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 (!ret) {
 153                 /*
 154                  * FIXME: clk_set_rate hasn't returned an error here however it
 155                  * may be that clk_change_rate failed due to hardware or
 156                  * firmware issues and wasn't able to report that due to the
 157                  * current design of the clk core layer. To work around this
 158                  * problem we will read back the clock rate and check it is
 159                  * correct. This needs to be removed once clk core is fixed.
 160                  */
 161                 if (clk_get_rate(clk[new_cluster]) != new_rate * 1000)
 162                         ret = -EIO;
 163         }
 164
 165         if (WARN_ON(ret)) {
 166                 pr_err("clk_set_rate failed: %d, new cluster: %d\n", ret,
 167                                 new_cluster);
 168                 if (bLs) {
 169                         per_cpu(cpu_last_req_freq, cpu) = prev_rate;
 170                         per_cpu(physical_cluster, cpu) = old_cluster;
 171                 }
 172
 173                 mutex_unlock(&cluster_lock[new_cluster]);
 174
 175                 return ret;
 176         }
 177
 178         mutex_unlock(&cluster_lock[new_cluster]);
 179
 180         /* Recalc freq for old cluster when switching clusters */
 181         if (old_cluster != new_cluster) {
 182                 pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d\n",
 183                                 __func__, cpu, old_cluster, new_cluster);
 184
 185                 /* Switch cluster */
 186                 bL_switch_request(cpu, new_cluster);
 187
 188                 mutex_lock(&cluster_lock[old_cluster]);
 189
 190                 /* Set freq of old cluster if there are cpus left on it */
 191                 new_rate = find_cluster_maxfreq(old_cluster);
 192                 new_rate = ACTUAL_FREQ(old_cluster, new_rate);
 193
 194                 if (new_rate) {
 195                         pr_debug("%s: Updating rate of old cluster: %d, to freq: %d\n",
 196                                         __func__, old_cluster, new_rate);
 197
 198                         if (clk_set_rate(clk[old_cluster], new_rate * 1000))
 199                                 pr_err("%s: clk_set_rate failed: %d, old cluster: %d\n",
 200                                                 __func__, ret, old_cluster);
 201                 }
 202                 mutex_unlock(&cluster_lock[old_cluster]);
 203         }
 204
 205         return 0;
 206 }
 207
 208 /* Set clock frequency */
 209 static int bL_cpufreq_set_target(struct cpufreq_policy *policy,
 210                 unsigned int index)
 211 {
 212         u32 cpu = policy->cpu, cur_cluster, new_cluster, actual_cluster;
 213         unsigned int freqs_new;
 214
 215         cur_cluster = cpu_to_cluster(cpu);
 216         new_cluster = actual_cluster = per_cpu(physical_cluster, cpu);
 217
 218         freqs_new = freq_table[cur_cluster][index].frequency;
 219
 220         if (is_bL_switching_enabled()) {
 221                 if ((actual_cluster == A15_CLUSTER) &&
 222                                 (freqs_new < clk_big_min)) {
 223                         new_cluster = A7_CLUSTER;
 224                 } else if ((actual_cluster == A7_CLUSTER) &&
 225                                 (freqs_new > clk_little_max)) {
 226                         new_cluster = A15_CLUSTER;
 227                 }
 228         }
 229
 230         return bL_cpufreq_set_rate(cpu, actual_cluster, new_cluster, freqs_new);
 231 }
 232
 233 static inline u32 get_table_count(struct cpufreq_frequency_table *table)
 234 {
 235         int count;
 236
 237         for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
 238                 ;
 239
 240         return count;
 241 }
 242
 243 /* get the minimum frequency in the cpufreq_frequency_table */
 244 static inline u32 get_table_min(struct cpufreq_frequency_table *table)
 245 {
 246         struct cpufreq_frequency_table *pos;
 247         uint32_t min_freq = ~0;
 248         cpufreq_for_each_entry(pos, table)
 249                 if (pos->frequency < min_freq)
 250                         min_freq = pos->frequency;
 251         return min_freq;
 252 }
 253
 254 /* get the maximum frequency in the cpufreq_frequency_table */
 255 static inline u32 get_table_max(struct cpufreq_frequency_table *table)
 256 {
 257         struct cpufreq_frequency_table *pos;
 258         uint32_t max_freq = 0;
 259         cpufreq_for_each_entry(pos, table)
