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Len Brown4f86d3a2007-10-03 18:58:00 -04001/*
2 * cpuidle.c - core cpuidle infrastructure
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/kernel.h>
12#include <linux/mutex.h>
13#include <linux/sched.h>
14#include <linux/notifier.h>
15#include <linux/latency.h>
16#include <linux/cpu.h>
17#include <linux/cpuidle.h>
18
19#include "cpuidle.h"
20
21DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
Len Brown4f86d3a2007-10-03 18:58:00 -040022
23DEFINE_MUTEX(cpuidle_lock);
24LIST_HEAD(cpuidle_detected_devices);
25static void (*pm_idle_old)(void);
26
27static int enabled_devices;
28
29/**
30 * cpuidle_idle_call - the main idle loop
31 *
32 * NOTE: no locks or semaphores should be used here
33 */
34static void cpuidle_idle_call(void)
35{
36 struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices);
37 struct cpuidle_state *target_state;
38 int next_state;
39
40 /* check if the device is ready */
41 if (!dev || !dev->enabled) {
42 if (pm_idle_old)
43 pm_idle_old();
44 else
45 local_irq_enable();
46 return;
47 }
48
49 /* ask the governor for the next state */
50 next_state = cpuidle_curr_governor->select(dev);
51 if (need_resched())
52 return;
53 target_state = &dev->states[next_state];
54
55 /* enter the state and update stats */
56 dev->last_residency = target_state->enter(dev, target_state);
57 dev->last_state = target_state;
58 target_state->time += dev->last_residency;
59 target_state->usage++;
60
61 /* give the governor an opportunity to reflect on the outcome */
62 if (cpuidle_curr_governor->reflect)
63 cpuidle_curr_governor->reflect(dev);
64}
65
66/**
67 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
68 */
69void cpuidle_install_idle_handler(void)
70{
71 if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
72 /* Make sure all changes finished before we switch to new idle */
73 smp_wmb();
74 pm_idle = cpuidle_idle_call;
75 }
76}
77
78/**
79 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
80 */
81void cpuidle_uninstall_idle_handler(void)
82{
83 if (enabled_devices && (pm_idle != pm_idle_old)) {
84 pm_idle = pm_idle_old;
85 cpu_idle_wait();
86 }
87}
88
89/**
90 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
91 */
92void cpuidle_pause_and_lock(void)
93{
94 mutex_lock(&cpuidle_lock);
95 cpuidle_uninstall_idle_handler();
96}
97
98EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
99
100/**
101 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
102 */
103void cpuidle_resume_and_unlock(void)
104{
105 cpuidle_install_idle_handler();
106 mutex_unlock(&cpuidle_lock);
107}
108
109EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
110
111/**
112 * cpuidle_enable_device - enables idle PM for a CPU
113 * @dev: the CPU
114 *
115 * This function must be called between cpuidle_pause_and_lock and
116 * cpuidle_resume_and_unlock when used externally.
117 */
118int cpuidle_enable_device(struct cpuidle_device *dev)
119{
120 int ret, i;
121
122 if (dev->enabled)
123 return 0;
124 if (!cpuidle_curr_driver || !cpuidle_curr_governor)
125 return -EIO;
126 if (!dev->state_count)
127 return -EINVAL;
128
129 if ((ret = cpuidle_add_state_sysfs(dev)))
130 return ret;
131
132 if (cpuidle_curr_governor->enable &&
133 (ret = cpuidle_curr_governor->enable(dev)))
134 goto fail_sysfs;
135
136 for (i = 0; i < dev->state_count; i++) {
137 dev->states[i].usage = 0;
138 dev->states[i].time = 0;
139 }
140 dev->last_residency = 0;
141 dev->last_state = NULL;
142
143 smp_wmb();
144
145 dev->enabled = 1;
146
147 enabled_devices++;
148 return 0;
149
150fail_sysfs:
151 cpuidle_remove_state_sysfs(dev);
152
153 return ret;
154}
155
156EXPORT_SYMBOL_GPL(cpuidle_enable_device);
157
158/**
159 * cpuidle_disable_device - disables idle PM for a CPU
160 * @dev: the CPU
161 *
162 * This function must be called between cpuidle_pause_and_lock and
163 * cpuidle_resume_and_unlock when used externally.
