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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
Ai Li71abbbf2010-08-09 17:20:13 -070077
78 /*
79 * Call the device's prepare function before calling the
80 * governor's select function. ->prepare gives the device's
81 * cpuidle driver a chance to update any dynamic information
82 * of its cpuidle states for the current idle period, e.g.
83 * state availability, latencies, residencies, etc.
84 */
85 if (dev->prepare)
86 dev->prepare(dev);
87
Len Brown4f86d3a2007-10-03 18:58:00 -040088 /* ask the governor for the next state */
89 next_state = cpuidle_curr_governor->select(dev);
Kevin Hilman246eb7f2009-10-26 16:50:18 -070090 if (need_resched()) {
91 local_irq_enable();
Len Brown4f86d3a2007-10-03 18:58:00 -040092 return;
Kevin Hilman246eb7f2009-10-26 16:50:18 -070093 }
94
Len Brown4f86d3a2007-10-03 18:58:00 -040095 target_state = &dev->states[next_state];
96
97 /* enter the state and update stats */
Len Brown4f86d3a2007-10-03 18:58:00 -040098 dev->last_state = target_state;
Venkatesh Pallipadi887e3012008-09-29 15:24:27 -070099 dev->last_residency = target_state->enter(dev, target_state);
100 if (dev->last_state)
101 target_state = dev->last_state;
102
Yi Yang8b78cf62008-02-25 08:46:12 +0800103 target_state->time += (unsigned long long)dev->last_residency;
Len Brown4f86d3a2007-10-03 18:58:00 -0400104 target_state->usage++;
105
106 /* give the governor an opportunity to reflect on the outcome */
107 if (cpuidle_curr_governor->reflect)
108 cpuidle_curr_governor->reflect(dev);
Thomas Renninger6f4f2722010-04-20 13:17:36 +0200109 trace_power_end(smp_processor_id());
Len Brown4f86d3a2007-10-03 18:58:00 -0400110}
111
112/**
113 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
114 */
115void cpuidle_install_idle_handler(void)
116{
117 if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
118 /* Make sure all changes finished before we switch to new idle */
119 smp_wmb();
120 pm_idle = cpuidle_idle_call;
121 }
122}
123
124/**
125 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
126 */
127void cpuidle_uninstall_idle_handler(void)
128{
Thomas Gleixnerb032bf70d2008-07-27 23:47:12 +0200129 if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
Len Brown4f86d3a2007-10-03 18:58:00 -0400130 pm_idle = pm_idle_old;
Venki Pallipadia6869cc2008-02-08 17:05:44 -0800131 cpuidle_kick_cpus();
Len Brown4f86d3a2007-10-03 18:58:00 -0400132 }
133}
134
135/**
136 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
137 */
138void cpuidle_pause_and_lock(void)
139{
140 mutex_lock(&cpuidle_lock);
141 cpuidle_uninstall_idle_handler();
142}
143
144EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
145
146/**
147 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
148 */
149void cpuidle_resume_and_unlock(void)
150{
151 cpuidle_install_idle_handler();
152 mutex_unlock(&cpuidle_lock);
153}
154
155EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
156
157/**
158 * cpuidle_enable_device - enables idle PM for a CPU
159 * @dev: the CPU
160 *
161 * This function must be called between cpuidle_pause_and_lock and
162 * cpuidle_resume_and_unlock when used externally.
