Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6
[linux-2.6.git] / 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);