x86/mm/pat: Don't report PAT on CPUs that don't support it
[linux/fpc-iii.git] / drivers / cpuidle / driver.c
blobe53fb861beb0451c322ebb7667d5cb6e0630d867
1 /*
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.
9 */
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>
20 #include "cpuidle.h"
22 DEFINE_SPINLOCK(cpuidle_driver_lock);
24 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
26 static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
28 /**
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);
40 /**
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)
50 int cpu;
52 for_each_cpu(cpu, drv->cpumask) {
54 if (drv != __cpuidle_get_cpu_driver(cpu))
55 continue;
57 per_cpu(cpuidle_drivers, cpu) = NULL;
61 /**
62 * __cpuidle_set_driver - set per CPU driver variables for the given driver.
63 * @drv: a valid pointer to a struct cpuidle_driver
65 * For each CPU in the driver's cpumask, unset the registered driver per CPU
66 * to @drv.
68 * Returns 0 on success, -EBUSY if the CPUs have driver(s) already.
70 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
72 int cpu;
74 for_each_cpu(cpu, drv->cpumask) {
76 if (__cpuidle_get_cpu_driver(cpu)) {
77 __cpuidle_unset_driver(drv);
78 return -EBUSY;
81 per_cpu(cpuidle_drivers, cpu) = drv;
84 return 0;
87 #else
89 static struct cpuidle_driver *cpuidle_curr_driver;
91 /**
92 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
93 * @cpu: ignored without the multiple driver support
95 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was
96 * previously registered.
98 static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
100 return cpuidle_curr_driver;
104 * __cpuidle_set_driver - assign the global cpuidle driver variable.
105 * @drv: pointer to a struct cpuidle_driver object
107 * Returns 0 on success, -EBUSY if the driver is already registered.
109 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
111 if (cpuidle_curr_driver)
112 return -EBUSY;
114 cpuidle_curr_driver = drv;
116 return 0;
120 * __cpuidle_unset_driver - unset the global cpuidle driver variable.
121 * @drv: a pointer to a struct cpuidle_driver
123 * Reset the global cpuidle variable to NULL. If @drv does not match the
124 * registered driver, do nothing.
126 static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
128 if (drv == cpuidle_curr_driver)
129 cpuidle_curr_driver = NULL;
132 #endif
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
138 * If @arg is NULL broadcast is disabled otherwise enabled
140 * This function is executed per CPU by an SMP cross call. It's not
141 * supposed to be called directly.
143 static void cpuidle_setup_broadcast_timer(void *arg)
145 if (arg)
146 tick_broadcast_enable();
147 else
148 tick_broadcast_disable();
152 * __cpuidle_driver_init - initialize the driver's internal data
153 * @drv: a valid pointer to a struct cpuidle_driver
155 static void __cpuidle_driver_init(struct cpuidle_driver *drv)
157 int i;
159 drv->refcnt = 0;
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.
166 if (!drv->cpumask)
167 drv->cpumask = (struct cpumask *)cpu_possible_mask;
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 one of the deeper states have this flag set.
174 for (i = drv->state_count - 1; i >= 0 ; i--) {
175 if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) {
176 drv->bctimer = 1;
177 break;
182 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
183 static int __cpuidle poll_idle(struct cpuidle_device *dev,
184 struct cpuidle_driver *drv, int index)
186 local_irq_enable();
187 if (!current_set_polling_and_test()) {
188 while (!need_resched())
189 cpu_relax();
191 current_clr_polling();
193 return index;
196 static void poll_idle_init(struct cpuidle_driver *drv)
198 struct cpuidle_state *state = &drv->states[0];
200 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
201 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
202 state->exit_latency = 0;
203 state->target_residency = 0;
204 state->power_usage = -1;
205 state->enter = poll_idle;
206 state->disabled = false;
208 #else
209 static void poll_idle_init(struct cpuidle_driver *drv) {}
210 #endif /* !CONFIG_ARCH_HAS_CPU_RELAX */
213 * __cpuidle_register_driver: register the driver
214 * @drv: a valid pointer to a struct cpuidle_driver
216 * Do some sanity checks, initialize the driver, assign the driver to the
217 * global cpuidle driver variable(s) and set up the broadcast timer if the
218 * cpuidle driver has some states that shut down the local timer.