163 */
164int cpuidle_enable_device(struct cpuidle_device *dev)
165{
166 int ret, i;
167
168 if (dev->enabled)
169 return 0;
Len Brown752138d2010-05-22 16:57:26 -0400170 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
Len Brown4f86d3a2007-10-03 18:58:00 -0400171 return -EIO;
172 if (!dev->state_count)
173 return -EINVAL;
174
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400175 if (dev->registered == 0) {
176 ret = __cpuidle_register_device(dev);
177 if (ret)
178 return ret;
179 }
180
Len Brown4f86d3a2007-10-03 18:58:00 -0400181 if ((ret = cpuidle_add_state_sysfs(dev)))
182 return ret;
183
184 if (cpuidle_curr_governor->enable &&
185 (ret = cpuidle_curr_governor->enable(dev)))
186 goto fail_sysfs;
187
188 for (i = 0; i < dev->state_count; i++) {
189 dev->states[i].usage = 0;
190 dev->states[i].time = 0;
191 }
192 dev->last_residency = 0;
193 dev->last_state = NULL;
194
195 smp_wmb();
196
197 dev->enabled = 1;
198
199 enabled_devices++;
200 return 0;
201
202fail_sysfs:
203 cpuidle_remove_state_sysfs(dev);
204
205 return ret;
206}
207
208EXPORT_SYMBOL_GPL(cpuidle_enable_device);
209
210/**
211 * cpuidle_disable_device - disables idle PM for a CPU
212 * @dev: the CPU
213 *
214 * This function must be called between cpuidle_pause_and_lock and
215 * cpuidle_resume_and_unlock when used externally.
216 */
217void cpuidle_disable_device(struct cpuidle_device *dev)
218{
219 if (!dev->enabled)
220 return;
Len Brown752138d2010-05-22 16:57:26 -0400221 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
Len Brown4f86d3a2007-10-03 18:58:00 -0400222 return;
223
224 dev->enabled = 0;
225
226 if (cpuidle_curr_governor->disable)
227 cpuidle_curr_governor->disable(dev);
228
229 cpuidle_remove_state_sysfs(dev);
230 enabled_devices--;
231}
232
233EXPORT_SYMBOL_GPL(cpuidle_disable_device);
234
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800235#ifdef CONFIG_ARCH_HAS_CPU_RELAX
236static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
237{
238 ktime_t t1, t2;
239 s64 diff;
240 int ret;
241
242 t1 = ktime_get();
243 local_irq_enable();
244 while (!need_resched())
245 cpu_relax();
246
247 t2 = ktime_get();
248 diff = ktime_to_us(ktime_sub(t2, t1));
249 if (diff > INT_MAX)
250 diff = INT_MAX;
251
252 ret = (int) diff;
253 return ret;
254}
255
256static void poll_idle_init(struct cpuidle_device *dev)
257{
258 struct cpuidle_state *state = &dev->states[0];
259
260 cpuidle_set_statedata(state, NULL);
261
Venkatesh Pallipadi4fcb2fc2008-02-11 17:46:31 -0800262 snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
263 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800264 state->exit_latency = 0;
265 state->target_residency = 0;
266 state->power_usage = -1;
Venki Pallipadi8e92b662008-02-29 10:24:32 -0800267 state->flags = CPUIDLE_FLAG_POLL;
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800268 state->enter = poll_idle;
269}
270#else
271static void poll_idle_init(struct cpuidle_device *dev) {}
272#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
273
Len Brown4f86d3a2007-10-03 18:58:00 -0400274/**
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400275 * __cpuidle_register_device - internal register function called before register
276 * and enable routines
Len Brown4f86d3a2007-10-03 18:58:00 -0400277 * @dev: the cpu
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400278 *
279 * cpuidle_lock mutex must be held before this is called
Len Brown4f86d3a2007-10-03 18:58:00 -0400280 */
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400281static int __cpuidle_register_device(struct cpuidle_device *dev)
Len Brown4f86d3a2007-10-03 18:58:00 -0400282{
283 int ret;
284 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
Len Brown752138d2010-05-22 16:57:26 -0400285 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
Len Brown4f86d3a2007-10-03 18:58:00 -0400286
287 if (!sys_dev)
288 return -EINVAL;
Len Brown752138d2010-05-22 16:57:26 -0400289 if (!try_module_get(cpuidle_driver->owner))
Len Brown4f86d3a2007-10-03 18:58:00 -0400290 return -EINVAL;
291
292 init_completion(&dev->kobj_unregister);
293
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800294 poll_idle_init(dev);
295
Ai Li71abbbf2010-08-09 17:20:13 -0700296 /*
297 * cpuidle driver should set the dev->power_specified bit
298 * before registering the device if the driver provides
299 * power_usage numbers.
300 *
301 * For those devices whose ->power_specified is not set,
302 * we fill in power_usage with decreasing values as the
303 * cpuidle code has an implicit assumption that state Cn
304 * uses less power than C(n-1).
