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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> |
4c822698 | 14 | #include <linux/sched/idle.h> |
4f86d3a8 | 15 | #include <linux/cpuidle.h> |
a06df062 | 16 | #include <linux/cpumask.h> |
ee7a1438 | 17 | #include <linux/tick.h> |
6727ad9e | 18 | #include <linux/cpu.h> |
4f86d3a8 LB |
19 | |
20 | #include "cpuidle.h" | |
21 | ||
4f86d3a8 LB |
22 | DEFINE_SPINLOCK(cpuidle_driver_lock); |
23 | ||
82467a5a | 24 | #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS |
bf4d1b5d | 25 | |
82467a5a DL |
26 | static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers); |
27 | ||
6d19cb93 DL |
28 | /** |
29 | * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU. | |
30 | * @cpu: the CPU handled by the driver | |
31 | * | |
32 | * Returns a pointer to struct cpuidle_driver or NULL if no driver has been | |
33 | * registered for @cpu. | |
34 | */ | |
82467a5a | 35 | static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
13dd52f1 | 36 | { |
82467a5a | 37 | return per_cpu(cpuidle_drivers, cpu); |
a06df062 DL |
38 | } |
39 | ||
6d19cb93 DL |
40 | /** |
41 | * __cpuidle_unset_driver - unset per CPU driver variables. | |
42 | * @drv: a valid pointer to a struct cpuidle_driver | |
43 | * | |
44 | * For each CPU in the driver's CPU mask, unset the registered driver per CPU | |
45 | * variable. If @drv is different from the registered driver, the corresponding | |
46 | * variable is not cleared. | |
47 | */ | |
82467a5a | 48 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
a06df062 | 49 | { |
82467a5a | 50 | int cpu; |
a06df062 | 51 | |
82467a5a | 52 | for_each_cpu(cpu, drv->cpumask) { |
a06df062 | 53 | |
82467a5a | 54 | if (drv != __cpuidle_get_cpu_driver(cpu)) |
a06df062 DL |
55 | continue; |
56 | ||
82467a5a | 57 | per_cpu(cpuidle_drivers, cpu) = NULL; |
a06df062 | 58 | } |
13dd52f1 DL |
59 | } |
60 | ||
6d19cb93 | 61 | /** |
caf4a36e | 62 | * __cpuidle_set_driver - set per CPU driver variables for the given driver. |
6d19cb93 DL |
63 | * @drv: a valid pointer to a struct cpuidle_driver |
64 | * | |
65 | * For each CPU in the driver's cpumask, unset the registered driver per CPU | |
66 | * to @drv. | |
67 | * | |
68 | * Returns 0 on success, -EBUSY if the CPUs have driver(s) already. | |
69 | */ | |
82467a5a | 70 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
4f86d3a8 | 71 | { |
82467a5a | 72 | int cpu; |
62027aea | 73 | |
82467a5a | 74 | for_each_cpu(cpu, drv->cpumask) { |
ed953472 | 75 | |
82467a5a DL |
76 | if (__cpuidle_get_cpu_driver(cpu)) { |
77 | __cpuidle_unset_driver(drv); | |
78 | return -EBUSY; | |
79 | } | |
ed953472 | 80 | |
82467a5a DL |
81 | per_cpu(cpuidle_drivers, cpu) = drv; |
82 | } | |
42f67f2a | 83 | |
13dd52f1 DL |
84 | return 0; |
85 | } | |
86 | ||
82467a5a | 87 | #else |
13dd52f1 | 88 | |
82467a5a | 89 | static struct cpuidle_driver *cpuidle_curr_driver; |
a06df062 | 90 | |
6d19cb93 DL |
91 | /** |
92 | * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer. | |
93 | * @cpu: ignored without the multiple driver support | |
94 | * | |
95 | * Return a pointer to a struct cpuidle_driver object or NULL if no driver was | |
96 | * previously registered. | |
97 | */ | |
82467a5a DL |
98 | static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
