1*4882a593Smuzhiyun /*
2*4882a593Smuzhiyun * governor.c - governor support
3*4882a593Smuzhiyun *
4*4882a593Smuzhiyun * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
5*4882a593Smuzhiyun * Shaohua Li <shaohua.li@intel.com>
6*4882a593Smuzhiyun * Adam Belay <abelay@novell.com>
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun * This code is licenced under the GPL.
9*4882a593Smuzhiyun */
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun #include <linux/cpu.h>
12*4882a593Smuzhiyun #include <linux/cpuidle.h>
13*4882a593Smuzhiyun #include <linux/mutex.h>
14*4882a593Smuzhiyun #include <linux/module.h>
15*4882a593Smuzhiyun #include <linux/pm_qos.h>
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #include "cpuidle.h"
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun char param_governor[CPUIDLE_NAME_LEN];
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun LIST_HEAD(cpuidle_governors);
22*4882a593Smuzhiyun struct cpuidle_governor *cpuidle_curr_governor;
23*4882a593Smuzhiyun struct cpuidle_governor *cpuidle_prev_governor;
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun /**
26*4882a593Smuzhiyun * cpuidle_find_governor - finds a governor of the specified name
27*4882a593Smuzhiyun * @str: the name
28*4882a593Smuzhiyun *
29*4882a593Smuzhiyun * Must be called with cpuidle_lock acquired.
30*4882a593Smuzhiyun */
cpuidle_find_governor(const char * str)31*4882a593Smuzhiyun struct cpuidle_governor *cpuidle_find_governor(const char *str)
32*4882a593Smuzhiyun {
33*4882a593Smuzhiyun struct cpuidle_governor *gov;
34*4882a593Smuzhiyun
35*4882a593Smuzhiyun list_for_each_entry(gov, &cpuidle_governors, governor_list)
36*4882a593Smuzhiyun if (!strncasecmp(str, gov->name, CPUIDLE_NAME_LEN))
37*4882a593Smuzhiyun return gov;
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun return NULL;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun /**
43*4882a593Smuzhiyun * cpuidle_switch_governor - changes the governor
44*4882a593Smuzhiyun * @gov: the new target governor
45*4882a593Smuzhiyun * Must be called with cpuidle_lock acquired.
46*4882a593Smuzhiyun */
cpuidle_switch_governor(struct cpuidle_governor * gov)47*4882a593Smuzhiyun int cpuidle_switch_governor(struct cpuidle_governor *gov)
48*4882a593Smuzhiyun {
49*4882a593Smuzhiyun struct cpuidle_device *dev;
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun if (!gov)
52*4882a593Smuzhiyun return -EINVAL;
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun if (gov == cpuidle_curr_governor)
55*4882a593Smuzhiyun return 0;
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun cpuidle_uninstall_idle_handler();
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun if (cpuidle_curr_governor) {
60*4882a593Smuzhiyun list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
61*4882a593Smuzhiyun cpuidle_disable_device(dev);
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun cpuidle_curr_governor = gov;
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun if (gov) {
67*4882a593Smuzhiyun list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
68*4882a593Smuzhiyun cpuidle_enable_device(dev);
69*4882a593Smuzhiyun cpuidle_install_idle_handler();
70*4882a593Smuzhiyun printk(KERN_INFO "cpuidle: using governor %s\n", gov->name);
71*4882a593Smuzhiyun }
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun return 0;
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun /**
77*4882a593Smuzhiyun * cpuidle_register_governor - registers a governor
78*4882a593Smuzhiyun * @gov: the governor
79*4882a593Smuzhiyun */
cpuidle_register_governor(struct cpuidle_governor * gov)80*4882a593Smuzhiyun int cpuidle_register_governor(struct cpuidle_governor *gov)
81*4882a593Smuzhiyun {
82*4882a593Smuzhiyun int ret = -EEXIST;
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun if (!gov || !gov->select)
85*4882a593Smuzhiyun return -EINVAL;
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun if (cpuidle_disabled())
88*4882a593Smuzhiyun return -ENODEV;
89*4882a593Smuzhiyun
90*4882a593Smuzhiyun mutex_lock(&cpuidle_lock);
91*4882a593Smuzhiyun if (cpuidle_find_governor(gov->name) == NULL) {
92*4882a593Smuzhiyun ret = 0;
93*4882a593Smuzhiyun list_add_tail(&gov->governor_list, &cpuidle_governors);
94*4882a593Smuzhiyun if (!cpuidle_curr_governor ||
95*4882a593Smuzhiyun !strncasecmp(param_governor, gov->name, CPUIDLE_NAME_LEN) ||
96*4882a593Smuzhiyun (cpuidle_curr_governor->rating < gov->rating &&
97*4882a593Smuzhiyun strncasecmp(param_governor, cpuidle_curr_governor->name,
98*4882a593Smuzhiyun CPUIDLE_NAME_LEN)))
99*4882a593Smuzhiyun cpuidle_switch_governor(gov);
100*4882a593Smuzhiyun }
101*4882a593Smuzhiyun mutex_unlock(&cpuidle_lock);
102*4882a593Smuzhiyun
103*4882a593Smuzhiyun return ret;
104*4882a593Smuzhiyun }
105*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(cpuidle_register_governor);
106*4882a593Smuzhiyun
107*4882a593Smuzhiyun /**
108*4882a593Smuzhiyun * cpuidle_governor_latency_req - Compute a latency constraint for CPU
109*4882a593Smuzhiyun * @cpu: Target CPU
110*4882a593Smuzhiyun */
cpuidle_governor_latency_req(unsigned int cpu)111*4882a593Smuzhiyun s64 cpuidle_governor_latency_req(unsigned int cpu)
112*4882a593Smuzhiyun {
113*4882a593Smuzhiyun struct device *device = get_cpu_device(cpu);
114*4882a593Smuzhiyun int device_req = dev_pm_qos_raw_resume_latency(device);
115*4882a593Smuzhiyun int global_req = cpu_latency_qos_limit();
116*4882a593Smuzhiyun
117*4882a593Smuzhiyun if (device_req > global_req)
118*4882a593Smuzhiyun device_req = global_req;
119*4882a593Smuzhiyun
120*4882a593Smuzhiyun return (s64)device_req * NSEC_PER_USEC;
121*4882a593Smuzhiyun }
122*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(cpuidle_governor_latency_req);
123