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
  48 /*
  49  * locking rule: all changes to constraints or notifiers lists
  50  * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
  51  * held, taken with _irqsave.  One lock to rule them all
  52  */
  53 struct pm_qos_object {
  54         struct pm_qos_constraints *constraints;
  55         struct miscdevice pm_qos_power_miscdev;
  56         char *name;
  57 };
  58
  59 static DEFINE_SPINLOCK(pm_qos_lock);
  60
  61 static struct pm_qos_object null_pm_qos;
  62
  63 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
  64 static struct pm_qos_constraints cpu_dma_constraints = {
  65         .list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
  66         .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  67         .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  68         .type = PM_QOS_MIN,
  69         .notifiers = &cpu_dma_lat_notifier,
  70 };
  71 static struct pm_qos_object cpu_dma_pm_qos = {
  72         .constraints = &cpu_dma_constraints,
  73         .name = "cpu_dma_latency",
  74 };
  75
  76 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
  77 static struct pm_qos_constraints network_lat_constraints = {
  78         .list = PLIST_HEAD_INIT(network_lat_constraints.list),
  79         .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  80         .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  81         .type = PM_QOS_MIN,
  82         .notifiers = &network_lat_notifier,
  83 };
  84 static struct pm_qos_object network_lat_pm_qos = {
  85         .constraints = &network_lat_constraints,
  86         .name = "network_latency",
  87 };
  88
  89
  90 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
  91 static struct pm_qos_constraints network_tput_constraints = {
  92         .list = PLIST_HEAD_INIT(network_tput_constraints.list),
  93         .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  94         .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  95         .type = PM_QOS_MAX,
  96         .notifiers = &network_throughput_notifier,
  97 };
  98 static struct pm_qos_object network_throughput_pm_qos = {
  99         .constraints = &network_tput_constraints,
 100         .name = "network_throughput",
 101 };
 102
 103
 104 static struct pm_qos_object *pm_qos_array[] = {
 105         &null_pm_qos,
 106         &cpu_dma_pm_qos,
 107         &network_lat_pm_qos,
 108         &network_throughput_pm_qos
 109 };
 110
 111 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 112                 size_t count, loff_t *f_pos);
 113 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 114                 size_t count, loff_t *f_pos);
 115 static int pm_qos_power_open(struct inode *inode, struct file *filp);
 116 static int pm_qos_power_release(struct inode *inode, struct file *filp);
 117
 118 static const struct file_operations pm_qos_power_fops = {
 119         .write = pm_qos_power_write,
 120         .read = pm_qos_power_read,
 121         .open = pm_qos_power_open,
 122         .release = pm_qos_power_release,
 123         .llseek = noop_llseek,
 124 };
 125
 126 /* unlocked internal variant */
 127 static inline int pm_qos_get_value(struct pm_qos_constraints *c)
 128 {
 129         if (plist_head_empty(&c->list))
 130                 return c->default_value;
 131
 132         switch (c->type) {
 133         case PM_QOS_MIN:
 134                 return plist_first(&c->list)->prio;
 135
 136         case PM_QOS_MAX:
 137                 return plist_last(&c->list)->prio;
 138
 139         default:
 140                 /* runtime check for not using enum */
 141                 BUG();
 142                 return PM_QOS_DEFAULT_VALUE;
 143         }
 144 }
 145
 146 s32 pm_qos_read_value(struct pm_qos_constraints *c)
 147 {
 148         return c->target_value;
 149 }
 150
 151 static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
 152 {
 153         c->target_value = value;
 154 }
 155
 156 /**
 157  * pm_qos_update_target - manages the constraints list and calls the notifiers
 158  *  if needed
 159  * @c: constraints data struct
 160  * @node: request to add to the list, to update or to remove
 161  * @action: action to take on the constraints list
 162  * @value: value of the request to add or update
 163  *
 164  * This function returns 1 if the aggregated constraint value has changed, 0
 165  *  otherwise.
