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 #include <linux/debugfs.h>
  45 #include <linux/seq_file.h>
  46
  47 #include <linux/uaccess.h>
  48 #include <linux/export.h>
  49 #include <trace/events/power.h>
  50
  51 /*
  52  * locking rule: all changes to constraints or notifiers lists
  53  * or pm_qos_object list and pm_qos_objects need to happen with pm_qos_lock
  54  * held, taken with _irqsave.  One lock to rule them all
  55  */
  56 struct pm_qos_object {
  57         struct pm_qos_constraints *constraints;
  58         struct miscdevice pm_qos_power_miscdev;
  59         char *name;
  60 };
  61
  62 static DEFINE_SPINLOCK(pm_qos_lock);
  63
  64 static struct pm_qos_object null_pm_qos;
  65
  66 static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
  67 static struct pm_qos_constraints cpu_dma_constraints = {
  68         .list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
  69         .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  70         .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  71         .no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
  72         .type = PM_QOS_MIN,
  73         .notifiers = &cpu_dma_lat_notifier,
  74 };
  75 static struct pm_qos_object cpu_dma_pm_qos = {
  76         .constraints = &cpu_dma_constraints,
  77         .name = "cpu_dma_latency",
  78 };
  79
  80 static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
  81 static struct pm_qos_constraints network_lat_constraints = {
  82         .list = PLIST_HEAD_INIT(network_lat_constraints.list),
  83         .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  84         .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  85         .no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
  86         .type = PM_QOS_MIN,
  87         .notifiers = &network_lat_notifier,
  88 };
  89 static struct pm_qos_object network_lat_pm_qos = {
  90         .constraints = &network_lat_constraints,
  91         .name = "network_latency",
  92 };
  93
  94
  95 static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
  96 static struct pm_qos_constraints network_tput_constraints = {
  97         .list = PLIST_HEAD_INIT(network_tput_constraints.list),
  98         .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
  99         .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
 100         .no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
 101         .type = PM_QOS_MAX,
 102         .notifiers = &network_throughput_notifier,
 103 };
 104 static struct pm_qos_object network_throughput_pm_qos = {
 105         .constraints = &network_tput_constraints,
 106         .name = "network_throughput",
 107 };
 108
 109
 110 static BLOCKING_NOTIFIER_HEAD(memory_bandwidth_notifier);
 111 static struct pm_qos_constraints memory_bw_constraints = {
 112         .list = PLIST_HEAD_INIT(memory_bw_constraints.list),
 113         .target_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
 114         .default_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
 115         .no_constraint_value = PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE,
 116         .type = PM_QOS_SUM,
 117         .notifiers = &memory_bandwidth_notifier,
 118 };
 119 static struct pm_qos_object memory_bandwidth_pm_qos = {
 120         .constraints = &memory_bw_constraints,
 121         .name = "memory_bandwidth",
 122 };
 123
 124
 125 static struct pm_qos_object *pm_qos_array[] = {
 126         &null_pm_qos,
 127         &cpu_dma_pm_qos,
 128         &network_lat_pm_qos,
 129         &network_throughput_pm_qos,
 130         &memory_bandwidth_pm_qos,
 131 };
 132
 133 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 134                 size_t count, loff_t *f_pos);
 135 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 136                 size_t count, loff_t *f_pos);
 137 static int pm_qos_power_open(struct inode *inode, struct file *filp);
 138 static int pm_qos_power_release(struct inode *inode, struct file *filp);
 139
 140 static const struct file_operations pm_qos_power_fops = {
 141         .write = pm_qos_power_write,
 142         .read = pm_qos_power_read,
 143         .open = pm_qos_power_open,
 144         .release = pm_qos_power_release,
 145         .llseek = noop_llseek,
 146 };
 147
 148 /* unlocked internal variant */
 149 static inline int pm_qos_get_value(struct pm_qos_constraints *c)
 150 {
 151         struct plist_node *node;
 152         int total_value = 0;
 153
 154         if (plist_head_empty(&c->list))
 155                 return c->no_constraint_value;
 156
 157         switch (c->type) {
 158         case PM_QOS_MIN:
 159                 return plist_first(&c->list)->prio;
 160
 161         case PM_QOS_MAX:
 162                 return plist_last(&c->list)->prio;
 163
 164         case PM_QOS_SUM:
 165                 plist_for_each(node, &c->list)
 166                         total_value += node->prio;
 167
 168                 return total_value;
 169
 170         default:
 171                 /* runtime check for not using enum */
 172                 BUG();
 173                 return PM_QOS_DEFAULT_VALUE;
 174         }
 175 }
 176
 177 s32 pm_qos_read_value(struct pm_qos_constraints *c)
