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Commit | Line | Data |
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4f86d3a8 LB |
1 | /* |
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> | |
d7c7f103 | 13 | #include <linux/sched.h> |
4f86d3a8 | 14 | #include <linux/cpuidle.h> |
a06df062 | 15 | #include <linux/cpumask.h> |
ee7a1438 | 16 | #include <linux/tick.h> |
6727ad9e | 17 | #include <linux/cpu.h> |
4f86d3a8 LB |
18 | |
19 | #include "cpuidle.h" | |
20 | ||
4f86d3a8 LB |
21 | DEFINE_SPINLOCK(cpuidle_driver_lock); |
22 | ||
82467a5a | 23 | #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS |
bf4d1b5d | 24 | |
82467a5a DL |
25 | static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers); |
26 | ||
6d19cb93 DL |
27 | /** |
28 | * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU. | |
29 | * @cpu: the CPU handled by the driver | |
30 | * | |
31 | * Returns a pointer to struct cpuidle_driver or NULL if no driver has been | |
32 | * registered for @cpu. | |
33 | */ | |
82467a5a | 34 | static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
13dd52f1 | 35 | { |
82467a5a | 36 | return per_cpu(cpuidle_drivers, cpu); |
a06df062 DL |
37 | } |
38 | ||
6d19cb93 DL |
39 | /** |
40 | * __cpuidle_unset_driver - unset per CPU driver variables. | |
41 | * @drv: a valid pointer to a struct cpuidle_driver | |
42 | * | |
43 | * For each CPU in the driver's CPU mask, unset the registered driver per CPU | |
44 | * variable. If @drv is different from the registered driver, the corresponding | |
45 | * variable is not cleared. | |
46 | */ | |
82467a5a | 47 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
a06df062 | 48 | { |
82467a5a | 49 | int cpu; |
a06df062 | 50 | |
82467a5a | 51 | for_each_cpu(cpu, drv->cpumask) { |
a06df062 | 52 | |
82467a5a | 53 | if (drv != __cpuidle_get_cpu_driver(cpu)) |
a06df062 DL |
54 | continue; |
55 | ||
82467a5a | 56 | per_cpu(cpuidle_drivers, cpu) = NULL; |
a06df062 | 57 | } |
13dd52f1 DL |
58 | } |
59 | ||
6d19cb93 | 60 | /** |
caf4a36e | 61 | * __cpuidle_set_driver - set per CPU driver variables for the given driver. |
6d19cb93 DL |
62 | * @drv: a valid pointer to a struct cpuidle_driver |
63 | * | |
64 | * For each CPU in the driver's cpumask, unset the registered driver per CPU | |
65 | * to @drv. | |
66 | * | |
67 | * Returns 0 on success, -EBUSY if the CPUs have driver(s) already. | |
68 | */ | |
82467a5a | 69 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
4f86d3a8 | 70 | { |
82467a5a | 71 | int cpu; |
62027aea | 72 | |
82467a5a | 73 | for_each_cpu(cpu, drv->cpumask) { |
ed953472 | 74 | |
82467a5a DL |
75 | if (__cpuidle_get_cpu_driver(cpu)) { |
76 | __cpuidle_unset_driver(drv); | |
77 | return -EBUSY; | |
78 | } | |
ed953472 | 79 | |
82467a5a DL |
80 | per_cpu(cpuidle_drivers, cpu) = drv; |
81 | } | |
42f67f2a | 82 | |
13dd52f1 DL |
83 | return 0; |
84 | } | |
85 | ||
82467a5a | 86 | #else |
13dd52f1 | 87 | |
82467a5a | 88 | static struct cpuidle_driver *cpuidle_curr_driver; |
a06df062 | 89 | |
6d19cb93 DL |
90 | /** |
91 | * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer. | |
92 | * @cpu: ignored without the multiple driver support | |
93 | * | |
94 | * Return a pointer to a struct cpuidle_driver object or NULL if no driver was | |
95 | * previously registered. | |
96 | */ | |
82467a5a DL |
97 | static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
98 | { | |
99 | return cpuidle_curr_driver; | |
bf4d1b5d DL |
100 | } |
101 | ||
6d19cb93 DL |
102 | /** |
103 | * __cpuidle_set_driver - assign the global cpuidle driver variable. | |
