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/cpuidle.h>
15 #include <linux/cpumask.h>
16 #include <linux/clockchips.h>
20 DEFINE_SPINLOCK(cpuidle_driver_lock);
22 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
24 static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
27 * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
28 * @cpu: the CPU handled by the driver
30 * Returns a pointer to struct cpuidle_driver or NULL if no driver has been
31 * registered for @cpu.
33 static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
35 return per_cpu(cpuidle_drivers, cpu);
39 * __cpuidle_unset_driver - unset per CPU driver variables.
40 * @drv: a valid pointer to a struct cpuidle_driver
42 * For each CPU in the driver's CPU mask, unset the registered driver per CPU
43 * variable. If @drv is different from the registered driver, the corresponding
44 * variable is not cleared.
46 static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
50 for_each_cpu(cpu, drv->cpumask) {
52 if (drv != __cpuidle_get_cpu_driver(cpu))
55 per_cpu(cpuidle_drivers, cpu) = NULL;
60 * __cpuidle_set_driver - set per CPU driver variables for the given driver.
61 * @drv: a valid pointer to a struct cpuidle_driver
63 * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver
64 * different from drv already.
66 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
70 for_each_cpu(cpu, drv->cpumask) {
71 struct cpuidle_driver *old_drv;
73 old_drv = __cpuidle_get_cpu_driver(cpu);
74 if (old_drv && old_drv != drv)
78 for_each_cpu(cpu, drv->cpumask)
79 per_cpu(cpuidle_drivers, cpu) = drv;
86 static struct cpuidle_driver *cpuidle_curr_driver;
89 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
90 * @cpu: ignored without the multiple driver support
92 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was
93 * previously registered.
95 static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
97 return cpuidle_curr_driver;
101 * __cpuidle_set_driver - assign the global cpuidle driver variable.
102 * @drv: pointer to a struct cpuidle_driver object
104 * Returns 0 on success, -EBUSY if the driver is already registered.
106 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
108 if (cpuidle_curr_driver)
111 cpuidle_curr_driver = drv;
117 * __cpuidle_unset_driver - unset the global cpuidle driver variable.
118 * @drv: a pointer to a struct cpuidle_driver
120 * Reset the global cpuidle variable to NULL. If @drv does not match the
121 * registered driver, do nothing.
123 static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
125 if (drv == cpuidle_curr_driver)
126 cpuidle_curr_driver = NULL;
132 * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer
133 * @arg: a void pointer used to match the SMP cross call API
135 * @arg is used as a value of type 'long' with one of the two values:
136 * - CLOCK_EVT_NOTIFY_BROADCAST_ON
137 * - CLOCK_EVT_NOTIFY_BROADCAST_OFF
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
143 static void cpuidle_setup_broadcast_timer(void *arg)
145 int cpu = smp_processor_id();
146 clockevents_notify((long)(arg), &cpu);
150 * __cpuidle_driver_init - initialize the driver's internal data
151 * @drv: a valid pointer to a struct cpuidle_driver
153 static void __cpuidle_driver_init(struct cpuidle_driver *drv)
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.
165 drv->cpumask = (struct cpumask *)cpu_possible_mask;
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
170 * order, because usually one of the deeper states have this flag set.
172 for (i = drv->state_count - 1; i >= 0 ; i--) {
173 if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) {
180 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
181 static int poll_idle(struct cpuidle_device *dev,
182 struct cpuidle_driver *drv, int index)
189 if (!current_set_polling_and_test()) {
190 while (!need_resched())
193 current_clr_polling();
196 diff = ktime_to_us(ktime_sub(t2, t1));
200 dev->last_residency = (int) diff;
205 static void poll_idle_init(struct cpuidle_driver *drv)
207 struct cpuidle_state *state = &drv->states[0];
209 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
210 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
211 state->exit_latency = 0;
212 state->target_residency = 0;
213 state->power_usage = -1;
214 state->flags = CPUIDLE_FLAG_TIME_VALID;
215 state->enter = poll_idle;
216 state->disabled = false;
219 static void poll_idle_init(struct cpuidle_driver *drv) {}
220 #endif /* !CONFIG_ARCH_HAS_CPU_RELAX */
223 * __cpuidle_register_driver: register the driver
224 * @drv: a valid pointer to a struct cpuidle_driver
226 * Do some sanity checks, initialize the driver, assign the driver to the
227 * global cpuidle driver variable(s) and set up the broadcast timer if the
228 * cpuidle driver has some states that shut down the local timer.
