1 /* 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/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 20 #include "cpuidle.h" 21 22 DEFINE_SPINLOCK(cpuidle_driver_lock); 23 24 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS 25 26 static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers); 27 28 /** 29 * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU. 30 * @cpu: the CPU handled by the driver 31 * 32 * Returns a pointer to struct cpuidle_driver or NULL if no driver has been 33 * registered for @cpu. 34 */ 35 static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) 36 { 37 return per_cpu(cpuidle_drivers, cpu); 38 } 39 40 /** 41 * __cpuidle_unset_driver - unset per CPU driver variables. 42 * @drv: a valid pointer to a struct cpuidle_driver 43 * 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. 47 */ 48 static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) 49 { 50 int cpu; 51 52 for_each_cpu(cpu, drv->cpumask) { 53 54 if (drv != __cpuidle_get_cpu_driver(cpu)) 55 continue; 56 57 per_cpu(cpuidle_drivers, cpu) = NULL; 58 } 59 } 60 61 /** 62 * __cpuidle_set_driver - set per CPU driver variables for the given driver. 63 * @drv: a valid pointer to a struct cpuidle_driver 64 * 65 * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver 66 * different from drv already. 67 */ 68 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) 69 { 70 int cpu; 71 72 for_each_cpu(cpu, drv->cpumask) { 73 struct cpuidle_driver *old_drv; 74 75 old_drv = __cpuidle_get_cpu_driver(cpu); 76 if (old_drv && old_drv != drv) 77 return -EBUSY; 78 } 79 80 for_each_cpu(cpu, drv->cpumask) 81 per_cpu(cpuidle_drivers, cpu) = drv; 82 83 return 0; 84 } 85 86 #else 87 88 static struct cpuidle_driver *cpuidle_curr_driver; 89 90 /** 91 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer. 92 * @cpu: ignored without the multiple driver support 93 * 94 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was 95 * previously registered. 96 */ 97 static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) 98 { 99 return cpuidle_curr_driver; 100 } 101 102 /** 103 * __cpuidle_set_driver - assign the global cpuidle driver variable. 104 * @drv: pointer to a struct cpuidle_driver object 105 * 106 * Returns 0 on success, -EBUSY if the driver is already registered. 107 */ 108 static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) 109 { 110 if (cpuidle_curr_driver) 111 return -EBUSY; 112 113 cpuidle_curr_driver = drv; 114 115 return 0; 116 } 117 118 /** 119 * __cpuidle_unset_driver - unset the global cpuidle driver variable. 120 * @drv: a pointer to a struct cpuidle_driver 121 * 122 * Reset the global cpuidle variable to NULL. If @drv does not match the 123 * registered driver, do nothing. 124 */ 125 static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) 126 { 127 if (drv == cpuidle_curr_driver) 128 cpuidle_curr_driver = NULL; 129 } 130 131 #endif 132 133 /** 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 136 * 137 * If @arg is NULL broadcast is disabled otherwise enabled 138 * 139 * This function is executed per CPU by an SMP cross call. It's not 140 * supposed to be called directly. 141 */ 142 static void cpuidle_setup_broadcast_timer(void *arg) 143 { 144 if (arg) 145 tick_broadcast_enable(); 146 else 147 tick_broadcast_disable(); 148 } 149 150 /** 151 * __cpuidle_driver_init - initialize the driver's internal data 152 * @drv: a valid pointer to a struct cpuidle_driver 153 */ 154 static void __cpuidle_driver_init(struct cpuidle_driver *drv) 155 { 156 int i; 157 158 /* 159 * Use all possible CPUs as the default, because if the kernel boots 160 * with some CPUs offline and then we online one of them, the CPU 161 * notifier has to know which driver to assign. 162 */ 163 if (!drv->cpumask) 164 drv->cpumask = (struct cpumask *)cpu_possible_mask; 165 166 for (i = 0; i < drv->state_count; i++) { 167 struct cpuidle_state *s = &drv->states[i]; 168 169 /* 170 * Look for the timer stop flag in the different states and if 171 * it is found, indicate that the broadcast timer has to be set 172 * up. 173 */ 174 if (s->flags & CPUIDLE_FLAG_TIMER_STOP) 175 drv->bctimer = 1; 176 177 /* 178 * The core will use the target residency and exit latency 179 * values in nanoseconds, but allow drivers to provide them in 180 * microseconds too. 181 */ 182 if (s->target_residency > 0) 183 s->target_residency_ns = s->target_residency * NSEC_PER_USEC; 184 else if (s->target_residency_ns < 0) 185 s->target_residency_ns = 0; 186 187 if (s->exit_latency > 0) 188 s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC; 189 else if (s->exit_latency_ns < 0) 190 s->exit_latency_ns = 0; 191 } 192 } 193 194 /** 195 * __cpuidle_register_driver: register the driver 196 * @drv: a valid pointer to a struct cpuidle_driver 197 * 198 * Do some sanity checks, initialize the driver, assign the driver to the 199 * global cpuidle driver variable(s) and set up the broadcast timer if the 200 * cpuidle driver has some states that shut down the local timer. 