drivers/cpufreq/arm_big_little.c

   1 /*
   2  * ARM big.LITTLE Platforms CPUFreq support
   3  *
   4  * Copyright (C) 2013 ARM Ltd.
   5  * Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
   6  *
   7  * Copyright (C) 2013 Linaro.
   8  * Viresh Kumar <viresh.kumar@linaro.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  15  * kind, whether express or implied; without even the implied warranty
  16  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/clk.h>
  23 #include <linux/cpu.h>
  24 #include <linux/cpufreq.h>
  25 #include <linux/cpumask.h>
  26 #include <linux/export.h>
  27 #include <linux/module.h>
  28 #include <linux/mutex.h>
  29 #include <linux/of_platform.h>
  30 #include <linux/pm_opp.h>
  31 #include <linux/slab.h>
  32 #include <linux/topology.h>
  33 #include <linux/types.h>
  34
  35 #include "arm_big_little.h"
  36
  37 /* Currently we support only two clusters */
  38 #define A15_CLUSTER     0
  39 #define A7_CLUSTER      1
  40 #define MAX_CLUSTERS    2
  41
  42 #ifdef CONFIG_BL_SWITCHER
  43 #include <asm/bL_switcher.h>
  44 static bool bL_switching_enabled;
  45 #define is_bL_switching_enabled()       bL_switching_enabled
  46 #define set_switching_enabled(x)        (bL_switching_enabled = (x))
  47 #else
  48 #define is_bL_switching_enabled()       false
  49 #define set_switching_enabled(x)        do { } while (0)
  50 #define bL_switch_request(...)          do { } while (0)
  51 #define bL_switcher_put_enabled()       do { } while (0)
  52 #define bL_switcher_get_enabled()       do { } while (0)
  53 #endif
  54
  55 #define ACTUAL_FREQ(cluster, freq)  ((cluster == A7_CLUSTER) ? freq << 1 : freq)
  56 #define VIRT_FREQ(cluster, freq)    ((cluster == A7_CLUSTER) ? freq >> 1 : freq)
  57
  58 static struct cpufreq_arm_bL_ops *arm_bL_ops;
  59 static struct clk *clk[MAX_CLUSTERS];
  60 static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
  61 static atomic_t cluster_usage[MAX_CLUSTERS + 1];
  62
  63 static unsigned int clk_big_min;        /* (Big) clock frequencies */
  64 static unsigned int clk_little_max;     /* Maximum clock frequency (Little) */
  65
  66 static DEFINE_PER_CPU(unsigned int, physical_cluster);
  67 static DEFINE_PER_CPU(unsigned int, cpu_last_req_freq);
  68
  69 static struct mutex cluster_lock[MAX_CLUSTERS];
  70
  71 static inline int raw_cpu_to_cluster(int cpu)
  72 {
  73         return topology_physical_package_id(cpu);
  74 }
  75
  76 static inline int cpu_to_cluster(int cpu)
  77 {
  78         return is_bL_switching_enabled() ?
  79                 MAX_CLUSTERS : raw_cpu_to_cluster(cpu);
  80 }
  81
  82 static unsigned int find_cluster_maxfreq(int cluster)
  83 {
  84         int j;
  85         u32 max_freq = 0, cpu_freq;
  86
  87         for_each_online_cpu(j) {
  88                 cpu_freq = per_cpu(cpu_last_req_freq, j);
  89
  90                 if ((cluster == per_cpu(physical_cluster, j)) &&
  91                                 (max_freq < cpu_freq))
  92                         max_freq = cpu_freq;
  93         }
  94
  95         pr_debug("%s: cluster: %d, max freq: %d\n", __func__, cluster,
  96                         max_freq);
  97
  98         return max_freq;
  99 }
 100
 101 static unsigned int clk_get_cpu_rate(unsigned int cpu)
 102 {
 103         u32 cur_cluster = per_cpu(physical_cluster, cpu);
 104         u32 rate = clk_get_rate(clk[cur_cluster]) / 1000;
 105
 106         /* For switcher we use virtual A7 clock rates */
 107         if (is_bL_switching_enabled())
 108                 rate = VIRT_FREQ(cur_cluster, rate);
 109
 110         pr_debug("%s: cpu: %d, cluster: %d, freq: %u\n", __func__, cpu,
 111                         cur_cluster, rate);
 112
 113         return rate;
 114 }
 115
 116 static unsigned int bL_cpufreq_get_rate(unsigned int cpu)
 117 {
 118         if (is_bL_switching_enabled()) {
 119                 pr_debug("%s: freq: %d\n", __func__, per_cpu(cpu_last_req_freq,
 120                                         cpu));
 121
 122                 return per_cpu(cpu_last_req_freq, cpu);
 123         } else {
 124                 return clk_get_cpu_rate(cpu);
 125         }
 126 }
 127
 128 static unsigned int
 129 bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
 130 {
 131         u32 new_rate, prev_rate;
 132         int ret;
 133         bool bLs = is_bL_switching_enabled();
 134
 135         mutex_lock(&cluster_lock[new_cluster]);
 136
 137         if (bLs) {
 138                 prev_rate = per_cpu(cpu_last_req_freq, cpu);
 139                 per_cpu(cpu_last_req_freq, cpu) = rate;
 140                 per_cpu(physical_cluster, cpu) = new_cluster;
