linux/drivers/base/power/opp.c
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   1/*
   2 * Generic OPP Interface
   3 *
   4 * Copyright (C) 2009-2010 Texas Instruments Incorporated.
   5 *      Nishanth Menon
   6 *      Romit Dasgupta
   7 *      Kevin Hilman
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License version 2 as
  11 * published by the Free Software Foundation.
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/errno.h>
  16#include <linux/err.h>
  17#include <linux/init.h>
  18#include <linux/slab.h>
  19#include <linux/cpufreq.h>
  20#include <linux/device.h>
  21#include <linux/list.h>
  22#include <linux/rculist.h>
  23#include <linux/rcupdate.h>
  24#include <linux/opp.h>
  25#include <linux/of.h>
  26#include <linux/export.h>
  27
  28/*
  29 * Internal data structure organization with the OPP layer library is as
  30 * follows:
  31 * dev_opp_list (root)
  32 *      |- device 1 (represents voltage domain 1)
  33 *      |       |- opp 1 (availability, freq, voltage)
  34 *      |       |- opp 2 ..
  35 *      ...     ...
  36 *      |       `- opp n ..
  37 *      |- device 2 (represents the next voltage domain)
  38 *      ...
  39 *      `- device m (represents mth voltage domain)
  40 * device 1, 2.. are represented by dev_opp structure while each opp
  41 * is represented by the opp structure.
  42 */
  43
  44/**
  45 * struct opp - Generic OPP description structure
  46 * @node:       opp list node. The nodes are maintained throughout the lifetime
  47 *              of boot. It is expected only an optimal set of OPPs are
  48 *              added to the library by the SoC framework.
  49 *              RCU usage: opp list is traversed with RCU locks. node
  50 *              modification is possible realtime, hence the modifications
  51 *              are protected by the dev_opp_list_lock for integrity.
  52 *              IMPORTANT: the opp nodes should be maintained in increasing
  53 *              order.
  54 * @available:  true/false - marks if this OPP as available or not
  55 * @rate:       Frequency in hertz
  56 * @u_volt:     Nominal voltage in microvolts corresponding to this OPP
  57 * @dev_opp:    points back to the device_opp struct this opp belongs to
  58 * @head:       RCU callback head used for deferred freeing
  59 *
  60 * This structure stores the OPP information for a given device.
  61 */
  62struct opp {
  63        struct list_head node;
  64
  65        bool available;
  66        unsigned long rate;
  67        unsigned long u_volt;
  68
  69        struct device_opp *dev_opp;
  70        struct rcu_head head;
  71};
  72
  73/**
  74 * struct device_opp - Device opp structure
  75 * @node:       list node - contains the devices with OPPs that
  76 *              have been registered. Nodes once added are not modified in this
  77 *              list.
  78 *              RCU usage: nodes are not modified in the list of device_opp,
  79 *              however addition is possible and is secured by dev_opp_list_lock
  80 * @dev:        device pointer
  81 * @head:       notifier head to notify the OPP availability changes.
  82 * @opp_list:   list of opps
  83 *
  84 * This is an internal data structure maintaining the link to opps attached to
  85 * a device. This structure is not meant to be shared to users as it is
  86 * meant for book keeping and private to OPP library
  87 */
  88struct device_opp {
  89        struct list_head node;
  90
  91        struct device *dev;
  92        struct srcu_notifier_head head;
  93        struct list_head opp_list;
  94};
  95
  96/*
  97 * The root of the list of all devices. All device_opp structures branch off
  98 * from here, with each device_opp containing the list of opp it supports in
  99 * various states of availability.
 100 */
 101static LIST_HEAD(dev_opp_list);
 102/* Lock to allow exclusive modification to the device and opp lists */
 103static DEFINE_MUTEX(dev_opp_list_lock);
 104
 105/**
 106 * find_device_opp() - find device_opp struct using device pointer
 107 * @dev:        device pointer used to lookup device OPPs
 108 *
 109 * Search list of device OPPs for one containing matching device. Does a RCU
 110 * reader operation to grab the pointer needed.
