PM / Runtime: Rework RPM get callback routines

PM uses three separate functions to fetch RPM callbacks.
These functions uses quite complicated macro in their body.
The patch replaces these routines with one small macro and
one helper function.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/runtime.c

@@ -13,42 +13,39 @@
 #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;						\
-})
-
-static int (*rpm_get_suspend_cb(struct device *dev))(struct device *)
-{
-	return RPM_GET_CALLBACK(dev, runtime_suspend);
-}
+typedef int (*pm_callback_t)(struct device *);
 
-static int (*rpm_get_resume_cb(struct device *dev))(struct device *)
+static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
 {
-	return RPM_GET_CALLBACK(dev, runtime_resume);
+	pm_callback_t cb;
+	const struct dev_pm_ops *ops;
+
+	if (dev->pm_domain)
+		ops = &dev->pm_domain->ops;
+	else if (dev->type && dev->type->pm)
+		ops = dev->type->pm;
+	else if (dev->class && dev->class->pm)
+		ops = dev->class->pm;
+	else if (dev->bus && dev->bus->pm)
+		ops = dev->bus->pm;
+	else
+		ops = NULL;
+
+	if (ops)
+		cb = *(pm_callback_t *)((void *)ops + cb_offset);
+	else
+		cb = NULL;
+
+	if (!cb && dev->driver && dev->driver->pm)
+		cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
+
+	return cb;
 }
 
+#define RPM_GET_CALLBACK(dev, callback) \
+		__rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
+
 #ifdef CONFIG_PM_RUNTIME
-static int (*rpm_get_idle_cb(struct device *dev))(struct device *)
-{
-	return RPM_GET_CALLBACK(dev, runtime_idle);
-}
 
 static int rpm_resume(struct device *dev, int rpmflags);
 static int rpm_suspend(struct device *dev, int rpmflags);
@@ -347,7 +344,7 @@ static int rpm_idle(struct device *dev, int rpmflags)
 
 	dev->power.idle_notification = true;
 
-	callback = rpm_get_idle_cb(dev);
+	callback = RPM_GET_CALLBACK(dev, runtime_idle);
 
 	if (callback)
 		retval = __rpm_callback(callback, dev);
@@ -517,7 +514,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
 
 	__update_runtime_status(dev, RPM_SUSPENDING);
 
-	callback = rpm_get_suspend_cb(dev);
+	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 
 	retval = rpm_callback(callback, dev);
 	if (retval)
@@ -737,7 +734,7 @@ static int rpm_resume(struct device *dev, int rpmflags)
 
 	__update_runtime_status(dev, RPM_RESUMING);
 
-	callback = rpm_get_resume_cb(dev);
+	callback = RPM_GET_CALLBACK(dev, runtime_resume);
 
 	retval = rpm_callback(callback, dev);
 	if (retval) {
@@ -1431,7 +1428,7 @@ int pm_runtime_force_suspend(struct device *dev)
 	if (pm_runtime_status_suspended(dev))
 		return 0;
 
-	callback = rpm_get_suspend_cb(dev);
+	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 
 	if (!callback) {
 		ret = -ENOSYS;
@@ -1467,7 +1464,7 @@ int pm_runtime_force_resume(struct device *dev)
 	int (*callback)(struct device *);
 	int ret = 0;
 
-	callback = rpm_get_resume_cb(dev);
+	callback = RPM_GET_CALLBACK(dev, runtime_resume);
 
 	if (!callback) {
 		ret = -ENOSYS;