 260                 if (pos->frequency > max_freq)
 261                         max_freq = pos->frequency;
 262         return max_freq;
 263 }
 264
 265 static int merge_cluster_tables(void)
 266 {
 267         int i, j, k = 0, count = 1;
 268         struct cpufreq_frequency_table *table;
 269
 270         for (i = 0; i < MAX_CLUSTERS; i++)
 271                 count += get_table_count(freq_table[i]);
 272
 273         table = kzalloc(sizeof(*table) * count, GFP_KERNEL);
 274         if (!table)
 275                 return -ENOMEM;
 276
 277         freq_table[MAX_CLUSTERS] = table;
 278
 279         /* Add in reverse order to get freqs in increasing order */
 280         for (i = MAX_CLUSTERS - 1; i >= 0; i--) {
 281                 for (j = 0; freq_table[i][j].frequency != CPUFREQ_TABLE_END;
 282                                 j++) {
 283                         table[k].frequency = VIRT_FREQ(i,
 284                                         freq_table[i][j].frequency);
 285                         pr_debug("%s: index: %d, freq: %d\n", __func__, k,
 286                                         table[k].frequency);
 287                         k++;
 288                 }
 289         }
 290
 291         table[k].driver_data = k;
 292         table[k].frequency = CPUFREQ_TABLE_END;
 293
 294         pr_debug("%s: End, table: %p, count: %d\n", __func__, table, k);
 295
 296         return 0;
 297 }
 298
 299 static void _put_cluster_clk_and_freq_table(struct device *cpu_dev)
 300 {
 301         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 302
 303         if (!freq_table[cluster])
 304                 return;
 305
 306         clk_put(clk[cluster]);
 307         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 308         if (arm_bL_ops->free_opp_table)
 309                 arm_bL_ops->free_opp_table(cpu_dev);
 310         dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
 311 }
 312
 313 static void put_cluster_clk_and_freq_table(struct device *cpu_dev)
 314 {
 315         u32 cluster = cpu_to_cluster(cpu_dev->id);
 316         int i;
 317
 318         if (atomic_dec_return(&cluster_usage[cluster]))
 319                 return;
 320
 321         if (cluster < MAX_CLUSTERS)
 322                 return _put_cluster_clk_and_freq_table(cpu_dev);
 323
 324         for_each_present_cpu(i) {
 325                 struct device *cdev = get_cpu_device(i);
 326                 if (!cdev) {
 327                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 328                         return;
 329                 }
 330
 331                 _put_cluster_clk_and_freq_table(cdev);
 332         }
 333
 334         /* free virtual table */
 335         kfree(freq_table[cluster]);
 336 }
 337
 338 static int _get_cluster_clk_and_freq_table(struct device *cpu_dev)
 339 {
 340         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 341         int ret;
 342
 343         if (freq_table[cluster])
 344                 return 0;
 345
 346         ret = arm_bL_ops->init_opp_table(cpu_dev);
 347         if (ret) {
 348                 dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n",
 349                                 __func__, cpu_dev->id, ret);
 350                 goto out;
 351         }
 352
 353         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
 354         if (ret) {
 355                 dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n",
 356                                 __func__, cpu_dev->id, ret);
 357                 goto free_opp_table;
 358         }
 359
 360         clk[cluster] = clk_get(cpu_dev, NULL);
 361         if (!IS_ERR(clk[cluster])) {
 362                 dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p, cluster: %d\n",
 363                                 __func__, clk[cluster], freq_table[cluster],
 364                                 cluster);
 365                 return 0;
 366         }
 367
 368         dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
 369                         __func__, cpu_dev->id, cluster);
 370         ret = PTR_ERR(clk[cluster]);
 371         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 372
 373 free_opp_table:
 374         if (arm_bL_ops->free_opp_table)
 375                 arm_bL_ops->free_opp_table(cpu_dev);
 376 out:
 377         dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
 378                         cluster);
 379         return ret;
 380 }
 381
 382 static int get_cluster_clk_and_freq_table(struct device *cpu_dev)
 383 {
 384         u32 cluster = cpu_to_cluster(cpu_dev->id);
 385         int i, ret;
 386
