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         .type = PM_QOS_MIN,
  70         .notifiers = &cpu_dma_lat_notifier,
  71 };
  72 static struct pm_qos_object cpu_dma_pm_qos = {
  73         .constraints = &cpu_dma_constraints,
  74         .name = "cpu_dma_latency",
  75 };
  76
  77 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
  78 static struct pm_qos_constraints network_lat_constraints = {
  79         .list = PLIST_HEAD_INIT(network_lat_constraints.list),
  80         .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  81         .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  82         .type = PM_QOS_MIN,
  83         .notifiers = &network_lat_notifier,
  84 };
  85 static struct pm_qos_object network_lat_pm_qos = {
  86         .constraints = &network_lat_constraints,
  87         .name = "network_latency",
  88 };
  89
  90
  91 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
  92 static struct pm_qos_constraints network_tput_constraints = {
  93         .list = PLIST_HEAD_INIT(network_tput_constraints.list),
  94         .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  95         .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  96         .type = PM_QOS_MAX,
  97         .notifiers = &network_throughput_notifier,
  98 };
  99 static struct pm_qos_object network_throughput_pm_qos = {
 100         .constraints = &network_tput_constraints,
 101         .name = "network_throughput",
 102 };
 103
 104
 105 static struct pm_qos_object *pm_qos_array[] = {
 106         &null_pm_qos,
 107         &cpu_dma_pm_qos,
 108         &network_lat_pm_qos,
 109         &network_throughput_pm_qos
 110 };
 111
 112 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 113                 size_t count, loff_t *f_pos);
 114 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 115                 size_t count, loff_t *f_pos);
 116 static int pm_qos_power_open(struct inode *inode, struct file *filp);
 117 static int pm_qos_power_release(struct inode *inode, struct file *filp);
 118
 119 static const struct file_operations pm_qos_power_fops = {
 120         .write = pm_qos_power_write,
 121         .read = pm_qos_power_read,
 122         .open = pm_qos_power_open,
 123         .release = pm_qos_power_release,
 124         .llseek = noop_llseek,
 125 };
 126
 127 /* unlocked internal variant */
 128 static inline int pm_qos_get_value(struct pm_qos_constraints *c)
 129 {
 130         if (plist_head_empty(&c->list))
 131                 return c->default_value;
 132
 133         switch (c->type) {
 134         case PM_QOS_MIN:
 135                 return plist_first(&c->list)->prio;
 136
 137         case PM_QOS_MAX:
 138                 return plist_last(&c->list)->prio;
 139
 140         default:
 141                 /* runtime check for not using enum */
 142                 BUG();
 143                 return PM_QOS_DEFAULT_VALUE;
 144         }
 145 }
 146
 147 s32 pm_qos_read_value(struct pm_qos_constraints *c)
 148 {
 149         return c->target_value;
 150 }
 151
 152 static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
 153 {
 154         c->target_value = value;
 155 }
 156
 157 /**
 158  * pm_qos_update_target - manages the constraints list and calls the notifiers
 159  *  if needed
 160  * @c: constraints data struct
 161  * @node: request to add to the list, to update or to remove
 162  * @action: action to take on the constraints list
 163  * @value: value of the request to add or update
 164  *
 165  * This function returns 1 if the aggregated constraint value has changed, 0
 166  *  otherwise.
 167  */
 168 int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 169                          enum pm_qos_req_action action, int value)
 170 {
 171         unsigned long flags;
 172         int prev_value, curr_value, new_value;
 173
 174         spin_lock_irqsave(&pm_qos_lock, flags);
 175         prev_value = pm_qos_get_value(c);
 176         if (value == PM_QOS_DEFAULT_VALUE)
 177                 new_value = c->default_value;
 178         else
 179                 new_value = value;
 180
 181         switch (action) {
 182         case PM_QOS_REMOVE_REQ:
 183                 plist_del(node, &c->list);
 184                 break;
 185         case PM_QOS_UPDATE_REQ:
 186                 /*
 187                  * to change the list, we atomically remove, reinit
 188                  * with new value and add, then see if the extremal
 189                  * changed
 190                  */
 191                 plist_del(node, &c->list);
 192         case PM_QOS_ADD_REQ:
 193                 plist_node_init(node, new_value);
 194                 plist_add(node, &c->list);
 195                 break;
 196         default:
 197                 /* no action */
 198                 ;
 199         }
 200
 201         curr_value = pm_qos_get_value(c);
 202         pm_qos_set_value(c, curr_value);
 203
 204         spin_unlock_irqrestore(&pm_qos_lock, flags);
 205
 206         trace_pm_qos_update_target(action, prev_value, curr_value);
 207         if (prev_value != curr_value) {
 208                 blocking_notifier_call_chain(c->notifiers,
 209                                              (unsigned long)curr_value,
 210                                              NULL);
 211                 return 1;
 212         } else {
 213                 return 0;
 214         }
 215 }
 216
 217 /**
 218  * pm_qos_flags_remove_req - Remove device PM QoS flags request.
