kernel/power/qos.c

   1 /*
   2  * This module exposes the interface to kernel space for specifying
   3  * QoS dependencies.  It provides infrastructure for registration of:
   4  *
   5  * Dependents on a QoS value : register requests
   6  * Watchers of QoS value : get notified when target QoS value changes
   7  *
   8  * This QoS design is best effort based.  Dependents register their QoS needs.
   9  * Watchers register to keep track of the current QoS needs of the system.
  10  *
  11  * There are 3 basic classes of QoS parameter: latency, timeout, throughput
  12  * each have defined units:
  13  * latency: usec
  14  * timeout: usec <-- currently not used.
  15  * throughput: kbs (kilo byte / sec)
  16  *
  17  * There are lists of pm_qos_objects each one wrapping requests, notifiers
  18  *
  19  * User mode requests on a QOS parameter register themselves to the
  20  * subsystem by opening the device node /dev/... and writing there request to
  21  * the node.  As long as the process holds a file handle open to the node the
  22  * client continues to be accounted for.  Upon file release the usermode
  23  * request is removed and a new qos target is computed.  This way when the
  24  * request that the application has is cleaned up when closes the file
  25  * pointer or exits the pm_qos_object will get an opportunity to clean up.
  26  *
  27  * Mark Gross <mgross@linux.intel.com>
  28  */
  29
  30 /*#define DEBUG*/
  31
  32 #include <linux/pm_qos.h>
  33 #include <linux/sched.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/slab.h>
  36 #include <linux/time.h>
  37 #include <linux/fs.h>
  38 #include <linux/device.h>
  39 #include <linux/miscdevice.h>
  40 #include <linux/string.h>
  41 #include <linux/platform_device.h>
  42 #include <linux/init.h>
  43 #include <linux/kernel.h>
  44
  45 #include <linux/uaccess.h>
  46 #include <linux/export.h>
  47 #include <trace/events/power.h>
  48
  49 /*
  50  * locking rule: all changes to constraints or notifiers lists
  51  * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
  52  * held, taken with _irqsave.  One lock to rule them all
  53  */
  54 struct pm_qos_object {
  55         struct pm_qos_constraints *constraints;
  56         struct miscdevice pm_qos_power_miscdev;
  57         char *name;
  58 };
  59
  60 static DEFINE_SPINLOCK(pm_qos_lock);
  61
  62 static struct pm_qos_object null_pm_qos;
  63
  64 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
  65 static struct pm_qos_constraints cpu_dma_constraints = {
  66         .list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
  67         .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  68         .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  69         .no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  70         .type = PM_QOS_MIN,
  71         .notifiers = &cpu_dma_lat_notifier,
  72 };
  73 static struct pm_qos_object cpu_dma_pm_qos = {
  74         .constraints = &cpu_dma_constraints,
  75         .name = "cpu_dma_latency",
  76 };
  77
  78 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
  79 static struct pm_qos_constraints network_lat_constraints = {
  80         .list = PLIST_HEAD_INIT(network_lat_constraints.list),
  81         .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  82         .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  83         .no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  84         .type = PM_QOS_MIN,
  85         .notifiers = &network_lat_notifier,
  86 };
  87 static struct pm_qos_object network_lat_pm_qos = {
  88         .constraints = &network_lat_constraints,
  89         .name = "network_latency",
  90 };
  91
  92
  93 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
  94 static struct pm_qos_constraints network_tput_constraints = {
  95         .list = PLIST_HEAD_INIT(network_tput_constraints.list),
  96         .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  97         .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  98         .no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  99         .type = PM_QOS_MAX,
 100         .notifiers = &network_throughput_notifier,
 101 };
 102 static struct pm_qos_object network_throughput_pm_qos = {
 103         .constraints = &network_tput_constraints,
 104         .name = "network_throughput",
 105 };
 106
 107
 108 static BLOCKING_NOTIFIER_HEAD(memory_bandwidth_notifier);
 109 static struct pm_qos_constraints memory_bw_constraints = {
 110         .list = PLIST_HEAD_INIT(memory_bw_constraints.list),
 111         .target_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
 112         .default_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
