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/cpu_cooling.h>
  27 #include <linux/export.h>
  28 #include <linux/module.h>
  29 #include <linux/mutex.h>
  30 #include <linux/of_platform.h>
  31 #include <linux/pm_opp.h>
  32 #include <linux/slab.h>
  33 #include <linux/topology.h>
  34 #include <linux/types.h>
  35
  36 #include "arm_big_little.h"
  37
  38 /* Currently we support only two clusters */
  39 #define A15_CLUSTER     0
  40 #define A7_CLUSTER      1
  41 #define MAX_CLUSTERS    2
  42
  43 #ifdef CONFIG_BL_SWITCHER
  44 #include <asm/bL_switcher.h>
  45 static bool bL_switching_enabled;
  46 #define is_bL_switching_enabled()       bL_switching_enabled
  47 #define set_switching_enabled(x)        (bL_switching_enabled = (x))
  48 #else
  49 #define is_bL_switching_enabled()       false
  50 #define set_switching_enabled(x)        do { } while (0)
  51 #define bL_switch_request(...)          do { } while (0)
  52 #define bL_switcher_put_enabled()       do { } while (0)
  53 #define bL_switcher_get_enabled()       do { } while (0)
  54 #endif
  55
  56 #define ACTUAL_FREQ(cluster, freq)  ((cluster == A7_CLUSTER) ? freq << 1 : freq)
  57 #define VIRT_FREQ(cluster, freq)    ((cluster == A7_CLUSTER) ? freq >> 1 : freq)
  58
  59 static struct thermal_cooling_device *cdev[MAX_CLUSTERS];
  60 static const struct cpufreq_arm_bL_ops *arm_bL_ops;
  61 static struct clk *clk[MAX_CLUSTERS];
  62 static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
  63 static atomic_t cluster_usage[MAX_CLUSTERS + 1];
  64
  65 static unsigned int clk_big_min;        /* (Big) clock frequencies */
  66 static unsigned int clk_little_max;     /* Maximum clock frequency (Little) */
  67
  68 static DEFINE_PER_CPU(unsigned int, physical_cluster);
  69 static DEFINE_PER_CPU(unsigned int, cpu_last_req_freq);
  70
  71 static struct mutex cluster_lock[MAX_CLUSTERS];
  72
  73 static inline int raw_cpu_to_cluster(int cpu)
  74 {
  75         return topology_physical_package_id(cpu);
  76 }
  77
  78 static inline int cpu_to_cluster(int cpu)
  79 {
  80         return is_bL_switching_enabled() ?
  81                 MAX_CLUSTERS : raw_cpu_to_cluster(cpu);
  82 }
  83
  84 static unsigned int find_cluster_maxfreq(int cluster)
  85 {
  86         int j;
  87         u32 max_freq = 0, cpu_freq;
  88
  89         for_each_online_cpu(j) {
  90                 cpu_freq = per_cpu(cpu_last_req_freq, j);
  91
  92                 if ((cluster == per_cpu(physical_cluster, j)) &&
  93                                 (max_freq < cpu_freq))
  94                         max_freq = cpu_freq;
  95         }
  96
  97         pr_debug("%s: cluster: %d, max freq: %d\n", __func__, cluster,
  98                         max_freq);
  99
 100         return max_freq;
 101 }
 102
 103 static unsigned int clk_get_cpu_rate(unsigned int cpu)
 104 {
 105         u32 cur_cluster = per_cpu(physical_cluster, cpu);
 106         u32 rate = clk_get_rate(clk[cur_cluster]) / 1000;
 107
 108         /* For switcher we use virtual A7 clock rates */
 109         if (is_bL_switching_enabled())
 110                 rate = VIRT_FREQ(cur_cluster, rate);
 111
 112         pr_debug("%s: cpu: %d, cluster: %d, freq: %u\n", __func__, cpu,
 113                         cur_cluster, rate);
 114
 115         return rate;
 116 }
 117
 118 static unsigned int bL_cpufreq_get_rate(unsigned int cpu)
 119 {
 120         if (is_bL_switching_enabled()) {
 121                 pr_debug("%s: freq: %d\n", __func__, per_cpu(cpu_last_req_freq,
 122                                         cpu));
 123
 124                 return per_cpu(cpu_last_req_freq, cpu);
 125         } else {
 126                 return clk_get_cpu_rate(cpu);
 127         }
 128 }
 129
 130 static unsigned int
 131 bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
 132 {
 133         u32 new_rate, prev_rate;
 134         int ret;
 135         bool bLs = is_bL_switching_enabled();
 136
 137         mutex_lock(&cluster_lock[new_cluster]);