 178 {
 179         return c->target_value;
 180 }
 181
 182 static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
 183 {
 184         c->target_value = value;
 185 }
 186
 187 static inline int pm_qos_get_value(struct pm_qos_constraints *c);
 188 static int pm_qos_dbg_show_requests(struct seq_file *s, void *unused)
 189 {
 190         struct pm_qos_object *qos = (struct pm_qos_object *)s->private;
 191         struct pm_qos_constraints *c;
 192         struct pm_qos_request *req;
 193         char *type;
 194         unsigned long flags;
 195         int tot_reqs = 0;
 196         int active_reqs = 0;
 197
 198         if (IS_ERR_OR_NULL(qos)) {
 199                 pr_err("%s: bad qos param!\n", __func__);
 200                 return -EINVAL;
 201         }
 202         c = qos->constraints;
 203         if (IS_ERR_OR_NULL(c)) {
 204                 pr_err("%s: Bad constraints on qos?\n", __func__);
 205                 return -EINVAL;
 206         }
 207
 208         /* Lock to ensure we have a snapshot */
 209         spin_lock_irqsave(&pm_qos_lock, flags);
 210         if (plist_head_empty(&c->list)) {
 211                 seq_puts(s, "Empty!\n");
 212                 goto out;
 213         }
 214
 215         switch (c->type) {
 216         case PM_QOS_MIN:
 217                 type = "Minimum";
 218                 break;
 219         case PM_QOS_MAX:
 220                 type = "Maximum";
 221                 break;
 222         case PM_QOS_SUM:
 223                 type = "Sum";
 224                 break;
 225         default:
 226                 type = "Unknown";
 227         }
 228
 229         plist_for_each_entry(req, &c->list, node) {
 230                 char *state = "Default";
 231
 232                 if ((req->node).prio != c->default_value) {
 233                         active_reqs++;
 234                         state = "Active";
 235                 }
 236                 tot_reqs++;
 237                 seq_printf(s, "%d: %d: %s\n", tot_reqs,
 238                            (req->node).prio, state);
 239         }
 240
 241         seq_printf(s, "Type=%s, Value=%d, Requests: active=%d / total=%d\n",
 242                    type, pm_qos_get_value(c), active_reqs, tot_reqs);
 243
 244 out:
 245         spin_unlock_irqrestore(&pm_qos_lock, flags);
 246         return 0;
 247 }
 248
 249 static int pm_qos_dbg_open(struct inode *inode, struct file *file)
 250 {
 251         return single_open(file, pm_qos_dbg_show_requests,
 252                            inode->i_private);
 253 }
 254
 255 static const struct file_operations pm_qos_debug_fops = {
 256         .open           = pm_qos_dbg_open,
 257         .read           = seq_read,
 258         .llseek         = seq_lseek,
 259         .release        = single_release,
 260 };
 261
 262 /**
 263  * pm_qos_update_target - manages the constraints list and calls the notifiers
 264  *  if needed
 265  * @c: constraints data struct
 266  * @node: request to add to the list, to update or to remove
 267  * @action: action to take on the constraints list
 268  * @value: value of the request to add or update
 269  *
 270  * This function returns 1 if the aggregated constraint value has changed, 0
 271  *  otherwise.
 272  */
 273 int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 274                          enum pm_qos_req_action action, int value)
 275 {
 276         unsigned long flags;
 277         int prev_value, curr_value, new_value;
 278         int ret;
 279
 280         spin_lock_irqsave(&pm_qos_lock, flags);
 281         prev_value = pm_qos_get_value(c);
 282         if (value == PM_QOS_DEFAULT_VALUE)
 283                 new_value = c->default_value;
 284         else
 285                 new_value = value;
 286
 287         switch (action) {
 288         case PM_QOS_REMOVE_REQ:
 289                 plist_del(node, &c->list);
 290                 break;
 291         case PM_QOS_UPDATE_REQ:
 292                 /*
 293                  * to change the list, we atomically remove, reinit
 294                  * with new value and add, then see if the extremal
 295                  * changed
 296                  */
 297                 plist_del(node, &c->list);
 298         case PM_QOS_ADD_REQ:
 299                 plist_node_init(node, new_value);
 300                 plist_add(node, &c->list);
 301                 break;
 302         default:
 303                 /* no action */
 304                 ;
 305         }
 306
 307         curr_value = pm_qos_get_value(c);
 308         pm_qos_set_value(c, curr_value);
 309
 310         spin_unlock_irqrestore(&pm_qos_lock, flags);
 311
 312         trace_pm_qos_update_target(action, prev_value, curr_value);
 313         if (prev_value != curr_value) {
 314                 ret = 1;
 315                 if (c->notifiers)
 316                         blocking_notifier_call_chain(c->notifiers,
 317                                                      (unsigned long)curr_value,
 318                                                      NULL);
 319         } else {
 320                 ret = 0;
 321         }
 322         return ret;
 323 }
 324
 325 /**
 326  * pm_qos_flags_remove_req - Remove device PM QoS flags request.