230 * Returns 0 on success, a negative error code otherwise:
231 * * -EINVAL if the driver pointer is NULL or no idle states are available
232 * * -ENODEV if the cpuidle framework is disabled
233 * * -EBUSY if the driver is already assigned to the global variable(s)
235 static int __cpuidle_register_driver(struct cpuidle_driver *drv)
239 if (!drv || !drv->state_count)
242 if (cpuidle_disabled())
245 __cpuidle_driver_init(drv);
247 ret = __cpuidle_set_driver(drv);
252 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
253 (void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, 1);
261 * __cpuidle_unregister_driver - unregister the driver
262 * @drv: a valid pointer to a struct cpuidle_driver
264 * Check if the driver is no longer in use, reset the global cpuidle driver
265 * variable(s) and disable the timer broadcast notification mechanism if it was
269 static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
271 if (WARN_ON(drv->refcnt > 0))
276 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
277 (void *)CLOCK_EVT_NOTIFY_BROADCAST_OFF, 1);
280 __cpuidle_unset_driver(drv);
284 * cpuidle_register_driver - registers a driver
285 * @drv: a pointer to a valid struct cpuidle_driver
287 * Register the driver under a lock to prevent concurrent attempts to
288 * [un]register the driver from occuring at the same time.
290 * Returns 0 on success, a negative error code (returned by
291 * __cpuidle_register_driver()) otherwise.
293 int cpuidle_register_driver(struct cpuidle_driver *drv)
297 spin_lock(&cpuidle_driver_lock);
298 ret = __cpuidle_register_driver(drv);
299 spin_unlock(&cpuidle_driver_lock);
303 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
306 * cpuidle_unregister_driver - unregisters a driver
307 * @drv: a pointer to a valid struct cpuidle_driver
309 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
310 * to [un]register the driver from occuring at the same time. @drv has to
311 * match the currently registered driver.
313 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
315 spin_lock(&cpuidle_driver_lock);
316 __cpuidle_unregister_driver(drv);
317 spin_unlock(&cpuidle_driver_lock);
319 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
322 * cpuidle_get_driver - return the driver tied to the current CPU.
324 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
326 struct cpuidle_driver *cpuidle_get_driver(void)
328 struct cpuidle_driver *drv;
332 drv = __cpuidle_get_cpu_driver(cpu);
337 EXPORT_SYMBOL_GPL(cpuidle_get_driver);
340 * cpuidle_get_cpu_driver - return the driver registered for a CPU.
341 * @dev: a valid pointer to a struct cpuidle_device
343 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
344 * for the CPU associated with @dev.
346 struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
351 return __cpuidle_get_cpu_driver(dev->cpu);
353 EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
356 * cpuidle_driver_ref - get a reference to the driver.
358 * Increment the reference counter of the cpuidle driver associated with
361 * Returns a pointer to the driver, or NULL if the current CPU has no driver.
363 struct cpuidle_driver *cpuidle_driver_ref(void)
365 struct cpuidle_driver *drv;
367 spin_lock(&cpuidle_driver_lock);
369 drv = cpuidle_get_driver();
373 spin_unlock(&cpuidle_driver_lock);
378 * cpuidle_driver_unref - puts down the refcount for the driver
380 * Decrement the reference counter of the cpuidle driver associated with
383 void cpuidle_driver_unref(void)
385 struct cpuidle_driver *drv;
387 spin_lock(&cpuidle_driver_lock);
389 drv = cpuidle_get_driver();
390 if (drv && !WARN_ON(drv->refcnt <= 0))
393 spin_unlock(&cpuidle_driver_lock);