 138
 139         if (bLs) {
 140                 prev_rate = per_cpu(cpu_last_req_freq, cpu);
 141                 per_cpu(cpu_last_req_freq, cpu) = rate;
 142                 per_cpu(physical_cluster, cpu) = new_cluster;
 143
 144                 new_rate = find_cluster_maxfreq(new_cluster);
 145                 new_rate = ACTUAL_FREQ(new_cluster, new_rate);
 146         } else {
 147                 new_rate = rate;
 148         }
 149
 150         pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d, freq: %d\n",
 151                         __func__, cpu, old_cluster, new_cluster, new_rate);
 152
 153         ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
 154         if (!ret) {
 155                 /*
 156                  * FIXME: clk_set_rate hasn't returned an error here however it
 157                  * may be that clk_change_rate failed due to hardware or
 158                  * firmware issues and wasn't able to report that due to the
 159                  * current design of the clk core layer. To work around this
 160                  * problem we will read back the clock rate and check it is
 161                  * correct. This needs to be removed once clk core is fixed.
 162                  */
 163                 if (clk_get_rate(clk[new_cluster]) != new_rate * 1000)
 164                         ret = -EIO;
 165         }
 166
 167         if (WARN_ON(ret)) {
 168                 pr_err("clk_set_rate failed: %d, new cluster: %d\n", ret,
 169                                 new_cluster);
 170                 if (bLs) {
 171                         per_cpu(cpu_last_req_freq, cpu) = prev_rate;
 172                         per_cpu(physical_cluster, cpu) = old_cluster;
 173                 }
 174
 175                 mutex_unlock(&cluster_lock[new_cluster]);
 176
 177                 return ret;
 178         }
 179
 180         mutex_unlock(&cluster_lock[new_cluster]);
 181
 182         /* Recalc freq for old cluster when switching clusters */
 183         if (old_cluster != new_cluster) {
 184                 pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d\n",
 185                                 __func__, cpu, old_cluster, new_cluster);
 186
 187                 /* Switch cluster */
 188                 bL_switch_request(cpu, new_cluster);
 189
 190                 mutex_lock(&cluster_lock[old_cluster]);
 191
 192                 /* Set freq of old cluster if there are cpus left on it */
 193                 new_rate = find_cluster_maxfreq(old_cluster);
 194                 new_rate = ACTUAL_FREQ(old_cluster, new_rate);
 195
 196                 if (new_rate) {
 197                         pr_debug("%s: Updating rate of old cluster: %d, to freq: %d\n",
 198                                         __func__, old_cluster, new_rate);
 199
 200                         if (clk_set_rate(clk[old_cluster], new_rate * 1000))
 201                                 pr_err("%s: clk_set_rate failed: %d, old cluster: %d\n",
 202                                                 __func__, ret, old_cluster);
 203                 }
 204                 mutex_unlock(&cluster_lock[old_cluster]);
 205         }
 206
 207         return 0;
 208 }
 209
 210 /* Set clock frequency */
 211 static int bL_cpufreq_set_target(struct cpufreq_policy *policy,
 212                 unsigned int index)
 213 {
 214         u32 cpu = policy->cpu, cur_cluster, new_cluster, actual_cluster;
 215         unsigned int freqs_new;
 216         int ret;
 217
 218         cur_cluster = cpu_to_cluster(cpu);
 219         new_cluster = actual_cluster = per_cpu(physical_cluster, cpu);
 220
 221         freqs_new = freq_table[cur_cluster][index].frequency;
 222
 223         if (is_bL_switching_enabled()) {
 224                 if ((actual_cluster == A15_CLUSTER) &&
 225                                 (freqs_new < clk_big_min)) {
 226                         new_cluster = A7_CLUSTER;
 227                 } else if ((actual_cluster == A7_CLUSTER) &&