 113         .no_constraint_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
 114         .type = PM_QOS_SUM,
 115         .notifiers = &memory_bandwidth_notifier,
 116 };
 117 static struct pm_qos_object memory_bandwidth_pm_qos = {
 118         .constraints = &memory_bw_constraints,
 119         .name = "memory_bandwidth",
 120 };
 121
 122
 123 static struct pm_qos_object *pm_qos_array[] = {
 124         &null_pm_qos,
 125         &cpu_dma_pm_qos,
 126         &network_lat_pm_qos,
 127         &network_throughput_pm_qos,
 128         &memory_bandwidth_pm_qos,
 129 };
 130
 131 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 132                 size_t count, loff_t *f_pos);
 133 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 134                 size_t count, loff_t *f_pos);
 135 static int pm_qos_power_open(struct inode *inode, struct file *filp);
 136 static int pm_qos_power_release(struct inode *inode, struct file *filp);
 137
 138 static const struct file_operations pm_qos_power_fops = {
 139         .write = pm_qos_power_write,
 140         .read = pm_qos_power_read,
 141         .open = pm_qos_power_open,
 142         .release = pm_qos_power_release,
 143         .llseek = noop_llseek,
 144 };
 145
 146 /* unlocked internal variant */
 147 static inline int pm_qos_get_value(struct pm_qos_constraints *c)
 148 {
 149         struct plist_node *node;
 150         int total_value = 0;
 151
 152         if (plist_head_empty(&c->list))
 153                 return c->no_constraint_value;
 154
 155         switch (c->type) {
 156         case PM_QOS_MIN:
 157                 return plist_first(&c->list)->prio;
 158
 159         case PM_QOS_MAX:
 160                 return plist_last(&c->list)->prio;
 161
 162         case PM_QOS_SUM:
 163                 plist_for_each(node, &c->list)
 164                         total_value += node->prio;
 165
 166                 return total_value;
 167
 168         default:
 169                 /* runtime check for not using enum */
 170                 BUG();
 171                 return PM_QOS_DEFAULT_VALUE;
 172         }
 173 }
 174
 175 s32 pm_qos_read_value(struct pm_qos_constraints *c)
 176 {
 177         return c->target_value;
 178 }
 179
 180 static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
 181 {
 182         c->target_value = value;
 183 }
 184
 185 /**
 186  * pm_qos_update_target - manages the constraints list and calls the notifiers
 187  *  if needed
 188  * @c: constraints data struct
 189  * @node: request to add to the list, to update or to remove
 190  * @action: action to take on the constraints list
 191  * @value: value of the request to add or update
 192  *
 193  * This function returns 1 if the aggregated constraint value has changed, 0
 194  *  otherwise.
 195  */
 196 int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 197                          enum pm_qos_req_action action, int value)
 198 {
 199         unsigned long flags;
 200         int prev_value, curr_value, new_value;
 201         int ret;
 202
 203         spin_lock_irqsave(&pm_qos_lock, flags);
 204         prev_value = pm_qos_get_value(c);
 205         if (value == PM_QOS_DEFAULT_VALUE)
 206                 new_value = c->default_value;
 207         else
 208                 new_value = value;
 209
 210         switch (action) {
 211         case PM_QOS_REMOVE_REQ:
 212                 plist_del(node, &c->list);
 213                 break;
 214         case PM_QOS_UPDATE_REQ:
 215                 /*
 216                  * to change the list, we atomically remove, reinit
 217                  * with new value and add, then see if the extremal
 218                  * changed
 219                  */
 220                 plist_del(node, &c->list);
 221         case PM_QOS_ADD_REQ:
 222                 plist_node_init(node, new_value);
 223                 plist_add(node, &c->list);
 224                 break;
 225         default:
 226                 /* no action */
 227                 ;
 228         }
 229
 230         curr_value = pm_qos_get_value(c);
 231         pm_qos_set_value(c, curr_value);
 232
 233         spin_unlock_irqrestore(&pm_qos_lock, flags);
 234
 235         trace_pm_qos_update_target(action, prev_value, curr_value);
 236         if (prev_value != curr_value) {
 237                 ret = 1;
 238                 if (c->notifiers)
 239                         blocking_notifier_call_chain(c->notifiers,
 240                                                      (unsigned long)curr_value,
 241                                                      NULL);
 242         } else {
 243                 ret = 0;
 244         }
 245         return ret;
 246 }
 247
 248 /**
 249  * pm_qos_flags_remove_req - Remove device PM QoS flags request.