99 | { | |
100 | return cpuidle_curr_driver; | |
bf4d1b5d DL |
101 | } |
102 | ||
6d19cb93 DL |
103 | /** |
104 | * __cpuidle_set_driver - assign the global cpuidle driver variable. | |
105 | * @drv: pointer to a struct cpuidle_driver object | |
106 | * | |
107 | * Returns 0 on success, -EBUSY if the driver is already registered. | |
108 | */ | |
82467a5a DL |
109 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
110 | { | |
111 | if (cpuidle_curr_driver) | |
112 | return -EBUSY; | |
bf4d1b5d | 113 | |
82467a5a | 114 | cpuidle_curr_driver = drv; |
bf4d1b5d | 115 | |
82467a5a | 116 | return 0; |
bf4d1b5d DL |
117 | } |
118 | ||
6d19cb93 DL |
119 | /** |
120 | * __cpuidle_unset_driver - unset the global cpuidle driver variable. | |
121 | * @drv: a pointer to a struct cpuidle_driver | |
122 | * | |
123 | * Reset the global cpuidle variable to NULL. If @drv does not match the | |
124 | * registered driver, do nothing. | |
125 | */ | |
82467a5a | 126 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
bf4d1b5d | 127 | { |
82467a5a DL |
128 | if (drv == cpuidle_curr_driver) |
129 | cpuidle_curr_driver = NULL; | |
bf4d1b5d DL |
130 | } |
131 | ||
82467a5a DL |
132 | #endif |
133 | ||
6d19cb93 | 134 | /** |
ee7a1438 | 135 | * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu |
6d19cb93 DL |
136 | * @arg: a void pointer used to match the SMP cross call API |
137 | * | |
ee7a1438 | 138 | * If @arg is NULL broadcast is disabled otherwise enabled |
6d19cb93 | 139 | * |
ee7a1438 TG |
140 | * This function is executed per CPU by an SMP cross call. It's not |
141 | * supposed to be called directly. | |
6d19cb93 | 142 | */ |
82467a5a | 143 | static void cpuidle_setup_broadcast_timer(void *arg) |
bf4d1b5d | 144 | { |
ee7a1438 TG |
145 | if (arg) |
146 | tick_broadcast_enable(); | |
147 | else | |
148 | tick_broadcast_disable(); | |
bf4d1b5d DL |
149 | } |
150 | ||
6d19cb93 DL |
151 | /** |
152 | * __cpuidle_driver_init - initialize the driver's internal data | |
153 | * @drv: a valid pointer to a struct cpuidle_driver | |
6d19cb93 | 154 | */ |
e437f3e3 | 155 | static void __cpuidle_driver_init(struct cpuidle_driver *drv) |
bf4d1b5d | 156 | { |
82467a5a | 157 | int i; |
bf4d1b5d | 158 | |
82467a5a | 159 | drv->refcnt = 0; |
bf4d1b5d | 160 | |
6d19cb93 DL |
161 | /* |
162 | * Use all possible CPUs as the default, because if the kernel boots | |
163 | * with some CPUs offline and then we online one of them, the CPU | |
164 | * notifier has to know which driver to assign. | |
165 | */ | |
82467a5a DL |
166 | if (!drv->cpumask) |
167 | drv->cpumask = (struct cpumask *)cpu_possible_mask; | |
bf4d1b5d | 168 | |
6d19cb93 DL |
169 | /* |
170 | * Look for the timer stop flag in the different states, so that we know | |
171 | * if the broadcast timer has to be set up. The loop is in the reverse | |
caf4a36e | 172 | * order, because usually one of the deeper states have this flag set. |
6d19cb93 | 173 | */ |
82467a5a | 174 | for (i = drv->state_count - 1; i >= 0 ; i--) { |
b171a856 VK |
175 | if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) { |
176 | drv->bctimer = 1; | |
177 | break; | |
178 | } | |
82467a5a | 179 | } |
bf4d1b5d DL |
180 | } |
181 | ||
6d19cb93 DL |
182 | /** |
183 | * __cpuidle_register_driver: register the driver | |
