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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
Len Brown4f86d3a2007-10-03 18:58:00 -040041/**
42 * cpuidle_idle_call - the main idle loop
43 *
44 * NOTE: no locks or semaphores should be used here
45 */
46static 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;
70 target_state->time += dev->last_residency;
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 */
81void 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 */
93void cpuidle_uninstall_idle_handler(void)
94{
95 if (enabled_devices && (pm_idle != pm_idle_old)) {
96 pm_idle = pm_idle_old;
Venki Pallipadia6869cc2008-02-08 17:05:44 -080097 cpuidle_kick_cpus();
Len Brown4f86d3a2007-10-03 18:58:00 -040098 }
99}
100
101/**
102 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
103 */
104void cpuidle_pause_and_lock(void)
105{
106 mutex_lock(&cpuidle_lock);
107 cpuidle_uninstall_idle_handler();
108}
109
110EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
111
112/**
113 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
114 */
115void cpuidle_resume_and_unlock(void)
116{
117 cpuidle_install_idle_handler();
118 mutex_unlock(&cpuidle_lock);
119}
120
121EXPORT_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 */
130int 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
162fail_sysfs:
163 cpuidle_remove_state_sysfs(dev);
164
165 return ret;
166}
167
168EXPORT_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 */
177void 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
193EXPORT_SYMBOL_GPL(cpuidle_disable_device);
194
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800195#ifdef CONFIG_ARCH_HAS_CPU_RELAX
196static 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
216static 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
Venkatesh Pallipadi4fcb2fc2008-02-11 17:46:31 -0800222 snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
223 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800224 state->exit_latency = 0;
225 state->target_residency = 0;
226 state->power_usage = -1;
227 state->flags = CPUIDLE_FLAG_POLL | CPUIDLE_FLAG_TIME_VALID;
228 state->enter = poll_idle;
229}
230#else
231static void poll_idle_init(struct cpuidle_device *dev) {}
232#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
233
Len Brown4f86d3a2007-10-03 18:58:00 -0400234/**
235 * cpuidle_register_device - registers a CPU's idle PM feature
236 * @dev: the cpu
237 */
238int 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
venkatesh.pallipadi@intel.com9a0b8412008-01-31 17:35:06 -0800252 poll_idle_init(dev);
253
Len Brown4f86d3a2007-10-03 18:58:00 -0400254 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
271EXPORT_SYMBOL_GPL(cpuidle_register_device);
272
273/**
274 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
275 * @dev: the cpu
276 */
277void 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
295EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
296
297#ifdef CONFIG_SMP
298
299static 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 */
310static 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
317static struct notifier_block cpuidle_latency_notifier = {
318 .notifier_call = cpuidle_latency_notify,
319};
320
Mark Grossd82b3512008-02-04 22:30:08 -0800321static inline void latency_notifier_init(struct notifier_block *n)
322{
323 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
324}
Len Brown4f86d3a2007-10-03 18:58:00 -0400325
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 */
335static 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
350core_initcall(cpuidle_init);