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1 | /* |
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/pm_qos_params.h> |
16 | #include <linux/cpu.h> |
17 | #include <linux/cpuidle.h> |
18 | #include <linux/ktime.h> |
19 | #include <linux/hrtimer.h> |
20 | #include <trace/events/power.h> |
21 | |
22 | #include "cpuidle.h" |
23 | |
24 | DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); |
25 | |
26 | DEFINE_MUTEX(cpuidle_lock); |
27 | LIST_HEAD(cpuidle_detected_devices); |
28 | static void (*pm_idle_old)(void); |
29 | |
30 | static int enabled_devices; |
31 | |
32 | #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT) |
33 | static void cpuidle_kick_cpus(void) |
34 | { |
35 | cpu_idle_wait(); |
36 | } |
37 | #elif defined(CONFIG_SMP) |
38 | # error "Arch needs cpu_idle_wait() equivalent here" |
39 | #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */ |
40 | static void cpuidle_kick_cpus(void) {} |
41 | #endif |
42 | |
43 | static int __cpuidle_register_device(struct cpuidle_device *dev); |
44 | |
45 | /** |
46 | * cpuidle_idle_call - the main idle loop |
47 | * |
48 | * NOTE: no locks or semaphores should be used here |
49 | */ |
50 | static void cpuidle_idle_call(void) |
51 | { |
52 | struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices); |
53 | struct cpuidle_state *target_state; |
54 | int next_state; |
55 | |
56 | /* check if the device is ready */ |
57 | if (!dev || !dev->enabled) { |
58 | if (pm_idle_old) |
59 | pm_idle_old(); |
60 | else |
61 | #if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE) |
62 | default_idle(); |
63 | #else |
64 | local_irq_enable(); |
65 | #endif |
66 | return; |
67 | } |
68 | |
69 | #if 0 |
70 | /* shows regressions, re-enable for 2.6.29 */ |
71 | /* |
72 | * run any timers that can be run now, at this point |
73 | * before calculating the idle duration etc. |
74 | */ |
75 | hrtimer_peek_ahead_timers(); |
76 | #endif |
77 | /* ask the governor for the next state */ |
78 | next_state = cpuidle_curr_governor->select(dev); |
79 | if (need_resched()) { |
80 | local_irq_enable(); |
81 | return; |
82 | } |
83 | |
84 | target_state = &dev->states[next_state]; |
85 | |
86 | /* enter the state and update stats */ |
87 | dev->last_state = target_state; |
88 | dev->last_residency = target_state->enter(dev, target_state); |
89 | if (dev->last_state) |
90 | target_state = dev->last_state; |
91 | |
92 | target_state->time += (unsigned long long)dev->last_residency; |
93 | target_state->usage++; |
94 | |
95 | /* give the governor an opportunity to reflect on the outcome */ |
96 | if (cpuidle_curr_governor->reflect) |
97 | cpuidle_curr_governor->reflect(dev); |
98 | trace_power_end(0); |
99 | } |
100 | |
101 | /** |
102 | * cpuidle_install_idle_handler - installs the cpuidle idle loop handler |
103 | */ |
104 | void cpuidle_install_idle_handler(void) |
105 | { |
106 | if (enabled_devices && (pm_idle != cpuidle_idle_call)) { |
107 | /* Make sure all changes finished before we switch to new idle */ |
108 | smp_wmb(); |
109 | pm_idle = cpuidle_idle_call; |
110 | } |
111 | } |
112 | |
113 | /** |
114 | * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler |
115 | */ |
116 | void cpuidle_uninstall_idle_handler(void) |
117 | { |
118 | if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) { |
119 | pm_idle = pm_idle_old; |
120 | cpuidle_kick_cpus(); |
121 | } |
122 | } |
123 | |
124 | /** |
125 | * cpuidle_pause_and_lock - temporarily disables CPUIDLE |
126 | */ |
127 | void cpuidle_pause_and_lock(void) |
128 | { |
129 | mutex_lock(&cpuidle_lock); |
130 | cpuidle_uninstall_idle_handler(); |
131 | } |
132 | |
133 | EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); |
134 | |
135 | /** |