 387         if (atomic_inc_return(&cluster_usage[cluster]) != 1)
 388                 return 0;
 389
 390         if (cluster < MAX_CLUSTERS) {
 391                 ret = _get_cluster_clk_and_freq_table(cpu_dev);
 392                 if (ret)
 393                         atomic_dec(&cluster_usage[cluster]);
 394                 return ret;
 395         }
 396
 397         /*
 398          * Get data for all clusters and fill virtual cluster with a merge of
 399          * both
 400          */
 401         for_each_present_cpu(i) {
 402                 struct device *cdev = get_cpu_device(i);
 403                 if (!cdev) {
 404                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 405                         return -ENODEV;
 406                 }
 407
 408                 ret = _get_cluster_clk_and_freq_table(cdev);
 409                 if (ret)
 410                         goto put_clusters;
 411         }
 412
 413         ret = merge_cluster_tables();
 414         if (ret)
 415                 goto put_clusters;
 416
 417         /* Assuming 2 cluster, set clk_big_min and clk_little_max */
 418         clk_big_min = get_table_min(freq_table[0]);
 419         clk_little_max = VIRT_FREQ(1, get_table_max(freq_table[1]));
 420
 421         pr_debug("%s: cluster: %d, clk_big_min: %d, clk_little_max: %d\n",
 422                         __func__, cluster, clk_big_min, clk_little_max);
 423
 424         return 0;
 425
 426 put_clusters:
 427         for_each_present_cpu(i) {
 428                 struct device *cdev = get_cpu_device(i);
 429                 if (!cdev) {
 430                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 431                         return -ENODEV;
 432                 }
 433
 434                 _put_cluster_clk_and_freq_table(cdev);
 435         }
 436
 437         atomic_dec(&cluster_usage[cluster]);
 438
 439         return ret;
 440 }
 441
 442 /* Per-CPU initialization */
 443 static int bL_cpufreq_init(struct cpufreq_policy *policy)
 444 {
 445         u32 cur_cluster = cpu_to_cluster(policy->cpu);
 446         struct device *cpu_dev;
 447         int ret;
 448
 449         cpu_dev = get_cpu_device(policy->cpu);
 450         if (!cpu_dev) {
 451                 pr_err("%s: failed to get cpu%d device\n", __func__,
 452                                 policy->cpu);
 453                 return -ENODEV;
 454         }
 455
 456         ret = get_cluster_clk_and_freq_table(cpu_dev);
 457         if (ret)
 458                 return ret;
 459
 460         ret = cpufreq_table_validate_and_show(policy, freq_table[cur_cluster]);
 461         if (ret) {
 462                 dev_err(cpu_dev, "CPU %d, cluster: %d invalid freq table\n",
 463                                 policy->cpu, cur_cluster);
 464                 put_cluster_clk_and_freq_table(cpu_dev);
 465                 return ret;
 466         }
 467
 468         if (cur_cluster < MAX_CLUSTERS) {
 469                 int cpu;
 470
 471                 cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
 472
 473                 for_each_cpu(cpu, policy->cpus)
 474                         per_cpu(physical_cluster, cpu) = cur_cluster;
 475         } else {
 476                 /* Assumption: during init, we are always running on A15 */
 477                 per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;
 478         }
 479
 480         if (arm_bL_ops->get_transition_latency)
 481                 policy->cpuinfo.transition_latency =
 482                         arm_bL_ops->get_transition_latency(cpu_dev);
 483         else
 484                 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 485
 486         if (is_bL_switching_enabled())
 487                 per_cpu(cpu_last_req_freq, policy->cpu) = clk_get_cpu_rate(policy->cpu);
 488
 489         dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
 490         return 0;
 491 }
 492
 493 static int bL_cpufreq_exit(struct cpufreq_policy *policy)
 494 {
 495         struct device *cpu_dev;
 496
 497         cpu_dev = get_cpu_device(policy->cpu);
 498         if (!cpu_dev) {
 499                 pr_err("%s: failed to get cpu%d device\n", __func__,
 500                                 policy->cpu);
 501                 return -ENODEV;
 502         }
 503
 504         put_cluster_clk_and_freq_table(cpu_dev);
 505         dev_dbg(cpu_dev, "%s: Exited, cpu: %d\n", __func__, policy->cpu);
 506
 507         return 0;
 508 }
 509
 510 static struct cpufreq_driver bL_cpufreq_driver = {
 511         .name                   = "arm-big-little",