 219  * @pqf: Device PM QoS flags set to remove the request from.
 220  * @req: Request to remove from the set.
 221  */
 222 static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
 223                                     struct pm_qos_flags_request *req)
 224 {
 225         s32 val = 0;
 226
 227         list_del(&req->node);
 228         list_for_each_entry(req, &pqf->list, node)
 229                 val |= req->flags;
 230
 231         pqf->effective_flags = val;
 232 }
 233
 234 /**
 235  * pm_qos_update_flags - Update a set of PM QoS flags.
 236  * @pqf: Set of flags to update.
 237  * @req: Request to add to the set, to modify, or to remove from the set.
 238  * @action: Action to take on the set.
 239  * @val: Value of the request to add or modify.
 240  *
 241  * Update the given set of PM QoS flags and call notifiers if the aggregate
 242  * value has changed.  Returns 1 if the aggregate constraint value has changed,
 243  * 0 otherwise.
 244  */
 245 bool pm_qos_update_flags(struct pm_qos_flags *pqf,
 246                          struct pm_qos_flags_request *req,
 247                          enum pm_qos_req_action action, s32 val)
 248 {
 249         unsigned long irqflags;
 250         s32 prev_value, curr_value;
 251
 252         spin_lock_irqsave(&pm_qos_lock, irqflags);
 253
 254         prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 255
 256         switch (action) {
 257         case PM_QOS_REMOVE_REQ:
 258                 pm_qos_flags_remove_req(pqf, req);
 259                 break;
 260         case PM_QOS_UPDATE_REQ:
 261                 pm_qos_flags_remove_req(pqf, req);
 262         case PM_QOS_ADD_REQ:
 263                 req->flags = val;
 264                 INIT_LIST_HEAD(&req->node);
 265                 list_add_tail(&req->node, &pqf->list);
 266                 pqf->effective_flags |= val;
 267                 break;
 268         default:
 269                 /* no action */
 270                 ;
 271         }
 272
 273         curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 274
 275         spin_unlock_irqrestore(&pm_qos_lock, irqflags);
 276
 277         trace_pm_qos_update_flags(action, prev_value, curr_value);
 278         return prev_value != curr_value;
 279 }
 280
 281 /**
 282  * pm_qos_request - returns current system wide qos expectation
 283  * @pm_qos_class: identification of which qos value is requested
 284  *
 285  * This function returns the current target value.
 286  */
 287 int pm_qos_request(int pm_qos_class)
 288 {
 289         return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
 290 }
 291 EXPORT_SYMBOL_GPL(pm_qos_request);
 292
 293 int pm_qos_request_active(struct pm_qos_request *req)
 294 {
 295         return req->pm_qos_class != 0;
 296 }
 297 EXPORT_SYMBOL_GPL(pm_qos_request_active);
 298
 299 /**
 300  * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
 301  * @work: work struct for the delayed work (timeout)
 302  *
 303  * This cancels the timeout request by falling back to the default at timeout.
 304  */
 305 static void pm_qos_work_fn(struct work_struct *work)
 306 {
 307         struct pm_qos_request *req = container_of(to_delayed_work(work),
 308                                                   struct pm_qos_request,
 309                                                   work);
 310
 311         pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
 312 }
 313
 314 /**
 315  * pm_qos_add_request - inserts new qos request into the list
 316  * @req: pointer to a preallocated handle
 317  * @pm_qos_class: identifies which list of qos request to use
 318  * @value: defines the qos request
 319  *
 320  * This function inserts a new entry in the pm_qos_class list of requested qos
 321  * performance characteristics.  It recomputes the aggregate QoS expectations
 322  * for the pm_qos_class of parameters and initializes the pm_qos_request
 323  * handle.  Caller needs to save this handle for later use in updates and
 324  * removal.
