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 | #include <linux/math64.h> |
20 | |
21 | #include "cpuidle.h" |
22 | |
23 | DEFINE_SPINLOCK(cpuidle_driver_lock); |
24 | |
25 | #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS |
26 | |
27 | static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers); |
28 | |
29 | /** |
30 | * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU. |
31 | * @cpu: the CPU handled by the driver |
32 | * |
33 | * Returns a pointer to struct cpuidle_driver or NULL if no driver has been |
34 | * registered for @cpu. |
35 | */ |
36 | static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
37 | { |
38 | return per_cpu(cpuidle_drivers, cpu); |
39 | } |
40 | |
41 | /** |
42 | * __cpuidle_unset_driver - unset per CPU driver variables. |
43 | * @drv: a valid pointer to a struct cpuidle_driver |
44 | * |
45 | * For each CPU in the driver's CPU mask, unset the registered driver per CPU |
46 | * variable. If @drv is different from the registered driver, the corresponding |
47 | * variable is not cleared. |
48 | */ |
49 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
50 | { |
51 | int cpu; |
52 | |
53 | for_each_cpu(cpu, drv->cpumask) { |
54 | |
55 | if (drv != __cpuidle_get_cpu_driver(cpu)) |
56 | continue; |
57 | |
58 | per_cpu(cpuidle_drivers, cpu) = NULL; |
59 | } |
60 | } |
61 | |
62 | /** |
63 | * __cpuidle_set_driver - set per CPU driver variables for the given driver. |
64 | * @drv: a valid pointer to a struct cpuidle_driver |
65 | * |
66 | * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver |
67 | * different from drv already. |
68 | */ |
69 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
70 | { |
71 | int cpu; |
72 | |
73 | for_each_cpu(cpu, drv->cpumask) { |
74 | struct cpuidle_driver *old_drv; |
75 | |
76 | old_drv = __cpuidle_get_cpu_driver(cpu); |
77 | if (old_drv && old_drv != drv) |
78 | return -EBUSY; |
79 | } |
80 | |
81 | for_each_cpu(cpu, drv->cpumask) |
82 | per_cpu(cpuidle_drivers, cpu) = drv; |
83 | |
84 | return 0; |
85 | } |
86 | |
87 | #else |
88 | |
89 | static struct cpuidle_driver *cpuidle_curr_driver; |
90 | |
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 | */ |
98 | static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
99 | { |
100 | return cpuidle_curr_driver; |
101 | } |
102 | |
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 | */ |
109 | static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
110 | { |
111 | if (cpuidle_curr_driver) |
112 | return -EBUSY; |
113 | |
114 | cpuidle_curr_driver = drv; |
115 | |
116 | return 0; |
117 | } |
118 | |
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 | */ |
126 | static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
127 | { |
128 | if (drv == cpuidle_curr_driver) |
129 | cpuidle_curr_driver = NULL; |
130 | } |
131 | |
132 | #endif |
133 | |
134 | /** |
135 | * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu |
136 | * @arg: a void pointer used to match the SMP cross call API |
137 | * |
138 | * If @arg is NULL broadcast is disabled otherwise enabled |
139 | * |
140 | * This function is executed per CPU by an SMP cross call. It's not |
141 | * supposed to be called directly. |
142 | */ |
143 | static void cpuidle_setup_broadcast_timer(void *arg) |
144 | { |
145 | if (arg) |
146 | tick_broadcast_enable(); |
147 | else |
148 | tick_broadcast_disable(); |
149 | } |
150 | |
151 | /** |
152 | * __cpuidle_driver_init - initialize the driver's internal data |
153 | * @drv: a valid pointer to a struct cpuidle_driver |
154 | */ |
155 | static void __cpuidle_driver_init(struct cpuidle_driver *drv) |
156 | { |
157 | int i; |
158 | |
159 | /* |
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 | */ |
164 | if (!drv->cpumask) |
