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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>
Mark Grossd82b3512008-02-04 22:30:08 -080015#include <linux/pm_qos_params.h>
Len Brown4f86d3a2007-10-03 18:58:00 -040016#include <linux/cpu.h>
17#include <linux/cpuidle.h>
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -080018#include <linux/ktime.h>
Arjan van de Ven2e94d1f2008-09-10 16:06:00 -070019#include <linux/hrtimer.h>
Arjan van de Ven288f0232009-09-19 13:35:33 +020020#include <trace/events/power.h>
Len Brown4f86d3a2007-10-03 18:58:00 -040021
22#include "cpuidle.h"
23
24DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
Len Brown4f86d3a2007-10-03 18:58:00 -040025
26DEFINE_MUTEX(cpuidle_lock);
27LIST_HEAD(cpuidle_detected_devices);
28static void (*pm_idle_old)(void);
29
30static int enabled_devices;
31
Venki Pallipadia6869cc2008-02-08 17:05:44 -080032#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
33static 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 */
40static void cpuidle_kick_cpus(void) {}
41#endif
42
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -040043static int __cpuidle_register_device(struct cpuidle_device *dev);
44
Len Brown4f86d3a2007-10-03 18:58:00 -040045/**
46 * cpuidle_idle_call - the main idle loop
47 *
48 * NOTE: no locks or semaphores should be used here
49 */
50static 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
Venkatesh Pallipadi89cedfe2008-10-16 19:00:08 -040061#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
62 default_idle();
63#else
Len Brown4f86d3a2007-10-03 18:58:00 -040064 local_irq_enable();
Venkatesh Pallipadi89cedfe2008-10-16 19:00:08 -040065#endif
Len Brown4f86d3a2007-10-03 18:58:00 -040066 return;
67 }
68
Arjan van de Ven9a655832008-11-09 12:45:10 -080069#if 0
70 /* shows regressions, re-enable for 2.6.29 */
Arjan van de Ven2e94d1f2008-09-10 16:06:00 -070071 /*
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();
Arjan van de Ven9a655832008-11-09 12:45:10 -080076#endif
Len Brown4f86d3a2007-10-03 18:58:00 -040077 /* ask the governor for the next state */
78 next_state = cpuidle_curr_governor->select(dev);
Kevin Hilman246eb7f2009-10-26 16:50:18 -070079 if (need_resched()) {
80 local_irq_enable();
Len Brown4f86d3a2007-10-03 18:58:00 -040081 return;
Kevin Hilman246eb7f2009-10-26 16:50:18 -070082 }
83
Len Brown4f86d3a2007-10-03 18:58:00 -040084 target_state = &dev->states[next_state];
85
86 /* enter the state and update stats */
Len Brown4f86d3a2007-10-03 18:58:00 -040087 dev->last_state = target_state;
Venkatesh Pallipadi887e3012008-09-29 15:24:27 -070088 dev->last_residency = target_state->enter(dev, target_state);
89 if (dev->last_state)
90 target_state = dev->last_state;
91
Yi Yang8b78cf62008-02-25 08:46:12 +080092 target_state->time += (unsigned long long)dev->last_residency;
Len Brown4f86d3a2007-10-03 18:58:00 -040093 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);
Arjan van de Ven288f0232009-09-19 13:35:33 +020098 trace_power_end(0);
Len Brown4f86d3a2007-10-03 18:58:00 -040099}
100
101/**
102 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
103 */
104void 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 */
116void cpuidle_uninstall_idle_handler(void)
117{
Thomas Gleixnerb032bf70d2008-07-27 23:47:12 +0200118 if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
Len Brown4f86d3a2007-10-03 18:58:00 -0400119 pm_idle = pm_idle_old;
Venki Pallipadia6869cc2008-02-08 17:05:44 -0800120 cpuidle_kick_cpus();
Len Brown4f86d3a2007-10-03 18:58:00 -0400121 }
122}
123
124/**
125 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
126 */
127void cpuidle_pause_and_lock(void)
128{
129 mutex_lock(&cpuidle_lock);
130 cpuidle_uninstall_idle_handler();
131}
132
133EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
134
135/**
136 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
137 */
138void cpuidle_resume_and_unlock(void)
139{
140 cpuidle_install_idle_handler();
141 mutex_unlock(&cpuidle_lock);
142}
143
144EXPORT_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 */
153int 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
