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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>
Len Brown4f86d3a2007-10-03 18:58:00 -040019
20#include "cpuidle.h"
21
22DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
Len Brown4f86d3a2007-10-03 18:58:00 -040023
24DEFINE_MUTEX(cpuidle_lock);
25LIST_HEAD(cpuidle_detected_devices);
26static void (*pm_idle_old)(void);
27
28static int enabled_devices;
29
Venki Pallipadia6869cc2008-02-08 17:05:44 -080030#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
31static 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 */
38static void cpuidle_kick_cpus(void) {}
39#endif
40
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -040041static int __cpuidle_register_device(struct cpuidle_device *dev);
42
Len Brown4f86d3a2007-10-03 18:58:00 -040043/**
44 * cpuidle_idle_call - the main idle loop
45 *
46 * NOTE: no locks or semaphores should be used here
47 */
48static 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;
Yi Yang8b78cf62008-02-25 08:46:12 +080072 target_state->time += (unsigned long long)dev->last_residency;
Len Brown4f86d3a2007-10-03 18:58:00 -040073 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 */
83void 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 */
95void cpuidle_uninstall_idle_handler(void)
96{
97 if (enabled_devices && (pm_idle != pm_idle_old)) {
98 pm_idle = pm_idle_old;
Venki Pallipadia6869cc2008-02-08 17:05:44 -080099 cpuidle_kick_cpus();
Len Brown4f86d3a2007-10-03 18:58:00 -0400100 }
101}
102
103/**
104 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
105 */
106void cpuidle_pause_and_lock(void)
107{
108 mutex_lock(&cpuidle_lock);
109 cpuidle_uninstall_idle_handler();
110}
111
112EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
113
114/**
115 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
116 */
117void cpuidle_resume_and_unlock(void)
118{
119 cpuidle_install_idle_handler();
120 mutex_unlock(&cpuidle_lock);
121}
122
123EXPORT_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 */
132int 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
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400143 if (dev->registered == 0) {
144 ret = __cpuidle_register_device(dev);
145 if (ret)
146 return ret;
147 }
148
Len Brown4f86d3a2007-10-03 18:58:00 -0400149 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
170fail_sysfs:
171 cpuidle_remove_state_sysfs(dev);
172
173 return ret;
174}
175
176EXPORT_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 */
185void 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
201EXPORT_SYMBOL_GPL(cpuidle_disable_device);
202
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800203#ifdef CONFIG_ARCH_HAS_CPU_RELAX
204static 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
224static 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
Venkatesh Pallipadi4fcb2fc2008-02-11 17:46:31 -0800230 snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
231 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800232 state->exit_latency = 0;
233 state->target_residency = 0;
234 state->power_usage = -1;
Venki Pallipadi8e92b662008-02-29 10:24:32 -0800235 state->flags = CPUIDLE_FLAG_POLL;
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800236 state->enter = poll_idle;
237}
238#else
239static void poll_idle_init(struct cpuidle_device *dev) {}
240#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
241
Len Brown4f86d3a2007-10-03 18:58:00 -0400242/**
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400243 * __cpuidle_register_device - internal register function called before register
244 * and enable routines
Len Brown4f86d3a2007-10-03 18:58:00 -0400245 * @dev: the cpu
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400246 *
247 * cpuidle_lock mutex must be held before this is called
Len Brown4f86d3a2007-10-03 18:58:00 -0400248 */
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400249static int __cpuidle_register_device(struct cpuidle_device *dev)
Len Brown4f86d3a2007-10-03 18:58:00 -0400250{
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
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800261 poll_idle_init(dev);
262
Len Brown4f86d3a2007-10-03 18:58:00 -0400263 per_cpu(cpuidle_devices, dev->cpu) = dev;
264 list_add(&dev->device_list, &cpuidle_detected_devices);
265 if ((ret = cpuidle_add_sysfs(sys_dev))) {
Len Brown4f86d3a2007-10-03 18:58:00 -0400266 module_put(cpuidle_curr_driver->owner);
267 return ret;
268 }
269
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400270 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 */
278int 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
Len Brown4f86d3a2007-10-03 18:58:00 -0400289 cpuidle_enable_device(dev);
290 cpuidle_install_idle_handler();
291
292 mutex_unlock(&cpuidle_lock);
293
294 return 0;
295
296}
297
298EXPORT_SYMBOL_GPL(cpuidle_register_device);
299
300/**
301 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
302 * @dev: the cpu
303 */
304void cpuidle_unregister_device(struct cpuidle_device *dev)
305{
306 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
307
Venkatesh Pallipadidcb84f32008-05-19 19:09:27 -0400308 if (dev->registered == 0)
309 return;
310
Len Brown4f86d3a2007-10-03 18:58:00 -0400311 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
325EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
326
327#ifdef CONFIG_SMP
328
329static 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 */
340static int cpuidle_latency_notify(struct notifier_block *b,
341 unsigned long l, void *v)
342{
343 smp_call_function(smp_callback, NULL, 0, 1);
344 return NOTIFY_OK;
345}
346
347static struct notifier_block cpuidle_latency_notifier = {
348 .notifier_call = cpuidle_latency_notify,
349};
350
Mark Grossd82b3512008-02-04 22:30:08 -0800351static inline void latency_notifier_init(struct notifier_block *n)
352{
353 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
354}
Len Brown4f86d3a2007-10-03 18:58:00 -0400355
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 */
365static 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
380core_initcall(cpuidle_init);