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> |
13 | #include <linux/sched.h> |
14 | #include <linux/sched/idle.h> |
15 | #include <linux/cpuidle.h> |
16 | #include <linux/cpumask.h> |
17 | #include <linux/tick.h> |
18 | #include <linux/cpu.h> |
19 | |
20 | #include "cpuidle.h" |
21 | |
22 | DEFINE_SPINLOCK(cpuidle_driver_lock); |
23 | |
24 | #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS |
25 | |
26 | static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers); |
27 | |
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 | */ |
35 | static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
36 | { |
37 | return per_cpu(cpuidle_drivers, cpu); |
38 | } |
39 | |
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 | */ |
48 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
49 | { |
50 | int cpu; |
51 | |
52 | for_each_cpu(cpu, drv->cpumask) { |
53 | |
54 | if (drv != __cpuidle_get_cpu_driver(cpu)) |
55 | continue; |
56 | |
57 | per_cpu(cpuidle_drivers, cpu) = NULL; |
58 | } |
59 | } |
60 | |
61 | /** |
62 | * __cpuidle_set_driver - set per CPU driver variables for the given driver. |
63 | * @drv: a valid pointer to a struct cpuidle_driver |
64 | * |
65 | * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver |
66 | * different from drv already. |
67 | */ |
68 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
69 | { |
70 | int cpu; |
71 | |
72 | for_each_cpu(cpu, drv->cpumask) { |
73 | struct cpuidle_driver *old_drv; |
74 | |
75 | old_drv = __cpuidle_get_cpu_driver(cpu); |
76 | if (old_drv && old_drv != drv) |
77 | return -EBUSY; |
78 | } |
79 | |
80 | for_each_cpu(cpu, drv->cpumask) |
81 | per_cpu(cpuidle_drivers, cpu) = drv; |
82 | |
83 | return 0; |
84 | } |
85 | |
86 | #else |
87 | |
88 | static struct cpuidle_driver *cpuidle_curr_driver; |
89 | |
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 | */ |
97 | static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
98 | { |
99 | return cpuidle_curr_driver; |
100 | } |
101 | |
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 | */ |
108 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
109 | { |
110 | if (cpuidle_curr_driver) |
111 | return -EBUSY; |
112 | |
113 | cpuidle_curr_driver = drv; |
114 | |
115 | return 0; |
116 | } |
117 | |
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 | */ |
125 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
126 | { |
127 | if (drv == cpuidle_curr_driver) |
128 | cpuidle_curr_driver = NULL; |
129 | } |
130 | |
131 | #endif |
132 | |
133 | /** |
134 | * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu |
135 | * @arg: a void pointer used to match the SMP cross call API |
136 | * |
137 | * If @arg is NULL broadcast is disabled otherwise enabled |
138 | * |
139 | * This function is executed per CPU by an SMP cross call. It's not |
140 | * supposed to be called directly. |
141 | */ |
142 | static void cpuidle_setup_broadcast_timer(void *arg) |
143 | { |
144 | if (arg) |
145 | tick_broadcast_enable(); |
146 | else |
147 | tick_broadcast_disable(); |
148 | } |
149 | |
150 | /** |
151 | * __cpuidle_driver_init - initialize the driver's internal data |
152 | * @drv: a valid pointer to a struct cpuidle_driver |
153 | */ |
154 | static void __cpuidle_driver_init(struct cpuidle_driver *drv) |
155 | { |
156 | int i; |
157 | |
158 | /* |
159 | * Use all possible CPUs as the default, because if the kernel boots |
160 | * with some CPUs offline and then we online one of them, the CPU |
161 | * notifier has to know which driver to assign. |
162 | */ |
163 | if (!drv->cpumask) |
164 | drv->cpumask = (struct cpumask *)cpu_possible_mask; |
