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Len Brown4f86d3a2007-10-03 18:58:00 -04001/*
2 * driver.c - driver support
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/mutex.h>
12#include <linux/module.h>
Viresh Kumard7c7f102013-10-03 21:26:54 +053013#include <linux/sched.h>
Len Brown4f86d3a2007-10-03 18:58:00 -040014#include <linux/cpuidle.h>
Daniel Lezcanoa06df062013-03-27 10:22:10 +000015#include <linux/cpumask.h>
Thomas Gleixneree7a1432015-04-03 02:02:18 +020016#include <linux/tick.h>
Len Brown4f86d3a2007-10-03 18:58:00 -040017
18#include "cpuidle.h"
19
Len Brown4f86d3a2007-10-03 18:58:00 -040020DEFINE_SPINLOCK(cpuidle_driver_lock);
21
Daniel Lezcano82467a52013-06-07 21:53:09 +000022#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
23
24static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
25
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000026/**
27 * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
28 * @cpu: the CPU handled by the driver
29 *
30 * Returns a pointer to struct cpuidle_driver or NULL if no driver has been
31 * registered for @cpu.
32 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000033static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
34{
35 return per_cpu(cpuidle_drivers, cpu);
36}
37
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000038/**
39 * __cpuidle_unset_driver - unset per CPU driver variables.
40 * @drv: a valid pointer to a struct cpuidle_driver
41 *
42 * For each CPU in the driver's CPU mask, unset the registered driver per CPU
43 * variable. If @drv is different from the registered driver, the corresponding
44 * variable is not cleared.
45 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000046static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
47{
48 int cpu;
49
50 for_each_cpu(cpu, drv->cpumask) {
51
52 if (drv != __cpuidle_get_cpu_driver(cpu))
53 continue;
54
55 per_cpu(cpuidle_drivers, cpu) = NULL;
56 }
57}
58
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000059/**
Viresh Kumarcaf4a362013-10-03 21:26:41 +053060 * __cpuidle_set_driver - set per CPU driver variables for the given driver.
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000061 * @drv: a valid pointer to a struct cpuidle_driver
62 *
63 * For each CPU in the driver's cpumask, unset the registered driver per CPU
64 * to @drv.
65 *
66 * Returns 0 on success, -EBUSY if the CPUs have driver(s) already.
67 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000068static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
69{
70 int cpu;
71
72 for_each_cpu(cpu, drv->cpumask) {
73
74 if (__cpuidle_get_cpu_driver(cpu)) {
75 __cpuidle_unset_driver(drv);
76 return -EBUSY;
77 }
78
79 per_cpu(cpuidle_drivers, cpu) = drv;
80 }
81
82 return 0;
83}
84
85#else
86
87static struct cpuidle_driver *cpuidle_curr_driver;
88
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000089/**
90 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
91 * @cpu: ignored without the multiple driver support
92 *
93 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was
94 * previously registered.
95 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000096static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
97{
98 return cpuidle_curr_driver;
99}
100
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000101/**
102 * __cpuidle_set_driver - assign the global cpuidle driver variable.
103 * @drv: pointer to a struct cpuidle_driver object
104 *
105 * Returns 0 on success, -EBUSY if the driver is already registered.
106 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000107static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
108{
109 if (cpuidle_curr_driver)
110 return -EBUSY;
111
112 cpuidle_curr_driver = drv;
113
114 return 0;
115}
116
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000117/**
118 * __cpuidle_unset_driver - unset the global cpuidle driver variable.
119 * @drv: a pointer to a struct cpuidle_driver
120 *
121 * Reset the global cpuidle variable to NULL. If @drv does not match the
122 * registered driver, do nothing.
123 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000124static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
125{
126 if (drv == cpuidle_curr_driver)
127 cpuidle_curr_driver = NULL;
128}
129
130#endif
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000131
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000132/**
Thomas Gleixneree7a1432015-04-03 02:02:18 +0200133 * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000134 * @arg: a void pointer used to match the SMP cross call API
135 *
Thomas Gleixneree7a1432015-04-03 02:02:18 +0200136 * If @arg is NULL broadcast is disabled otherwise enabled
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000137 *
Thomas Gleixneree7a1432015-04-03 02:02:18 +0200138 * This function is executed per CPU by an SMP cross call. It's not
139 * supposed to be called directly.
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000140 */
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000141static void cpuidle_setup_broadcast_timer(void *arg)
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000142{
Thomas Gleixneree7a1432015-04-03 02:02:18 +0200143 if (arg)
144 tick_broadcast_enable();
145 else
146 tick_broadcast_disable();
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000147}
148
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000149/**
150 * __cpuidle_driver_init - initialize the driver's internal data
151 * @drv: a valid pointer to a struct cpuidle_driver
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000152 */
Viresh Kumare437f3e2013-10-03 21:26:44 +0530153static void __cpuidle_driver_init(struct cpuidle_driver *drv)
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000154{
155 int i;
156
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000157 drv->refcnt = 0;
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000158
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000159 /*
160 * Use all possible CPUs as the default, because if the kernel boots
161 * with some CPUs offline and then we online one of them, the CPU
162 * notifier has to know which driver to assign.
