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