PM / devfreq: Change prototype of devfreq_get_devfreq_by_phandle function

Previously, devfreq core support 'devfreq' property in order to get
the devfreq device by phandle. But, 'devfreq' property name is not proper
on devicetree binding because this name doesn't mean the any h/w attribute.

The devfreq core hand over the right to decide the property name
for getting the devfreq device on devicetree. Each devfreq driver
will decide the property name on devicetree binding and pass
the their own property name to devfreq_get_devfreq_by_phandle function.

Acked-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Chanwoo Choi <[e-mail]>

drivers/devfreq/devfreq.c

···
 /*
  * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
  * @dev - instance to the given device
+ * @phandle_name - name of property holding a phandle value
  * @index - index into list of devfreq
  *
  * return the instance of devfreq device
  */
-struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
+struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
+					const char *phandle_name, int index)
 {
 	struct device_node *node;
 	struct devfreq *devfreq;
 
-	if (!dev)
+	if (!dev || !phandle_name)
 		return ERR_PTR(-EINVAL);
 
 	if (!dev->of_node)
 		return ERR_PTR(-EINVAL);
 
-	node = of_parse_phandle(dev->of_node, "devfreq", index);
+	node = of_parse_phandle(dev->of_node, phandle_name, index);
 	if (!node)
 		return ERR_PTR(-ENODEV);
 
···
 	return ERR_PTR(-ENODEV);
 }
 
-struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
+struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
+					const char *phandle_name, int index)
 {
 	return ERR_PTR(-ENODEV);
 }

drivers/devfreq/exynos-bus.c

···
 	profile->exit = exynos_bus_passive_exit;
 
 	/* Get the instance of parent devfreq device */
-	parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
+	parent_devfreq = devfreq_get_devfreq_by_phandle(dev, "devfreq", 0);
 	if (IS_ERR(parent_devfreq))
 		return -EPROBE_DEFER;
 

include/linux/devfreq.h

···
 				struct notifier_block *nb,
 				unsigned int list);
 struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node);
-struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index);
+struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
+				const char *phandle_name, int index);
 
 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
 /**
···
 }
 
 static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
-					int index)
+					const char *phandle_name, int index)
 {
 	return ERR_PTR(-ENODEV);
 }