164 */
165void cpuidle_disable_device(struct cpuidle_device *dev)
166{
167 if (!dev->enabled)
168 return;
169 if (!cpuidle_curr_driver || !cpuidle_curr_governor)
170 return;
171
172 dev->enabled = 0;
173
174 if (cpuidle_curr_governor->disable)
175 cpuidle_curr_governor->disable(dev);
176
177 cpuidle_remove_state_sysfs(dev);
178 enabled_devices--;
179}
180
181EXPORT_SYMBOL_GPL(cpuidle_disable_device);
182
183/**
184 * cpuidle_register_device - registers a CPU's idle PM feature
185 * @dev: the cpu
186 */
187int cpuidle_register_device(struct cpuidle_device *dev)
188{
189 int ret;
190 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
191
192 if (!sys_dev)
193 return -EINVAL;
194 if (!try_module_get(cpuidle_curr_driver->owner))
195 return -EINVAL;
196
197 init_completion(&dev->kobj_unregister);
198
199 mutex_lock(&cpuidle_lock);
200
201 per_cpu(cpuidle_devices, dev->cpu) = dev;
202 list_add(&dev->device_list, &cpuidle_detected_devices);
203 if ((ret = cpuidle_add_sysfs(sys_dev))) {
204 mutex_unlock(&cpuidle_lock);
205 module_put(cpuidle_curr_driver->owner);
206 return ret;
207 }
208
209 cpuidle_enable_device(dev);
210 cpuidle_install_idle_handler();
211
212 mutex_unlock(&cpuidle_lock);
213
214 return 0;
215
216}
217
218EXPORT_SYMBOL_GPL(cpuidle_register_device);
219
220/**
221 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
222 * @dev: the cpu
223 */
224void cpuidle_unregister_device(struct cpuidle_device *dev)
225{
226 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
227
228 cpuidle_pause_and_lock();
229
230 cpuidle_disable_device(dev);
231
232 cpuidle_remove_sysfs(sys_dev);
233 list_del(&dev->device_list);
234 wait_for_completion(&dev->kobj_unregister);
235 per_cpu(cpuidle_devices, dev->cpu) = NULL;
236
237 cpuidle_resume_and_unlock();
238
239 module_put(cpuidle_curr_driver->owner);
240}
241
242EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
243
244#ifdef CONFIG_SMP
245
246static void smp_callback(void *v)
247{
248 /* we already woke the CPU up, nothing more to do */
249}
250
251/*
252 * This function gets called when a part of the kernel has a new latency
253 * requirement. This means we need to get all processors out of their C-state,
254 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
255 * wakes them all right up.
256 */
257static int cpuidle_latency_notify(struct notifier_block *b,
258 unsigned long l, void *v)
259{
260 smp_call_function(smp_callback, NULL, 0, 1);
261 return NOTIFY_OK;
262}
263
264static struct notifier_block cpuidle_latency_notifier = {
265 .notifier_call = cpuidle_latency_notify,
266};
267
268#define latency_notifier_init(x) do { register_latency_notifier(x); } while (0)
269
270#else /* CONFIG_SMP */
271
272#define latency_notifier_init(x) do { } while (0)
273
274#endif /* CONFIG_SMP */
275
276/**
277 * cpuidle_init - core initializer
278 */
279static int __init cpuidle_init(void)
280{
281 int ret;
282
283 pm_idle_old = pm_idle;
284
285 ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
286 if (ret)
287 return ret;
288
289 latency_notifier_init(&cpuidle_latency_notifier);
290
291 return 0;
292}
293
294core_initcall(cpuidle_init);