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400164 if (dev->registered == 0) {
165 ret = __cpuidle_register_device(dev);
166 if (ret)
167 return ret;
168 }
169
Len Brown4f86d3a2007-10-03 18:58:00 -0400170 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
191fail_sysfs:
192 cpuidle_remove_state_sysfs(dev);
193
194 return ret;
195}
196
197EXPORT_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 */
206void 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
222EXPORT_SYMBOL_GPL(cpuidle_disable_device);
223
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800224#ifdef CONFIG_ARCH_HAS_CPU_RELAX
225static 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
245static 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
Venkatesh Pallipadi4fcb2fc2008-02-11 17:46:31 -0800251 snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
252 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800253 state->exit_latency = 0;
254 state->target_residency = 0;
255 state->power_usage = -1;
Venki Pallipadi8e92b662008-02-29 10:24:32 -0800256 state->flags = CPUIDLE_FLAG_POLL;
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800257 state->enter = poll_idle;
258}
259#else
260static void poll_idle_init(struct cpuidle_device *dev) {}
261#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
262
Len Brown4f86d3a2007-10-03 18:58:00 -0400263/**
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400264 * __cpuidle_register_device - internal register function called before register
265 * and enable routines
Len Brown4f86d3a2007-10-03 18:58:00 -0400266 * @dev: the cpu
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400267 *
268 * cpuidle_lock mutex must be held before this is called
Len Brown4f86d3a2007-10-03 18:58:00 -0400269 */
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400270static int __cpuidle_register_device(struct cpuidle_device *dev)
Len Brown4f86d3a2007-10-03 18:58:00 -0400271{
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
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800282 poll_idle_init(dev);
283
Len Brown4f86d3a2007-10-03 18:58:00 -0400284 per_cpu(cpuidle_devices, dev->cpu) = dev;
285 list_add(&dev->device_list, &cpuidle_detected_devices);
286 if ((ret = cpuidle_add_sysfs(sys_dev))) {
Len Brown4f86d3a2007-10-03 18:58:00 -0400287 module_put(cpuidle_curr_driver->owner);
288 return ret;
289 }
290
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400291 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 */
299int 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
Len Brown4f86d3a2007-10-03 18:58:00 -0400310 cpuidle_enable_device(dev);
311 cpuidle_install_idle_handler();
312
313 mutex_unlock(&cpuidle_lock);
314
315 return 0;
316
317}
318
319EXPORT_SYMBOL_GPL(cpuidle_register_device);
320
321/**
322 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
323 * @dev: the cpu
324 */
325void cpuidle_unregister_device(struct cpuidle_device *dev)
326{
327 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
328
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400329 if (dev->registered == 0)
330 return;
331
Len Brown4f86d3a2007-10-03 18:58:00 -0400332 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
346EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
347
348#ifdef CONFIG_SMP
349
350static 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 */
361static int cpuidle_latency_notify(struct notifier_block *b,
362 unsigned long l, void *v)
363{
Jens Axboe8691e5a2008-06-06 11:18:06 +0200364 smp_call_function(smp_callback, NULL, 1);
Len Brown4f86d3a2007-10-03 18:58:00 -0400365 return NOTIFY_OK;
366}
367
368static struct notifier_block cpuidle_latency_notifier = {
369 .notifier_call = cpuidle_latency_notify,
370};
371
Mark Grossd82b3512008-02-04 22:30:08 -0800372static inline void latency_notifier_init(struct notifier_block *n)
373{
374 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
375}
Len Brown4f86d3a2007-10-03 18:58:00 -0400376
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 */
386static 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
401core_initcall(cpuidle_init);