drivers/cpuidle/driver.c

   1 /*
   2  * driver.c - driver support
   3  *
   4  * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   5  *               Shaohua Li <shaohua.li@intel.com>
   6  *               Adam Belay <abelay@novell.com>
   7  *
   8  * This code is licenced under the GPL.
   9  */
  10
  11 #include <linux/mutex.h>
  12 #include <linux/module.h>
  13 #include <linux/cpuidle.h>
  14
  15 #include "cpuidle.h"
  16
  17 struct cpuidle_driver *cpuidle_curr_driver;
  18 DEFINE_SPINLOCK(cpuidle_driver_lock);
  19
  20 /**
  21  * cpuidle_register_driver - registers a driver
  22  * @drv: the driver
  23  */
  24 int cpuidle_register_driver(struct cpuidle_driver *drv)
  25 {
  26         if (!drv)
  27                 return -EINVAL;
  28
  29         spin_lock(&cpuidle_driver_lock);
  30         if (cpuidle_curr_driver) {
  31                 spin_unlock(&cpuidle_driver_lock);
  32                 return -EBUSY;
  33         }
  34         cpuidle_curr_driver = drv;
  35         spin_unlock(&cpuidle_driver_lock);
  36
  37         return 0;
  38 }
  39
  40 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
  41
  42 /**
  43  * cpuidle_unregister_driver - unregisters a driver
  44  * @drv: the driver
  45  */
  46 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
  47 {
  48         if (!drv)
  49                 return;
  50
  51         spin_lock(&cpuidle_driver_lock);
  52         cpuidle_curr_driver = NULL;
  53         spin_unlock(&cpuidle_driver_lock);
  54 }
  55
  56 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);