 111 *
 112 * Returns pointer to 'struct device_opp' if found, otherwise -ENODEV or
 113 * -EINVAL based on type of error.
 114 *
 115 * Locking: This function must be called under rcu_read_lock(). device_opp
 116 * is a RCU protected pointer. This means that device_opp is valid as long
 117 * as we are under RCU lock.
 118 */
 119static struct device_opp *find_device_opp(struct device *dev)
 120{
 121        struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
 122
 123        if (unlikely(IS_ERR_OR_NULL(dev))) {
 124                pr_err("%s: Invalid parameters\n", __func__);
 125                return ERR_PTR(-EINVAL);
 126        }
 127
 128        list_for_each_entry_rcu(tmp_dev_opp, &dev_opp_list, node) {
 129                if (tmp_dev_opp->dev == dev) {
 130                        dev_opp = tmp_dev_opp;
 131                        break;
 132                }
 133        }
 134
 135        return dev_opp;
 136}
 137
 138/**
 139 * opp_get_voltage() - Gets the voltage corresponding to an available opp
 140 * @opp:        opp for which voltage has to be returned for
 141 *
 142 * Return voltage in micro volt corresponding to the opp, else
 143 * return 0
 144 *
 145 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 146 * protected pointer. This means that opp which could have been fetched by
 147 * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are
 148 * under RCU lock. The pointer returned by the opp_find_freq family must be
 149 * used in the same section as the usage of this function with the pointer
 150 * prior to unlocking with rcu_read_unlock() to maintain the integrity of the
 151 * pointer.
 152 */
 153unsigned long opp_get_voltage(struct opp *opp)
 154{
 155        struct opp *tmp_opp;
 156        unsigned long v = 0;
 157
 158        tmp_opp = rcu_dereference(opp);
 159        if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
 160                pr_err("%s: Invalid parameters\n", __func__);
 161        else
 162                v = tmp_opp->u_volt;
 163
 164        return v;
 165}
 166EXPORT_SYMBOL_GPL(opp_get_voltage);
 167
 168/**
 169 * opp_get_freq() - Gets the frequency corresponding to an available opp
 170 * @opp:        opp for which frequency has to be returned for
 171 *
 172 * Return frequency in hertz corresponding to the opp, else
 173 * return 0
 174 *
 175 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 176 * protected pointer. This means that opp which could have been fetched by
 177 * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are
 178 * under RCU lock. The pointer returned by the opp_find_freq family must be
 179 * used in the same section as the usage of this function with the pointer
 180 * prior to unlocking with rcu_read_unlock() to maintain the integrity of the
 181 * pointer.
 182 */
 183unsigned long opp_get_freq(struct opp *opp)
 184{
 185        struct opp *tmp_opp;
 186        unsigned long f = 0;
 187
 188        tmp_opp = rcu_dereference(opp);
 189        if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
 190                pr_err("%s: Invalid parameters\n", __func__);
 191        else
 192                f = tmp_opp->rate;
 193
 194        return f;
 195}
 196EXPORT_SYMBOL_GPL(opp_get_freq);
 197
 198/**
 199 * opp_get_opp_count() - Get number of opps available in the opp list
 200 * @dev:        device for which we do this operation
 201 *
 202 * This function returns the number of available opps if there are any,
 203 * else returns 0 if none or the corresponding error value.
 204 *
 205 * Locking: This function must be called under rcu_read_lock(). This function
 206 * internally references two RCU protected structures: device_opp and opp which
 207 * are safe as long as we are under a common RCU locked section.
