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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> | |
4f86d3a8 LB |
12 | #include <linux/cpuidle.h> |
13 | ||
14 | #include "cpuidle.h" | |
15 | ||
16 | LIST_HEAD(cpuidle_governors); | |
17 | struct cpuidle_governor *cpuidle_curr_governor; | |
18 | ||
19 | /** | |
20 | * __cpuidle_find_governor - finds a governor of the specified name | |
21 | * @str: the name | |
22 | * | |
21ae2956 | 23 | * Must be called with cpuidle_lock acquired. |
4f86d3a8 LB |
24 | */ |
25 | static struct cpuidle_governor * __cpuidle_find_governor(const char *str) | |
26 | { | |
27 | struct cpuidle_governor *gov; | |
28 | ||
29 | list_for_each_entry(gov, &cpuidle_governors, governor_list) | |
91336640 | 30 | if (!strncasecmp(str, gov->name, CPUIDLE_NAME_LEN)) |
4f86d3a8 LB |
31 | return gov; |
32 | ||
33 | return NULL; | |
34 | } | |
35 | ||
36 | /** | |
37 | * cpuidle_switch_governor - changes the governor | |
38 | * @gov: the new target governor | |
39 | * | |
40 | * NOTE: "gov" can be NULL to specify disabled | |
21ae2956 | 41 | * Must be called with cpuidle_lock acquired. |
4f86d3a8 LB |
42 | */ |
43 | int cpuidle_switch_governor(struct cpuidle_governor *gov) | |
44 | { | |
45 | struct cpuidle_device *dev; | |
46 | ||
47 | if (gov == cpuidle_curr_governor) | |
48 | return 0; | |
49 | ||
50 | cpuidle_uninstall_idle_handler(); | |
51 | ||
52 | if (cpuidle_curr_governor) { | |
53 | list_for_each_entry(dev, &cpuidle_detected_devices, device_list) | |
54 | cpuidle_disable_device(dev); | |
4f86d3a8 LB |
55 | } |
56 | ||
57 | cpuidle_curr_governor = gov; | |
58 | ||
59 | if (gov) { | |
4f86d3a8 LB |
60 | list_for_each_entry(dev, &cpuidle_detected_devices, device_list) |
61 | cpuidle_enable_device(dev); | |
62 | cpuidle_install_idle_handler(); | |
63 | printk(KERN_INFO "cpuidle: using governor %s\n", gov->name); | |
64 | } | |
65 | ||
66 | return 0; | |
67 | } | |
68 | ||
69 | /** | |
70 | * cpuidle_register_governor - registers a governor | |
71 | * @gov: the governor | |
72 | */ | |
73 | int cpuidle_register_governor(struct cpuidle_governor *gov) | |
74 | { | |
75 | int ret = -EEXIST; | |
76 | ||
77 | if (!gov || !gov->select) | |
78 | return -EINVAL; | |
79 | ||
62027aea LB |
80 | if (cpuidle_disabled()) |
81 | return -ENODEV; | |
82 | ||
4f86d3a8 LB |
83 | mutex_lock(&cpuidle_lock); |
84 | if (__cpuidle_find_governor(gov->name) == NULL) { | |
85 | ret = 0; | |
86 | list_add_tail(&gov->governor_list, &cpuidle_governors); | |
87 | if (!cpuidle_curr_governor || | |
88 | cpuidle_curr_governor->rating < gov->rating) | |
89 | cpuidle_switch_governor(gov); | |
90 | } | |
91 | mutex_unlock(&cpuidle_lock); | |
92 | ||
93 | return ret; | |
94 | } |