 141
 142                 new_rate = find_cluster_maxfreq(new_cluster);
 143                 new_rate = ACTUAL_FREQ(new_cluster, new_rate);
 144         } else {
 145                 new_rate = rate;
 146         }
 147
 148         pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d, freq: %d\n",
 149                         __func__, cpu, old_cluster, new_cluster, new_rate);
 150
 151         ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
 152         if (WARN_ON(ret)) {
 153                 pr_err("clk_set_rate failed: %d, new cluster: %d\n", ret,
 154                                 new_cluster);
 155                 if (bLs) {
 156                         per_cpu(cpu_last_req_freq, cpu) = prev_rate;
 157                         per_cpu(physical_cluster, cpu) = old_cluster;
 158                 }
 159
 160                 mutex_unlock(&cluster_lock[new_cluster]);
 161
 162                 return ret;
 163         }
 164
 165         mutex_unlock(&cluster_lock[new_cluster]);
 166
 167         /* Recalc freq for old cluster when switching clusters */
 168         if (old_cluster != new_cluster) {
 169                 pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d\n",
 170                                 __func__, cpu, old_cluster, new_cluster);
 171
 172                 /* Switch cluster */
 173                 bL_switch_request(cpu, new_cluster);
 174
 175                 mutex_lock(&cluster_lock[old_cluster]);
 176
 177                 /* Set freq of old cluster if there are cpus left on it */
 178                 new_rate = find_cluster_maxfreq(old_cluster);
 179                 new_rate = ACTUAL_FREQ(old_cluster, new_rate);
 180
 181                 if (new_rate) {
 182                         pr_debug("%s: Updating rate of old cluster: %d, to freq: %d\n",
 183                                         __func__, old_cluster, new_rate);
 184
 185                         if (clk_set_rate(clk[old_cluster], new_rate * 1000))
 186                                 pr_err("%s: clk_set_rate failed: %d, old cluster: %d\n",
 187                                                 __func__, ret, old_cluster);
 188                 }
 189                 mutex_unlock(&cluster_lock[old_cluster]);
 190         }
 191
 192         /*
 193          * FIXME: clk_set_rate has to handle the case where clk_change_rate
 194          * can fail due to hardware or firmware issues. Until the clk core
 195          * layer is fixed, we can check here. In most of the cases we will
 196          * be reading only the cached value anyway. This needs to  be removed
 197          * once clk core is fixed.
 198          */
 199         if (bL_cpufreq_get_rate(cpu) != new_rate)
 200                 return -EIO;
 201         return 0;
 202 }
 203
 204 /* Set clock frequency */
 205 static int bL_cpufreq_set_target(struct cpufreq_policy *policy,
 206                 unsigned int index)
 207 {
 208         u32 cpu = policy->cpu, cur_cluster, new_cluster, actual_cluster;
 209         unsigned int freqs_new;
 210
 211         cur_cluster = cpu_to_cluster(cpu);
 212         new_cluster = actual_cluster = per_cpu(physical_cluster, cpu);
 213
 214         freqs_new = freq_table[cur_cluster][index].frequency;
 215
 216         if (is_bL_switching_enabled()) {
 217                 if ((actual_cluster == A15_CLUSTER) &&
 218                                 (freqs_new < clk_big_min)) {
 219                         new_cluster = A7_CLUSTER;
 220                 } else if ((actual_cluster == A7_CLUSTER) &&
 221                                 (freqs_new > clk_little_max)) {
 222                         new_cluster = A15_CLUSTER;
 223                 }
 224         }
 225
 226         return bL_cpufreq_set_rate(cpu, actual_cluster, new_cluster, freqs_new);
 227 }
 228
 229 static inline u32 get_table_count(struct cpufreq_frequency_table *table)
 230 {
 231         int count;
 232
 233         for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
 234                 ;
 235
 236         return count;
 237 }
 238
 239 /* get the minimum frequency in the cpufreq_frequency_table */
 240 static inline u32 get_table_min(struct cpufreq_frequency_table *table)
 241 {
 242         struct cpufreq_frequency_table *pos;
 243         uint32_t min_freq = ~0;
 244         cpufreq_for_each_entry(pos, table)
 245                 if (pos->frequency < min_freq)
 246                         min_freq = pos->frequency;
 247         return min_freq;
 248 }
 249
 250 /* get the maximum frequency in the cpufreq_frequency_table */
 251 static inline u32 get_table_max(struct cpufreq_frequency_table *table)
 252 {
