_musb_trace.o	:= -I$(src)
+
 obj-$(CONFIG_USB_MUSB_HDRC) += musb_hdrc.o
 
-musb_hdrc-y := musb_core.o
+musb_hdrc-y := musb_core.o musb_trace.o
 
 musb_hdrc-$(CONFIG_USB_MUSB_HOST)$(CONFIG_USB_MUSB_DUAL_ROLE) += musb_virthub.o musb_host.o
 musb_hdrc-$(CONFIG_USB_MUSB_GADGET)$(CONFIG_USB_MUSB_DUAL_ROLE) += musb_gadget_ep0.o musb_gadget.o

drivers/usb/musb/musb_debug.h

@@ -42,6 +42,8 @@
 #define INFO(fmt, args...) yprintk(KERN_INFO, fmt, ## args)
 #define ERR(fmt, args...) yprintk(KERN_ERR, fmt, ## args)
 
+void musb_dbg(struct musb *musb, const char *fmt, ...);
+
 #ifdef CONFIG_DEBUG_FS
 int musb_init_debugfs(struct musb *musb);
 void musb_exit_debugfs(struct musb *musb);

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);
+}

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>