104 | * @drv: pointer to a struct cpuidle_driver object | |
105 | * | |
106 | * Returns 0 on success, -EBUSY if the driver is already registered. | |
107 | */ | |
82467a5a DL |
108 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
109 | { | |
110 | if (cpuidle_curr_driver) | |
111 | return -EBUSY; | |
bf4d1b5d | 112 | |
82467a5a | 113 | cpuidle_curr_driver = drv; |
bf4d1b5d | 114 | |
82467a5a | 115 | return 0; |
bf4d1b5d DL |
116 | } |
117 | ||
6d19cb93 DL |
118 | /** |
119 | * __cpuidle_unset_driver - unset the global cpuidle driver variable. | |
120 | * @drv: a pointer to a struct cpuidle_driver | |
121 | * | |
122 | * Reset the global cpuidle variable to NULL. If @drv does not match the | |
123 | * registered driver, do nothing. | |
124 | */ | |
82467a5a | 125 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
bf4d1b5d | 126 | { |
82467a5a DL |
127 | if (drv == cpuidle_curr_driver) |
128 | cpuidle_curr_driver = NULL; | |
bf4d1b5d DL |
129 | } |
130 | ||
82467a5a DL |
131 | #endif |
132 | ||
6d19cb93 | 133 | /** |
ee7a1438 | 134 | * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu |
6d19cb93 DL |
135 | * @arg: a void pointer used to match the SMP cross call API |
136 | * | |
ee7a1438 | 137 | * If @arg is NULL broadcast is disabled otherwise enabled |
6d19cb93 | 138 | * |
ee7a1438 TG |
139 | * This function is executed per CPU by an SMP cross call. It's not |
140 | * supposed to be called directly. | |
6d19cb93 | 141 | */ |
82467a5a | 142 | static void cpuidle_setup_broadcast_timer(void *arg) |
bf4d1b5d | 143 | { |
ee7a1438 TG |
144 | if (arg) |
145 | tick_broadcast_enable(); | |
146 | else | |
147 | tick_broadcast_disable(); | |
bf4d1b5d DL |
148 | } |
149 | ||
6d19cb93 DL |
150 | /** |
151 | * __cpuidle_driver_init - initialize the driver's internal data | |
152 | * @drv: a valid pointer to a struct cpuidle_driver | |
6d19cb93 | 153 | */ |
e437f3e3 | 154 | static void __cpuidle_driver_init(struct cpuidle_driver *drv) |
bf4d1b5d | 155 | { |
82467a5a | 156 | int i; |
bf4d1b5d | 157 | |
82467a5a | 158 | drv->refcnt = 0; |
bf4d1b5d | 159 | |
6d19cb93 DL |
160 | /* |
161 | * Use all possible CPUs as the default, because if the kernel boots | |
162 | * with some CPUs offline and then we online one of them, the CPU | |
163 | * notifier has to know which driver to assign. | |
164 | */ | |
82467a5a DL |
165 | if (!drv->cpumask) |
166 | drv->cpumask = (struct cpumask *)cpu_possible_mask; | |
bf4d1b5d | 167 | |
6d19cb93 DL |
168 | /* |
169 | * Look for the timer stop flag in the different states, so that we know | |
170 | * if the broadcast timer has to be set up. The loop is in the reverse | |
caf4a36e | 171 | * order, because usually one of the deeper states have this flag set. |
6d19cb93 | 172 | */ |
82467a5a | 173 | for (i = drv->state_count - 1; i >= 0 ; i--) { |
b171a856 VK |
174 | if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) { |
175 | drv->bctimer = 1; | |
176 | break; | |
177 | } | |
82467a5a | 178 | } |
bf4d1b5d DL |
179 | } |
180 | ||
d7c7f103 | 181 | #ifdef CONFIG_ARCH_HAS_CPU_RELAX |
6727ad9e CM |
182 | static int __cpuidle poll_idle(struct cpuidle_device *dev, |
183 | struct cpuidle_driver *drv, int index) | |
d7c7f103 | 184 | { |
d7c7f103 | 185 | local_irq_enable(); |
84c40708 AL |
186 | if (!current_set_polling_and_test()) { |
187 | while (!need_resched()) | |
188 | cpu_relax(); | |
189 | } | |
190 | current_clr_polling(); | |
d7c7f103 | 191 | |
d7c7f103 VK |
192 | return index; |
193 | } | |
194 | ||
195 | static void poll_idle_init(struct cpuidle_driver *drv) | |
196 | { | |
197 | struct cpuidle_state *state = &drv->states[0]; | |
