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4f86d3a8 LB |
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> | |
d82b3518 | 15 | #include <linux/pm_qos_params.h> |
4f86d3a8 LB |
16 | #include <linux/cpu.h> |
17 | #include <linux/cpuidle.h> | |
9a0b8415 | 18 | #include <linux/ktime.h> |
2e94d1f7 | 19 | #include <linux/hrtimer.h> |
4f86d3a8 LB |
20 | |
21 | #include "cpuidle.h" | |
22 | ||
23 | DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); | |
4f86d3a8 LB |
24 | |
25 | DEFINE_MUTEX(cpuidle_lock); | |
26 | LIST_HEAD(cpuidle_detected_devices); | |
27 | static void (*pm_idle_old)(void); | |
28 | ||
29 | static int enabled_devices; | |
30 | ||
a6869cc4 VP |
31 | #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT) |
32 | static void cpuidle_kick_cpus(void) | |
33 | { | |
34 | cpu_idle_wait(); | |
35 | } | |
36 | #elif defined(CONFIG_SMP) | |
37 | # error "Arch needs cpu_idle_wait() equivalent here" | |
38 | #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */ | |
39 | static void cpuidle_kick_cpus(void) {} | |
40 | #endif | |
41 | ||
dcb84f33 VP |
42 | static int __cpuidle_register_device(struct cpuidle_device *dev); |
43 | ||
4f86d3a8 LB |
44 | /** |
45 | * cpuidle_idle_call - the main idle loop | |
46 | * | |
47 | * NOTE: no locks or semaphores should be used here | |
48 | */ | |
49 | static void cpuidle_idle_call(void) | |
50 | { | |
51 | struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices); | |
52 | struct cpuidle_state *target_state; | |
53 | int next_state; | |
54 | ||
55 | /* check if the device is ready */ | |
56 | if (!dev || !dev->enabled) { | |
57 | if (pm_idle_old) | |
58 | pm_idle_old(); | |
59 | else | |
89cedfef VP |
60 | #if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE) |
61 | default_idle(); | |
62 | #else | |
4f86d3a8 | 63 | local_irq_enable(); |
89cedfef | 64 | #endif |
4f86d3a8 LB |
65 | return; |
66 | } | |
67 | ||
2e94d1f7 AV |
68 | /* |
69 | * run any timers that can be run now, at this point | |
70 | * before calculating the idle duration etc. | |
71 | */ | |
72 | hrtimer_peek_ahead_timers(); | |
73 | ||
4f86d3a8 LB |
74 | /* ask the governor for the next state */ |
75 | next_state = cpuidle_curr_governor->select(dev); | |
76 | if (need_resched()) | |
77 | return; | |
78 | target_state = &dev->states[next_state]; | |
79 | ||
80 | /* enter the state and update stats */ | |
4f86d3a8 | 81 | dev->last_state = target_state; |
887e301a VP |
82 | dev->last_residency = target_state->enter(dev, target_state); |
83 | if (dev->last_state) | |
84 | target_state = dev->last_state; | |
85 | ||
8b78cf60 | 86 | target_state->time += (unsigned long long)dev->last_residency; |
4f86d3a8 LB |
87 | target_state->usage++; |
88 | ||
89 | /* give the governor an opportunity to reflect on the outcome */ | |
90 | if (cpuidle_curr_governor->reflect) | |
91 | cpuidle_curr_governor->reflect(dev); | |
92 | } | |
93 | ||
94 | /** | |
95 | * cpuidle_install_idle_handler - installs the cpuidle idle loop handler | |
96 | */ | |
97 | void cpuidle_install_idle_handler(void) | |
98 | { | |
99 | if (enabled_devices && (pm_idle != cpuidle_idle_call)) { | |
100 | /* Make sure all changes finished before we switch to new idle */ | |
101 | smp_wmb(); | |
102 | pm_idle = cpuidle_idle_call; | |
103 | } | |
104 | } | |
105 | ||
106 | /** | |
107 | * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler | |
108 | */ | |
109 | void cpuidle_uninstall_idle_handler(void) | |
110 | { | |
b032bf70 | 111 | if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) { |
4f86d3a8 | 112 | pm_idle = pm_idle_old; |
a6869cc4 | 113 | cpuidle_kick_cpus(); |
4f86d3a8 LB |
114 | } |
115 | } | |
116 | ||
117 | /** | |
118 | * cpuidle_pause_and_lock - temporarily disables CPUIDLE | |
119 | */ | |
120 | void cpuidle_pause_and_lock(void) | |
121 | { | |
122 | mutex_lock(&cpuidle_lock); | |
123 | cpuidle_uninstall_idle_handler(); | |
124 | } | |
125 | ||
126 | EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); | |
127 | ||
128 | /** | |
129 | * cpuidle_resume_and_unlock - resumes CPUIDLE operation | |