 250  * @pqf: Device PM QoS flags set to remove the request from.
 251  * @req: Request to remove from the set.
 252  */
 253 static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
 254                                     struct pm_qos_flags_request *req)
 255 {
 256         s32 val = 0;
 257
 258         list_del(&req->node);
 259         list_for_each_entry(req, &pqf->list, node)
 260                 val |= req->flags;
 261
 262         pqf->effective_flags = val;
 263 }
 264
 265 /**
 266  * pm_qos_update_flags - Update a set of PM QoS flags.
 267  * @pqf: Set of flags to update.
 268  * @req: Request to add to the set, to modify, or to remove from the set.
 269  * @action: Action to take on the set.
 270  * @val: Value of the request to add or modify.
 271  *
 272  * Update the given set of PM QoS flags and call notifiers if the aggregate
 273  * value has changed.  Returns 1 if the aggregate constraint value has changed,
 274  * 0 otherwise.
 275  */
 276 bool pm_qos_update_flags(struct pm_qos_flags *pqf,
 277                          struct pm_qos_flags_request *req,
 278                          enum pm_qos_req_action action, s32 val)
 279 {
 280         unsigned long irqflags;
 281         s32 prev_value, curr_value;
 282
 283         spin_lock_irqsave(&pm_qos_lock, irqflags);
 284
 285         prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 286
 287         switch (action) {
 288         case PM_QOS_REMOVE_REQ:
 289                 pm_qos_flags_remove_req(pqf, req);
 290                 break;
 291         case PM_QOS_UPDATE_REQ:
 292                 pm_qos_flags_remove_req(pqf, req);
 293         case PM_QOS_ADD_REQ:
 294                 req->flags = val;
 295                 INIT_LIST_HEAD(&req->node);
 296                 list_add_tail(&req->node, &pqf->list);
 297                 pqf->effective_flags |= val;
 298                 break;
 299         default:
 300                 /* no action */
 301                 ;
 302         }
 303
 304         curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 305
 306         spin_unlock_irqrestore(&pm_qos_lock, irqflags);
 307
 308         trace_pm_qos_update_flags(action, prev_value, curr_value);
 309         return prev_value != curr_value;
 310 }
 311
 312 /**
 313  * pm_qos_request - returns current system wide qos expectation
 314  * @pm_qos_class: identification of which qos value is requested
 315  *
 316  * This function returns the current target value.
 317  */
 318 int pm_qos_request(int pm_qos_class)
 319 {
 320         return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
 321 }
 322 EXPORT_SYMBOL_GPL(pm_qos_request);
 323
 324 int pm_qos_request_active(struct pm_qos_request *req)
 325 {
 326         return req->pm_qos_class != 0;
 327 }
 328 EXPORT_SYMBOL_GPL(pm_qos_request_active);
 329
 330 static void __pm_qos_update_request(struct pm_qos_request *req,
 331                            s32 new_value)
 332 {
 333         trace_pm_qos_update_request(req->pm_qos_class, new_value);
 334
 335         if (new_value != req->node.prio)
 336                 pm_qos_update_target(
 337                         pm_qos_array[req->pm_qos_class]->constraints,
 338                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 339 }
 340
 341 /**
 342  * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
 343  * @work: work struct for the delayed work (timeout)
 344  *
 345  * This cancels the timeout request by falling back to the default at timeout.