 166  */
 167 int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 168                          enum pm_qos_req_action action, int value)
 169 {
 170         unsigned long flags;
 171         int prev_value, curr_value, new_value;
 172
 173         spin_lock_irqsave(&pm_qos_lock, flags);
 174         prev_value = pm_qos_get_value(c);
 175         if (value == PM_QOS_DEFAULT_VALUE)
 176                 new_value = c->default_value;
 177         else
 178                 new_value = value;
 179
 180         switch (action) {
 181         case PM_QOS_REMOVE_REQ:
 182                 plist_del(node, &c->list);
 183                 break;
 184         case PM_QOS_UPDATE_REQ:
 185                 /*
 186                  * to change the list, we atomically remove, reinit
 187                  * with new value and add, then see if the extremal
 188                  * changed
 189                  */
 190                 plist_del(node, &c->list);
 191         case PM_QOS_ADD_REQ:
 192                 plist_node_init(node, new_value);
 193                 plist_add(node, &c->list);
 194                 break;
 195         default:
 196                 /* no action */
 197                 ;
 198         }
 199
 200         curr_value = pm_qos_get_value(c);
 201         pm_qos_set_value(c, curr_value);
 202
 203         spin_unlock_irqrestore(&pm_qos_lock, flags);
 204
 205         if (prev_value != curr_value) {
 206                 blocking_notifier_call_chain(c->notifiers,
 207                                              (unsigned long)curr_value,
 208                                              NULL);
 209                 return 1;
 210         } else {
 211                 return 0;
 212         }
 213 }
 214
 215 /**
 216  * pm_qos_flags_remove_req - Remove device PM QoS flags request.
 217  * @pqf: Device PM QoS flags set to remove the request from.
 218  * @req: Request to remove from the set.
 219  */
 220 static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
 221                                     struct pm_qos_flags_request *req)
 222 {
 223         s32 val = 0;
 224
 225         list_del(&req->node);
 226         list_for_each_entry(req, &pqf->list, node)
 227                 val |= req->flags;
 228
 229         pqf->effective_flags = val;
 230 }
 231
 232 /**
 233  * pm_qos_update_flags - Update a set of PM QoS flags.
 234  * @pqf: Set of flags to update.
 235  * @req: Request to add to the set, to modify, or to remove from the set.
 236  * @action: Action to take on the set.
 237  * @val: Value of the request to add or modify.
 238  *
 239  * Update the given set of PM QoS flags and call notifiers if the aggregate
 240  * value has changed.  Returns 1 if the aggregate constraint value has changed,
 241  * 0 otherwise.
 242  */
 243 bool pm_qos_update_flags(struct pm_qos_flags *pqf,
 244                          struct pm_qos_flags_request *req,
 245                          enum pm_qos_req_action action, s32 val)
 246 {
 247         unsigned long irqflags;
 248         s32 prev_value, curr_value;
 249
 250         spin_lock_irqsave(&pm_qos_lock, irqflags);
 251
 252         prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 253
 254         switch (action) {
 255         case PM_QOS_REMOVE_REQ:
 256                 pm_qos_flags_remove_req(pqf, req);
 257                 break;
 258         case PM_QOS_UPDATE_REQ:
 259                 pm_qos_flags_remove_req(pqf, req);
 260         case PM_QOS_ADD_REQ:
 261                 req->flags = val;
 262                 INIT_LIST_HEAD(&req->node);
 263                 list_add_tail(&req->node, &pqf->list);
 264                 pqf->effective_flags |= val;
 265                 break;
 266         default:
 267                 /* no action */
 268                 ;
 269         }
 270
 271         curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 272
 273         spin_unlock_irqrestore(&pm_qos_lock, irqflags);
 274
 275         return prev_value != curr_value;
 276 }
 277
 278 /**
 279  * pm_qos_request - returns current system wide qos expectation
 280  * @pm_qos_class: identification of which qos value is requested
 281  *
 282  * This function returns the current target value.
 283  */
 284 int pm_qos_request(int pm_qos_class)
 285 {
 286         return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
 287 }
 288 EXPORT_SYMBOL_GPL(pm_qos_request);
 289
 290 int pm_qos_request_active(struct pm_qos_request *req)
 291 {
 292         return req->pm_qos_class != 0;
 293 }
 294 EXPORT_SYMBOL_GPL(pm_qos_request_active);
 295
 296 static void __pm_qos_update_request(struct pm_qos_request *req,
 297                            s32 new_value)
 298 {
 299         if (new_value != req->node.prio)
 300                 pm_qos_update_target(
 301                         pm_qos_array[req->pm_qos_class]->constraints,
 302                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 303 }
 304
 305 /**
 306  * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
 307  * @work: work struct for the delayed work (timeout)
 308  *
 309  * This cancels the timeout request by falling back to the default at timeout.