 325  */
 326
 327 void pm_qos_add_request(struct pm_qos_request *req,
 328                         int pm_qos_class, s32 value)
 329 {
 330         if (!req) /*guard against callers passing in null */
 331                 return;
 332
 333         if (pm_qos_request_active(req)) {
 334                 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
 335                 return;
 336         }
 337         req->pm_qos_class = pm_qos_class;
 338         INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
 339         trace_pm_qos_add_request(pm_qos_class, value);
 340         pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
 341                              &req->node, PM_QOS_ADD_REQ, value);
 342 }
 343 EXPORT_SYMBOL_GPL(pm_qos_add_request);
 344
 345 /**
 346  * pm_qos_update_request - modifies an existing qos request
 347  * @req : handle to list element holding a pm_qos request to use
 348  * @value: defines the qos request
 349  *
 350  * Updates an existing qos request for the pm_qos_class of parameters along
 351  * with updating the target pm_qos_class value.
 352  *
 353  * Attempts are made to make this code callable on hot code paths.
 354  */
 355 void pm_qos_update_request(struct pm_qos_request *req,
 356                            s32 new_value)
 357 {
 358         if (!req) /*guard against callers passing in null */
 359                 return;
 360
 361         if (!pm_qos_request_active(req)) {
 362                 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
 363                 return;
 364         }
 365
 366         cancel_delayed_work_sync(&req->work);
 367
 368         trace_pm_qos_update_request(req->pm_qos_class, new_value);
 369         if (new_value != req->node.prio)
 370                 pm_qos_update_target(
 371                         pm_qos_array[req->pm_qos_class]->constraints,
 372                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 373 }
 374 EXPORT_SYMBOL_GPL(pm_qos_update_request);
 375
 376 /**
 377  * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
 378  * @req : handle to list element holding a pm_qos request to use
 379  * @new_value: defines the temporal qos request
 380  * @timeout_us: the effective duration of this qos request in usecs.
 381  *
 382  * After timeout_us, this qos request is cancelled automatically.
 383  */
 384 void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
 385                                    unsigned long timeout_us)
 386 {
 387         if (!req)
 388                 return;
 389         if (WARN(!pm_qos_request_active(req),
 390                  "%s called for unknown object.", __func__))
 391                 return;
 392
 393         cancel_delayed_work_sync(&req->work);
 394
 395         trace_pm_qos_update_request_timeout(req->pm_qos_class,
 396                                             new_value, timeout_us);
 397         if (new_value != req->node.prio)
 398                 pm_qos_update_target(
 399                         pm_qos_array[req->pm_qos_class]->constraints,
 400                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 401
 402         schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
 403 }
 404
 405 /**
 406  * pm_qos_remove_request - modifies an existing qos request
 407  * @req: handle to request list element
 408  *
 409  * Will remove pm qos request from the list of constraints and
 410  * recompute the current target value for the pm_qos_class.  Call this
 411  * on slow code paths.
 412  */
 413 void pm_qos_remove_request(struct pm_qos_request *req)
 414 {
 415         if (!req) /*guard against callers passing in null */
 416                 return;
 417                 /* silent return to keep pcm code cleaner */
 418
 419         if (!pm_qos_request_active(req)) {
 420                 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
 421                 return;
 422         }
 423
 424         cancel_delayed_work_sync(&req->work);
 425
 426         trace_pm_qos_remove_request(req->pm_qos_class, PM_QOS_DEFAULT_VALUE);
 427         pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
 428                              &req->node, PM_QOS_REMOVE_REQ,
 429                              PM_QOS_DEFAULT_VALUE);
 430         memset(req, 0, sizeof(*req));
 431 }
 432 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
 433
 434 /**
 435  * pm_qos_add_notifier - sets notification entry for changes to target value
 436  * @pm_qos_class: identifies which qos target changes should be notified.
 437  * @notifier: notifier block managed by caller.
 438  *
 439  * will register the notifier into a notification chain that gets called
 440  * upon changes to the pm_qos_class target value.
 441  */
 442 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 443 {
 444         int retval;
 445
 446         retval = blocking_notifier_chain_register(
 447                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 448                         notifier);
 449
 450         return retval;
 451 }
 452 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
 453
 454 /**
 455  * pm_qos_remove_notifier - deletes notification entry from chain.