130 | */ | |
131 | void cpuidle_resume_and_unlock(void) | |
132 | { | |
133 | cpuidle_install_idle_handler(); | |
134 | mutex_unlock(&cpuidle_lock); | |
135 | } | |
136 | ||
137 | EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); | |
138 | ||
139 | /** | |
140 | * cpuidle_enable_device - enables idle PM for a CPU | |
141 | * @dev: the CPU | |
142 | * | |
143 | * This function must be called between cpuidle_pause_and_lock and | |
144 | * cpuidle_resume_and_unlock when used externally. | |
145 | */ | |
146 | int cpuidle_enable_device(struct cpuidle_device *dev) | |
147 | { | |
148 | int ret, i; | |
149 | ||
150 | if (dev->enabled) | |
151 | return 0; | |
152 | if (!cpuidle_curr_driver || !cpuidle_curr_governor) | |
153 | return -EIO; | |
154 | if (!dev->state_count) | |
155 | return -EINVAL; | |
156 | ||
dcb84f33 VP |
157 | if (dev->registered == 0) { |
158 | ret = __cpuidle_register_device(dev); | |
159 | if (ret) | |
160 | return ret; | |
161 | } | |
162 | ||
4f86d3a8 LB |
163 | if ((ret = cpuidle_add_state_sysfs(dev))) |
164 | return ret; | |
165 | ||
166 | if (cpuidle_curr_governor->enable && | |
167 | (ret = cpuidle_curr_governor->enable(dev))) | |
168 | goto fail_sysfs; | |
169 | ||
170 | for (i = 0; i < dev->state_count; i++) { | |
171 | dev->states[i].usage = 0; | |
172 | dev->states[i].time = 0; | |
173 | } | |
174 | dev->last_residency = 0; | |
175 | dev->last_state = NULL; | |
176 | ||
177 | smp_wmb(); | |
178 | ||
179 | dev->enabled = 1; | |
180 | ||
181 | enabled_devices++; | |
182 | return 0; | |
183 | ||
184 | fail_sysfs: | |
185 | cpuidle_remove_state_sysfs(dev); | |
186 | ||
187 | return ret; | |
188 | } | |
189 | ||
190 | EXPORT_SYMBOL_GPL(cpuidle_enable_device); | |
191 | ||
192 | /** | |
193 | * cpuidle_disable_device - disables idle PM for a CPU | |
194 | * @dev: the CPU | |
195 | * | |
196 | * This function must be called between cpuidle_pause_and_lock and | |
197 | * cpuidle_resume_and_unlock when used externally. | |
198 | */ | |
199 | void cpuidle_disable_device(struct cpuidle_device *dev) | |
200 | { | |
201 | if (!dev->enabled) | |
202 | return; | |
203 | if (!cpuidle_curr_driver || !cpuidle_curr_governor) | |
204 | return; | |
205 | ||
206 | dev->enabled = 0; | |
207 | ||
208 | if (cpuidle_curr_governor->disable) | |
209 | cpuidle_curr_governor->disable(dev); | |
210 | ||
211 | cpuidle_remove_state_sysfs(dev); | |
212 | enabled_devices--; | |
213 | } | |
214 | ||
215 | EXPORT_SYMBOL_GPL(cpuidle_disable_device); | |
216 | ||
9a0b8415 | 217 | #ifdef CONFIG_ARCH_HAS_CPU_RELAX |
218 | static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st) | |
219 | { | |
220 | ktime_t t1, t2; | |
221 | s64 diff; | |
222 | int ret; | |
223 | ||
224 | t1 = ktime_get(); | |
225 | local_irq_enable(); | |
226 | while (!need_resched()) | |
227 | cpu_relax(); | |
228 | ||
229 | t2 = ktime_get(); | |
230 | diff = ktime_to_us(ktime_sub(t2, t1)); | |
231 | if (diff > INT_MAX) | |
232 | diff = INT_MAX; | |
233 | ||
234 | ret = (int) diff; | |
235 | return ret; | |
236 | } | |
237 | ||
238 | static void poll_idle_init(struct cpuidle_device *dev) | |
239 | { | |
240 | struct cpuidle_state *state = &dev->states[0]; | |
241 | ||
242 | cpuidle_set_statedata(state, NULL); | |
243 | ||
4fcb2fcd VP |
244 | snprintf(state->name, CPUIDLE_NAME_LEN, "C0"); |
245 | snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); | |
9a0b8415 | 246 | state->exit_latency = 0; |
247 | state->target_residency = 0; | |
248 | state->power_usage = -1; | |
8e92b660 | 249 | state->flags = CPUIDLE_FLAG_POLL; |
9a0b8415 | 250 | state->enter = poll_idle; |
251 | } | |
252 | #else | |
253 | static void poll_idle_init(struct cpuidle_device *dev) {} | |
254 | #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ | |
255 | ||
4f86d3a8 | 256 | /** |
dcb84f33 VP |
257 | * __cpuidle_register_device - internal register function called before register |
258 | * and enable routines | |
4f86d3a8 | 259 | * @dev: the cpu |
dcb84f33 VP |
260 | * |
261 | * cpuidle_lock mutex must be held before this is called | |