165 | drv->cpumask = (struct cpumask *)cpu_possible_mask; |
166 | |
167 | for (i = 0; i < drv->state_count; i++) { |
168 | struct cpuidle_state *s = &drv->states[i]; |
169 | |
170 | /* |
171 | * Look for the timer stop flag in the different states and if |
172 | * it is found, indicate that the broadcast timer has to be set |
173 | * up. |
174 | */ |
175 | if (s->flags & CPUIDLE_FLAG_TIMER_STOP) |
176 | drv->bctimer = 1; |
177 | |
178 | /* |
179 | * The core will use the target residency and exit latency |
180 | * values in nanoseconds, but allow drivers to provide them in |
181 | * microseconds too. |
182 | */ |
183 | if (s->target_residency > 0) |
184 | s->target_residency_ns = s->target_residency * NSEC_PER_USEC; |
185 | else if (s->target_residency_ns < 0) |
186 | s->target_residency_ns = 0; |
187 | else |
188 | s->target_residency = div_u64(dividend: s->target_residency_ns, NSEC_PER_USEC); |
189 | |
190 | if (s->exit_latency > 0) |
191 | s->exit_latency_ns = mul_u32_u32(a: s->exit_latency, NSEC_PER_USEC); |
192 | else if (s->exit_latency_ns < 0) |
193 | s->exit_latency_ns = 0; |
194 | else |
195 | s->exit_latency = div_u64(dividend: s->exit_latency_ns, NSEC_PER_USEC); |
196 | } |
197 | } |
198 | |
199 | /** |
200 | * __cpuidle_register_driver: register the driver |
201 | * @drv: a valid pointer to a struct cpuidle_driver |
202 | * |
203 | * Do some sanity checks, initialize the driver, assign the driver to the |
204 | * global cpuidle driver variable(s) and set up the broadcast timer if the |
205 | * cpuidle driver has some states that shut down the local timer. |
206 | * |
207 | * Returns 0 on success, a negative error code otherwise: |
208 | * * -EINVAL if the driver pointer is NULL or no idle states are available |
209 | * * -ENODEV if the cpuidle framework is disabled |
210 | * * -EBUSY if the driver is already assigned to the global variable(s) |
211 | */ |
212 | static int __cpuidle_register_driver(struct cpuidle_driver *drv) |
213 | { |
214 | int ret; |
215 | |
216 | if (!drv || !drv->state_count) |
217 | return -EINVAL; |
218 | |
219 | ret = cpuidle_coupled_state_verify(drv); |
220 | if (ret) |
221 | return ret; |
222 | |
223 | if (cpuidle_disabled()) |
224 | return -ENODEV; |
225 | |
226 | __cpuidle_driver_init(drv); |
227 | |
228 | ret = __cpuidle_set_driver(drv); |
229 | if (ret) |
230 | return ret; |
231 | |
232 | if (drv->bctimer) |
233 | on_each_cpu_mask(mask: drv->cpumask, func: cpuidle_setup_broadcast_timer, |
234 | info: (void *)1, wait: 1); |
235 | |
236 | return 0; |
237 | } |
238 | |
239 | /** |
240 | * __cpuidle_unregister_driver - unregister the driver |
241 | * @drv: a valid pointer to a struct cpuidle_driver |
242 | * |
243 | * Check if the driver is no longer in use, reset the global cpuidle driver |
244 | * variable(s) and disable the timer broadcast notification mechanism if it was |
245 | * in use. |
246 | * |
247 | */ |
248 | static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) |
249 | { |
250 | if (drv->bctimer) { |
251 | drv->bctimer = 0; |
252 | on_each_cpu_mask(mask: drv->cpumask, func: cpuidle_setup_broadcast_timer, |
253 | NULL, wait: 1); |
254 | } |
255 | |
256 | __cpuidle_unset_driver(drv); |
257 | } |
258 | |
259 | /** |
260 | * cpuidle_register_driver - registers a driver |
261 | * @drv: a pointer to a valid struct cpuidle_driver |
262 | * |
263 | * Register the driver under a lock to prevent concurrent attempts to |
264 | * [un]register the driver from occuring at the same time. |
265 | * |
266 | * Returns 0 on success, a negative error code (returned by |
267 | * __cpuidle_register_driver()) otherwise. |
268 | */ |
269 | int cpuidle_register_driver(struct cpuidle_driver *drv) |
270 | { |
271 | struct cpuidle_governor *gov; |
272 | int ret; |
273 | |
