393 lines · c
1/*2 * driver.c - driver support3 *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/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>19#include <linux/math64.h>20 21#include "cpuidle.h"22 23DEFINE_SPINLOCK(cpuidle_driver_lock);24 25#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS26 27static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);28 29/**30 * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.31 * @cpu: the CPU handled by the driver32 *33 * Returns a pointer to struct cpuidle_driver or NULL if no driver has been34 * registered for @cpu.35 */36static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)37{38 return per_cpu(cpuidle_drivers, cpu);39}40 41/**42 * __cpuidle_unset_driver - unset per CPU driver variables.43 * @drv: a valid pointer to a struct cpuidle_driver44 *45 * For each CPU in the driver's CPU mask, unset the registered driver per CPU46 * variable. If @drv is different from the registered driver, the corresponding47 * variable is not cleared.48 */49static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)50{51 int cpu;52 53 for_each_cpu(cpu, drv->cpumask) {54 55 if (drv != __cpuidle_get_cpu_driver(cpu))56 continue;57 58 per_cpu(cpuidle_drivers, cpu) = NULL;59 }60}61 62/**63 * __cpuidle_set_driver - set per CPU driver variables for the given driver.64 * @drv: a valid pointer to a struct cpuidle_driver65 *66 * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver67 * different from drv already.68 */69static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)70{71 int cpu;72 73 for_each_cpu(cpu, drv->cpumask) {74 struct cpuidle_driver *old_drv;75 76 old_drv = __cpuidle_get_cpu_driver(cpu);77 if (old_drv && old_drv != drv)78 return -EBUSY;79 }80 81 for_each_cpu(cpu, drv->cpumask)82 per_cpu(cpuidle_drivers, cpu) = drv;83 84 return 0;85}86 87#else88 89static struct cpuidle_driver *cpuidle_curr_driver;90 91/**92 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.93 * @cpu: ignored without the multiple driver support94 *95 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was96 * previously registered.97 */98static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)99{100 return cpuidle_curr_driver;101}102 103/**104 * __cpuidle_set_driver - assign the global cpuidle driver variable.105 * @drv: pointer to a struct cpuidle_driver object106 *107 * Returns 0 on success, -EBUSY if the driver is already registered.108 */109static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)110{111 if (cpuidle_curr_driver)112 return -EBUSY;113 114 cpuidle_curr_driver = drv;115 116 return 0;117}118 119/**120 * __cpuidle_unset_driver - unset the global cpuidle driver variable.121 * @drv: a pointer to a struct cpuidle_driver122 *123 * Reset the global cpuidle variable to NULL. If @drv does not match the124 * registered driver, do nothing.125 */126static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)127{128 if (drv == cpuidle_curr_driver)129 cpuidle_curr_driver = NULL;130}131 132#endif133 134/**135 * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu136 * @arg: a void pointer used to match the SMP cross call API137 *138 * If @arg is NULL broadcast is disabled otherwise enabled139 *140 * This function is executed per CPU by an SMP cross call. It's not141 * supposed to be called directly.142 */143static void cpuidle_setup_broadcast_timer(void *arg)144{145 if (arg)146 tick_broadcast_enable();147 else148 tick_broadcast_disable();149}150 151/**152 * __cpuidle_driver_init - initialize the driver's internal data153 * @drv: a valid pointer to a struct cpuidle_driver154 */155static void __cpuidle_driver_init(struct cpuidle_driver *drv)156{157 int i;158 159 /*160 * Use all possible CPUs as the default, because if the kernel boots161 * with some CPUs offline and then we online one of them, the CPU162 * notifier has to know which driver to assign.163 */164 if (!drv->cpumask)165 drv->cpumask = (struct cpumask *)cpu_possible_mask;166 167 for (i = 0; i < drv->state_count; i++) {168 struct cpuidle_state *s = &drv->states[i];169 170 /*171 * Look for the timer stop flag in the different states and if172 * it is found, indicate that the broadcast timer has to be set173 * up.174 */175 if (s->flags & CPUIDLE_FLAG_TIMER_STOP)176 drv->bctimer = 1;177 178 /*179 * The core will use the target residency and exit latency180 * values in nanoseconds, but allow drivers to provide them in181 * microseconds too.182 */183 if (s->target_residency > 0)184 s->target_residency_ns = s->target_residency * NSEC_PER_USEC;185 else if (s->target_residency_ns < 0)186 s->target_residency_ns = 0;187 else188 s->target_residency = div_u64(s->target_residency_ns, NSEC_PER_USEC);189 190 if (s->exit_latency > 0)191 s->exit_latency_ns = mul_u32_u32(s->exit_latency, NSEC_PER_USEC);192 else if (s->exit_latency_ns < 0)193 s->exit_latency_ns = 0;194 else195 s->exit_latency = div_u64(s->exit_latency_ns, NSEC_PER_USEC);196 }197}198 199/**200 * __cpuidle_register_driver: register the driver201 * @drv: a valid pointer to a struct cpuidle_driver202 *203 * Do some