 208 */
 209int opp_get_opp_count(struct device *dev)
 210{
 211        struct device_opp *dev_opp;
 212        struct opp *temp_opp;
 213        int count = 0;
 214
 215        dev_opp = find_device_opp(dev);
 216        if (IS_ERR(dev_opp)) {
 217                int r = PTR_ERR(dev_opp);
 218                dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);
 219                return r;
 220        }
 221
 222        list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
 223                if (temp_opp->available)
 224                        count++;
 225        }
 226
 227        return count;
 228}
 229EXPORT_SYMBOL_GPL(opp_get_opp_count);
 230
 231/**
 232 * opp_find_freq_exact() - search for an exact frequency
 233 * @dev:                device for which we do this operation
 234 * @freq:               frequency to search for
 235 * @available:          true/false - match for available opp
 236 *
 237 * Searches for exact match in the opp list and returns pointer to the matching
 238 * opp if found, else returns ERR_PTR in case of error and should be handled
 239 * using IS_ERR. Error return values can be:
 240 * EINVAL:      for bad pointer
 241 * ERANGE:      no match found for search
 242 * ENODEV:      if device not found in list of registered devices
 243 *
 244 * Note: available is a modifier for the search. if available=true, then the
 245 * match is for exact matching frequency and is available in the stored OPP
 246 * table. if false, the match is for exact frequency which is not available.
 247 *
 248 * This provides a mechanism to enable an opp which is not available currently
 249 * or the opposite as well.
 250 *
 251 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 252 * protected pointer. The reason for the same is that the opp pointer which is
 253 * returned will remain valid for use with opp_get_{voltage, freq} only while
 254 * under the locked area. The pointer returned must be used prior to unlocking
 255 * with rcu_read_unlock() to maintain the integrity of the pointer.
 256 */
 257struct opp *opp_find_freq_exact(struct device *dev, unsigned long freq,
 258                                bool available)
 259{
 260        struct device_opp *dev_opp;
 261        struct opp *temp_opp, *opp = ERR_PTR(-ERANGE);
 262
 263        dev_opp = find_device_opp(dev);
 264        if (IS_ERR(dev_opp)) {
 265                int r = PTR_ERR(dev_opp);
 266                dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);
 267                return ERR_PTR(r);
 268        }
 269
 270        list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
 271                if (temp_opp->available == available &&
 272                                temp_opp->rate == freq) {
 273                        opp = temp_opp;
 274                        break;
 275                }
 276        }
 277
 278        return opp;
 279}
 280EXPORT_SYMBOL_GPL(opp_find_freq_exact);
 281
 282/**
 283 * opp_find_freq_ceil() - Search for an rounded ceil freq
 284 * @dev:        device for which we do this operation
 285 * @freq:       Start frequency
 286 *
 287 * Search for the matching ceil *available* OPP from a starting freq
 288 * for a device.
 289 *
 290 * Returns matching *opp and refreshes *freq accordingly, else returns
 291 * ERR_PTR in case of error and should be handled using IS_ERR. Error return
 292 * values can be:
 293 * EINVAL:      for bad pointer
 294 * ERANGE:      no match found for search
 295 * ENODEV:      if device not found in list of registered devices
 296 *
 297 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 298 * protected pointer. The reason for the same is that the opp pointer which is
 299 * returned will remain valid for use with opp_get_{voltage, freq} only while
 300 * under the locked area. The pointer returned must be used prior to unlocking
 301 * with rcu_read_unlock() to maintain the integrity of the pointer.
 302 */
 303struct opp *opp_find_freq_ceil(struct device *dev, unsigned long *freq)
 304{
 305        struct device_opp *dev_opp;
 306        struct opp *temp_opp, *opp = ERR_PTR(-ERANGE);
 307
 308        if (!dev || !freq) {
 309                dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
 310                return ERR_PTR(-EINVAL);
 311        }
 312
 313        dev_opp = find_device_opp(dev);
 314        if (IS_ERR(dev_opp))
 315                return ERR_CAST(dev_opp);
 316
 317        list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
 318                if (temp_opp->available && temp_opp->rate >= *freq) {
 319                        opp = temp_opp;
 320                        *freq = opp->rate;
 321                        break;
 322                }
 323        }
 324
 325        return opp;
 326}
 327EXPORT_SYMBOL_GPL(opp_find_freq_ceil);
 328
 329/**
 330 * opp_find_freq_floor() - Search for a rounded floor freq
 331 * @dev:        device for which we do this operation
 332 * @freq:       Start frequency
 333 *
 334 * Search for the matching floor *available* OPP from a starting freq
 335 * for a device.
