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/cpu.h> |
12 | #include <linux/cpuidle.h> |
13 | #include <linux/mutex.h> |
14 | #include <linux/module.h> |
15 | #include <linux/pm_qos.h> |
16 | |
17 | #include "cpuidle.h" |
18 | |
19 | char param_governor[CPUIDLE_NAME_LEN]; |
20 | |
21 | LIST_HEAD(cpuidle_governors); |
22 | struct cpuidle_governor *cpuidle_curr_governor; |
23 | struct cpuidle_governor *cpuidle_prev_governor; |
24 | |
25 | /** |
26 | * cpuidle_find_governor - finds a governor of the specified name |
27 | * @str: the name |
28 | * |
29 | * Must be called with cpuidle_lock acquired. |
30 | */ |
31 | struct cpuidle_governor *cpuidle_find_governor(const char *str) |
32 | { |
33 | struct cpuidle_governor *gov; |
34 | |
35 | list_for_each_entry(gov, &cpuidle_governors, governor_list) |
36 | if (!strncasecmp(s1: str, s2: gov->name, CPUIDLE_NAME_LEN)) |
37 | return gov; |
38 | |
39 | return NULL; |
40 | } |
41 | |
42 | /** |
43 | * cpuidle_switch_governor - changes the governor |
44 | * @gov: the new target governor |
45 | * Must be called with cpuidle_lock acquired. |
46 | */ |
47 | int cpuidle_switch_governor(struct cpuidle_governor *gov) |
48 | { |
49 | struct cpuidle_device *dev; |
50 | |
51 | if (!gov) |
52 | return -EINVAL; |
53 | |
54 | if (gov == cpuidle_curr_governor) |
55 | return 0; |
56 | |
57 | cpuidle_uninstall_idle_handler(); |
58 | |
59 | if (cpuidle_curr_governor) { |
60 | list_for_each_entry(dev, &cpuidle_detected_devices, device_list) |
61 | cpuidle_disable_device(dev); |
62 | } |
63 | |
64 | cpuidle_curr_governor = gov; |
65 | |
66 | list_for_each_entry(dev, &cpuidle_detected_devices, device_list) |
67 | cpuidle_enable_device(dev); |
68 | |
69 | cpuidle_install_idle_handler(); |
70 | pr_info("cpuidle: using governor %s\n" , gov->name); |
71 | |
72 | return 0; |
73 | } |
74 | |
75 | /** |
76 | * cpuidle_register_governor - registers a governor |
77 | * @gov: the governor |
78 | */ |
79 | int cpuidle_register_governor(struct cpuidle_governor *gov) |
80 | { |
81 | int ret = -EEXIST; |
82 | |
83 | if (!gov || !gov->select) |
84 | return -EINVAL; |
85 | |
86 | if (cpuidle_disabled()) |
87 | return -ENODEV; |
88 | |
89 | mutex_lock(&cpuidle_lock); |
90 | if (cpuidle_find_governor(str: gov->name) == NULL) { |
91 | ret = 0; |
92 | list_add_tail(new: &gov->governor_list, head: &cpuidle_governors); |
93 | if (!cpuidle_curr_governor || |
94 | !strncasecmp(s1: param_governor, s2: gov->name, CPUIDLE_NAME_LEN) || |
95 | (cpuidle_curr_governor->rating < gov->rating && |
96 | strncasecmp(s1: param_governor, s2: cpuidle_curr_governor->name, |
97 | CPUIDLE_NAME_LEN))) |
98 | cpuidle_switch_governor(gov); |
99 | } |
100 | mutex_unlock(lock: &cpuidle_lock); |
101 | |
102 | return ret; |
103 | } |
104 | |
105 | /** |
106 | * cpuidle_governor_latency_req - Compute a latency constraint for CPU |
107 | * @cpu: Target CPU |
108 | */ |
109 | s64 cpuidle_governor_latency_req(unsigned int cpu) |
110 | { |
111 | struct device *device = get_cpu_device(cpu); |
112 | int device_req = dev_pm_qos_raw_resume_latency(dev: device); |
113 | int global_req = cpu_latency_qos_limit(); |
114 | |
115 | if (device_req > global_req) |
116 | device_req = global_req; |
117 | |
118 | return (s64)device_req * NSEC_PER_USEC; |
119 | } |
120 | |