184 | * @drv: a valid pointer to a struct cpuidle_driver | |
185 | * | |
186 | * Do some sanity checks, initialize the driver, assign the driver to the | |
187 | * global cpuidle driver variable(s) and set up the broadcast timer if the | |
188 | * cpuidle driver has some states that shut down the local timer. | |
189 | * | |
190 | * Returns 0 on success, a negative error code otherwise: | |
191 | * * -EINVAL if the driver pointer is NULL or no idle states are available | |
192 | * * -ENODEV if the cpuidle framework is disabled | |
193 | * * -EBUSY if the driver is already assigned to the global variable(s) | |
194 | */ | |
82467a5a | 195 | static int __cpuidle_register_driver(struct cpuidle_driver *drv) |
bf4d1b5d DL |
196 | { |
197 | int ret; | |
198 | ||
82467a5a DL |
199 | if (!drv || !drv->state_count) |
200 | return -EINVAL; | |
bf4d1b5d | 201 | |
abceaa9c XP |
202 | ret = cpuidle_coupled_state_verify(drv); |
203 | if (ret) | |
204 | return ret; | |
205 | ||
82467a5a DL |
206 | if (cpuidle_disabled()) |
207 | return -ENODEV; | |
bf4d1b5d | 208 | |
e437f3e3 | 209 | __cpuidle_driver_init(drv); |
ed953472 | 210 | |
82467a5a DL |
211 | ret = __cpuidle_set_driver(drv); |
212 | if (ret) | |
213 | return ret; | |
13dd52f1 | 214 | |
82467a5a DL |
215 | if (drv->bctimer) |
216 | on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, | |
ee7a1438 | 217 | (void *)1, 1); |
4f86d3a8 | 218 | |
82467a5a | 219 | return 0; |
4f86d3a8 | 220 | } |
4f86d3a8 | 221 | |
752138df | 222 | /** |
6d19cb93 DL |
223 | * __cpuidle_unregister_driver - unregister the driver |
224 | * @drv: a valid pointer to a struct cpuidle_driver | |
225 | * | |
226 | * Check if the driver is no longer in use, reset the global cpuidle driver | |
227 | * variable(s) and disable the timer broadcast notification mechanism if it was | |
228 | * in use. | |
229 | * | |
752138df | 230 | */ |
82467a5a | 231 | static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) |
bf4d1b5d | 232 | { |
82467a5a DL |
233 | if (WARN_ON(drv->refcnt > 0)) |
234 | return; | |
bf4d1b5d | 235 | |
82467a5a DL |
236 | if (drv->bctimer) { |
237 | drv->bctimer = 0; | |
238 | on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, | |
ee7a1438 | 239 | NULL, 1); |
82467a5a | 240 | } |
bf4d1b5d | 241 | |
82467a5a | 242 | __cpuidle_unset_driver(drv); |
752138df | 243 | } |
bf4d1b5d DL |
244 | |
245 | /** | |
246 | * cpuidle_register_driver - registers a driver | |
6d19cb93 DL |
247 | * @drv: a pointer to a valid struct cpuidle_driver |
248 | * | |
249 | * Register the driver under a lock to prevent concurrent attempts to | |
250 | * [un]register the driver from occuring at the same time. | |
251 | * | |
252 | * Returns 0 on success, a negative error code (returned by | |
253 | * __cpuidle_register_driver()) otherwise. | |
bf4d1b5d DL |
254 | */ |
255 | int cpuidle_register_driver(struct cpuidle_driver *drv) | |
256 | { | |
82467a5a | 257 | int ret; |
bf4d1b5d | 258 | |
bf4d1b5d | 259 | spin_lock(&cpuidle_driver_lock); |
82467a5a | 260 | ret = __cpuidle_register_driver(drv); |
bf4d1b5d | 261 | spin_unlock(&cpuidle_driver_lock); |
bf4d1b5d DL |
262 | |
263 | return ret; | |
264 | } | |
265 | EXPORT_SYMBOL_GPL(cpuidle_register_driver); | |
752138df | 266 | |
4f86d3a8 LB |