 228                                 (freqs_new > clk_little_max)) {
 229                         new_cluster = A15_CLUSTER;
 230                 }
 231         }
 232
 233         ret = bL_cpufreq_set_rate(cpu, actual_cluster, new_cluster, freqs_new);
 234
 235         if (!ret) {
 236                 arch_set_freq_scale(policy->related_cpus, freqs_new,
 237                                     policy->cpuinfo.max_freq);
 238         }
 239
 240         return ret;
 241 }
 242
 243 static inline u32 get_table_count(struct cpufreq_frequency_table *table)
 244 {
 245         int count;
 246
 247         for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
 248                 ;
 249
 250         return count;
 251 }
 252
 253 /* get the minimum frequency in the cpufreq_frequency_table */
 254 static inline u32 get_table_min(struct cpufreq_frequency_table *table)
 255 {
 256         struct cpufreq_frequency_table *pos;
 257         uint32_t min_freq = ~0;
 258         cpufreq_for_each_entry(pos, table)
 259                 if (pos->frequency < min_freq)
 260                         min_freq = pos->frequency;
 261         return min_freq;
 262 }
 263
 264 /* get the maximum frequency in the cpufreq_frequency_table */
 265 static inline u32 get_table_max(struct cpufreq_frequency_table *table)
 266 {
 267         struct cpufreq_frequency_table *pos;
 268         uint32_t max_freq = 0;
 269         cpufreq_for_each_entry(pos, table)
 270                 if (pos->frequency > max_freq)
 271                         max_freq = pos->frequency;
 272         return max_freq;
 273 }
 274
 275 static int merge_cluster_tables(void)
 276 {
 277         int i, j, k = 0, count = 1;
 278         struct cpufreq_frequency_table *table;
 279
 280         for (i = 0; i < MAX_CLUSTERS; i++)
 281                 count += get_table_count(freq_table[i]);
 282
 283         table = kcalloc(count, sizeof(*table), GFP_KERNEL);
 284         if (!table)
 285                 return -ENOMEM;
 286
 287         freq_table[MAX_CLUSTERS] = table;
 288
 289         /* Add in reverse order to get freqs in increasing order */
 290         for (i = MAX_CLUSTERS - 1; i >= 0; i--) {
 291                 for (j = 0; freq_table[i][j].frequency != CPUFREQ_TABLE_END;
 292                                 j++) {
 293                         table[k].frequency = VIRT_FREQ(i,
 294                                         freq_table[i][j].frequency);
 295                         pr_debug("%s: index: %d, freq: %d\n", __func__, k,
 296                                         table[k].frequency);
 297                         k++;
 298                 }
 299         }
 300
 301         table[k].driver_data = k;
 302         table[k].frequency = CPUFREQ_TABLE_END;
 303
 304         pr_debug("%s: End, table: %p, count: %d\n", __func__, table, k);
 305
 306         return 0;
 307 }
 308
 309 static void _put_cluster_clk_and_freq_table(struct device *cpu_dev,
 310                                             const struct cpumask *cpumask)
 311 {
 312         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 313
 314         if (!freq_table[cluster])
 315                 return;
 316
 317         clk_put(clk[cluster]);
 318         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 319         if (arm_bL_ops->free_opp_table)
 320                 arm_bL_ops->free_opp_table(cpumask);
 321         dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
 322 }
 323
 324 static void put_cluster_clk_and_freq_table(struct device *cpu_dev,
 325                                            const struct cpumask *cpumask)
 326 {
 327         u32 cluster = cpu_to_cluster(cpu_dev->id);
 328         int i;
 329
 330         if (atomic_dec_return(&cluster_usage[cluster]))
 331                 return;
 332
 333         if (cluster < MAX_CLUSTERS)
 334                 return _put_cluster_clk_and_freq_table(cpu_dev, cpumask);
 335
 336         for_each_present_cpu(i) {
 337                 struct device *cdev = get_cpu_device(i);