163 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000164 if (!drv->cpumask)
165 drv->cpumask = (struct cpumask *)cpu_possible_mask;
166
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000167 /*
168 * Look for the timer stop flag in the different states, so that we know
169 * if the broadcast timer has to be set up. The loop is in the reverse
Viresh Kumarcaf4a362013-10-03 21:26:41 +0530170 * order, because usually one of the deeper states have this flag set.
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000171 */
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000172 for (i = drv->state_count - 1; i >= 0 ; i--) {
Viresh Kumarb171a852013-10-03 21:26:45 +0530173 if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) {
174 drv->bctimer = 1;
175 break;
176 }
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000177 }
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000178}
179
Viresh Kumard7c7f102013-10-03 21:26:54 +0530180#ifdef CONFIG_ARCH_HAS_CPU_RELAX
181static int poll_idle(struct cpuidle_device *dev,
182 struct cpuidle_driver *drv, int index)
183{
Viresh Kumard7c7f102013-10-03 21:26:54 +0530184 local_irq_enable();
Andy Lutomirski84c40702014-06-04 10:31:14 -0700185 if (!current_set_polling_and_test()) {
186 while (!need_resched())
187 cpu_relax();
188 }
189 current_clr_polling();
Viresh Kumard7c7f102013-10-03 21:26:54 +0530190
Viresh Kumard7c7f102013-10-03 21:26:54 +0530191 return index;
192}
193
194static void poll_idle_init(struct cpuidle_driver *drv)
195{
196 struct cpuidle_state *state = &drv->states[0];
197
198 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
199 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
200 state->exit_latency = 0;
201 state->target_residency = 0;
202 state->power_usage = -1;
Viresh Kumard7c7f102013-10-03 21:26:54 +0530203 state->enter = poll_idle;
204 state->disabled = false;
205}
206#else
207static void poll_idle_init(struct cpuidle_driver *drv) {}
208#endif /* !CONFIG_ARCH_HAS_CPU_RELAX */
209
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000210/**
211 * __cpuidle_register_driver: register the driver
212 * @drv: a valid pointer to a struct cpuidle_driver
213 *
214 * Do some sanity checks, initialize the driver, assign the driver to the
215 * global cpuidle driver variable(s) and set up the broadcast timer if the
216 * cpuidle driver has some states that shut down the local timer.
217 *
218 * Returns 0 on success, a negative error code otherwise:
219 * * -EINVAL if the driver pointer is NULL or no idle states are available
220 * * -ENODEV if the cpuidle framework is disabled
221 * * -EBUSY if the driver is already assigned to the global variable(s)
222 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000223static int __cpuidle_register_driver(struct cpuidle_driver *drv)
Len Brown4f86d3a2007-10-03 18:58:00 -0400224{
Daniel Lezcano82467a52013-06-07 21:53:09 +0000225 int ret;
226
Daniel Lezcanofc850f32012-03-26 14:51:26 +0200227 if (!drv || !drv->state_count)
Len Brown4f86d3a2007-10-03 18:58:00 -0400228 return -EINVAL;
229
Len Brown62027ae2011-04-01 18:13:10 -0400230 if (cpuidle_disabled())
231 return -ENODEV;
232
Viresh Kumare437f3e2013-10-03 21:26:44 +0530233 __cpuidle_driver_init(drv);
Daniel Lezcanoed953472012-09-22 00:38:32 +0200234
Daniel Lezcano82467a52013-06-07 21:53:09 +0000235 ret = __cpuidle_set_driver(drv);
236 if (ret)
237 return ret;
Daniel Lezcanoed953472012-09-22 00:38:32 +0200238
Daniel Lezcano82467a52013-06-07 21:53:09 +0000239 if (drv->bctimer)
240 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
Thomas Gleixneree7a1432015-04-03 02:02:18 +0200241 (void *)1, 1);
Len Brown4f86d3a2007-10-03 18:58:00 -0400242
Viresh Kumard7c7f102013-10-03 21:26:54 +0530243 poll_idle_init(drv);
244
Len Brown4f86d3a2007-10-03 18:58:00 -0400245 return 0;
246}
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000247
Daniel Lezcano82467a52013-06-07 21:53:09 +0000248/**
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000249 * __cpuidle_unregister_driver - unregister the driver
250 * @drv: a valid pointer to a struct cpuidle_driver
251 *
252 * Check if the driver is no longer in use, reset the global cpuidle driver
253 * variable(s) and disable the timer broadcast notification mechanism if it was
254 * in use.