 336 *
 337 * Returns matching *opp and refreshes *freq accordingly, else returns
 338 * ERR_PTR in case of error and should be handled using IS_ERR. Error return
 339 * values can be:
 340 * EINVAL:      for bad pointer
 341 * ERANGE:      no match found for search
 342 * ENODEV:      if device not found in list of registered devices
 343 *
 344 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 345 * protected pointer. The reason for the same is that the opp pointer which is
 346 * returned will remain valid for use with opp_get_{voltage, freq} only while
 347 * under the locked area. The pointer returned must be used prior to unlocking
 348 * with rcu_read_unlock() to maintain the integrity of the pointer.
 349 */
 350struct opp *opp_find_freq_floor(struct device *dev, unsigned long *freq)
 351{
 352        struct device_opp *dev_opp;
 353        struct opp *temp_opp, *opp = ERR_PTR(-ERANGE);
 354
 355        if (!dev || !freq) {
 356                dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
 357                return ERR_PTR(-EINVAL);
 358        }
 359
 360        dev_opp = find_device_opp(dev);
 361        if (IS_ERR(dev_opp))
 362                return ERR_CAST(dev_opp);
 363
 364        list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
 365                if (temp_opp->available) {
 366                        /* go to the next node, before choosing prev */
 367                        if (temp_opp->rate > *freq)
 368                                break;
 369                        else
 370                                opp = temp_opp;
 371                }
 372        }
 373        if (!IS_ERR(opp))
 374                *freq = opp->rate;
 375
 376        return opp;
 377}
 378EXPORT_SYMBOL_GPL(opp_find_freq_floor);
 379
 380/**
 381 * opp_add()  - Add an OPP table from a table definitions
 382 * @dev:        device for which we do this operation
 383 * @freq:       Frequency in Hz for this OPP
 384 * @u_volt:     Voltage in uVolts for this OPP
 385 *
 386 * This function adds an opp definition to the opp list and returns status.
 387 * The opp is made available by default and it can be controlled using
 388 * opp_enable/disable functions.
 389 *
 390 * Locking: The internal device_opp and opp structures are RCU protected.
 391 * Hence this function internally uses RCU updater strategy with mutex locks
 392 * to keep the integrity of the internal data structures. Callers should ensure
 393 * that this function is *NOT* called under RCU protection or in contexts where
 394 * mutex cannot be locked.
 395 */
 396int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
 397{
 398        struct device_opp *dev_opp = NULL;
 399        struct opp *opp, *new_opp;
 400        struct list_head *head;
 401
 402        /* allocate new OPP node */
 403        new_opp = kzalloc(sizeof(struct opp), GFP_KERNEL);
 404        if (!new_opp) {
 405                dev_warn(dev, "%s: Unable to create new OPP node\n", __func__);
 406                return -ENOMEM;
 407        }
 408
 409        /* Hold our list modification lock here */
 410        mutex_lock(&dev_opp_list_lock);
 411
 412        /* Check for existing list for 'dev' */
 413        dev_opp = find_device_opp(dev);
 414        if (IS_ERR(dev_opp)) {
 415                /*
 416                 * Allocate a new device OPP table. In the infrequent case
 417                 * where a new device is needed to be added, we pay this
 418                 * penalty.
