diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index f3db11c..dd0cb04 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -249,6 +249,7 @@ extern int acpi_processor_register_performance(struct acpi_processor_performance
 					       *performance, unsigned int cpu);
 extern void acpi_processor_unregister_performance(unsigned int cpu);
 
+int acpi_processor_pstate_control(void);
 /* note: this locks both the calling module and the processor module
          if a _PPC object exists, rmmod is disallowed then */
 int acpi_processor_notify_smm(struct module *calling_module);