267 | /** |
268 | * cpuidle_unregister_driver - unregisters a driver | |
6d19cb93 DL |
269 | * @drv: a pointer to a valid struct cpuidle_driver |
270 | * | |
271 | * Unregisters the cpuidle driver under a lock to prevent concurrent attempts | |
272 | * to [un]register the driver from occuring at the same time. @drv has to | |
273 | * match the currently registered driver. | |
4f86d3a8 LB |
274 | */ |
275 | void cpuidle_unregister_driver(struct cpuidle_driver *drv) | |
276 | { | |
4f86d3a8 | 277 | spin_lock(&cpuidle_driver_lock); |
82467a5a | 278 | __cpuidle_unregister_driver(drv); |
4f86d3a8 LB |
279 | spin_unlock(&cpuidle_driver_lock); |
280 | } | |
4f86d3a8 | 281 | EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); |
bf4d1b5d DL |
282 | |
283 | /** | |
6d19cb93 DL |
284 | * cpuidle_get_driver - return the driver tied to the current CPU. |
285 | * | |
286 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered. | |
bf4d1b5d DL |
287 | */ |
288 | struct cpuidle_driver *cpuidle_get_driver(void) | |
289 | { | |
290 | struct cpuidle_driver *drv; | |
291 | int cpu; | |
292 | ||
293 | cpu = get_cpu(); | |
294 | drv = __cpuidle_get_cpu_driver(cpu); | |
295 | put_cpu(); | |
296 | ||
297 | return drv; | |
298 | } | |
299 | EXPORT_SYMBOL_GPL(cpuidle_get_driver); | |
300 | ||
301 | /** | |
6d19cb93 DL |
302 | * cpuidle_get_cpu_driver - return the driver registered for a CPU. |
303 | * @dev: a valid pointer to a struct cpuidle_device | |
304 | * | |
305 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered | |
306 | * for the CPU associated with @dev. | |
bf4d1b5d DL |
307 | */ |
308 | struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) | |
309 | { | |
bf4d1b5d DL |
310 | if (!dev) |
311 | return NULL; | |
312 | ||
ac34d7c8 | 313 | return __cpuidle_get_cpu_driver(dev->cpu); |
bf4d1b5d DL |
314 | } |
315 | EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver); | |
6e797a07 | 316 | |
6d19cb93 DL |
317 | /** |
318 | * cpuidle_driver_ref - get a reference to the driver. | |
319 | * | |
320 | * Increment the reference counter of the cpuidle driver associated with | |
321 | * the current CPU. | |
322 | * | |
323 | * Returns a pointer to the driver, or NULL if the current CPU has no driver. | |
324 | */ | |
6e797a07 RW |
325 | struct cpuidle_driver *cpuidle_driver_ref(void) |
326 | { | |
327 | struct cpuidle_driver *drv; | |
328 | ||
329 | spin_lock(&cpuidle_driver_lock); | |
330 | ||
13dd52f1 | 331 | drv = cpuidle_get_driver(); |
3b9c10e9 DF |
332 | if (drv) |
333 | drv->refcnt++; | |
6e797a07 RW |
334 | |
335 | spin_unlock(&cpuidle_driver_lock); | |
336 | return drv; | |
337 | } | |
338 | ||
6d19cb93 DL |
339 | /** |
340 | * cpuidle_driver_unref - puts down the refcount for the driver | |
341 | * | |
342 | * Decrement the reference counter of the cpuidle driver associated with | |
343 | * the current CPU. | |
344 | */ | |
6e797a07 RW |
345 | void cpuidle_driver_unref(void) |
346 | { | |
0d09d312 | 347 | struct cpuidle_driver *drv; |
42f67f2a | 348 | |
6e797a07 RW |
349 | spin_lock(&cpuidle_driver_lock); |
350 | ||
0d09d312 | 351 | drv = cpuidle_get_driver(); |
42f67f2a DL |
352 | if (drv && !WARN_ON(drv->refcnt <= 0)) |
353 | drv->refcnt--; | |
6e797a07 RW |
354 | |
355 | spin_unlock(&cpuidle_driver_lock); | |
356 | } |