 338                 if (!cdev) {
 339                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 340                         return;
 341                 }
 342
 343                 _put_cluster_clk_and_freq_table(cdev, cpumask);
 344         }
 345
 346         /* free virtual table */
 347         kfree(freq_table[cluster]);
 348 }
 349
 350 static int _get_cluster_clk_and_freq_table(struct device *cpu_dev,
 351                                            const struct cpumask *cpumask)
 352 {
 353         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 354         int ret;
 355
 356         if (freq_table[cluster])
 357                 return 0;
 358
 359         ret = arm_bL_ops->init_opp_table(cpumask);
 360         if (ret) {
 361                 dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n",
 362                                 __func__, cpu_dev->id, ret);
 363                 goto out;
 364         }
 365
 366         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
 367         if (ret) {
 368                 dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n",
 369                                 __func__, cpu_dev->id, ret);
 370                 goto free_opp_table;
 371         }
 372
 373         clk[cluster] = clk_get(cpu_dev, NULL);
 374         if (!IS_ERR(clk[cluster])) {
 375                 dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p, cluster: %d\n",
 376                                 __func__, clk[cluster], freq_table[cluster],
 377                                 cluster);
 378                 return 0;
 379         }
 380
 381         dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
 382                         __func__, cpu_dev->id, cluster);
 383         ret = PTR_ERR(clk[cluster]);
 384         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 385
 386 free_opp_table:
 387         if (arm_bL_ops->free_opp_table)
 388                 arm_bL_ops->free_opp_table(cpumask);
 389 out:
 390         dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
 391                         cluster);
 392         return ret;
 393 }
 394
 395 static int get_cluster_clk_and_freq_table(struct device *cpu_dev,
 396                                           const struct cpumask *cpumask)
 397 {
 398         u32 cluster = cpu_to_cluster(cpu_dev->id);
 399         int i, ret;
 400
 401         if (atomic_inc_return(&cluster_usage[cluster]) != 1)
 402                 return 0;
 403
 404         if (cluster < MAX_CLUSTERS) {
 405                 ret = _get_cluster_clk_and_freq_table(cpu_dev, cpumask);
 406                 if (ret)
 407                         atomic_dec(&cluster_usage[cluster]);
 408                 return ret;
 409         }
 410
 411         /*
 412          * Get data for all clusters and fill virtual cluster with a merge of
 413          * both
 414          */
 415         for_each_present_cpu(i) {
 416                 struct device *cdev = get_cpu_device(i);
 417                 if (!cdev) {
 418                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 419                         return -ENODEV;
 420                 }
 421
 422                 ret = _get_cluster_clk_and_freq_table(cdev, cpumask);
 423                 if (ret)
 424                         goto put_clusters;
 425         }
 426
 427         ret = merge_cluster_tables();
 428         if (ret)
 429                 goto put_clusters;
 430
 431         /* Assuming 2 cluster, set clk_big_min and clk_little_max */
 432         clk_big_min = get_table_min(freq_table[0]);
 433         clk_little_max = VIRT_FREQ(1, get_table_max(freq_table[1]));
 434
 435         pr_debug("%s: cluster: %d, clk_big_min: %d, clk_little_max: %d\n",
 436                         __func__, cluster, clk_big_min, clk_little_max);
 437
 438         return 0;
 439
 440 put_clusters:
 441         for_each_present_cpu(i) {
 442                 struct device *cdev = get_cpu_device(i);