 419                 */
 420                dev_opp = kzalloc(sizeof(struct device_opp), GFP_KERNEL);
 421                if (!dev_opp) {
 422                        mutex_unlock(&dev_opp_list_lock);
 423                        kfree(new_opp);
 424                        dev_warn(dev,
 425                                "%s: Unable to create device OPP structure\n",
 426                                __func__);
 427                        return -ENOMEM;
 428                }
 429
 430                dev_opp->dev = dev;
 431                srcu_init_notifier_head(&dev_opp->head);
 432                INIT_LIST_HEAD(&dev_opp->opp_list);
 433
 434                /* Secure the device list modification */
 435                list_add_rcu(&dev_opp->node, &dev_opp_list);
 436        }
 437
 438        /* populate the opp table */
 439        new_opp->dev_opp = dev_opp;
 440        new_opp->rate = freq;
 441        new_opp->u_volt = u_volt;
 442        new_opp->available = true;
 443
 444        /* Insert new OPP in order of increasing frequency */
 445        head = &dev_opp->opp_list;
 446        list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) {
 447                if (new_opp->rate < opp->rate)
 448                        break;
 449                else
 450                        head = &opp->node;
 451        }
 452
 453        list_add_rcu(&new_opp->node, head);
 454        mutex_unlock(&dev_opp_list_lock);
 455
 456        /*
 457         * Notify the changes in the availability of the operable
 458         * frequency/voltage list.
 459         */
 460        srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ADD, new_opp);
 461        return 0;
 462}
 463EXPORT_SYMBOL_GPL(opp_add);
 464
 465/**
 466 * opp_set_availability() - helper to set the availability of an opp
 467 * @dev:                device for which we do this operation
 468 * @freq:               OPP frequency to modify availability
 469 * @availability_req:   availability status requested for this opp
 470 *
 471 * Set the availability of an OPP with an RCU operation, opp_{enable,disable}
 472 * share a common logic which is isolated here.
 473 *
 474 * Returns -EINVAL for bad pointers, -ENOMEM if no memory available for the
 475 * copy operation, returns 0 if no modifcation was done OR modification was
 476 * successful.
 477 *
 478 * Locking: The internal device_opp and opp structures are RCU protected.
 479 * Hence this function internally uses RCU updater strategy with mutex locks to
 480 * keep the integrity of the internal data structures. Callers should ensure
 481 * that this function is *NOT* called under RCU protection or in contexts where
 482 * mutex locking or synchronize_rcu() blocking calls cannot be used.
 483 */
 484static int opp_set_availability(struct device *dev, unsigned long freq,
 485                bool availability_req)
 486{
 487        struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
 488        struct opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
 489        int r = 0;
 490
 491        /* keep the node allocated */
 492        new_opp = kmalloc(sizeof(struct opp), GFP_KERNEL);
 493        if (!new_opp) {
 494                dev_warn(dev, "%s: Unable to create OPP\n", __func__);
 495                return -ENOMEM;
 496        }
 497
 498        mutex_lock(&dev_opp_list_lock);
 499
 500        /* Find the device_opp */
 501        list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) {
 502                if (dev == tmp_dev_opp->dev) {
 503                        dev_opp = tmp_dev_opp;
 504                        break;
 505                }
 506        }
 507        if (IS_ERR(dev_opp)) {
 508                r = PTR_ERR(dev_opp);
 509                dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
 510                goto unlock;
 511        }
 512
 513        /* Do we have the frequency? */
 514        list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) {
 515                if (tmp_opp->rate == freq) {
 516                        opp = tmp_opp;
 517                        break;
 518                }
 519        }
 520        if (IS_ERR(opp)) {
 521                r = PTR_ERR(opp);
 522                goto unlock;
 523        }
 524
 525        /* Is update really needed? */
 526        if (opp->available == availability_req)
 527                goto unlock;
 528        /* copy the old data over */
 529        *new_opp = *opp;
 530
 531        /* plug in new node */
 532        new_opp->available = availability_req;
 533
 534        list_replace_rcu(&opp->node, &new_opp->node);
 535        mutex_unlock(&dev_opp_list_lock);
 536        kfree_rcu(opp, head);
 537
 538        /* Notify the change of the OPP availability */
 539        if (availability_req)
 540                srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ENABLE,
 541                                         new_opp);
 542        else
 543                srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_DISABLE,
 544                                         new_opp);
 545
 546        return 0;
 547
 548unlock:
 549        mutex_unlock(&dev_opp_list_lock);
 550        kfree(new_opp);
 551        return r;
 552}
 553
 554/**
 555 * opp_enable() - Enable a specific OPP
 556 * @dev:        device for which we do this operation
 557 * @freq:       OPP frequency to enable
 558 *
 559 * Enables a provided opp. If the operation is valid, this returns 0, else the
 560 * corresponding error value. It is meant to be used for users an OPP available
 561 * after being temporarily made unavailable with opp_disable.
