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4f86d3a8 LB |
1 | /* |
2 | * governor.c - governor 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 | LIST_HEAD(cpuidle_governors); | |
18 | struct cpuidle_governor *cpuidle_curr_governor; | |
19 | ||
20 | /** | |
21 | * __cpuidle_find_governor - finds a governor of the specified name | |
22 | * @str: the name | |
23 | * | |
21ae2956 | 24 | * Must be called with cpuidle_lock acquired. |
4f86d3a8 LB |
25 | */ |
26 | static struct cpuidle_governor * __cpuidle_find_governor(const char *str) | |
27 | { | |
28 | struct cpuidle_governor *gov; | |
29 | ||
30 | list_for_each_entry(gov, &cpuidle_governors, governor_list) | |
31 | if (!strnicmp(str, gov->name, CPUIDLE_NAME_LEN)) | |
32 | return gov; | |
33 | ||
34 | return NULL; | |
35 | } | |
36 | ||
37 | /** | |
38 | * cpuidle_switch_governor - changes the governor | |
39 | * @gov: the new target governor | |
40 | * | |
41 | * NOTE: "gov" can be NULL to specify disabled | |
21ae2956 | 42 | * Must be called with cpuidle_lock acquired. |
4f86d3a8 LB |
43 | */ |
44 | int cpuidle_switch_governor(struct cpuidle_governor *gov) | |
45 | { | |
46 | struct cpuidle_device *dev; | |
47 | ||
48 | if (gov == cpuidle_curr_governor) | |
49 | return 0; | |
50 | ||
51 | cpuidle_uninstall_idle_handler(); | |
52 | ||
53 | if (cpuidle_curr_governor) { | |
54 | list_for_each_entry(dev, &cpuidle_detected_devices, device_list) | |
55 | cpuidle_disable_device(dev); | |
56 | module_put(cpuidle_curr_governor->owner); | |
57 | } | |
58 | ||
59 | cpuidle_curr_governor = gov; | |
60 | ||
61 | if (gov) { | |
62 | if (!try_module_get(cpuidle_curr_governor->owner)) | |
63 | return -EINVAL; | |
64 | list_for_each_entry(dev, &cpuidle_detected_devices, device_list) | |
65 | cpuidle_enable_device(dev); | |
66 | cpuidle_install_idle_handler(); | |
67 | printk(KERN_INFO "cpuidle: using governor %s\n", gov->name); | |
68 | } | |
69 | ||
70 | return 0; | |
71 | } | |
72 | ||
73 | /** | |
74 | * cpuidle_register_governor - registers a governor | |
75 | * @gov: the governor | |
76 | */ | |
77 | int cpuidle_register_governor(struct cpuidle_governor *gov) | |
78 | { | |
79 | int ret = -EEXIST; | |
80 | ||
81 | if (!gov || !gov->select) | |
82 | return -EINVAL; | |
83 | ||
62027aea LB |
84 | if (cpuidle_disabled()) |
85 | return -ENODEV; | |
86 | ||
4f86d3a8 LB |
87 | mutex_lock(&cpuidle_lock); |
88 | if (__cpuidle_find_governor(gov->name) == NULL) { | |
89 | ret = 0; | |
90 | list_add_tail(&gov->governor_list, &cpuidle_governors); | |
91 | if (!cpuidle_curr_governor || | |
92 | cpuidle_curr_governor->rating < gov->rating) | |
93 | cpuidle_switch_governor(gov); | |
94 | } | |
95 | mutex_unlock(&cpuidle_lock); | |
96 | ||
97 | return ret; | |
98 | } |