 253         struct cpufreq_frequency_table *pos;
 254         uint32_t max_freq = 0;
 255         cpufreq_for_each_entry(pos, table)
 256                 if (pos->frequency > max_freq)
 257                         max_freq = pos->frequency;
 258         return max_freq;
 259 }
 260
 261 static int merge_cluster_tables(void)
 262 {
 263         int i, j, k = 0, count = 1;
 264         struct cpufreq_frequency_table *table;
 265
 266         for (i = 0; i < MAX_CLUSTERS; i++)
 267                 count += get_table_count(freq_table[i]);
 268
 269         table = kzalloc(sizeof(*table) * count, GFP_KERNEL);
 270         if (!table)
 271                 return -ENOMEM;
 272
 273         freq_table[MAX_CLUSTERS] = table;
 274
 275         /* Add in reverse order to get freqs in increasing order */
 276         for (i = MAX_CLUSTERS - 1; i >= 0; i--) {
 277                 for (j = 0; freq_table[i][j].frequency != CPUFREQ_TABLE_END;
 278                                 j++) {
 279                         table[k].frequency = VIRT_FREQ(i,
 280                                         freq_table[i][j].frequency);
 281                         pr_debug("%s: index: %d, freq: %d\n", __func__, k,
 282                                         table[k].frequency);
 283                         k++;
 284                 }
 285         }
 286
 287         table[k].driver_data = k;
 288         table[k].frequency = CPUFREQ_TABLE_END;
 289
 290         pr_debug("%s: End, table: %p, count: %d\n", __func__, table, k);
 291
 292         return 0;
 293 }
 294
 295 static void _put_cluster_clk_and_freq_table(struct device *cpu_dev)
 296 {
 297         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 298
 299         if (!freq_table[cluster])
 300                 return;
 301
 302         clk_put(clk[cluster]);
 303         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 304         if (arm_bL_ops->free_opp_table)
 305                 arm_bL_ops->free_opp_table(cpu_dev);
 306         dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
 307 }
 308
 309 static void put_cluster_clk_and_freq_table(struct device *cpu_dev)
 310 {
 311         u32 cluster = cpu_to_cluster(cpu_dev->id);
 312         int i;
 313
 314         if (atomic_dec_return(&cluster_usage[cluster]))
 315                 return;
 316
 317         if (cluster < MAX_CLUSTERS)
 318                 return _put_cluster_clk_and_freq_table(cpu_dev);
 319
 320         for_each_present_cpu(i) {
 321                 struct device *cdev = get_cpu_device(i);
 322                 if (!cdev) {
 323                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 324                         return;
 325                 }
 326
 327                 _put_cluster_clk_and_freq_table(cdev);
 328         }
 329
 330         /* free virtual table */
 331         kfree(freq_table[cluster]);
 332 }
 333
 334 static int _get_cluster_clk_and_freq_table(struct device *cpu_dev)
 335 {
 336         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 337         int ret;
 338
 339         if (freq_table[cluster])
 340                 return 0;
 341
 342         ret = arm_bL_ops->init_opp_table(cpu_dev);
 343         if (ret) {
 344                 dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n",
 345                                 __func__, cpu_dev->id, ret);
 346                 goto out;
 347         }
 348
 349         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
 350         if (ret) {
 351                 dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n",
 352                                 __func__, cpu_dev->id, ret);
 353                 goto free_opp_table;
 354         }
 355
 356         clk[cluster] = clk_get(cpu_dev, NULL);
 357         if (!IS_ERR(clk[cluster])) {
 358                 dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p, cluster: %d\n",
 359                                 __func__, clk[cluster], freq_table[cluster],
 360                                 cluster);
 361                 return 0;
 362         }
 363
 364         dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
 365                         __func__, cpu_dev->id, cluster);
 366         ret = PTR_ERR(clk[cluster]);
 367         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 368
 369 free_opp_table:
 370         if (arm_bL_ops->free_opp_table)
 371                 arm_bL_ops->free_opp_table(cpu_dev);
 372 out:
 373         dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
 374                         cluster);
 375         return ret;
 376 }
 377
 378 static int get_cluster_clk_and_freq_table(struct device *cpu_dev)
