PM / sleep: add pm-trace support for suspending phase

Occasionally, the system can't come back up after suspend/resume
due to problems of device suspending phase. This patch make
PM_TRACE infrastructure cover device suspending phase of
suspend/resume process, and the information in RTC can tell
developers which device suspending function make system hang.

Signed-off-by: Zhonghui Fu <zhonghui.fu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/pm-trace.h

@@ -0,0 +1,35 @@
+#ifndef PM_TRACE_H
+#define PM_TRACE_H
+
+#ifdef CONFIG_PM_TRACE
+#include <asm/pm-trace.h>
+#include <linux/types.h>
+
+extern int pm_trace_enabled;
+
+static inline int pm_trace_is_enabled(void)
+{
+       return pm_trace_enabled;
+}
+
+struct device;
+extern void set_trace_device(struct device *);
+extern void generate_pm_trace(const void *tracedata, unsigned int user);
+extern int show_trace_dev_match(char *buf, size_t size);
+
+#define TRACE_DEVICE(dev) do { \
+	if (pm_trace_enabled) \
+		set_trace_device(dev); \
+	} while(0)
+
+#else
+
+static inline int pm_trace_is_enabled(void) { return 0; }
+
+#define TRACE_DEVICE(dev) do { } while (0)
+#define TRACE_RESUME(dev) do { } while (0)
+#define TRACE_SUSPEND(dev) do { } while (0)
+
+#endif
+
+#endif