255 *
Daniel Lezcano82467a52013-06-07 21:53:09 +0000256 */
257static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000258{
Daniel Lezcano82467a52013-06-07 21:53:09 +0000259 if (WARN_ON(drv->refcnt > 0))
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000260 return;
261
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000262 if (drv->bctimer) {
263 drv->bctimer = 0;
Daniel Lezcano82467a52013-06-07 21:53:09 +0000264 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
Thomas Gleixneree7a1432015-04-03 02:02:18 +0200265 NULL, 1);
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000266 }
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000267
Daniel Lezcano82467a52013-06-07 21:53:09 +0000268 __cpuidle_unset_driver(drv);
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000269}
270
271/**
272 * cpuidle_register_driver - registers a driver
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000273 * @drv: a pointer to a valid struct cpuidle_driver
274 *
275 * Register the driver under a lock to prevent concurrent attempts to
276 * [un]register the driver from occuring at the same time.
277 *
278 * Returns 0 on success, a negative error code (returned by
279 * __cpuidle_register_driver()) otherwise.
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000280 */
281int cpuidle_register_driver(struct cpuidle_driver *drv)
282{
283 int ret;
284
285 spin_lock(&cpuidle_driver_lock);
Daniel Lezcano82467a52013-06-07 21:53:09 +0000286 ret = __cpuidle_register_driver(drv);
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000287 spin_unlock(&cpuidle_driver_lock);
288
289 return ret;
290}
Len Brown4f86d3a2007-10-03 18:58:00 -0400291EXPORT_SYMBOL_GPL(cpuidle_register_driver);
292
293/**
294 * cpuidle_unregister_driver - unregisters a driver
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000295 * @drv: a pointer to a valid struct cpuidle_driver
296 *
297 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
298 * to [un]register the driver from occuring at the same time. @drv has to
299 * match the currently registered driver.
Len Brown4f86d3a2007-10-03 18:58:00 -0400300 */
301void cpuidle_unregister_driver(struct cpuidle_driver *drv)
302{
Len Brown4f86d3a2007-10-03 18:58:00 -0400303 spin_lock(&cpuidle_driver_lock);
Daniel Lezcano82467a52013-06-07 21:53:09 +0000304 __cpuidle_unregister_driver(drv);
Len Brown4f86d3a2007-10-03 18:58:00 -0400305 spin_unlock(&cpuidle_driver_lock);
306}
Len Brown4f86d3a2007-10-03 18:58:00 -0400307EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200308
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000309/**
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000310 * cpuidle_get_driver - return the driver tied to the current CPU.
311 *
312 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000313 */
314struct cpuidle_driver *cpuidle_get_driver(void)
315{
316 struct cpuidle_driver *drv;
317 int cpu;
318
319 cpu = get_cpu();
320 drv = __cpuidle_get_cpu_driver(cpu);
321 put_cpu();
322
323 return drv;
324}
325EXPORT_SYMBOL_GPL(cpuidle_get_driver);
326
327/**
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000328 * cpuidle_get_cpu_driver - return the driver registered for a CPU.
329 * @dev: a valid pointer to a struct cpuidle_device
330 *
331 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
332 * for the CPU associated with @dev.
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000333 */
334struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
335{
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000336 if (!dev)
337 return NULL;
338
Daniel Lezcanoac34d7c2013-01-03 13:03:18 +0100339 return __cpuidle_get_cpu_driver(dev->cpu);
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000340}
341EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
342
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000343/**
344 * cpuidle_driver_ref - get a reference to the driver.
345 *
346 * Increment the reference counter of the cpuidle driver associated with
347 * the current CPU.
348 *
349 * Returns a pointer to the driver, or NULL if the current CPU has no driver.
350 */
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200351struct cpuidle_driver *cpuidle_driver_ref(void)
352{
353 struct cpuidle_driver *drv;
354
355 spin_lock(&cpuidle_driver_lock);
356
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000357 drv = cpuidle_get_driver();
Daniel Fu3b9c10e2013-08-30 19:48:22 +0800358 if (drv)
359 drv->refcnt++;
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200360
361 spin_unlock(&cpuidle_driver_lock);
362 return drv;
363}
364
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000365/**
366 * cpuidle_driver_unref - puts down the refcount for the driver
367 *
368 * Decrement the reference counter of the cpuidle driver associated with
369 * the current CPU.
370 */
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200371void cpuidle_driver_unref(void)
372{
Viresh Kumar0d09d312013-10-03 21:26:50 +0530373 struct cpuidle_driver *drv;
Daniel Lezcano42f67f22012-10-31 16:44:45 +0000374
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200375 spin_lock(&cpuidle_driver_lock);
376
Viresh Kumar0d09d312013-10-03 21:26:50 +0530377 drv = cpuidle_get_driver();
Daniel Lezcano42f67f22012-10-31 16:44:45 +0000378 if (drv && !WARN_ON(drv->refcnt <= 0))
379 drv->refcnt--;
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200380
381 spin_unlock(&cpuidle_driver_lock);
382}