 346  */
 347 static void pm_qos_work_fn(struct work_struct *work)
 348 {
 349         struct pm_qos_request *req = container_of(to_delayed_work(work),
 350                                                   struct pm_qos_request,
 351                                                   work);
 352
 353         __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
 354 }
 355
 356 /**
 357  * pm_qos_add_request - inserts new qos request into the list
 358  * @req: pointer to a preallocated handle
 359  * @pm_qos_class: identifies which list of qos request to use
 360  * @value: defines the qos request
 361  *
 362  * This function inserts a new entry in the pm_qos_class list of requested qos
 363  * performance characteristics.  It recomputes the aggregate QoS expectations
 364  * for the pm_qos_class of parameters and initializes the pm_qos_request
 365  * handle.  Caller needs to save this handle for later use in updates and
 366  * removal.
 367  */
 368
 369 void pm_qos_add_request(struct pm_qos_request *req,
 370                         int pm_qos_class, s32 value)
 371 {
 372         if (!req) /*guard against callers passing in null */
 373                 return;
 374
 375         if (pm_qos_request_active(req)) {
 376                 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
 377                 return;
 378         }
 379         req->pm_qos_class = pm_qos_class;
 380         INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
 381         trace_pm_qos_add_request(pm_qos_class, value);
 382         pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
 383                              &req->node, PM_QOS_ADD_REQ, value);
 384 }
 385 EXPORT_SYMBOL_GPL(pm_qos_add_request);
 386
 387 /**
 388  * pm_qos_update_request - modifies an existing qos request
 389  * @req : handle to list element holding a pm_qos request to use
 390  * @value: defines the qos request
 391  *
 392  * Updates an existing qos request for the pm_qos_class of parameters along
 393  * with updating the target pm_qos_class value.
 394  *
 395  * Attempts are made to make this code callable on hot code paths.
 396  */
 397 void pm_qos_update_request(struct pm_qos_request *req,
 398                            s32 new_value)
 399 {
 400         if (!req) /*guard against callers passing in null */
 401                 return;
 402
 403         if (!pm_qos_request_active(req)) {
 404                 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
 405                 return;
 406         }
 407
 408         cancel_delayed_work_sync(&req->work);
 409         __pm_qos_update_request(req, new_value);
 410 }
 411 EXPORT_SYMBOL_GPL(pm_qos_update_request);
 412
 413 /**
 414  * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
 415  * @req : handle to list element holding a pm_qos request to use
 416  * @new_value: defines the temporal qos request
 417  * @timeout_us: the effective duration of this qos request in usecs.
 418  *
 419  * After timeout_us, this qos request is cancelled automatically.
 420  */
 421 void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
 422                                    unsigned long timeout_us)
 423 {
 424         if (!req)
 425                 return;
 426         if (WARN(!pm_qos_request_active(req),
 427                  "%s called for unknown object.", __func__))
 428                 return;
 429
 430         cancel_delayed_work_sync(&req->work);
 431
 432         trace_pm_qos_update_request_timeout(req->pm_qos_class,
 433                                             new_value, timeout_us);
 434         if (new_value != req->node.prio)
 435                 pm_qos_update_target(
 436                         pm_qos_array[req->pm_qos_class]->constraints,
 437                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 438
 439         schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
 440 }
 441
 442 /**
 443  * pm_qos_remove_request - modifies an existing qos request
 444  * @req: handle to request list element
 445  *
 446  * Will remove pm qos request from the list of constraints and
 447  * recompute the current target value for the pm_qos_class.  Call this
 448  * on slow code paths.
 449  */
 450 void pm_qos_remove_request(struct pm_qos_request *req)
 451 {
 452         if (!req) /*guard against callers passing in null */
 453                 return;
 454                 /* silent return to keep pcm code cleaner */
 455
 456         if (!pm_qos_request_active(req)) {
 457                 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
 458                 return;
 459         }
 460
 461         cancel_delayed_work_sync(&req->work);
 462
 463         trace_pm_qos_remove_request(req->pm_qos_class, PM_QOS_DEFAULT_VALUE);
 464         pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
 465                              &req->node, PM_QOS_REMOVE_REQ,
 466                              PM_QOS_DEFAULT_VALUE);
 467         memset(req, 0, sizeof(*req));
 468 }
 469 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
 470
 471 /**
 472  * pm_qos_add_notifier - sets notification entry for changes to target value
 473  * @pm_qos_class: identifies which qos target changes should be notified.