 327  * @pqf: Device PM QoS flags set to remove the request from.
 328  * @req: Request to remove from the set.
 329  */
 330 static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
 331                                     struct pm_qos_flags_request *req)
 332 {
 333         s32 val = 0;
 334
 335         list_del(&req->node);
 336         list_for_each_entry(req, &pqf->list, node)
 337                 val |= req->flags;
 338
 339         pqf->effective_flags = val;
 340 }
 341
 342 /**
 343  * pm_qos_update_flags - Update a set of PM QoS flags.
 344  * @pqf: Set of flags to update.
 345  * @req: Request to add to the set, to modify, or to remove from the set.
 346  * @action: Action to take on the set.
 347  * @val: Value of the request to add or modify.
 348  *
 349  * Update the given set of PM QoS flags and call notifiers if the aggregate
 350  * value has changed.  Returns 1 if the aggregate constraint value has changed,
 351  * 0 otherwise.
 352  */
 353 bool pm_qos_update_flags(struct pm_qos_flags *pqf,
 354                          struct pm_qos_flags_request *req,
 355                          enum pm_qos_req_action action, s32 val)
 356 {
 357         unsigned long irqflags;
 358         s32 prev_value, curr_value;
 359
 360         spin_lock_irqsave(&pm_qos_lock, irqflags);
 361
 362         prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 363
 364         switch (action) {
 365         case PM_QOS_REMOVE_REQ:
 366                 pm_qos_flags_remove_req(pqf, req);
 367                 break;
 368         case PM_QOS_UPDATE_REQ:
 369                 pm_qos_flags_remove_req(pqf, req);
 370         case PM_QOS_ADD_REQ:
 371                 req->flags = val;
 372                 INIT_LIST_HEAD(&req->node);
 373                 list_add_tail(&req->node, &pqf->list);
 374                 pqf->effective_flags |= val;
 375                 break;
 376         default:
 377                 /* no action */
 378                 ;
 379         }
 380
 381         curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
 382
 383         spin_unlock_irqrestore(&pm_qos_lock, irqflags);
 384
 385         trace_pm_qos_update_flags(action, prev_value, curr_value);
 386         return prev_value != curr_value;
 387 }
 388
 389 /**
 390  * pm_qos_request - returns current system wide qos expectation
 391  * @pm_qos_class: identification of which qos value is requested
 392  *
 393  * This function returns the current target value.
 394  */
 395 int pm_qos_request(int pm_qos_class)
 396 {
 397         return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
 398 }
 399 EXPORT_SYMBOL_GPL(pm_qos_request);
 400
 401 int pm_qos_request_active(struct pm_qos_request *req)
 402 {
 403         return req->pm_qos_class != 0;
 404 }
 405 EXPORT_SYMBOL_GPL(pm_qos_request_active);
 406
 407 static void __pm_qos_update_request(struct pm_qos_request *req,
 408                            s32 new_value)
 409 {
 410         trace_pm_qos_update_request(req->pm_qos_class, new_value);
 411
 412         if (new_value != req->node.prio)
 413                 pm_qos_update_target(
 414                         pm_qos_array[req->pm_qos_class]->constraints,
 415                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 416 }
 417
 418 /**
 419  * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
 420  * @work: work struct for the delayed work (timeout)
 421  *
 422  * This cancels the timeout request by falling back to the default at timeout.