 456  * @pm_qos_class: identifies which qos target changes are notified.
 457  * @notifier: notifier block to be removed.
 458  *
 459  * will remove the notifier from the notification chain that gets called
 460  * upon changes to the pm_qos_class target value.
 461  */
 462 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 463 {
 464         int retval;
 465
 466         retval = blocking_notifier_chain_unregister(
 467                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 468                         notifier);
 469
 470         return retval;
 471 }
 472 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 473
 474 /* User space interface to PM QoS classes via misc devices */
 475 static int register_pm_qos_misc(struct pm_qos_object *qos)
 476 {
 477         qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
 478         qos->pm_qos_power_miscdev.name = qos->name;
 479         qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
 480
 481         return misc_register(&qos->pm_qos_power_miscdev);
 482 }
 483
 484 static int find_pm_qos_object_by_minor(int minor)
 485 {
 486         int pm_qos_class;
 487
 488         for (pm_qos_class = PM_QOS_CPU_DMA_LATENCY;
 489                 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
 490                 if (minor ==
 491                         pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
 492                         return pm_qos_class;
 493         }
 494         return -1;
 495 }
 496
 497 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 498 {
 499         long pm_qos_class;
 500
 501         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 502         if (pm_qos_class >= PM_QOS_CPU_DMA_LATENCY) {
 503                 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
 504                 if (!req)
 505                         return -ENOMEM;
 506
 507                 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
 508                 filp->private_data = req;
 509
 510                 return 0;
 511         }
 512         return -EPERM;
 513 }
 514
 515 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 516 {
 517         struct pm_qos_request *req;
 518
 519         req = filp->private_data;
 520         pm_qos_remove_request(req);
 521         kfree(req);
 522
 523         return 0;
 524 }
 525
 526
 527 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 528                 size_t count, loff_t *f_pos)
 529 {
 530         s32 value;
 531         unsigned long flags;
 532         struct pm_qos_request *req = filp->private_data;
 533
 534         if (!req)
 535                 return -EINVAL;
 536         if (!pm_qos_request_active(req))
 537                 return -EINVAL;
 538
 539         spin_lock_irqsave(&pm_qos_lock, flags);
 540         value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
 541         spin_unlock_irqrestore(&pm_qos_lock, flags);
 542
 543         return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
 544 }
 545
 546 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 547                 size_t count, loff_t *f_pos)
 548 {
 549         s32 value;
 550         struct pm_qos_request *req;
 551
 552         if (count == sizeof(s32)) {
 553                 if (copy_from_user(&value, buf, sizeof(s32)))
 554                         return -EFAULT;
 555         } else if (count <= 11) { /* ASCII perhaps? */
 556                 char ascii_value[11];
 557                 unsigned long int ulval;
 558                 int ret;
 559
 560                 if (copy_from_user(ascii_value, buf, count))
 561                         return -EFAULT;
 562
 563                 if (count > 10) {
 564                         if (ascii_value[10] == '\n')
 565                                 ascii_value[10] = '\0';
 566                         else
 567                                 return -EINVAL;
 568                 } else {
 569                         ascii_value[count] = '\0';
 570                 }
 571                 ret = kstrtoul(ascii_value, 16, &ulval);
 572                 if (ret) {
 573                         pr_debug("%s, 0x%lx, 0x%x\n", ascii_value, ulval, ret);
 574                         return -EINVAL;
 575                 }
 576                 value = (s32)lower_32_bits(ulval);
 577         } else {
 578                 return -EINVAL;
 579         }
 580
 581         req = filp->private_data;
 582         pm_qos_update_request(req, value);
 583
 584         return count;
 585 }
 586
 587
 588 static int __init pm_qos_power_init(void)
 589 {
 590         int ret = 0;
 591         int i;
 592
 593         BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
 594
 595         for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
 596                 ret = register_pm_qos_misc(pm_qos_array[i]);
 597                 if (ret < 0) {
 598                         printk(KERN_ERR "pm_qos_param: %s setup failed\n",
 599                                pm_qos_array[i]->name);
 600                         return ret;
 601                 }
 602         }
 603
 604         return ret;
 605 }
 606
 607 late_initcall(pm_qos_power_init);