 474  * @notifier: notifier block managed by caller.
 475  *
 476  * will register the notifier into a notification chain that gets called
 477  * upon changes to the pm_qos_class target value.
 478  */
 479 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 480 {
 481         int retval;
 482
 483         retval = blocking_notifier_chain_register(
 484                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 485                         notifier);
 486
 487         return retval;
 488 }
 489 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
 490
 491 /**
 492  * pm_qos_remove_notifier - deletes notification entry from chain.
 493  * @pm_qos_class: identifies which qos target changes are notified.
 494  * @notifier: notifier block to be removed.
 495  *
 496  * will remove the notifier from the notification chain that gets called
 497  * upon changes to the pm_qos_class target value.
 498  */
 499 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 500 {
 501         int retval;
 502
 503         retval = blocking_notifier_chain_unregister(
 504                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 505                         notifier);
 506
 507         return retval;
 508 }
 509 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 510
 511 /* User space interface to PM QoS classes via misc devices */
 512 static int register_pm_qos_misc(struct pm_qos_object *qos)
 513 {
 514         qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
 515         qos->pm_qos_power_miscdev.name = qos->name;
 516         qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
 517
 518         return misc_register(&qos->pm_qos_power_miscdev);
 519 }
 520
 521 static int find_pm_qos_object_by_minor(int minor)
 522 {
 523         int pm_qos_class;
 524
 525         for (pm_qos_class = PM_QOS_CPU_DMA_LATENCY;
 526                 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
 527                 if (minor ==
 528                         pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
 529                         return pm_qos_class;
 530         }
 531         return -1;
 532 }
 533
 534 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 535 {
 536         long pm_qos_class;
 537
 538         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 539         if (pm_qos_class >= PM_QOS_CPU_DMA_LATENCY) {
 540                 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
 541                 if (!req)
 542                         return -ENOMEM;
 543
 544                 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
 545                 filp->private_data = req;
 546
 547                 return 0;
 548         }
 549         return -EPERM;
 550 }
 551
 552 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 553 {
 554         struct pm_qos_request *req;
 555
 556         req = filp->private_data;
 557         pm_qos_remove_request(req);
 558         kfree(req);
 559
 560         return 0;
 561 }
 562
 563
 564 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 565                 size_t count, loff_t *f_pos)
 566 {
 567         s32 value;
 568         unsigned long flags;
 569         struct pm_qos_request *req = filp->private_data;
 570
 571         if (!req)
 572                 return -EINVAL;
 573         if (!pm_qos_request_active(req))
 574                 return -EINVAL;
 575
 576         spin_lock_irqsave(&pm_qos_lock, flags);
 577         value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
 578         spin_unlock_irqrestore(&pm_qos_lock, flags);
 579
 580         return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
 581 }
 582
 583 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 584                 size_t count, loff_t *f_pos)
 585 {
 586         s32 value;
 587         struct pm_qos_request *req;
 588
 589         if (count == sizeof(s32)) {
 590                 if (copy_from_user(&value, buf, sizeof(s32)))
 591                         return -EFAULT;
 592         } else {
 593                 int ret;
 594
 595                 ret = kstrtos32_from_user(buf, count, 16, &value);
 596                 if (ret)
 597                         return ret;
 598         }
 599
 600         req = filp->private_data;
 601         pm_qos_update_request(req, value);
 602
 603         return count;
 604 }
 605
 606
 607 static int __init pm_qos_power_init(void)
 608 {
 609         int ret = 0;
 610         int i;
 611
 612         BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
 613
 614         for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
 615                 ret = register_pm_qos_misc(pm_qos_array[i]);
 616                 if (ret < 0) {
 617                         printk(KERN_ERR "pm_qos_param: %s setup failed\n",
 618                                pm_qos_array[i]->name);
 619                         return ret;
 620                 }
 621         }
 622
 623         return ret;
 624 }
 625
 626 late_initcall(pm_qos_power_init);