 310  */
 311 static void pm_qos_work_fn(struct work_struct *work)
 312 {
 313         struct pm_qos_request *req = container_of(to_delayed_work(work),
 314                                                   struct pm_qos_request,
 315                                                   work);
 316
 317         __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
 318 }
 319
 320 /**
 321  * pm_qos_add_request - inserts new qos request into the list
 322  * @req: pointer to a preallocated handle
 323  * @pm_qos_class: identifies which list of qos request to use
 324  * @value: defines the qos request
 325  *
 326  * This function inserts a new entry in the pm_qos_class list of requested qos
 327  * performance characteristics.  It recomputes the aggregate QoS expectations
 328  * for the pm_qos_class of parameters and initializes the pm_qos_request
 329  * handle.  Caller needs to save this handle for later use in updates and
 330  * removal.
 331  */
 332
 333 void pm_qos_add_request(struct pm_qos_request *req,
 334                         int pm_qos_class, s32 value)
 335 {
 336         if (!req) /*guard against callers passing in null */
 337                 return;
 338
 339         if (pm_qos_request_active(req)) {
 340                 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
 341                 return;
 342         }
 343         req->pm_qos_class = pm_qos_class;
 344         INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
 345         pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
 346                              &req->node, PM_QOS_ADD_REQ, value);
 347 }
 348 EXPORT_SYMBOL_GPL(pm_qos_add_request);
 349
 350 /**
 351  * pm_qos_update_request - modifies an existing qos request
 352  * @req : handle to list element holding a pm_qos request to use
 353  * @value: defines the qos request
 354  *
 355  * Updates an existing qos request for the pm_qos_class of parameters along
 356  * with updating the target pm_qos_class value.
 357  *
 358  * Attempts are made to make this code callable on hot code paths.
 359  */
 360 void pm_qos_update_request(struct pm_qos_request *req,
 361                            s32 new_value)
 362 {
 363         if (!req) /*guard against callers passing in null */
 364                 return;
 365
 366         if (!pm_qos_request_active(req)) {
 367                 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
 368                 return;
 369         }
 370
 371         cancel_delayed_work_sync(&req->work);
 372         __pm_qos_update_request(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         if (new_value != req->node.prio)
 396                 pm_qos_update_target(
 397                         pm_qos_array[req->pm_qos_class]->constraints,
 398                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 399
 400         schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
 401 }
 402
 403 /**
 404  * pm_qos_remove_request - modifies an existing qos request
 405  * @req: handle to request list element
 406  *
 407  * Will remove pm qos request from the list of constraints and
 408  * recompute the current target value for the pm_qos_class.  Call this
 409  * on slow code paths.
 410  */
 411 void pm_qos_remove_request(struct pm_qos_request *req)
 412 {
 413         if (!req) /*guard against callers passing in null */
 414                 return;
 415                 /* silent return to keep pcm code cleaner */
 416
 417         if (!pm_qos_request_active(req)) {
 418                 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
 419                 return;
 420         }
 421
 422         cancel_delayed_work_sync(&req->work);
 423
 424         pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
 425                              &req->node, PM_QOS_REMOVE_REQ,
 426                              PM_QOS_DEFAULT_VALUE);
 427         memset(req, 0, sizeof(*req));
 428 }
 429 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
 430
 431 /**
 432  * pm_qos_add_notifier - sets notification entry for changes to target value
 433  * @pm_qos_class: identifies which qos target changes should be notified.
 434  * @notifier: notifier block managed by caller.
 435  *
 436  * will register the notifier into a notification chain that gets called
 437  * upon changes to the pm_qos_class target value.
 438  */
 439 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 440 {
 441         int retval;
 442
 443         retval = blocking_notifier_chain_register(
 444                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 445                         notifier);
 446
 447         return retval;
 448 }
 449 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
 450
 451 /**
 452  * pm_qos_remove_notifier - deletes notification entry from chain.
