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Len Brown4f86d3a2007-10-03 18:58:00 -04001/*
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>
Daniel Lezcanoa06df062013-03-27 10:22:10 +000014#include <linux/cpumask.h>
15#include <linux/clockchips.h>
Len Brown4f86d3a2007-10-03 18:58:00 -040016
17#include "cpuidle.h"
18
Len Brown4f86d3a2007-10-03 18:58:00 -040019DEFINE_SPINLOCK(cpuidle_driver_lock);
20
Daniel Lezcano82467a52013-06-07 21:53:09 +000021#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
22
23static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
24
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000025/**
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 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000032static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
33{
34 return per_cpu(cpuidle_drivers, cpu);
35}
36
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000037/**
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 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000045static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
46{
47 int cpu;
48
49 for_each_cpu(cpu, drv->cpumask) {
50
51 if (drv != __cpuidle_get_cpu_driver(cpu))
52 continue;
53
54 per_cpu(cpuidle_drivers, cpu) = NULL;
55 }
56}
57
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000058/**
59 * __cpuidle_set_driver - set per CPU driver variables the the given driver.
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 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000067static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
68{
69 int cpu;
70
71 for_each_cpu(cpu, drv->cpumask) {
72
73 if (__cpuidle_get_cpu_driver(cpu)) {
74 __cpuidle_unset_driver(drv);
75 return -EBUSY;
76 }
77
78 per_cpu(cpuidle_drivers, cpu) = drv;
79 }
80
81 return 0;
82}
83
84#else
85
86static struct cpuidle_driver *cpuidle_curr_driver;
87
Daniel Lezcano6d19cb92013-06-07 21:53:10 +000088/**
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 */
Daniel Lezcano82467a52013-06-07 21:53:09 +000095static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
96{
97 return cpuidle_curr_driver;
98}
99
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000100/**
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 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000106static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
107{
108 if (cpuidle_curr_driver)
109 return -EBUSY;
110
111 cpuidle_curr_driver = drv;
112
113 return 0;
114}
115
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000116/**
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 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000123static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
124{
125 if (drv == cpuidle_curr_driver)
126 cpuidle_curr_driver = NULL;
127}
128
129#endif
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000130
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000131/**
132 * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer
133 * @arg: a void pointer used to match the SMP cross call API
134 *
135 * @arg is used as a value of type 'long' with on of the two values:
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 */
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000143static void cpuidle_setup_broadcast_timer(void *arg)
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000144{
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000145 int cpu = smp_processor_id();
146 clockevents_notify((long)(arg), &cpu);
147}
148
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000149/**
150 * __cpuidle_driver_init - initialize the driver's internal data
151 * @drv: a valid pointer to a struct cpuidle_driver
152 *
153 * Returns 0 on success, a negative error code otherwise.
154 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000155static int __cpuidle_driver_init(struct cpuidle_driver *drv)
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000156{
157 int i;
158
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000159 drv->refcnt = 0;
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000160
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000161 /*
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 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000166 if (!drv->cpumask)
167 drv->cpumask = (struct cpumask *)cpu_possible_mask;
168
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000169 /*
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
172 * order, because usually on of the the deeper states has this flag set.
173 */
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000174 for (i = drv->state_count - 1; i >= 0 ; i--) {
175
176 if (!(drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP))
177 continue;
178
179 drv->bctimer = 1;
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000180 break;
181 }
Daniel Lezcano82467a52013-06-07 21:53:09 +0000182
183 return 0;
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000184}
185
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000186/**
187 * __cpuidle_register_driver: register the driver
188 * @drv: a valid pointer to a struct cpuidle_driver
189 *
190 * Do some sanity checks, initialize the driver, assign the driver to the
191 * global cpuidle driver variable(s) and set up the broadcast timer if the
192 * cpuidle driver has some states that shut down the local timer.
193 *
194 * Returns 0 on success, a negative error code otherwise:
195 * * -EINVAL if the driver pointer is NULL or no idle states are available
196 * * -ENODEV if the cpuidle framework is disabled
197 * * -EBUSY if the driver is already assigned to the global variable(s)
198 */
Daniel Lezcano82467a52013-06-07 21:53:09 +0000199static int __cpuidle_register_driver(struct cpuidle_driver *drv)
Len Brown4f86d3a2007-10-03 18:58:00 -0400200{
Daniel Lezcano82467a52013-06-07 21:53:09 +0000201 int ret;
202
Daniel Lezcanofc850f32012-03-26 14:51:26 +0200203 if (!drv || !drv->state_count)
Len Brown4f86d3a2007-10-03 18:58:00 -0400204 return -EINVAL;
205
Len Brown62027ae2011-04-01 18:13:10 -0400206 if (cpuidle_disabled())
207 return -ENODEV;
208
Daniel Lezcano82467a52013-06-07 21:53:09 +0000209 ret = __cpuidle_driver_init(drv);
210 if (ret)
211 return ret;
Daniel Lezcanoed953472012-09-22 00:38:32 +0200212
Daniel Lezcano82467a52013-06-07 21:53:09 +0000213 ret = __cpuidle_set_driver(drv);
214 if (ret)
215 return ret;
Daniel Lezcanoed953472012-09-22 00:38:32 +0200216
Daniel Lezcano82467a52013-06-07 21:53:09 +0000217 if (drv->bctimer)
218 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
219 (void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, 1);
Len Brown4f86d3a2007-10-03 18:58:00 -0400220
221 return 0;
222}
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000223
Daniel Lezcano82467a52013-06-07 21:53:09 +0000224/**
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000225 * __cpuidle_unregister_driver - unregister the driver
226 * @drv: a valid pointer to a struct cpuidle_driver
227 *
228 * Check if the driver is no longer in use, reset the global cpuidle driver
229 * variable(s) and disable the timer broadcast notification mechanism if it was
230 * in use.