198 | ||
199 | snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); | |
200 | snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); | |
201 | state->exit_latency = 0; | |
202 | state->target_residency = 0; | |
203 | state->power_usage = -1; | |
d7c7f103 VK |
204 | state->enter = poll_idle; |
205 | state->disabled = false; | |
206 | } | |
207 | #else | |
208 | static void poll_idle_init(struct cpuidle_driver *drv) {} | |
209 | #endif /* !CONFIG_ARCH_HAS_CPU_RELAX */ | |
210 | ||
6d19cb93 DL |
211 | /** |
212 | * __cpuidle_register_driver: register the driver | |
213 | * @drv: a valid pointer to a struct cpuidle_driver | |
214 | * | |
215 | * Do some sanity checks, initialize the driver, assign the driver to the | |
216 | * global cpuidle driver variable(s) and set up the broadcast timer if the | |
217 | * cpuidle driver has some states that shut down the local timer. | |
218 | * | |
219 | * Returns 0 on success, a negative error code otherwise: | |
220 | * * -EINVAL if the driver pointer is NULL or no idle states are available | |
221 | * * -ENODEV if the cpuidle framework is disabled | |
222 | * * -EBUSY if the driver is already assigned to the global variable(s) | |
223 | */ | |
82467a5a | 224 | static int __cpuidle_register_driver(struct cpuidle_driver *drv) |
bf4d1b5d DL |
225 | { |
226 | int ret; | |
227 | ||
82467a5a DL |
228 | if (!drv || !drv->state_count) |
229 | return -EINVAL; | |
bf4d1b5d | 230 | |
abceaa9c XP |
231 | ret = cpuidle_coupled_state_verify(drv); |
232 | if (ret) | |
233 | return ret; | |
234 | ||
82467a5a DL |
235 | if (cpuidle_disabled()) |
236 | return -ENODEV; | |
bf4d1b5d | 237 | |
e437f3e3 | 238 | __cpuidle_driver_init(drv); |
ed953472 | 239 | |
82467a5a DL |
240 | ret = __cpuidle_set_driver(drv); |
241 | if (ret) | |
242 | return ret; | |
13dd52f1 | 243 | |
82467a5a DL |
244 | if (drv->bctimer) |
245 | on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, | |
ee7a1438 | 246 | (void *)1, 1); |
4f86d3a8 | 247 | |
d7c7f103 VK |
248 | poll_idle_init(drv); |
249 | ||
82467a5a | 250 | return 0; |
4f86d3a8 | 251 | } |
4f86d3a8 | 252 | |
752138df | 253 | /** |
6d19cb93 DL |
254 | * __cpuidle_unregister_driver - unregister the driver |
255 | * @drv: a valid pointer to a struct cpuidle_driver | |
256 | * | |
257 | * Check if the driver is no longer in use, reset the global cpuidle driver | |
258 | * variable(s) and disable the timer broadcast notification mechanism if it was | |
259 | * in use. | |
260 | * | |
752138df | 261 | */ |
82467a5a | 262 | static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) |
bf4d1b5d | 263 | { |
82467a5a DL |
264 | if (WARN_ON(drv->refcnt > 0)) |
265 | return; | |
bf4d1b5d | 266 | |
82467a5a DL |
267 | if (drv->bctimer) { |
268 | drv->bctimer = 0; | |
269 | on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, | |
ee7a1438 | 270 | NULL, 1); |
82467a5a | 271 | } |
bf4d1b5d | 272 | |
82467a5a | 273 | __cpuidle_unset_driver(drv); |
752138df | 274 | } |
bf4d1b5d DL |
275 | |
276 | /** | |
277 | * cpuidle_register_driver - registers a driver | |
6d19cb93 DL |
278 | * @drv: a pointer to a valid struct cpuidle_driver |
279 | * | |
280 | * Register the driver under a lock to prevent concurrent attempts to | |
281 | * [un]register the driver from occuring at the same time. | |
282 | * | |
283 | * Returns 0 on success, a negative error code (returned by | |
284 | * __cpuidle_register_driver()) otherwise. | |
bf4d1b5d DL |
285 | */ |
286 | int cpuidle_register_driver(struct cpuidle_driver *drv) | |
287 | { | |
82467a5a | 288 | int ret; |
bf4d1b5d | 289 | |