 453  * @pm_qos_class: identifies which qos target changes are notified.
 454  * @notifier: notifier block to be removed.
 455  *
 456  * will remove the notifier from the notification chain that gets called
 457  * upon changes to the pm_qos_class target value.
 458  */
 459 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 460 {
 461         int retval;
 462
 463         retval = blocking_notifier_chain_unregister(
 464                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 465                         notifier);
 466
 467         return retval;
 468 }
 469 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 470
 471 /* User space interface to PM QoS classes via misc devices */
 472 static int register_pm_qos_misc(struct pm_qos_object *qos)
 473 {
 474         qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
 475         qos->pm_qos_power_miscdev.name = qos->name;
 476         qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
 477
 478         return misc_register(&qos->pm_qos_power_miscdev);
 479 }
 480
 481 static int find_pm_qos_object_by_minor(int minor)
 482 {
 483         int pm_qos_class;
 484
 485         for (pm_qos_class = 0;
 486                 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
 487                 if (minor ==
 488                         pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
 489                         return pm_qos_class;
 490         }
 491         return -1;
 492 }
 493
 494 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 495 {
 496         long pm_qos_class;
 497
 498         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 499         if (pm_qos_class >= 0) {
 500                 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
 501                 if (!req)
 502                         return -ENOMEM;
 503
 504                 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
 505                 filp->private_data = req;
 506
 507                 return 0;
 508         }
 509         return -EPERM;
 510 }
 511
 512 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 513 {
 514         struct pm_qos_request *req;
 515
 516         req = filp->private_data;
 517         pm_qos_remove_request(req);
 518         kfree(req);
 519
 520         return 0;
 521 }
 522
 523
 524 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 525                 size_t count, loff_t *f_pos)
 526 {
 527         s32 value;
 528         unsigned long flags;
 529         struct pm_qos_request *req = filp->private_data;
 530
 531         if (!req)
 532                 return -EINVAL;
 533         if (!pm_qos_request_active(req))
 534                 return -EINVAL;
 535
 536         spin_lock_irqsave(&pm_qos_lock, flags);
 537         value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
 538         spin_unlock_irqrestore(&pm_qos_lock, flags);
 539
 540         return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
 541 }
 542
 543 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 544                 size_t count, loff_t *f_pos)
 545 {
 546         s32 value;
 547         struct pm_qos_request *req;
 548
 549         if (count == sizeof(s32)) {
 550                 if (copy_from_user(&value, buf, sizeof(s32)))
 551                         return -EFAULT;
 552         } else if (count <= 11) { /* ASCII perhaps? */
 553                 char ascii_value[11];
 554                 unsigned long int ulval;
 555                 int ret;
 556
 557                 if (copy_from_user(ascii_value, buf, count))
 558                         return -EFAULT;
 559
 560                 if (count > 10) {
 561                         if (ascii_value[10] == '\n')
 562                                 ascii_value[10] = '\0';
 563                         else
 564                                 return -EINVAL;
 565                 } else {
 566                         ascii_value[count] = '\0';
 567                 }
 568                 ret = kstrtoul(ascii_value, 16, &ulval);
 569                 if (ret) {
 570                         pr_debug("%s, 0x%lx, 0x%x\n", ascii_value, ulval, ret);
 571                         return -EINVAL;
 572                 }
 573                 value = (s32)lower_32_bits(ulval);
 574         } else {
 575                 return -EINVAL;
 576         }
 577
 578         req = filp->private_data;
 579         pm_qos_update_request(req, value);
 580
 581         return count;
 582 }
 583
 584
 585 static int __init pm_qos_power_init(void)
 586 {
 587         int ret = 0;
 588         int i;
 589
 590         BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
 591
 592         for (i = 1; i < PM_QOS_NUM_CLASSES; i++) {
 593                 ret = register_pm_qos_misc(pm_qos_array[i]);
 594                 if (ret < 0) {
 595                         printk(KERN_ERR "pm_qos_param: %s setup failed\n",
 596                                pm_qos_array[i]->name);
 597                         return ret;
 598                 }
 599         }
 600
 601         return ret;
 602 }
 603
 604 late_initcall(pm_qos_power_init);