 443                 if (!cdev) {
 444                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 445                         return -ENODEV;
 446                 }
 447
 448                 _put_cluster_clk_and_freq_table(cdev, cpumask);
 449         }
 450
 451         atomic_dec(&cluster_usage[cluster]);
 452
 453         return ret;
 454 }
 455
 456 /* Per-CPU initialization */
 457 static int bL_cpufreq_init(struct cpufreq_policy *policy)
 458 {
 459         u32 cur_cluster = cpu_to_cluster(policy->cpu);
 460         struct device *cpu_dev;
 461         int ret;
 462
 463         cpu_dev = get_cpu_device(policy->cpu);
 464         if (!cpu_dev) {
 465                 pr_err("%s: failed to get cpu%d device\n", __func__,
 466                                 policy->cpu);
 467                 return -ENODEV;
 468         }
 469
 470         if (cur_cluster < MAX_CLUSTERS) {
 471                 int cpu;
 472
 473                 cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
 474
 475                 for_each_cpu(cpu, policy->cpus)
 476                         per_cpu(physical_cluster, cpu) = cur_cluster;
 477         } else {
 478                 /* Assumption: during init, we are always running on A15 */
 479                 per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;
 480         }
 481
 482         ret = get_cluster_clk_and_freq_table(cpu_dev, policy->cpus);
 483         if (ret)
 484                 return ret;
 485
 486         policy->freq_table = freq_table[cur_cluster];
 487         policy->cpuinfo.transition_latency =
 488                                 arm_bL_ops->get_transition_latency(cpu_dev);
 489
 490         dev_pm_opp_of_register_em(policy->cpus);
 491
 492         if (is_bL_switching_enabled())
 493                 per_cpu(cpu_last_req_freq, policy->cpu) = clk_get_cpu_rate(policy->cpu);
 494
 495         dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
 496         return 0;
 497 }
 498
 499 static int bL_cpufreq_exit(struct cpufreq_policy *policy)
 500 {
 501         struct device *cpu_dev;
 502         int cur_cluster = cpu_to_cluster(policy->cpu);
 503
 504         if (cur_cluster < MAX_CLUSTERS) {
 505                 cpufreq_cooling_unregister(cdev[cur_cluster]);
 506                 cdev[cur_cluster] = NULL;
 507         }
 508
 509         cpu_dev = get_cpu_device(policy->cpu);
 510         if (!cpu_dev) {
 511                 pr_err("%s: failed to get cpu%d device\n", __func__,
 512                                 policy->cpu);
 513                 return -ENODEV;
 514         }
 515
 516         put_cluster_clk_and_freq_table(cpu_dev, policy->related_cpus);
 517         dev_dbg(cpu_dev, "%s: Exited, cpu: %d\n", __func__, policy->cpu);
 518
 519         return 0;
 520 }
 521
 522 static void bL_cpufreq_ready(struct cpufreq_policy *policy)
 523 {
 524         int cur_cluster = cpu_to_cluster(policy->cpu);
 525
 526         /* Do not register a cpu_cooling device if we are in IKS mode */
 527         if (cur_cluster >= MAX_CLUSTERS)
 528                 return;
 529
 530         cdev[cur_cluster] = of_cpufreq_cooling_register(policy);
 531 }
 532
 533 static struct cpufreq_driver bL_cpufreq_driver = {
 534         .name                   = "arm-big-little",
 535         .flags                  = CPUFREQ_STICKY |
 536                                         CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 537                                         CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 538         .verify                 = cpufreq_generic_frequency_table_verify,
 539         .target_index           = bL_cpufreq_set_target,
 540         .get                    = bL_cpufreq_get_rate,
 541         .init                   = bL_cpufreq_init,
 542         .exit                   = bL_cpufreq_exit,
 543         .ready                  = bL_cpufreq_ready,
 544         .attr                   = cpufreq_generic_attr,
 545 };
 546
 547 #ifdef CONFIG_BL_SWITCHER
