2 * driver.c - driver support
4 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
5 * Shaohua Li <shaohua.li@intel.com>
6 * Adam Belay <abelay@novell.com>
8 * This code is licenced under the GPL.
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>
22 DEFINE_SPINLOCK(cpuidle_driver_lock);
24 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
26 static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
29 * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
30 * @cpu: the CPU handled by the driver
32 * Returns a pointer to struct cpuidle_driver or NULL if no driver has been
33 * registered for @cpu.
35 static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
37 return per_cpu(cpuidle_drivers, cpu);
41 * __cpuidle_unset_driver - unset per CPU driver variables.
42 * @drv: a valid pointer to a struct cpuidle_driver
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.
48 static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
52 for_each_cpu(cpu, drv->cpumask) {
54 if (drv != __cpuidle_get_cpu_driver(cpu))
57 per_cpu(cpuidle_drivers, cpu) = NULL;
62 * __cpuidle_set_driver - set per CPU driver variables for the given driver.
63 * @drv: a valid pointer to a struct cpuidle_driver
65 * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver
66 * different from drv already.
68 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
72 for_each_cpu(cpu, drv->cpumask) {
73 struct cpuidle_driver *old_drv;
75 old_drv = __cpuidle_get_cpu_driver(cpu);
76 if (old_drv && old_drv != drv)
80 for_each_cpu(cpu, drv->cpumask)
81 per_cpu(cpuidle_drivers, cpu) = drv;
88 static struct cpuidle_driver *cpuidle_curr_driver;
91 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
92 * @cpu: ignored without the multiple driver support
94 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was
95 * previously registered.
97 static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
99 return cpuidle_curr_driver;
103 * __cpuidle_set_driver - assign the global cpuidle driver variable.
104 * @drv: pointer to a struct cpuidle_driver object
106 * Returns 0 on success, -EBUSY if the driver is already registered.
108 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
110 if (cpuidle_curr_driver)
113 cpuidle_curr_driver = drv;
119 * __cpuidle_unset_driver - unset the global cpuidle driver variable.
120 * @drv: a pointer to a struct cpuidle_driver
122 * Reset the global cpuidle variable to NULL. If @drv does not match the
123 * registered driver, do nothing.
125 static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
127 if (drv == cpuidle_curr_driver)
128 cpuidle_curr_driver = NULL;
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
137 * If @arg is NULL broadcast is disabled otherwise enabled
139 * This function is executed per CPU by an SMP cross call. It's not
140 * supposed to be called directly.
142 static void cpuidle_setup_broadcast_timer(void *arg)
145 tick_broadcast_enable();
147 tick_broadcast_disable();
151 * __cpuidle_driver_init - initialize the driver's internal data
152 * @drv: a valid pointer to a struct cpuidle_driver
154 static void __cpuidle_driver_init(struct cpuidle_driver *drv)
161 * Use all possible CPUs as the default, because if the kernel boots
162 * with some CPUs offline and then we online one of them, the CPU
163 * notifier has to know which driver to assign.
166 drv->cpumask = (struct cpumask *)cpu_possible_mask;
168 for (i = 0; i < drv->state_count; i++) {
169 struct cpuidle_state *s = &drv->states[i];
172 * Look for the timer stop flag in the different states and if
173 * it is found, indicate that the broadcast timer has to be set
176 if (s->flags & CPUIDLE_FLAG_TIMER_STOP)
180 * The core will use the target residency and exit latency
181 * values in nanoseconds, but allow drivers to provide them in
184 if (s->target_residency > 0)
185 s->target_residency_ns = s->target_residency * NSEC_PER_USEC;
187 if (s->exit_latency > 0)
188 s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC;
193 * __cpuidle_register_driver: register the driver
194 * @drv: a valid pointer to a struct cpuidle_driver
196 * Do some sanity checks, initialize the driver, assign the driver to the
197 * global cpuidle driver variable(s) and set up the broadcast timer if the
198 * cpuidle driver has some states that shut down the local timer.