136 | * cpuidle_resume_and_unlock - resumes CPUIDLE operation |
137 | */ |
138 | void cpuidle_resume_and_unlock(void) |
139 | { |
140 | cpuidle_install_idle_handler(); |
141 | mutex_unlock(&cpuidle_lock); |
142 | } |
143 | |
144 | EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); |
145 | |
146 | /** |
147 | * cpuidle_enable_device - enables idle PM for a CPU |
148 | * @dev: the CPU |
149 | * |
150 | * This function must be called between cpuidle_pause_and_lock and |
151 | * cpuidle_resume_and_unlock when used externally. |
152 | */ |
153 | int cpuidle_enable_device(struct cpuidle_device *dev) |
154 | { |
155 | int ret, i; |
156 | |
157 | if (dev->enabled) |
158 | return 0; |
159 | if (!cpuidle_curr_driver || !cpuidle_curr_governor) |
160 | return -EIO; |
161 | if (!dev->state_count) |
162 | return -EINVAL; |
163 | |
164 | if (dev->registered == 0) { |
165 | ret = __cpuidle_register_device(dev); |
166 | if (ret) |
167 | return ret; |
168 | } |
169 | |
170 | if ((ret = cpuidle_add_state_sysfs(dev))) |
171 | return ret; |
172 | |
173 | if (cpuidle_curr_governor->enable && |
174 | (ret = cpuidle_curr_governor->enable(dev))) |
175 | goto fail_sysfs; |
176 | |
177 | for (i = 0; i < dev->state_count; i++) { |
178 | dev->states[i].usage = 0; |
179 | dev->states[i].time = 0; |
180 | } |
181 | dev->last_residency = 0; |
182 | dev->last_state = NULL; |
183 | |
184 | smp_wmb(); |
185 | |
186 | dev->enabled = 1; |
187 | |
188 | enabled_devices++; |
189 | return 0; |
190 | |
191 | fail_sysfs: |
192 | cpuidle_remove_state_sysfs(dev); |
193 | |
194 | return ret; |
195 | } |
196 | |
197 | EXPORT_SYMBOL_GPL(cpuidle_enable_device); |
198 | |
199 | /** |
200 | * cpuidle_disable_device - disables idle PM for a CPU |
201 | * @dev: the CPU |
202 | * |
203 | * This function must be called between cpuidle_pause_and_lock and |
204 | * cpuidle_resume_and_unlock when used externally. |
205 | */ |
206 | void cpuidle_disable_device(struct cpuidle_device *dev) |
207 | { |
208 | if (!dev->enabled) |
209 | return; |
210 | if (!cpuidle_curr_driver || !cpuidle_curr_governor) |
211 | return; |
212 | |
213 | dev->enabled = 0; |
214 | |
215 | if (cpuidle_curr_governor->disable) |
216 | cpuidle_curr_governor->disable(dev); |
217 | |
218 | cpuidle_remove_state_sysfs(dev); |
219 | enabled_devices--; |
220 | } |
221 | |
222 | EXPORT_SYMBOL_GPL(cpuidle_disable_device); |
223 | |
224 | #ifdef CONFIG_ARCH_HAS_CPU_RELAX |
225 | static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st) |
226 | { |
227 | ktime_t t1, t2; |
228 | s64 diff; |
229 | int ret; |
230 | |
231 | t1 = ktime_get(); |
232 | local_irq_enable(); |
233 | while (!need_resched()) |
234 | cpu_relax(); |
235 | |
236 | t2 = ktime_get(); |
237 | diff = ktime_to_us(ktime_sub(t2, t1)); |
238 | if (diff > INT_MAX) |
239 | diff = INT_MAX; |
240 | |
241 | ret = (int) diff; |
242 | return ret; |
243 | } |
244 | |
245 | static void poll_idle_init(struct cpuidle_device *dev) |
246 | { |
247 | struct cpuidle_state *state = &dev->states[0]; |
248 | |
249 | cpuidle_set_statedata(state, NULL); |
250 | |
251 | snprintf(state->name, CPUIDLE_NAME_LEN, "C0"); |
252 | snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); |
253 | state->exit_latency = 0; |
254 | state->target_residency = 0; |
255 | state->power_usage = -1; |
256 | state->flags = CPUIDLE_FLAG_POLL; |
257 | state->enter = poll_idle; |
258 | } |
259 | #else |
260 | static void poll_idle_init(struct cpuidle_device *dev) {} |
261 | #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ |
262 | |
263 | /** |
264 | * __cpuidle_register_device - internal register function called before register |
265 | * and enable routines |
266 | * @dev: the cpu |
267 | * |
268 | * cpuidle_lock mutex must be held before this is called |