165 | |
166 | for (i = 0; i < drv->state_count; i++) { |
167 | struct cpuidle_state *s = &drv->states[i]; |
168 | |
169 | /* |
170 | * Look for the timer stop flag in the different states and if |
171 | * it is found, indicate that the broadcast timer has to be set |
172 | * up. |
173 | */ |
174 | if (s->flags & CPUIDLE_FLAG_TIMER_STOP) |
175 | drv->bctimer = 1; |
176 | |
177 | /* |
178 | * The core will use the target residency and exit latency |
179 | * values in nanoseconds, but allow drivers to provide them in |
180 | * microseconds too. |
181 | */ |
182 | if (s->target_residency > 0) |
183 | s->target_residency_ns = s->target_residency * NSEC_PER_USEC; |
184 | else if (s->target_residency_ns < 0) |
185 | s->target_residency_ns = 0; |
186 | else |
187 | s->target_residency = div_u64(dividend: s->target_residency_ns, NSEC_PER_USEC); |
188 | |
189 | if (s->exit_latency > 0) |
190 | s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC; |
191 | else if (s->exit_latency_ns < 0) |
192 | s->exit_latency_ns = 0; |
193 | else |
194 | s->exit_latency = div_u64(dividend: s->exit_latency_ns, NSEC_PER_USEC); |
195 | } |
196 | } |
197 | |
198 | /** |
199 | * __cpuidle_register_driver: register the driver |
200 | * @drv: a valid pointer to a struct cpuidle_driver |
201 | * |
202 | * Do some sanity checks, initialize the driver, assign the driver to the |
203 | * global cpuidle driver variable(s) and set up the broadcast timer if the |
204 | * cpuidle driver has some states that shut down the local timer. |
205 | * |
206 | * Returns 0 on success, a negative error code otherwise: |
207 | * * -EINVAL if the driver pointer is NULL or no idle states are available |
208 | * * -ENODEV if the cpuidle framework is disabled |
209 | * * -EBUSY if the driver is already assigned to the global variable(s) |
210 | */ |
211 | static int __cpuidle_register_driver(struct cpuidle_driver *drv) |
212 | { |
213 | int ret; |
214 | |
215 | if (!drv || !drv->state_count) |
216 | return -EINVAL; |
217 | |
218 | ret = cpuidle_coupled_state_verify(drv); |
219 | if (ret) |
220 | return ret; |
221 | |
222 | if (cpuidle_disabled()) |
223 | return -ENODEV; |
224 | |
225 | __cpuidle_driver_init(drv); |
226 | |
227 | ret = __cpuidle_set_driver(drv); |
228 | if (ret) |
229 | return ret; |
230 | |
231 | if (drv->bctimer) |
232 | on_each_cpu_mask(mask: drv->cpumask, func: cpuidle_setup_broadcast_timer, |
233 | info: (void *)1, wait: 1); |
234 | |
235 | return 0; |
236 | } |
237 | |
238 | /** |
239 | * __cpuidle_unregister_driver - unregister the driver |
240 | * @drv: a valid pointer to a struct cpuidle_driver |
241 | * |
242 | * Check if the driver is no longer in use, reset the global cpuidle driver |
243 | * variable(s) and disable the timer broadcast notification mechanism if it was |
244 | * in use. |
245 | * |
246 | */ |
247 | static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) |
248 | { |
249 | if (drv->bctimer) { |
250 | drv->bctimer = 0; |
251 | on_each_cpu_mask(mask: drv->cpumask, func: cpuidle_setup_broadcast_timer, |
252 | NULL, wait: 1); |
253 | } |
254 | |
255 | __cpuidle_unset_driver(drv); |
256 | } |
257 | |
258 | /** |
259 | * cpuidle_register_driver - registers a driver |
260 | * @drv: a pointer to a valid struct cpuidle_driver |
261 | * |
262 | * Register the driver under a lock to prevent concurrent attempts to |
263 | * [un]register the driver from occuring at the same time. |
264 | * |
265 | * Returns 0 on success, a negative error code (returned by |
266 | * __cpuidle_register_driver()) otherwise. |
267 | */ |
268 | int cpuidle_register_driver(struct cpuidle_driver *drv) |