274 | spin_lock(lock: &cpuidle_driver_lock); |
275 | ret = __cpuidle_register_driver(drv); |
276 | spin_unlock(lock: &cpuidle_driver_lock); |
277 | |
278 | if (!ret && !strlen(param_governor) && drv->governor && |
279 | (cpuidle_get_driver() == drv)) { |
280 | mutex_lock(&cpuidle_lock); |
281 | gov = cpuidle_find_governor(str: drv->governor); |
282 | if (gov) { |
283 | cpuidle_prev_governor = cpuidle_curr_governor; |
284 | if (cpuidle_switch_governor(gov) < 0) |
285 | cpuidle_prev_governor = NULL; |
286 | } |
287 | mutex_unlock(lock: &cpuidle_lock); |
288 | } |
289 | |
290 | return ret; |
291 | } |
292 | EXPORT_SYMBOL_GPL(cpuidle_register_driver); |
293 | |
294 | /** |
295 | * cpuidle_unregister_driver - unregisters a driver |
296 | * @drv: a pointer to a valid struct cpuidle_driver |
297 | * |
298 | * Unregisters the cpuidle driver under a lock to prevent concurrent attempts |
299 | * to [un]register the driver from occuring at the same time. @drv has to |
300 | * match the currently registered driver. |
301 | */ |
302 | void cpuidle_unregister_driver(struct cpuidle_driver *drv) |
303 | { |
304 | bool enabled = (cpuidle_get_driver() == drv); |
305 | |
306 | spin_lock(lock: &cpuidle_driver_lock); |
307 | __cpuidle_unregister_driver(drv); |
308 | spin_unlock(lock: &cpuidle_driver_lock); |
309 | |
310 | if (!enabled) |
311 | return; |
312 | |
313 | mutex_lock(&cpuidle_lock); |
314 | if (cpuidle_prev_governor) { |
315 | if (!cpuidle_switch_governor(gov: cpuidle_prev_governor)) |
316 | cpuidle_prev_governor = NULL; |
317 | } |
318 | mutex_unlock(lock: &cpuidle_lock); |
319 | } |
320 | EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); |
321 | |
322 | /** |
323 | * cpuidle_get_driver - return the driver tied to the current CPU. |
324 | * |
325 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered. |
326 | */ |
327 | struct cpuidle_driver *cpuidle_get_driver(void) |
328 | { |
329 | struct cpuidle_driver *drv; |
330 | int cpu; |
331 | |
332 | cpu = get_cpu(); |
333 | drv = __cpuidle_get_cpu_driver(cpu); |
334 | put_cpu(); |
335 | |
336 | return drv; |
337 | } |
338 | EXPORT_SYMBOL_GPL(cpuidle_get_driver); |
339 | |
340 | /** |
341 | * cpuidle_get_cpu_driver - return the driver registered for a CPU. |
342 | * @dev: a valid pointer to a struct cpuidle_device |
343 | * |
344 | * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered |
345 | * for the CPU associated with @dev. |
346 | */ |
347 | struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) |
348 | { |
349 | if (!dev) |
350 | return NULL; |
351 | |
352 | return __cpuidle_get_cpu_driver(cpu: dev->cpu); |
353 | } |
354 | EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver); |
355 | |
356 | /** |
357 | * cpuidle_driver_state_disabled - Disable or enable an idle state |
358 | * @drv: cpuidle driver owning the state |
359 | * @idx: State index |
360 | * @disable: Whether or not to disable the state |
361 | */ |
362 | void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx, |
363 | bool disable) |
364 | { |
365 | unsigned int cpu; |
366 | |
367 | mutex_lock(&cpuidle_lock); |
368 | |
369 | spin_lock(lock: &cpuidle_driver_lock); |
370 | |
371 | if (!drv->cpumask) { |
372 | drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE; |
373 | goto unlock; |
374 | } |
375 | |
376 | for_each_cpu(cpu, drv->cpumask) { |
377 | struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); |
378 | |
379 | if (!dev) |
380 | continue; |
381 | |
382 | if (disable) |
383 | dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER; |
384 | else |
385 | dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER; |
386 | } |
387 | |
388 | unlock: |
389 | spin_unlock(lock: &cpuidle_driver_lock); |
390 | |
391 | mutex_unlock(lock: &cpuidle_lock); |
392 | } |
393 | |