 548 static int bL_cpufreq_switcher_notifier(struct notifier_block *nfb,
 549                                         unsigned long action, void *_arg)
 550 {
 551         pr_debug("%s: action: %ld\n", __func__, action);
 552
 553         switch (action) {
 554         case BL_NOTIFY_PRE_ENABLE:
 555         case BL_NOTIFY_PRE_DISABLE:
 556                 cpufreq_unregister_driver(&bL_cpufreq_driver);
 557                 break;
 558
 559         case BL_NOTIFY_POST_ENABLE:
 560                 set_switching_enabled(true);
 561                 cpufreq_register_driver(&bL_cpufreq_driver);
 562                 break;
 563
 564         case BL_NOTIFY_POST_DISABLE:
 565                 set_switching_enabled(false);
 566                 cpufreq_register_driver(&bL_cpufreq_driver);
 567                 break;
 568
 569         default:
 570                 return NOTIFY_DONE;
 571         }
 572
 573         return NOTIFY_OK;
 574 }
 575
 576 static struct notifier_block bL_switcher_notifier = {
 577         .notifier_call = bL_cpufreq_switcher_notifier,
 578 };
 579
 580 static int __bLs_register_notifier(void)
 581 {
 582         return bL_switcher_register_notifier(&bL_switcher_notifier);
 583 }
 584
 585 static int __bLs_unregister_notifier(void)
 586 {
 587         return bL_switcher_unregister_notifier(&bL_switcher_notifier);
 588 }
 589 #else
 590 static int __bLs_register_notifier(void) { return 0; }
 591 static int __bLs_unregister_notifier(void) { return 0; }
 592 #endif
 593
 594 int bL_cpufreq_register(const struct cpufreq_arm_bL_ops *ops)
 595 {
 596         int ret, i;
 597
 598         if (arm_bL_ops) {
 599                 pr_debug("%s: Already registered: %s, exiting\n", __func__,
 600                                 arm_bL_ops->name);
 601                 return -EBUSY;
 602         }
 603
 604         if (!ops || !strlen(ops->name) || !ops->init_opp_table ||
 605             !ops->get_transition_latency) {
 606                 pr_err("%s: Invalid arm_bL_ops, exiting\n", __func__);
 607                 return -ENODEV;
 608         }
 609
 610         arm_bL_ops = ops;
 611
 612         set_switching_enabled(bL_switcher_get_enabled());
 613
 614         for (i = 0; i < MAX_CLUSTERS; i++)
 615                 mutex_init(&cluster_lock[i]);
 616
 617         ret = cpufreq_register_driver(&bL_cpufreq_driver);
 618         if (ret) {
 619                 pr_info("%s: Failed registering platform driver: %s, err: %d\n",
 620                                 __func__, ops->name, ret);
 621                 arm_bL_ops = NULL;
 622         } else {
 623                 ret = __bLs_register_notifier();
 624                 if (ret) {
 625                         cpufreq_unregister_driver(&bL_cpufreq_driver);
 626                         arm_bL_ops = NULL;
 627                 } else {
 628                         pr_info("%s: Registered platform driver: %s\n",
 629                                         __func__, ops->name);
 630                 }
 631         }
 632
 633         bL_switcher_put_enabled();
 634         return ret;
 635 }
 636 EXPORT_SYMBOL_GPL(bL_cpufreq_register);
 637
 638 void bL_cpufreq_unregister(const struct cpufreq_arm_bL_ops *ops)
 639 {
 640         if (arm_bL_ops != ops) {
 641                 pr_err("%s: Registered with: %s, can't unregister, exiting\n",
 642                                 __func__, arm_bL_ops->name);
 643                 return;
 644         }
 645
 646         bL_switcher_get_enabled();
 647         __bLs_unregister_notifier();
 648         cpufreq_unregister_driver(&bL_cpufreq_driver);
 649         bL_switcher_put_enabled();
 650         pr_info("%s: Un-registered platform driver: %s\n", __func__,
 651                         arm_bL_ops->name);
 652         arm_bL_ops = NULL;
 653 }
 654 EXPORT_SYMBOL_GPL(bL_cpufreq_unregister);
 655
 656 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
 657 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver");
 658 MODULE_LICENSE("GPL v2");