 423  */
 424 static void pm_qos_work_fn(struct work_struct *work)
 425 {
 426         struct pm_qos_request *req = container_of(to_delayed_work(work),
 427                                                   struct pm_qos_request,
 428                                                   work);
 429
 430         __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
 431 }
 432
 433 /**
 434  * pm_qos_add_request - inserts new qos request into the list
 435  * @req: pointer to a preallocated handle
 436  * @pm_qos_class: identifies which list of qos request to use
 437  * @value: defines the qos request
 438  *
 439  * This function inserts a new entry in the pm_qos_class list of requested qos
 440  * performance characteristics.  It recomputes the aggregate QoS expectations
 441  * for the pm_qos_class of parameters and initializes the pm_qos_request
 442  * handle.  Caller needs to save this handle for later use in updates and
 443  * removal.
 444  */
 445
 446 void pm_qos_add_request(struct pm_qos_request *req,
 447                         int pm_qos_class, s32 value)
 448 {
 449         if (!req) /*guard against callers passing in null */
 450                 return;
 451
 452         if (pm_qos_request_active(req)) {
 453                 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
 454                 return;
 455         }
 456         req->pm_qos_class = pm_qos_class;
 457         INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
 458         trace_pm_qos_add_request(pm_qos_class, value);
 459         pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
 460                              &req->node, PM_QOS_ADD_REQ, value);
 461 }
 462 EXPORT_SYMBOL_GPL(pm_qos_add_request);
 463
 464 /**
 465  * pm_qos_update_request - modifies an existing qos request
 466  * @req : handle to list element holding a pm_qos request to use
 467  * @value: defines the qos request
 468  *
 469  * Updates an existing qos request for the pm_qos_class of parameters along
 470  * with updating the target pm_qos_class value.
 471  *
 472  * Attempts are made to make this code callable on hot code paths.
 473  */
 474 void pm_qos_update_request(struct pm_qos_request *req,
 475                            s32 new_value)
 476 {
 477         if (!req) /*guard against callers passing in null */
 478                 return;
 479
 480         if (!pm_qos_request_active(req)) {
 481                 WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
 482                 return;
 483         }
 484
 485         cancel_delayed_work_sync(&req->work);
 486         __pm_qos_update_request(req, new_value);
 487 }
 488 EXPORT_SYMBOL_GPL(pm_qos_update_request);
 489
 490 /**
 491  * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
 492  * @req : handle to list element holding a pm_qos request to use
 493  * @new_value: defines the temporal qos request
 494  * @timeout_us: the effective duration of this qos request in usecs.
 495  *
 496  * After timeout_us, this qos request is cancelled automatically.
 497  */
 498 void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
 499                                    unsigned long timeout_us)
 500 {
 501         if (!req)
 502                 return;
 503         if (WARN(!pm_qos_request_active(req),
 504                  "%s called for unknown object.", __func__))
 505                 return;
 506
 507         cancel_delayed_work_sync(&req->work);
 508
 509         trace_pm_qos_update_request_timeout(req->pm_qos_class,
 510                                             new_value, timeout_us);
 511         if (new_value != req->node.prio)
 512                 pm_qos_update_target(
 513                         pm_qos_array[req->pm_qos_class]->constraints,
 514                         &req->node, PM_QOS_UPDATE_REQ, new_value);
 515
 516         schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
 517 }
 518
 519 /**
 520  * pm_qos_remove_request - modifies an existing qos request
 521  * @req: handle to request list element
 522  *
 523  * Will remove pm qos request from the list of constraints and
 524  * recompute the current target value for the pm_qos_class.  Call this
 525  * on slow code paths.
 526  */
 527 void pm_qos_remove_request(struct pm_qos_request *req)
 528 {
 529         if (!req) /*guard against callers passing in null */
 530                 return;
 531                 /* silent return to keep pcm code cleaner */
 532
 533         if (!pm_qos_request_active(req)) {
 534                 WARN(1, KERN_ERR "pm_qos_remove_request() called for unknown object\n");
 535                 return;
 536         }
 537
 538         cancel_delayed_work_sync(&req->work);
 539
 540         trace_pm_qos_remove_request(req->pm_qos_class, PM_QOS_DEFAULT_VALUE);
 541         pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
 542                              &req->node, PM_QOS_REMOVE_REQ,
 543                              PM_QOS_DEFAULT_VALUE);
 544         memset(req, 0, sizeof(*req));
 545 }
 546 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
 547
 548 /**
 549  * pm_qos_add_notifier - sets notification entry for changes to target value
 550  * @pm_qos_class: identifies which qos target changes should be notified.
 551  * @notifier: notifier block managed by caller.
 552  *
 553  * will register the notifier into a notification chain that gets called
 554  * upon changes to the pm_qos_class target value.