 379 {
 380         u32 cluster = cpu_to_cluster(cpu_dev->id);
 381         int i, ret;
 382
 383         if (atomic_inc_return(&cluster_usage[cluster]) != 1)
 384                 return 0;
 385
 386         if (cluster < MAX_CLUSTERS) {
 387                 ret = _get_cluster_clk_and_freq_table(cpu_dev);
 388                 if (ret)
 389                         atomic_dec(&cluster_usage[cluster]);
 390                 return ret;
 391         }
 392
 393         /*
 394          * Get data for all clusters and fill virtual cluster with a merge of
 395          * both
 396          */
 397         for_each_present_cpu(i) {
 398                 struct device *cdev = get_cpu_device(i);
 399                 if (!cdev) {
 400                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 401                         return -ENODEV;
 402                 }
 403
 404                 ret = _get_cluster_clk_and_freq_table(cdev);
 405                 if (ret)
 406                         goto put_clusters;
 407         }
 408
 409         ret = merge_cluster_tables();
 410         if (ret)
 411                 goto put_clusters;
 412
 413         /* Assuming 2 cluster, set clk_big_min and clk_little_max */
 414         clk_big_min = get_table_min(freq_table[0]);
 415         clk_little_max = VIRT_FREQ(1, get_table_max(freq_table[1]));
 416
 417         pr_debug("%s: cluster: %d, clk_big_min: %d, clk_little_max: %d\n",
 418                         __func__, cluster, clk_big_min, clk_little_max);
 419
 420         return 0;
 421
 422 put_clusters:
 423         for_each_present_cpu(i) {
 424                 struct device *cdev = get_cpu_device(i);
 425                 if (!cdev) {
 426                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 427                         return -ENODEV;
 428                 }
 429
 430                 _put_cluster_clk_and_freq_table(cdev);
 431         }
 432
 433         atomic_dec(&cluster_usage[cluster]);
 434
 435         return ret;
 436 }
 437
 438 /* Per-CPU initialization */
 439 static int bL_cpufreq_init(struct cpufreq_policy *policy)
 440 {
 441         u32 cur_cluster = cpu_to_cluster(policy->cpu);
 442         struct device *cpu_dev;
 443         int ret;
 444
 445         cpu_dev = get_cpu_device(policy->cpu);
 446         if (!cpu_dev) {
 447                 pr_err("%s: failed to get cpu%d device\n", __func__,
 448                                 policy->cpu);
 449                 return -ENODEV;
 450         }
 451
 452         ret = get_cluster_clk_and_freq_table(cpu_dev);
 453         if (ret)
 454                 return ret;
 455
 456         ret = cpufreq_table_validate_and_show(policy, freq_table[cur_cluster]);
 457         if (ret) {
 458                 dev_err(cpu_dev, "CPU %d, cluster: %d invalid freq table\n",
 459                                 policy->cpu, cur_cluster);
 460                 put_cluster_clk_and_freq_table(cpu_dev);
 461                 return ret;
 462         }
 463
 464         if (cur_cluster < MAX_CLUSTERS) {
 465                 int cpu;
 466
 467                 cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
 468
 469                 for_each_cpu(cpu, policy->cpus)
 470                         per_cpu(physical_cluster, cpu) = cur_cluster;
 471         } else {
 472                 /* Assumption: during init, we are always running on A15 */
 473                 per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;
 474         }
 475
 476         if (arm_bL_ops->get_transition_latency)
 477                 policy->cpuinfo.transition_latency =
 478                         arm_bL_ops->get_transition_latency(cpu_dev);
 479         else
 480                 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 481
 482         if (is_bL_switching_enabled())
 483                 per_cpu(cpu_last_req_freq, policy->cpu) = clk_get_cpu_rate(policy->cpu);
 484
 485         dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
 486         return 0;
 487 }
 488
 489 static int bL_cpufreq_exit(struct cpufreq_policy *policy)
 490 {
 491         struct device *cpu_dev;
 492
 493         cpu_dev = get_cpu_device(policy->cpu);
 494         if (!cpu_dev) {
 495                 pr_err("%s: failed to get cpu%d device\n", __func__,
 496                                 policy->cpu);
 497                 return -ENODEV;
 498         }
 499
 500         put_cluster_clk_and_freq_table(cpu_dev);
 501         dev_dbg(cpu_dev, "%s: Exited, cpu: %d\n", __func__, policy->cpu);
 502
 503         return 0;
 504 }
 505
 506 static struct cpufreq_driver bL_cpufreq_driver = {