bf4d1b5d | 290 | spin_lock(&cpuidle_driver_lock); |
82467a5a | 291 | ret = __cpuidle_register_driver(drv); |
bf4d1b5d | 292 | spin_unlock(&cpuidle_driver_lock); |
bf4d1b5d DL |
293 | |
294 | return ret; | |
295 | } | |
296 | EXPORT_SYMBOL_GPL(cpuidle_register_driver); | |
752138df | 297 | |
4f86d3a8 LB |
298 | /** |
299 | * cpuidle_unregister_driver - unregisters a driver | |
6d19cb93 DL |
300 | * @drv: a pointer to a valid struct cpuidle_driver |
301 | * | |
302 | * Unregisters the cpuidle driver under a lock to prevent concurrent attempts | |
303 | * to [un]register the driver from occuring at the same time. @drv has to | |
304 | * match the currently registered driver. | |
4f86d3a8 LB |
305 | */ |
306 | void cpuidle_unregister_driver(struct cpuidle_driver *drv) | |
307 | { | |
4f86d3a8 | 308 | spin_lock(&cpuidle_driver_lock); |
82467a5a | 309 | __cpuidle_unregister_driver(drv); |
4f86d3a8 LB |
310 | spin_unlock(&cpuidle_driver_lock); |
311 | } | |
4f86d3a8 | 312 | EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); |
bf4d1b5d DL |
313 | |
314 | /** | |
6d19cb93 DL |
315 | * cpuidle_get_driver - return the driver tied to the current CPU. |
316 | * | |
317 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered. | |
bf4d1b5d DL |
318 | */ |
319 | struct cpuidle_driver *cpuidle_get_driver(void) | |
320 | { | |
321 | struct cpuidle_driver *drv; | |
322 | int cpu; | |
323 | ||
324 | cpu = get_cpu(); | |
325 | drv = __cpuidle_get_cpu_driver(cpu); | |
326 | put_cpu(); | |
327 | ||
328 | return drv; | |
329 | } | |
330 | EXPORT_SYMBOL_GPL(cpuidle_get_driver); | |
331 | ||
332 | /** | |
6d19cb93 DL |
333 | * cpuidle_get_cpu_driver - return the driver registered for a CPU. |
334 | * @dev: a valid pointer to a struct cpuidle_device | |
335 | * | |
336 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered | |
337 | * for the CPU associated with @dev. | |
bf4d1b5d DL |
338 | */ |
339 | struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) | |
340 | { | |
bf4d1b5d DL |
341 | if (!dev) |
342 | return NULL; | |
343 | ||
ac34d7c8 | 344 | return __cpuidle_get_cpu_driver(dev->cpu); |
bf4d1b5d DL |
345 | } |
346 | EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver); | |
6e797a07 | 347 | |
6d19cb93 DL |
348 | /** |
349 | * cpuidle_driver_ref - get a reference to the driver. | |
350 | * | |
351 | * Increment the reference counter of the cpuidle driver associated with | |
352 | * the current CPU. | |
353 | * | |
354 | * Returns a pointer to the driver, or NULL if the current CPU has no driver. | |
355 | */ | |
6e797a07 RW |
356 | struct cpuidle_driver *cpuidle_driver_ref(void) |
357 | { | |
358 | struct cpuidle_driver *drv; | |
359 | ||
360 | spin_lock(&cpuidle_driver_lock); | |
361 | ||
13dd52f1 | 362 | drv = cpuidle_get_driver(); |
3b9c10e9 DF |
363 | if (drv) |
364 | drv->refcnt++; | |
6e797a07 RW |
365 | |
366 | spin_unlock(&cpuidle_driver_lock); | |
367 | return drv; | |
368 | } | |
369 | ||
6d19cb93 DL |
370 | /** |
371 | * cpuidle_driver_unref - puts down the refcount for the driver | |
372 | * | |
373 | * Decrement the reference counter of the cpuidle driver associated with | |
374 | * the current CPU. | |
375 | */ | |
6e797a07 RW |
376 | void cpuidle_driver_unref(void) |
377 | { | |
0d09d312 | 378 | struct cpuidle_driver *drv; |
42f67f2a | 379 | |
6e797a07 RW |
380 | spin_lock(&cpuidle_driver_lock); |
381 | ||
0d09d312 | 382 | drv = cpuidle_get_driver(); |
42f67f2a DL |
383 | if (drv && !WARN_ON(drv->refcnt <= 0)) |
384 | drv->refcnt--; | |
6e797a07 RW |
385 | |
386 | spin_unlock(&cpuidle_driver_lock); | |
387 | } |