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