 555  */
 556 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
 557 {
 558         int retval;
 559
 560         retval = blocking_notifier_chain_register(
 561                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 562                         notifier);
 563
 564         return retval;
 565 }
 566 EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
 567
 568 /**
 569  * pm_qos_remove_notifier - deletes notification entry from chain.
 570  * @pm_qos_class: identifies which qos target changes are notified.
 571  * @notifier: notifier block to be removed.
 572  *
 573  * will remove the notifier from the notification chain that gets called
 574  * upon changes to the pm_qos_class target value.
 575  */
 576 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
 577 {
 578         int retval;
 579
 580         retval = blocking_notifier_chain_unregister(
 581                         pm_qos_array[pm_qos_class]->constraints->notifiers,
 582                         notifier);
 583
 584         return retval;
 585 }
 586 EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
 587
 588 /* User space interface to PM QoS classes via misc devices */
 589 static int register_pm_qos_misc(struct pm_qos_object *qos, struct dentry *d)
 590 {
 591         qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
 592         qos->pm_qos_power_miscdev.name = qos->name;
 593         qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
 594
 595         if (d) {
 596                 (void)debugfs_create_file(qos->name, S_IRUGO, d,
 597                                           (void *)qos, &pm_qos_debug_fops);
 598         }
 599
 600         return misc_register(&qos->pm_qos_power_miscdev);
 601 }
 602
 603 static int find_pm_qos_object_by_minor(int minor)
 604 {
 605         int pm_qos_class;
 606
 607         for (pm_qos_class = PM_QOS_CPU_DMA_LATENCY;
 608                 pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
 609                 if (minor ==
 610                         pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
 611                         return pm_qos_class;
 612         }
 613         return -1;
 614 }
 615
 616 static int pm_qos_power_open(struct inode *inode, struct file *filp)
 617 {
 618         long pm_qos_class;
 619
 620         pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
 621         if (pm_qos_class >= PM_QOS_CPU_DMA_LATENCY) {
 622                 struct pm_qos_request *req = kzalloc(sizeof(*req), GFP_KERNEL);
 623                 if (!req)
 624                         return -ENOMEM;
 625
 626                 pm_qos_add_request(req, pm_qos_class, PM_QOS_DEFAULT_VALUE);
 627                 filp->private_data = req;
 628
 629                 return 0;
 630         }
 631         return -EPERM;
 632 }
 633
 634 static int pm_qos_power_release(struct inode *inode, struct file *filp)
 635 {
 636         struct pm_qos_request *req;
 637
 638         req = filp->private_data;
 639         pm_qos_remove_request(req);
 640         kfree(req);
 641
 642         return 0;
 643 }
 644
 645
 646 static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 647                 size_t count, loff_t *f_pos)
 648 {
 649         s32 value;
 650         unsigned long flags;
 651         struct pm_qos_request *req = filp->private_data;
 652
 653         if (!req)
 654                 return -EINVAL;
 655         if (!pm_qos_request_active(req))
 656                 return -EINVAL;
 657
 658         spin_lock_irqsave(&pm_qos_lock, flags);
 659         value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
 660         spin_unlock_irqrestore(&pm_qos_lock, flags);
 661
 662         return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
 663 }
 664
 665 static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
 666                 size_t count, loff_t *f_pos)
 667 {
 668         s32 value;
 669         struct pm_qos_request *req;
 670
 671         if (count == sizeof(s32)) {
 672                 if (copy_from_user(&value, buf, sizeof(s32)))
 673                         return -EFAULT;
 674         } else {
 675                 int ret;
 676
 677                 ret = kstrtos32_from_user(buf, count, 16, &value);
 678                 if (ret)
 679                         return ret;
 680         }
 681
 682         req = filp->private_data;
 683         pm_qos_update_request(req, value);
 684
 685         return count;
 686 }
 687
 688
 689 static int __init pm_qos_power_init(void)
 690 {
 691         int ret = 0;
 692         int i;
 693         struct dentry *d;
 694
 695         BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
 696
 697         d = debugfs_create_dir("pm_qos", NULL);
 698         if (IS_ERR_OR_NULL(d))
 699                 d = NULL;
 700
 701         for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
 702                 ret = register_pm_qos_misc(pm_qos_array[i], d);
 703                 if (ret < 0) {
 704                         printk(KERN_ERR "pm_qos_param: %s setup failed\n",
 705                                pm_qos_array[i]->name);
 706                         return ret;
 707                 }
 708         }
 709
 710         return ret;
 711 }
 712
 713 late_initcall(pm_qos_power_init);