231 *
Daniel Lezcano82467a52013-06-07 21:53:09 +0000232 */
233static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000234{
Daniel Lezcano82467a52013-06-07 21:53:09 +0000235 if (WARN_ON(drv->refcnt > 0))
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000236 return;
237
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000238 if (drv->bctimer) {
239 drv->bctimer = 0;
Daniel Lezcano82467a52013-06-07 21:53:09 +0000240 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
Daniel Lezcanoa06df062013-03-27 10:22:10 +0000241 (void *)CLOCK_EVT_NOTIFY_BROADCAST_OFF, 1);
242 }
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000243
Daniel Lezcano82467a52013-06-07 21:53:09 +0000244 __cpuidle_unset_driver(drv);
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000245}
246
247/**
248 * cpuidle_register_driver - registers a driver
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000249 * @drv: a pointer to a valid struct cpuidle_driver
250 *
251 * Register the driver under a lock to prevent concurrent attempts to
252 * [un]register the driver from occuring at the same time.
253 *
254 * Returns 0 on success, a negative error code (returned by
255 * __cpuidle_register_driver()) otherwise.
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000256 */
257int cpuidle_register_driver(struct cpuidle_driver *drv)
258{
259 int ret;
260
261 spin_lock(&cpuidle_driver_lock);
Daniel Lezcano82467a52013-06-07 21:53:09 +0000262 ret = __cpuidle_register_driver(drv);
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000263 spin_unlock(&cpuidle_driver_lock);
264
265 return ret;
266}
Len Brown4f86d3a2007-10-03 18:58:00 -0400267EXPORT_SYMBOL_GPL(cpuidle_register_driver);
268
269/**
270 * cpuidle_unregister_driver - unregisters a driver
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000271 * @drv: a pointer to a valid struct cpuidle_driver
272 *
273 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
274 * to [un]register the driver from occuring at the same time. @drv has to
275 * match the currently registered driver.
Len Brown4f86d3a2007-10-03 18:58:00 -0400276 */
277void cpuidle_unregister_driver(struct cpuidle_driver *drv)
278{
Len Brown4f86d3a2007-10-03 18:58:00 -0400279 spin_lock(&cpuidle_driver_lock);
Daniel Lezcano82467a52013-06-07 21:53:09 +0000280 __cpuidle_unregister_driver(drv);
Len Brown4f86d3a2007-10-03 18:58:00 -0400281 spin_unlock(&cpuidle_driver_lock);
282}
Len Brown4f86d3a2007-10-03 18:58:00 -0400283EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200284
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000285/**
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000286 * cpuidle_get_driver - return the driver tied to the current CPU.
287 *
288 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000289 */
290struct cpuidle_driver *cpuidle_get_driver(void)
291{
292 struct cpuidle_driver *drv;
293 int cpu;
294
295 cpu = get_cpu();
296 drv = __cpuidle_get_cpu_driver(cpu);
297 put_cpu();
298
299 return drv;
300}
301EXPORT_SYMBOL_GPL(cpuidle_get_driver);
302
303/**
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000304 * cpuidle_get_cpu_driver - return the driver registered for a CPU.
305 * @dev: a valid pointer to a struct cpuidle_device
306 *
307 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
308 * for the CPU associated with @dev.
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000309 */
310struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
311{
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000312 if (!dev)
313 return NULL;
314
Daniel Lezcanoac34d7c2013-01-03 13:03:18 +0100315 return __cpuidle_get_cpu_driver(dev->cpu);
Daniel Lezcanobf4d1b52012-10-31 16:44:48 +0000316}
317EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
318
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000319/**
320 * cpuidle_driver_ref - get a reference to the driver.
321 *
322 * Increment the reference counter of the cpuidle driver associated with
323 * the current CPU.
324 *
325 * Returns a pointer to the driver, or NULL if the current CPU has no driver.
326 */
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200327struct cpuidle_driver *cpuidle_driver_ref(void)
328{
329 struct cpuidle_driver *drv;
330
331 spin_lock(&cpuidle_driver_lock);
332
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000333 drv = cpuidle_get_driver();
Daniel Fu3b9c10e2013-08-30 19:48:22 +0800334 if (drv)
335 drv->refcnt++;
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200336
337 spin_unlock(&cpuidle_driver_lock);
338 return drv;
339}
340
Daniel Lezcano6d19cb92013-06-07 21:53:10 +0000341/**
342 * cpuidle_driver_unref - puts down the refcount for the driver
343 *
344 * Decrement the reference counter of the cpuidle driver associated with
345 * the current CPU.
346 */
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200347void cpuidle_driver_unref(void)
348{
Daniel Lezcano13dd52f2012-10-31 16:44:47 +0000349 struct cpuidle_driver *drv = cpuidle_get_driver();
Daniel Lezcano42f67f22012-10-31 16:44:45 +0000350
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200351 spin_lock(&cpuidle_driver_lock);
352
Daniel Lezcano42f67f22012-10-31 16:44:45 +0000353 if (drv && !WARN_ON(drv->refcnt <= 0))
354 drv->refcnt--;
Rafael J. Wysocki6e797a02012-06-16 15:20:11 +0200355
356 spin_unlock(&cpuidle_driver_lock);
357}