269 | { |
270 | struct cpuidle_governor *gov; |
271 | int ret; |
272 | |
273 | spin_lock(lock: &cpuidle_driver_lock); |
274 | ret = __cpuidle_register_driver(drv); |
275 | spin_unlock(lock: &cpuidle_driver_lock); |
276 | |
277 | if (!ret && !strlen(param_governor) && drv->governor && |
278 | (cpuidle_get_driver() == drv)) { |
279 | mutex_lock(&cpuidle_lock); |
280 | gov = cpuidle_find_governor(str: drv->governor); |
281 | if (gov) { |
282 | cpuidle_prev_governor = cpuidle_curr_governor; |
283 | if (cpuidle_switch_governor(gov) < 0) |
284 | cpuidle_prev_governor = NULL; |
285 | } |
286 | mutex_unlock(lock: &cpuidle_lock); |
287 | } |
288 | |
289 | return ret; |
290 | } |
291 | EXPORT_SYMBOL_GPL(cpuidle_register_driver); |
292 | |
293 | /** |
294 | * cpuidle_unregister_driver - unregisters a driver |
295 | * @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. |
300 | */ |
301 | void cpuidle_unregister_driver(struct cpuidle_driver *drv) |
302 | { |
303 | bool enabled = (cpuidle_get_driver() == drv); |
304 | |
305 | spin_lock(lock: &cpuidle_driver_lock); |
306 | __cpuidle_unregister_driver(drv); |
307 | spin_unlock(lock: &cpuidle_driver_lock); |
308 | |
309 | if (!enabled) |
310 | return; |
311 | |
312 | mutex_lock(&cpuidle_lock); |
313 | if (cpuidle_prev_governor) { |
314 | if (!cpuidle_switch_governor(gov: cpuidle_prev_governor)) |
315 | cpuidle_prev_governor = NULL; |
316 | } |
317 | mutex_unlock(lock: &cpuidle_lock); |
318 | } |
319 | EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); |
320 | |
321 | /** |
322 | * cpuidle_get_driver - return the driver tied to the current CPU. |
323 | * |
324 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered. |
325 | */ |
326 | struct cpuidle_driver *cpuidle_get_driver(void) |
327 | { |
328 | struct cpuidle_driver *drv; |
329 | int cpu; |
330 | |
331 | cpu = get_cpu(); |
332 | drv = __cpuidle_get_cpu_driver(cpu); |
333 | put_cpu(); |
334 | |
335 | return drv; |
336 | } |
337 | EXPORT_SYMBOL_GPL(cpuidle_get_driver); |
338 | |
339 | /** |
340 | * cpuidle_get_cpu_driver - return the driver registered for a CPU. |
341 | * @dev: a valid pointer to a struct cpuidle_device |
342 | * |
343 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered |
344 | * for the CPU associated with @dev. |
345 | */ |
346 | struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) |
347 | { |
348 | if (!dev) |
349 | return NULL; |
350 | |
351 | return __cpuidle_get_cpu_driver(cpu: dev->cpu); |
352 | } |
353 | EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver); |
354 | |
355 | /** |
356 | * cpuidle_driver_state_disabled - Disable or enable an idle state |
357 | * @drv: cpuidle driver owning the state |
358 | * @idx: State index |
359 | * @disable: Whether or not to disable the state |
360 | */ |
361 | void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx, |
362 | bool disable) |
363 | { |
364 | unsigned int cpu; |
365 | |
366 | mutex_lock(&cpuidle_lock); |
367 | |
368 | spin_lock(lock: &cpuidle_driver_lock); |
369 | |
370 | if (!drv->cpumask) { |
371 | drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE; |
372 | goto unlock; |
373 | } |
374 | |
375 | for_each_cpu(cpu, drv->cpumask) { |
376 | struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); |
377 | |
378 | if (!dev) |
379 | continue; |
380 | |
381 | if (disable) |
382 | dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER; |
383 | else |
384 | dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER; |
385 | } |
386 | |
387 | unlock: |
388 | spin_unlock(lock: &cpuidle_driver_lock); |
389 | |
390 | mutex_unlock(lock: &cpuidle_lock); |
391 | } |
392 | |