201 * 202 * Returns 0 on success, a negative error code otherwise: 203 * * -EINVAL if the driver pointer is NULL or no idle states are available 204 * * -ENODEV if the cpuidle framework is disabled 205 * * -EBUSY if the driver is already assigned to the global variable(s) 206 */ 207 static int __cpuidle_register_driver(struct cpuidle_driver *drv) 208 { 209 int ret; 210 211 if (!drv || !drv->state_count) 212 return -EINVAL; 213 214 ret = cpuidle_coupled_state_verify(drv); 215 if (ret) 216 return ret; 217 218 if (cpuidle_disabled()) 219 return -ENODEV; 220 221 __cpuidle_driver_init(drv); 222 223 ret = __cpuidle_set_driver(drv); 224 if (ret) 225 return ret; 226 227 if (drv->bctimer) 228 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, 229 (void *)1, 1); 230 231 return 0; 232 } 233 234 /** 235 * __cpuidle_unregister_driver - unregister the driver 236 * @drv: a valid pointer to a struct cpuidle_driver 237 * 238 * Check if the driver is no longer in use, reset the global cpuidle driver 239 * variable(s) and disable the timer broadcast notification mechanism if it was 240 * in use. 241 * 242 */ 243 static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) 244 { 245 if (drv->bctimer) { 246 drv->bctimer = 0; 247 on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, 248 NULL, 1); 249 } 250 251 __cpuidle_unset_driver(drv); 252 } 253 254 /** 255 * cpuidle_register_driver - registers a driver 256 * @drv: a pointer to a valid struct cpuidle_driver 257 * 258 * Register the driver under a lock to prevent concurrent attempts to 259 * [un]register the driver from occuring at the same time. 260 * 261 * Returns 0 on success, a negative error code (returned by 262 * __cpuidle_register_driver()) otherwise. 263 */ 264 int cpuidle_register_driver(struct cpuidle_driver *drv) 265 { 266 struct cpuidle_governor *gov; 267 int ret; 268 269 spin_lock(&cpuidle_driver_lock); 270 ret = __cpuidle_register_driver(drv); 271 spin_unlock(&cpuidle_driver_lock); 272 273 if (!ret && !strlen(param_governor) && drv->governor && 274 (cpuidle_get_driver() == drv)) { 275 mutex_lock(&cpuidle_lock); 276 gov = cpuidle_find_governor(drv->governor); 277 if (gov) { 278 cpuidle_prev_governor = cpuidle_curr_governor; 279 if (cpuidle_switch_governor(gov) < 0) 280 cpuidle_prev_governor = NULL; 281 } 282 mutex_unlock(&cpuidle_lock); 283 } 284 285 return ret; 286 } 287 EXPORT_SYMBOL_GPL(cpuidle_register_driver); 288 289 /** 290 * cpuidle_unregister_driver - unregisters a driver 291 * @drv: a pointer to a valid struct cpuidle_driver 292 * 293 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts 294 * to [un]register the driver from occuring at the same time. @drv has to 295 * match the currently registered driver. 296 */ 297 void cpuidle_unregister_driver(struct cpuidle_driver *drv) 298 { 299 bool enabled = (cpuidle_get_driver() == drv); 300 301 spin_lock(&cpuidle_driver_lock); 302 __cpuidle_unregister_driver(drv); 303 spin_unlock(&cpuidle_driver_lock); 304 305 if (!enabled) 306 return; 307 308 mutex_lock(&cpuidle_lock); 309 if (cpuidle_prev_governor) { 310 if (!cpuidle_switch_governor(cpuidle_prev_governor)) 311 cpuidle_prev_governor = NULL; 312 } 313 mutex_unlock(&cpuidle_lock); 314 } 315 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); 316 317 /** 318 * cpuidle_get_driver - return the driver tied to the current CPU. 319 * 320 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered. 321 */ 322 struct cpuidle_driver *cpuidle_get_driver(void) 323 { 324 struct cpuidle_driver *drv; 325 int cpu; 326 327 cpu = get_cpu(); 328 drv = __cpuidle_get_cpu_driver(cpu); 329 put_cpu(); 330 331 return drv; 332 } 333 EXPORT_SYMBOL_GPL(cpuidle_get_driver); 334 335 /** 336 * cpuidle_get_cpu_driver - return the driver registered for a CPU. 337 * @dev: a valid pointer to a struct cpuidle_device 338 * 339 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered 340 * for the CPU associated with @dev. 341 */ 342 struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) 343 { 344 if (!dev) 345 return NULL; 346 347 return __cpuidle_get_cpu_driver(dev->cpu); 348 } 349 EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver); 350 351 /** 352 * cpuidle_driver_state_disabled - Disable or enable an idle state 353 * @drv: cpuidle driver owning the state 354 * @idx: State index 355 * @disable: Whether or not to disable the state 356 */ 357 void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx, 358 bool disable) 359 { 360 unsigned int cpu; 361 362 mutex_lock(&cpuidle_lock); 363 364 spin_lock(&cpuidle_driver_lock); 365 366 if (!drv->cpumask) { 367 drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE; 368 goto unlock; 369 } 370 371 for_each_cpu(cpu, drv->cpumask) { 372 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); 373 374 if (!dev) 375 continue; 376 377 if (disable) 378 dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER; 379 else 380 dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER; 381 } 382 383 unlock: 384 spin_unlock(&cpuidle_driver_lock); 385 386 mutex_unlock(&cpuidle_lock); 387 } 388