firewire: ohci: add support for Linux kernel tracepoints

The Linux Kernel Tracepoints framework is enough useful to trace the
interaction between 1394 OHCI hardware and its driver.

This commit adds firewire_ohci subsystem to use the framework. It is
defined as the different subsystem from the existing firewire subsystem.
The definition file for the existing subsystem is slightly changed so that
both subsystems are available in 1394 OHCI driver.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Sakamoto <[email protected]>

Author: takaswie

drivers/firewire/ohci.c

@@ -45,6 +45,9 @@
 
 #include <trace/events/firewire.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/firewire_ohci.h>
+
 #define ohci_info(ohci, f, args...)	dev_info(ohci->card.device, f, ##args)
 #define ohci_notice(ohci, f, args...)	dev_notice(ohci->card.device, f, ##args)
 #define ohci_err(ohci, f, args...)	dev_err(ohci->card.device, f, ##args)

include/trace/events/firewire.h

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 // Copyright (c) 2024 Takashi Sakamoto
 
+#undef TRACE_SYSTEM
 #define TRACE_SYSTEM	firewire
 
 #if !defined(_FIREWIRE_TRACE_EVENT_H) || defined(TRACE_HEADER_MULTI_READ)

include/trace/events/firewire_ohci.h

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright (c) 2024 Takashi Sakamoto
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM	firewire_ohci
+
+#if !defined(_FIREWIRE_OHCI_TRACE_EVENT_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _FIREWIRE_OHCI_TRACE_EVENT_H
+
+#include <linux/tracepoint.h>
+
+// Placeholder for future use.
+
+#endif // _FIREWIRE_OHCI_TRACE_EVENT_H
+
+#include <trace/define_trace.h>