sanity checks, initialize the driver, assign the driver to the204 * global cpuidle driver variable(s) and set up the broadcast timer if the205 * cpuidle driver has some states that shut down the local timer.206 *207 * Returns 0 on success, a negative error code otherwise:208 * * -EINVAL if the driver pointer is NULL or no idle states are available209 * * -ENODEV if the cpuidle framework is disabled210 * * -EBUSY if the driver is already assigned to the global variable(s)211 */212static int __cpuidle_register_driver(struct cpuidle_driver *drv)213{214 int ret;215 216 if (!drv || !drv->state_count)217 return -EINVAL;218 219 ret = cpuidle_coupled_state_verify(drv);220 if (ret)221 return ret;222 223 if (cpuidle_disabled())224 return -ENODEV;225 226 __cpuidle_driver_init(drv);227 228 ret = __cpuidle_set_driver(drv);229 if (ret)230 return ret;231 232 if (drv->bctimer)233 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,234 (void *)1, 1);235 236 return 0;237}238 239/**240 * __cpuidle_unregister_driver - unregister the driver241 * @drv: a valid pointer to a struct cpuidle_driver242 *243 * Check if the driver is no longer in use, reset the global cpuidle driver244 * variable(s) and disable the timer broadcast notification mechanism if it was245 * in use.246 *247 */248static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)249{250 if (drv->bctimer) {251 drv->bctimer = 0;252 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,253 NULL, 1);254 }255 256 __cpuidle_unset_driver(drv);257}258 259/**260 * cpuidle_register_driver - registers a driver261 * @drv: a pointer to a valid struct cpuidle_driver262 *263 * Register the driver under a lock to prevent concurrent attempts to264 * [un]register the driver from occuring at the same time.265 *266 * Returns 0 on success, a negative error code (returned by267 * __cpuidle_register_driver()) otherwise.268 */269int cpuidle_register_driver(struct cpuidle_driver *drv)270{271 struct cpuidle_governor *gov;272 int ret;273 274 spin_lock(&cpuidle_driver_lock);275 ret = __cpuidle_register_driver(drv);276 spin_unlock(&cpuidle_driver_lock);277 278 if (!ret && !strlen(param_governor) && drv->governor &&279 (cpuidle_get_driver() == drv)) {280 mutex_lock(&cpuidle_lock);281 gov = cpuidle_find_governor(drv->governor);282 if (gov) {283 cpuidle_prev_governor = cpuidle_curr_governor;284 if (cpuidle_switch_governor(gov) < 0)285 cpuidle_prev_governor = NULL;286 }287 mutex_unlock(&cpuidle_lock);288 }289 290 return ret;291}292EXPORT_SYMBOL_GPL(cpuidle_register_driver);293 294/**295 * cpuidle_unregister_driver - unregisters a driver296 * @drv: a pointer to a valid struct cpuidle_driver297 *298 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts299 * to [un]register the driver from occuring at the same time. @drv has to300 * match the currently registered driver.301 */302void cpuidle_unregister_driver(struct cpuidle_driver *drv)303{304 bool enabled = (cpuidle_get_driver() == drv);305 306 spin_lock(&cpuidle_driver_lock);307 __cpuidle_unregister_driver(drv);308 spin_unlock(&cpuidle_driver_lock);309 310 if (!enabled)311 return;312 313 mutex_lock(&cpuidle_lock);314 if (cpuidle_prev_governor) {315 if (!cpuidle_switch_governor(cpuidle_prev_governor))316 cpuidle_prev_governor = NULL;317 }318 mutex_unlock(&cpuidle_lock);319}320EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);321 322/**323 * cpuidle_get_driver - return the driver tied to the current CPU.324 *325 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.326 */327struct cpuidle_driver *cpuidle_get_driver(void)328{329 struct cpuidle_driver *drv;330 int cpu;331 332 cpu = get_cpu();333 drv = __cpuidle_get_cpu_driver(cpu);334 put_cpu();335 336 return drv;337}338EXPORT_SYMBOL_GPL(cpuidle_get_driver);339 340/**341 * cpuidle_get_cpu_driver - return the driver registered for a CPU.342 * @dev: a valid pointer to a struct cpuidle_device343 *344 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered345 * for the CPU associated with @dev.346 */347struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)348{349 if (!dev)350 return NULL;351 352 return __cpuidle_get_cpu_driver(dev->cpu);353}354EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);355 356/**357 * cpuidle_driver_state_disabled - Disable or enable an idle state358 * @drv: cpuidle driver owning the state359 * @idx: State index360 * @disable: Whether or not to disable the state361 */362void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,363 bool disable)364{365 unsigned int cpu;366 367 mutex_lock(&cpuidle_lock);368 369 spin_lock(&cpuidle_driver_lock);370 371 if (!drv->cpumask) {372 drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE;373 goto unlock;374 }375 376 for_each_cpu(cpu, drv->cpumask) {377 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);378 379 if (!dev)380 continue;381 382 if (disable)383 dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;384 else385 dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;386 }387 388unlock:389 spin_unlock(&cpuidle_driver_lock);390 391 mutex_unlock(&cpuidle_lock);392}393