4f86d3a8 | 262 | */ |
dcb84f33 | 263 | static int __cpuidle_register_device(struct cpuidle_device *dev) |
4f86d3a8 LB |
264 | { |
265 | int ret; | |
266 | struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); | |
267 | ||
268 | if (!sys_dev) | |
269 | return -EINVAL; | |
270 | if (!try_module_get(cpuidle_curr_driver->owner)) | |
271 | return -EINVAL; | |
272 | ||
273 | init_completion(&dev->kobj_unregister); | |
274 | ||
9a0b8415 | 275 | poll_idle_init(dev); |
276 | ||
4f86d3a8 LB |
277 | per_cpu(cpuidle_devices, dev->cpu) = dev; |
278 | list_add(&dev->device_list, &cpuidle_detected_devices); | |
279 | if ((ret = cpuidle_add_sysfs(sys_dev))) { | |
4f86d3a8 LB |
280 | module_put(cpuidle_curr_driver->owner); |
281 | return ret; | |
282 | } | |
283 | ||
dcb84f33 VP |
284 | dev->registered = 1; |
285 | return 0; | |
286 | } | |
287 | ||
288 | /** | |
289 | * cpuidle_register_device - registers a CPU's idle PM feature | |
290 | * @dev: the cpu | |
291 | */ | |
292 | int cpuidle_register_device(struct cpuidle_device *dev) | |
293 | { | |
294 | int ret; | |
295 | ||
296 | mutex_lock(&cpuidle_lock); | |
297 | ||
298 | if ((ret = __cpuidle_register_device(dev))) { | |
299 | mutex_unlock(&cpuidle_lock); | |
300 | return ret; | |
301 | } | |
302 | ||
4f86d3a8 LB |
303 | cpuidle_enable_device(dev); |
304 | cpuidle_install_idle_handler(); | |
305 | ||
306 | mutex_unlock(&cpuidle_lock); | |
307 | ||
308 | return 0; | |
309 | ||
310 | } | |
311 | ||
312 | EXPORT_SYMBOL_GPL(cpuidle_register_device); | |
313 | ||
314 | /** | |
315 | * cpuidle_unregister_device - unregisters a CPU's idle PM feature | |
316 | * @dev: the cpu | |
317 | */ | |
318 | void cpuidle_unregister_device(struct cpuidle_device *dev) | |
319 | { | |
320 | struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); | |
321 | ||
dcb84f33 VP |
322 | if (dev->registered == 0) |
323 | return; | |
324 | ||
4f86d3a8 LB |
325 | cpuidle_pause_and_lock(); |
326 | ||
327 | cpuidle_disable_device(dev); | |
328 | ||
329 | cpuidle_remove_sysfs(sys_dev); | |
330 | list_del(&dev->device_list); | |
331 | wait_for_completion(&dev->kobj_unregister); | |
332 | per_cpu(cpuidle_devices, dev->cpu) = NULL; | |
333 | ||
334 | cpuidle_resume_and_unlock(); | |
335 | ||
336 | module_put(cpuidle_curr_driver->owner); | |
337 | } | |
338 | ||
339 | EXPORT_SYMBOL_GPL(cpuidle_unregister_device); | |
340 | ||
341 | #ifdef CONFIG_SMP | |
342 | ||
343 | static void smp_callback(void *v) | |
344 | { | |
345 | /* we already woke the CPU up, nothing more to do */ | |
346 | } | |
347 | ||
348 | /* | |
349 | * This function gets called when a part of the kernel has a new latency | |
350 | * requirement. This means we need to get all processors out of their C-state, | |
351 | * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that | |
352 | * wakes them all right up. | |
353 | */ | |
354 | static int cpuidle_latency_notify(struct notifier_block *b, | |
355 | unsigned long l, void *v) | |
356 | { | |
8691e5a8 | 357 | smp_call_function(smp_callback, NULL, 1); |
4f86d3a8 LB |
358 | return NOTIFY_OK; |
359 | } | |
360 | ||
361 | static struct notifier_block cpuidle_latency_notifier = { | |
362 | .notifier_call = cpuidle_latency_notify, | |
363 | }; | |
364 | ||
d82b3518 MG |
365 | static inline void latency_notifier_init(struct notifier_block *n) |
366 | { | |
367 | pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); | |
368 | } | |
4f86d3a8 LB |
369 | |
370 | #else /* CONFIG_SMP */ | |
371 | ||
372 | #define latency_notifier_init(x) do { } while (0) | |
373 | ||
374 | #endif /* CONFIG_SMP */ | |
375 | ||
376 | /** | |
377 | * cpuidle_init - core initializer | |
378 | */ | |
379 | static int __init cpuidle_init(void) | |
380 | { | |
381 | int ret; | |
382 | ||
383 | pm_idle_old = pm_idle; | |
384 | ||
385 | ret = cpuidle_add_class_sysfs(&cpu_sysdev_class); | |
386 | if (ret) | |
387 | return ret; | |
388 | ||
389 | latency_notifier_init(&cpuidle_latency_notifier); | |
390 | ||
391 | return 0; | |
392 | } | |
393 | ||
394 | core_initcall(cpuidle_init); |