While fetching the proper runtime PM callback, we walk the hierarchy of
device's power domains, subsystems and drivers.

This is common for rpm_suspend(), rpm_idle() and rpm_resume(). Let's
clean up the code by using a macro that handles this.

Cc: Kevin Hilman <redacted>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Russell King <redacted>
Cc: Linus Walleij <redacted>
Cc: Wolfram Sang <redacted>
Cc: Alessandro Rubini <redacted>
Signed-off-by: Ulf Hansson <redacted>
---

Changes in v2:
	Updated the macro to return a callback instead.
	Suggested by Josh Cartwright.

---
 drivers/base/power/runtime.c |   63 ++++++++++++++++--------------------------
 1 file changed, 24 insertions(+), 39 deletions(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 72e00e6..cc7d1ed 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c

@@ -13,6 +13,27 @@
 #include <trace/events/rpm.h>
 #include "power.h"
 
+#define RPM_GET_CALLBACK(dev, cb)				\
+({								\
+	int (*__rpm_cb)(struct device *__d);			\
+								\
+	if (dev->pm_domain)					\
+		__rpm_cb = dev->pm_domain->ops.cb;		\
+	else if (dev->type && dev->type->pm)			\
+		__rpm_cb = dev->type->pm->cb;			\
+	else if (dev->class && dev->class->pm)			\
+		__rpm_cb = dev->class->pm->cb;			\
+	else if (dev->bus && dev->bus->pm)			\
+		__rpm_cb = dev->bus->pm->cb;			\
+	else							\
+		__rpm_cb = NULL;				\
+								\
+	if (!__rpm_cb && dev->driver && dev->driver->pm)	\
+		__rpm_cb = dev->driver->pm->cb;			\
+								\
+	__rpm_cb;						\
+})