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