 512         .flags                  = CPUFREQ_STICKY |
 513                                         CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 514                                         CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 515         .verify                 = cpufreq_generic_frequency_table_verify,
 516         .target_index           = bL_cpufreq_set_target,
 517         .get                    = bL_cpufreq_get_rate,
 518         .init                   = bL_cpufreq_init,
 519         .exit                   = bL_cpufreq_exit,
 520         .attr                   = cpufreq_generic_attr,
 521 };
 522
 523 #ifdef CONFIG_BL_SWITCHER
 524 static int bL_cpufreq_switcher_notifier(struct notifier_block *nfb,
 525                                         unsigned long action, void *_arg)
 526 {
 527         pr_debug("%s: action: %ld\n", __func__, action);
 528
 529         switch (action) {
 530         case BL_NOTIFY_PRE_ENABLE:
 531         case BL_NOTIFY_PRE_DISABLE:
 532                 cpufreq_unregister_driver(&bL_cpufreq_driver);
 533                 break;
 534
 535         case BL_NOTIFY_POST_ENABLE:
 536                 set_switching_enabled(true);
 537                 cpufreq_register_driver(&bL_cpufreq_driver);
 538                 break;
 539
 540         case BL_NOTIFY_POST_DISABLE:
 541                 set_switching_enabled(false);
 542                 cpufreq_register_driver(&bL_cpufreq_driver);
 543                 break;
 544
 545         default:
 546                 return NOTIFY_DONE;
 547         }
 548
 549         return NOTIFY_OK;
 550 }
 551
 552 static struct notifier_block bL_switcher_notifier = {
 553         .notifier_call = bL_cpufreq_switcher_notifier,
 554 };
 555
 556 static int __bLs_register_notifier(void)
 557 {
 558         return bL_switcher_register_notifier(&bL_switcher_notifier);
 559 }
 560
 561 static int __bLs_unregister_notifier(void)
 562 {
 563         return bL_switcher_unregister_notifier(&bL_switcher_notifier);
 564 }
 565 #else
 566 static int __bLs_register_notifier(void) { return 0; }
 567 static int __bLs_unregister_notifier(void) { return 0; }
 568 #endif
 569
 570 int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
 571 {
 572         int ret, i;
 573
 574         if (arm_bL_ops) {
 575                 pr_debug("%s: Already registered: %s, exiting\n", __func__,
 576                                 arm_bL_ops->name);
 577                 return -EBUSY;
 578         }
 579
 580         if (!ops || !strlen(ops->name) || !ops->init_opp_table) {
 581                 pr_err("%s: Invalid arm_bL_ops, exiting\n", __func__);
 582                 return -ENODEV;
 583         }
 584
 585         arm_bL_ops = ops;
 586
 587         set_switching_enabled(bL_switcher_get_enabled());
 588
 589         for (i = 0; i < MAX_CLUSTERS; i++)
 590                 mutex_init(&cluster_lock[i]);
 591
 592         ret = cpufreq_register_driver(&bL_cpufreq_driver);
 593         if (ret) {
 594                 pr_info("%s: Failed registering platform driver: %s, err: %d\n",
 595                                 __func__, ops->name, ret);
 596                 arm_bL_ops = NULL;
 597         } else {
 598                 ret = __bLs_register_notifier();
 599                 if (ret) {
 600                         cpufreq_unregister_driver(&bL_cpufreq_driver);
 601                         arm_bL_ops = NULL;
 602                 } else {
 603                         pr_info("%s: Registered platform driver: %s\n",
 604                                         __func__, ops->name);
 605                 }
 606         }
 607
 608         bL_switcher_put_enabled();
 609         return ret;
 610 }
 611 EXPORT_SYMBOL_GPL(bL_cpufreq_register);
 612
 613 void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops)
 614 {
 615         if (arm_bL_ops != ops) {
 616                 pr_err("%s: Registered with: %s, can't unregister, exiting\n",
 617                                 __func__, arm_bL_ops->name);
 618                 return;
 619         }
 620
 621         bL_switcher_get_enabled();
 622         __bLs_unregister_notifier();
 623         cpufreq_unregister_driver(&bL_cpufreq_driver);
 624         bL_switcher_put_enabled();
 625         pr_info("%s: Un-registered platform driver: %s\n", __func__,
 626                         arm_bL_ops->name);
 627         arm_bL_ops = NULL;
 628 }
 629 EXPORT_SYMBOL_GPL(bL_cpufreq_unregister);
 630
 631 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
 632 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver");
 633 MODULE_LICENSE("GPL v2");