 562 *
 563 * Locking: The internal device_opp and opp structures are RCU protected.
 564 * Hence this function indirectly uses RCU and mutex locks to keep the
 565 * integrity of the internal data structures. Callers should ensure that
 566 * this function is *NOT* called under RCU protection or in contexts where
 567 * mutex locking or synchronize_rcu() blocking calls cannot be used.
 568 */
 569int opp_enable(struct device *dev, unsigned long freq)
 570{
 571        return opp_set_availability(dev, freq, true);
 572}
 573EXPORT_SYMBOL_GPL(opp_enable);
 574
 575/**
 576 * opp_disable() - Disable a specific OPP
 577 * @dev:        device for which we do this operation
 578 * @freq:       OPP frequency to disable
 579 *
 580 * Disables a provided opp. If the operation is valid, this returns
 581 * 0, else the corresponding error value. It is meant to be a temporary
 582 * control by users to make this OPP not available until the circumstances are
 583 * right to make it available again (with a call to opp_enable).
 584 *
 585 * Locking: The internal device_opp and opp structures are RCU protected.
 586 * Hence this function indirectly uses RCU and mutex locks to keep the
 587 * integrity of the internal data structures. Callers should ensure that
 588 * this function is *NOT* called under RCU protection or in contexts where
 589 * mutex locking or synchronize_rcu() blocking calls cannot be used.
 590 */
 591int opp_disable(struct device *dev, unsigned long freq)
 592{
 593        return opp_set_availability(dev, freq, false);
 594}
 595EXPORT_SYMBOL_GPL(opp_disable);
 596
 597#ifdef CONFIG_CPU_FREQ
 598/**
 599 * opp_init_cpufreq_table() - create a cpufreq table for a device
 600 * @dev:        device for which we do this operation
 601 * @table:      Cpufreq table returned back to caller
 602 *
 603 * Generate a cpufreq table for a provided device- this assumes that the
 604 * opp list is already initialized and ready for usage.
 605 *
 606 * This function allocates required memory for the cpufreq table. It is
 607 * expected that the caller does the required maintenance such as freeing
 608 * the table as required.
 609 *
 610 * Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM
 611 * if no memory available for the operation (table is not populated), returns 0
 612 * if successful and table is populated.
 613 *
 614 * WARNING: It is  important for the callers to ensure refreshing their copy of
 615 * the table if any of the mentioned functions have been invoked in the interim.
 616 *
 617 * Locking: The internal device_opp and opp structures are RCU protected.
 618 * To simplify the logic, we pretend we are updater and hold relevant mutex here
 619 * Callers should ensure that this function is *NOT* called under RCU protection
 620 * or in contexts where mutex locking cannot be used.