269 | */ |
270 | static int __cpuidle_register_device(struct cpuidle_device *dev) |
271 | { |
272 | int ret; |
273 | struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); |
274 | |
275 | if (!sys_dev) |
276 | return -EINVAL; |
277 | if (!try_module_get(cpuidle_curr_driver->owner)) |
278 | return -EINVAL; |
279 | |
280 | init_completion(&dev->kobj_unregister); |
281 | |
282 | poll_idle_init(dev); |
283 | |
284 | per_cpu(cpuidle_devices, dev->cpu) = dev; |
285 | list_add(&dev->device_list, &cpuidle_detected_devices); |
286 | if ((ret = cpuidle_add_sysfs(sys_dev))) { |
287 | module_put(cpuidle_curr_driver->owner); |
288 | return ret; |
289 | } |
290 | |
291 | dev->registered = 1; |
292 | return 0; |
293 | } |
294 | |
295 | /** |
296 | * cpuidle_register_device - registers a CPU's idle PM feature |
297 | * @dev: the cpu |
298 | */ |
299 | int cpuidle_register_device(struct cpuidle_device *dev) |
300 | { |
301 | int ret; |
302 | |
303 | mutex_lock(&cpuidle_lock); |
304 | |
305 | if ((ret = __cpuidle_register_device(dev))) { |
306 | mutex_unlock(&cpuidle_lock); |
307 | return ret; |
308 | } |
309 | |
310 | cpuidle_enable_device(dev); |
311 | cpuidle_install_idle_handler(); |
312 | |
313 | mutex_unlock(&cpuidle_lock); |
314 | |
315 | return 0; |
316 | |
317 | } |
318 | |
319 | EXPORT_SYMBOL_GPL(cpuidle_register_device); |
320 | |
321 | /** |
322 | * cpuidle_unregister_device - unregisters a CPU's idle PM feature |
323 | * @dev: the cpu |
324 | */ |
325 | void cpuidle_unregister_device(struct cpuidle_device *dev) |
326 | { |
327 | struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); |
328 | |
329 | if (dev->registered == 0) |
330 | return; |
331 | |
332 | cpuidle_pause_and_lock(); |
333 | |
334 | cpuidle_disable_device(dev); |
335 | |
336 | cpuidle_remove_sysfs(sys_dev); |
337 | list_del(&dev->device_list); |
338 | wait_for_completion(&dev->kobj_unregister); |
339 | per_cpu(cpuidle_devices, dev->cpu) = NULL; |
340 | |
341 | cpuidle_resume_and_unlock(); |
342 | |
343 | module_put(cpuidle_curr_driver->owner); |
344 | } |
345 | |
346 | EXPORT_SYMBOL_GPL(cpuidle_unregister_device); |
347 | |
348 | #ifdef CONFIG_SMP |
349 | |
350 | static void smp_callback(void *v) |
351 | { |
352 | /* we already woke the CPU up, nothing more to do */ |
353 | } |
354 | |
355 | /* |
356 | * This function gets called when a part of the kernel has a new latency |
357 | * requirement. This means we need to get all processors out of their C-state, |
358 | * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that |
359 | * wakes them all right up. |
360 | */ |
361 | static int cpuidle_latency_notify(struct notifier_block *b, |
362 | unsigned long l, void *v) |
363 | { |
364 | smp_call_function(smp_callback, NULL, 1); |
365 | return NOTIFY_OK; |
366 | } |
367 | |
368 | static struct notifier_block cpuidle_latency_notifier = { |
369 | .notifier_call = cpuidle_latency_notify, |
370 | }; |
371 | |
372 | static inline void latency_notifier_init(struct notifier_block *n) |
373 | { |
374 | pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); |
375 | } |
376 | |
377 | #else /* CONFIG_SMP */ |
378 | |
379 | #define latency_notifier_init(x) do { } while (0) |
380 | |
381 | #endif /* CONFIG_SMP */ |
382 | |
383 | /** |
384 | * cpuidle_init - core initializer |
385 | */ |
386 | static int __init cpuidle_init(void) |
387 | { |
388 | int ret; |
389 | |
390 | pm_idle_old = pm_idle; |
391 | |
392 | ret = cpuidle_add_class_sysfs(&cpu_sysdev_class); |
393 | if (ret) |
394 | return ret; |
395 | |
396 | latency_notifier_init(&cpuidle_latency_notifier); |
397 | |
398 | return 0; |
399 | } |
400 | |
401 | core_initcall(cpuidle_init); |
402 |
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