PM / Domains: Export of_genpd_get_from_provider function

This function looks up a PM domain form the provider. This will be
useful to add parent/child domain relationship from the SoC specific
code. The caller of the function must make sure that PM domain provider
is already registered.
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -2108,7 +2108,7 @@ EXPORT_SYMBOL_GPL(of_genpd_del_provider);
  * Returns a valid pointer to struct generic_pm_domain on success or ERR_PTR()
  * on failure.
  */
-static struct generic_pm_domain *of_genpd_get_from_provider(
+struct generic_pm_domain *of_genpd_get_from_provider(
 					struct of_phandle_args *genpdspec)
 {
 	struct generic_pm_domain *genpd = ERR_PTR(-ENOENT);
@@ -2128,6 +2128,7 @@ static struct generic_pm_domain *of_genpd_get_from_provider(
 
 	return genpd;
 }
+EXPORT_SYMBOL_GPL(of_genpd_get_from_provider);
 
 /**
  * genpd_dev_pm_detach - Detach a device from its PM domain.

include/linux/pm_domain.h

@@ -275,6 +275,8 @@ typedef struct generic_pm_domain *(*genpd_xlate_t)(struct of_phandle_args *args,
 int __of_genpd_add_provider(struct device_node *np, genpd_xlate_t xlate,
 			void *data);
 void of_genpd_del_provider(struct device_node *np);
+struct generic_pm_domain *of_genpd_get_from_provider(
+			struct of_phandle_args *genpdspec);
 
 struct generic_pm_domain *__of_genpd_xlate_simple(
 					struct of_phandle_args *genpdspec,
@@ -292,6 +294,12 @@ static inline int __of_genpd_add_provider(struct device_node *np,
 }
 static inline void of_genpd_del_provider(struct device_node *np) {}
 
+static inline struct generic_pm_domain *of_genpd_get_from_provider(
+			struct of_phandle_args *genpdspec)
+{
+	return NULL;
+}
+
 #define __of_genpd_xlate_simple		NULL
 #define __of_genpd_xlate_onecell	NULL