305 *
306 * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
307 * an power value of -1. So we use -2, -3, etc, for other
308 * c-states.
309 */
310 if (!dev->power_specified) {
311 int i;
312 for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
313 dev->states[i].power_usage = -1 - i;
314 }
315
Len Brown4f86d3a2007-10-03 18:58:00 -0400316 per_cpu(cpuidle_devices, dev->cpu) = dev;
317 list_add(&dev->device_list, &cpuidle_detected_devices);
318 if ((ret = cpuidle_add_sysfs(sys_dev))) {
Len Brown752138d2010-05-22 16:57:26 -0400319 module_put(cpuidle_driver->owner);
Len Brown4f86d3a2007-10-03 18:58:00 -0400320 return ret;
321 }
322
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400323 dev->registered = 1;
324 return 0;
325}
326
327/**
328 * cpuidle_register_device - registers a CPU's idle PM feature
329 * @dev: the cpu
330 */
331int cpuidle_register_device(struct cpuidle_device *dev)
332{
333 int ret;
334
335 mutex_lock(&cpuidle_lock);
336
337 if ((ret = __cpuidle_register_device(dev))) {
338 mutex_unlock(&cpuidle_lock);
339 return ret;
340 }
341
Len Brown4f86d3a2007-10-03 18:58:00 -0400342 cpuidle_enable_device(dev);
343 cpuidle_install_idle_handler();
344
345 mutex_unlock(&cpuidle_lock);
346
347 return 0;
348
349}
350
351EXPORT_SYMBOL_GPL(cpuidle_register_device);
352
353/**
354 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
355 * @dev: the cpu
356 */
357void cpuidle_unregister_device(struct cpuidle_device *dev)
358{
359 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
Len Brown752138d2010-05-22 16:57:26 -0400360 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
Len Brown4f86d3a2007-10-03 18:58:00 -0400361
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400362 if (dev->registered == 0)
363 return;
364
Len Brown4f86d3a2007-10-03 18:58:00 -0400365 cpuidle_pause_and_lock();
366
367 cpuidle_disable_device(dev);
368
369 cpuidle_remove_sysfs(sys_dev);
370 list_del(&dev->device_list);
371 wait_for_completion(&dev->kobj_unregister);
372 per_cpu(cpuidle_devices, dev->cpu) = NULL;
373
374 cpuidle_resume_and_unlock();
375
Len Brown752138d2010-05-22 16:57:26 -0400376 module_put(cpuidle_driver->owner);
Len Brown4f86d3a2007-10-03 18:58:00 -0400377}
378
379EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
380
381#ifdef CONFIG_SMP
382
383static void smp_callback(void *v)
384{
385 /* we already woke the CPU up, nothing more to do */
386}
387
388/*
389 * This function gets called when a part of the kernel has a new latency
390 * requirement. This means we need to get all processors out of their C-state,
391 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
392 * wakes them all right up.
393 */
394static int cpuidle_latency_notify(struct notifier_block *b,
395 unsigned long l, void *v)
396{
Jens Axboe8691e5a2008-06-06 11:18:06 +0200397 smp_call_function(smp_callback, NULL, 1);
Len Brown4f86d3a2007-10-03 18:58:00 -0400398 return NOTIFY_OK;
399}
400
401static struct notifier_block cpuidle_latency_notifier = {
402 .notifier_call = cpuidle_latency_notify,
403};
404
Mark Grossd82b3512008-02-04 22:30:08 -0800405static inline void latency_notifier_init(struct notifier_block *n)
406{
407 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
408}
Len Brown4f86d3a2007-10-03 18:58:00 -0400409
410#else /* CONFIG_SMP */
411
412#define latency_notifier_init(x) do { } while (0)
413
414#endif /* CONFIG_SMP */
415
416/**
417 * cpuidle_init - core initializer
418 */
419static int __init cpuidle_init(void)
420{
421 int ret;
422
423 pm_idle_old = pm_idle;
424
425 ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
426 if (ret)
427 return ret;
428
429 latency_notifier_init(&cpuidle_latency_notifier);
430
431 return 0;
432}
433
434core_initcall(cpuidle_init);