 621 */
 622int opp_init_cpufreq_table(struct device *dev,
 623                            struct cpufreq_frequency_table **table)
 624{
 625        struct device_opp *dev_opp;
 626        struct opp *opp;
 627        struct cpufreq_frequency_table *freq_table;
 628        int i = 0;
 629
 630        /* Pretend as if I am an updater */
 631        mutex_lock(&dev_opp_list_lock);
 632
 633        dev_opp = find_device_opp(dev);
 634        if (IS_ERR(dev_opp)) {
 635                int r = PTR_ERR(dev_opp);
 636                mutex_unlock(&dev_opp_list_lock);
 637                dev_err(dev, "%s: Device OPP not found (%d)\n", __func__, r);
 638                return r;
 639        }
 640
 641        freq_table = kzalloc(sizeof(struct cpufreq_frequency_table) *
 642                             (opp_get_opp_count(dev) + 1), GFP_KERNEL);
 643        if (!freq_table) {
 644                mutex_unlock(&dev_opp_list_lock);
 645                dev_warn(dev, "%s: Unable to allocate frequency table\n",
 646                        __func__);
 647                return -ENOMEM;
 648        }
 649
 650        list_for_each_entry(opp, &dev_opp->opp_list, node) {
 651                if (opp->available) {
 652                        freq_table[i].driver_data = i;
 653                        freq_table[i].frequency = opp->rate / 1000;
 654                        i++;
 655                }
 656        }
 657        mutex_unlock(&dev_opp_list_lock);
 658
 659        freq_table[i].driver_data = i;
 660        freq_table[i].frequency = CPUFREQ_TABLE_END;
 661
 662        *table = &freq_table[0];
 663
 664        return 0;
 665}
 666EXPORT_SYMBOL_GPL(opp_init_cpufreq_table);
 667
 668/**
 669 * opp_free_cpufreq_table() - free the cpufreq table
 670 * @dev:        device for which we do this operation
 671 * @table:      table to free
 672 *
 673 * Free up the table allocated by opp_init_cpufreq_table
 674 */
 675void opp_free_cpufreq_table(struct device *dev,
 676                                struct cpufreq_frequency_table **table)
 677{
 678        if (!table)
 679                return;
 680
 681        kfree(*table);
 682        *table = NULL;
 683}
 684EXPORT_SYMBOL_GPL(opp_free_cpufreq_table);
 685#endif          /* CONFIG_CPU_FREQ */
 686
 687/**
 688 * opp_get_notifier() - find notifier_head of the device with opp
 689 * @dev:        device pointer used to lookup device OPPs.
 690 */
 691struct srcu_notifier_head *opp_get_notifier(struct device *dev)
 692{
 693        struct device_opp *dev_opp = find_device_opp(dev);
 694
 695        if (IS_ERR(dev_opp))
 696                return ERR_CAST(dev_opp); /* matching type */
 697
 698        return &dev_opp->head;
 699}
 700
 701#ifdef CONFIG_OF
 702/**
 703 * of_init_opp_table() - Initialize opp table from device tree
 704 * @dev:        device pointer used to lookup device OPPs.
 705 *
 706 * Register the initial OPP table with the OPP library for given device.
 707 */
 708int of_init_opp_table(struct device *dev)
 709{
 710        const struct property *prop;
 711        const __be32 *val;
 712        int nr;
 713
 714        prop = of_find_property(dev->of_node, "operating-points", NULL);
 715        if (!prop)
 716                return -ENODEV;
 717        if (!prop->value)
 718                return -ENODATA;
 719
 720        /*
 721         * Each OPP is a set of tuples consisting of frequency and
 722         * voltage like <freq-kHz vol-uV>.
 723         */
 724        nr = prop->length / sizeof(u32);
 725        if (nr % 2) {
 726                dev_err(dev, "%s: Invalid OPP list\n", __func__);
 727                return -EINVAL;
 728        }
 729
 730        val = prop->value;
 731        while (nr) {
 732                unsigned long freq = be32_to_cpup(val++) * 1000;
 733                unsigned long volt = be32_to_cpup(val++);
 734
 735                if (opp_add(dev, freq, volt)) {
 736                        dev_warn(dev, "%s: Failed to add OPP %ld\n",
 737                                 __func__, freq);
 738                        continue;
 739                }
 740                nr -= 2;
 741        }
 742
 743        return 0;
 744}
 745EXPORT_SYMBOL_GPL(of_init_opp_table);
 746#endif
 747