 507         .name                   = "arm-big-little",
 508         .flags                  = CPUFREQ_STICKY |
 509                                         CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 510                                         CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 511         .verify                 = cpufreq_generic_frequency_table_verify,
 512         .target_index           = bL_cpufreq_set_target,
 513         .get                    = bL_cpufreq_get_rate,
 514         .init                   = bL_cpufreq_init,
 515         .exit                   = bL_cpufreq_exit,
 516         .attr                   = cpufreq_generic_attr,
 517 };
 518
 519 #ifdef CONFIG_BL_SWITCHER
 520 static int bL_cpufreq_switcher_notifier(struct notifier_block *nfb,
 521                                         unsigned long action, void *_arg)
 522 {
 523         pr_debug("%s: action: %ld\n", __func__, action);
 524
 525         switch (action) {
 526         case BL_NOTIFY_PRE_ENABLE:
 527         case BL_NOTIFY_PRE_DISABLE:
 528                 cpufreq_unregister_driver(&bL_cpufreq_driver);
 529                 break;
 530
 531         case BL_NOTIFY_POST_ENABLE:
 532                 set_switching_enabled(true);
 533                 cpufreq_register_driver(&bL_cpufreq_driver);
 534                 break;
 535
 536         case BL_NOTIFY_POST_DISABLE:
 537                 set_switching_enabled(false);
 538                 cpufreq_register_driver(&bL_cpufreq_driver);
 539                 break;
 540
 541         default:
 542                 return NOTIFY_DONE;
 543         }
 544
 545         return NOTIFY_OK;
 546 }
 547
 548 static struct notifier_block bL_switcher_notifier = {
 549         .notifier_call = bL_cpufreq_switcher_notifier,
 550 };
 551
 552 static int __bLs_register_notifier(void)
 553 {
 554         return bL_switcher_register_notifier(&bL_switcher_notifier);
 555 }
 556
 557 static int __bLs_unregister_notifier(void)
 558 {
 559         return bL_switcher_unregister_notifier(&bL_switcher_notifier);
 560 }
 561 #else
 562 static int __bLs_register_notifier(void) { return 0; }
 563 static int __bLs_unregister_notifier(void) { return 0; }
 564 #endif
 565
 566 int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
 567 {
 568         int ret, i;
 569
 570         if (arm_bL_ops) {
 571                 pr_debug("%s: Already registered: %s, exiting\n", __func__,
 572                                 arm_bL_ops->name);
 573                 return -EBUSY;
 574         }
 575
 576         if (!ops || !strlen(ops->name) || !ops->init_opp_table) {
 577                 pr_err("%s: Invalid arm_bL_ops, exiting\n", __func__);
 578                 return -ENODEV;
 579         }
 580
 581         arm_bL_ops = ops;
 582
 583         set_switching_enabled(bL_switcher_get_enabled());
 584
 585         for (i = 0; i < MAX_CLUSTERS; i++)
 586                 mutex_init(&cluster_lock[i]);
 587
 588         ret = cpufreq_register_driver(&bL_cpufreq_driver);
 589         if (ret) {
 590                 pr_info("%s: Failed registering platform driver: %s, err: %d\n",
 591                                 __func__, ops->name, ret);
 592                 arm_bL_ops = NULL;
 593         } else {
 594                 ret = __bLs_register_notifier();
 595                 if (ret) {
 596                         cpufreq_unregister_driver(&bL_cpufreq_driver);
 597                         arm_bL_ops = NULL;
 598                 } else {
 599                         pr_info("%s: Registered platform driver: %s\n",
 600                                         __func__, ops->name);
 601                 }
 602         }
 603
 604         bL_switcher_put_enabled();
 605         return ret;
 606 }
 607 EXPORT_SYMBOL_GPL(bL_cpufreq_register);
 608
 609 void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops)
 610 {
 611         if (arm_bL_ops != ops) {
 612                 pr_err("%s: Registered with: %s, can't unregister, exiting\n",
 613                                 __func__, arm_bL_ops->name);
 614                 return;
 615         }
 616
 617         bL_switcher_get_enabled();
 618         __bLs_unregister_notifier();
 619         cpufreq_unregister_driver(&bL_cpufreq_driver);
 620         bL_switcher_put_enabled();
 621         pr_info("%s: Un-registered platform driver: %s\n", __func__,
 622                         arm_bL_ops->name);
 623         arm_bL_ops = NULL;
 624 }
 625 EXPORT_SYMBOL_GPL(bL_cpufreq_unregister);
 626
 627 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
 628 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver");
 629 MODULE_LICENSE("GPL v2");