200 * Returns 0 on success, a negative error code otherwise:
201 * * -EINVAL if the driver pointer is NULL or no idle states are available
202 * * -ENODEV if the cpuidle framework is disabled
203 * * -EBUSY if the driver is already assigned to the global variable(s)
205 static int __cpuidle_register_driver(struct cpuidle_driver *drv)
209 if (!drv || !drv->state_count)
212 ret = cpuidle_coupled_state_verify(drv);
216 if (cpuidle_disabled())
219 __cpuidle_driver_init(drv);
221 ret = __cpuidle_set_driver(drv);
226 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
233 * __cpuidle_unregister_driver - unregister the driver
234 * @drv: a valid pointer to a struct cpuidle_driver
236 * Check if the driver is no longer in use, reset the global cpuidle driver
237 * variable(s) and disable the timer broadcast notification mechanism if it was
241 static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
243 if (WARN_ON(drv->refcnt > 0))
248 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
252 __cpuidle_unset_driver(drv);
256 * cpuidle_register_driver - registers a driver
257 * @drv: a pointer to a valid struct cpuidle_driver
259 * Register the driver under a lock to prevent concurrent attempts to
260 * [un]register the driver from occuring at the same time.
262 * Returns 0 on success, a negative error code (returned by
263 * __cpuidle_register_driver()) otherwise.
265 int cpuidle_register_driver(struct cpuidle_driver *drv)
267 struct cpuidle_governor *gov;
270 spin_lock(&cpuidle_driver_lock);
271 ret = __cpuidle_register_driver(drv);
272 spin_unlock(&cpuidle_driver_lock);
274 if (!ret && !strlen(param_governor) && drv->governor &&
275 (cpuidle_get_driver() == drv)) {
276 mutex_lock(&cpuidle_lock);
277 gov = cpuidle_find_governor(drv->governor);
279 cpuidle_prev_governor = cpuidle_curr_governor;
280 if (cpuidle_switch_governor(gov) < 0)
281 cpuidle_prev_governor = NULL;
283 mutex_unlock(&cpuidle_lock);
288 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
291 * cpuidle_unregister_driver - unregisters a driver
292 * @drv: a pointer to a valid struct cpuidle_driver
294 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
295 * to [un]register the driver from occuring at the same time. @drv has to
296 * match the currently registered driver.
298 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
300 bool enabled = (cpuidle_get_driver() == drv);
302 spin_lock(&cpuidle_driver_lock);
303 __cpuidle_unregister_driver(drv);
304 spin_unlock(&cpuidle_driver_lock);
309 mutex_lock(&cpuidle_lock);
310 if (cpuidle_prev_governor) {
311 if (!cpuidle_switch_governor(cpuidle_prev_governor))
312 cpuidle_prev_governor = NULL;
314 mutex_unlock(&cpuidle_lock);
316 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
319 * cpuidle_get_driver - return the driver tied to the current CPU.
321 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
323 struct cpuidle_driver *cpuidle_get_driver(void)
325 struct cpuidle_driver *drv;
329 drv = __cpuidle_get_cpu_driver(cpu);
334 EXPORT_SYMBOL_GPL(cpuidle_get_driver);
337 * cpuidle_get_cpu_driver - return the driver registered for a CPU.
338 * @dev: a valid pointer to a struct cpuidle_device
340 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
341 * for the CPU associated with @dev.
343 struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
348 return __cpuidle_get_cpu_driver(dev->cpu);
350 EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
353 * cpuidle_driver_ref - get a reference to the driver.
355 * Increment the reference counter of the cpuidle driver associated with
358 * Returns a pointer to the driver, or NULL if the current CPU has no driver.
360 struct cpuidle_driver *cpuidle_driver_ref(void)
362 struct cpuidle_driver *drv;
364 spin_lock(&cpuidle_driver_lock);
366 drv = cpuidle_get_driver();
370 spin_unlock(&cpuidle_driver_lock);
375 * cpuidle_driver_unref - puts down the refcount for the driver
377 * Decrement the reference counter of the cpuidle driver associated with
380 void cpuidle_driver_unref(void)
382 struct cpuidle_driver *drv;
384 spin_lock(&cpuidle_driver_lock);
386 drv = cpuidle_get_driver();
387 if (drv && !WARN_ON(drv->refcnt <= 0))
390 spin_unlock(&cpuidle_driver_lock);
394 * cpuidle_driver_state_disabled - Disable or enable an idle state
395 * @drv: cpuidle driver owning the state
397 * @disable: Whether or not to disable the state
399 void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
404 mutex_lock(&cpuidle_lock);
406 spin_lock(&cpuidle_driver_lock);
409 drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE;
413 for_each_cpu(cpu, drv->cpumask) {
414 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
420 dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
422 dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
426 spin_unlock(&cpuidle_driver_lock);
428 mutex_unlock(&cpuidle_lock);