220 * Returns 0 on success, a negative error code otherwise:
221 * * -EINVAL if the driver pointer is NULL or no idle states are available
222 * * -ENODEV if the cpuidle framework is disabled
223 * * -EBUSY if the driver is already assigned to the global variable(s)
225 static int __cpuidle_register_driver(struct cpuidle_driver *drv)
227 int ret;
229 if (!drv || !drv->state_count)
230 return -EINVAL;
232 ret = cpuidle_coupled_state_verify(drv);
233 if (ret)
234 return ret;
236 if (cpuidle_disabled())
237 return -ENODEV;
239 __cpuidle_driver_init(drv);
241 ret = __cpuidle_set_driver(drv);
242 if (ret)
243 return ret;
245 if (drv->bctimer)
246 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
247 (void *)1, 1);
249 poll_idle_init(drv);
251 return 0;
255 * __cpuidle_unregister_driver - unregister the driver
256 * @drv: a valid pointer to a struct cpuidle_driver
258 * Check if the driver is no longer in use, reset the global cpuidle driver
259 * variable(s) and disable the timer broadcast notification mechanism if it was
260 * in use.
263 static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
265 if (WARN_ON(drv->refcnt > 0))
266 return;
268 if (drv->bctimer) {
269 drv->bctimer = 0;
270 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
271 NULL, 1);
274 __cpuidle_unset_driver(drv);
278 * cpuidle_register_driver - registers a driver
279 * @drv: a pointer to a valid struct cpuidle_driver
281 * Register the driver under a lock to prevent concurrent attempts to
282 * [un]register the driver from occuring at the same time.
284 * Returns 0 on success, a negative error code (returned by
285 * __cpuidle_register_driver()) otherwise.
287 int cpuidle_register_driver(struct cpuidle_driver *drv)
289 int ret;
291 spin_lock(&cpuidle_driver_lock);
292 ret = __cpuidle_register_driver(drv);
293 spin_unlock(&cpuidle_driver_lock);
295 return ret;
297 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
300 * cpuidle_unregister_driver - unregisters a driver
301 * @drv: a pointer to a valid struct cpuidle_driver
303 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
304 * to [un]register the driver from occuring at the same time. @drv has to
305 * match the currently registered driver.
307 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
309 spin_lock(&cpuidle_driver_lock);
310 __cpuidle_unregister_driver(drv);
311 spin_unlock(&cpuidle_driver_lock);
313 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
316 * cpuidle_get_driver - return the driver tied to the current CPU.
318 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
320 struct cpuidle_driver *cpuidle_get_driver(void)
322 struct cpuidle_driver *drv;
323 int cpu;
325 cpu = get_cpu();
326 drv = __cpuidle_get_cpu_driver(cpu);
327 put_cpu();
329 return drv;
331 EXPORT_SYMBOL_GPL(cpuidle_get_driver);
334 * cpuidle_get_cpu_driver - return the driver registered for a CPU.
335 * @dev: a valid pointer to a struct cpuidle_device
337 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
338 * for the CPU associated with @dev.
340 struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
342 if (!dev)
343 return NULL;
345 return __cpuidle_get_cpu_driver(dev->cpu);
347 EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
350 * cpuidle_driver_ref - get a reference to the driver.
352 * Increment the reference counter of the cpuidle driver associated with
353 * the current CPU.
355 * Returns a pointer to the driver, or NULL if the current CPU has no driver.
357 struct cpuidle_driver *cpuidle_driver_ref(void)
359 struct cpuidle_driver *drv;
361 spin_lock(&cpuidle_driver_lock);
363 drv = cpuidle_get_driver();
364 if (drv)
365 drv->refcnt++;
367 spin_unlock(&cpuidle_driver_lock);
368 return drv;
372 * cpuidle_driver_unref - puts down the refcount for the driver
374 * Decrement the reference counter of the cpuidle driver associated with
375 * the current CPU.
377 void cpuidle_driver_unref(void)
379 struct cpuidle_driver *drv;
381 spin_lock(&cpuidle_driver_lock);
383 drv = cpuidle_get_driver();
384 if (drv && !WARN_ON(drv->refcnt <= 0))
385 drv->refcnt--;
387 spin_unlock(&cpuidle_driver_lock);