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 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
 217         cur_cluster = cpu_to_cluster(cpu);
 218         new_cluster = actual_cluster = per_cpu(physical_cluster, cpu);
 219
 220         freqs_new = freq_table[cur_cluster][index].frequency;
 221
 222         if (is_bL_switching_enabled()) {
 223                 if ((actual_cluster == A15_CLUSTER) &&
 224                                 (freqs_new < clk_big_min)) {
 225                         new_cluster = A7_CLUSTER;
 226                 } else if ((actual_cluster == A7_CLUSTER) &&
 227                                 (freqs_new > clk_little_max)) {
 228                         new_cluster = A15_CLUSTER;
 229                 }
 230         }
 231
 232         return bL_cpufreq_set_rate(cpu, actual_cluster, new_cluster, freqs_new);
 233 }
 234
 235 static inline u32 get_table_count(struct cpufreq_frequency_table *table)
 236 {
 237         int count;
 238
 239         for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
 240                 ;
 241
 242         return count;
 243 }
 244
 245 /* get the minimum frequency in the cpufreq_frequency_table */
 246 static inline u32 get_table_min(struct cpufreq_frequency_table *table)
 247 {
 248         struct cpufreq_frequency_table *pos;
 249         uint32_t min_freq = ~0;
 250         cpufreq_for_each_entry(pos, table)
 251                 if (pos->frequency < min_freq)
 252                         min_freq = pos->frequency;
 253         return min_freq;
 254 }
 255
 256 /* get the maximum frequency in the cpufreq_frequency_table */
 257 static inline u32 get_table_max(struct cpufreq_frequency_table *table)
 258 {
 259         struct cpufreq_frequency_table *pos;
 260         uint32_t max_freq = 0;
 261         cpufreq_for_each_entry(pos, table)
 262                 if (pos->frequency > max_freq)
 263                         max_freq = pos->frequency;
 264         return max_freq;
 265 }
 266
 267 static int merge_cluster_tables(void)
 268 {
 269         int i, j, k = 0, count = 1;
 270         struct cpufreq_frequency_table *table;
 271
 272         for (i = 0; i < MAX_CLUSTERS; i++)
 273                 count += get_table_count(freq_table[i]);
 274
 275         table = kzalloc(sizeof(*table) * count, GFP_KERNEL);
 276         if (!table)
 277                 return -ENOMEM;
 278
 279         freq_table[MAX_CLUSTERS] = table;
 280
 281         /* Add in reverse order to get freqs in increasing order */
 282         for (i = MAX_CLUSTERS - 1; i >= 0; i--) {
 283                 for (j = 0; freq_table[i][j].frequency != CPUFREQ_TABLE_END;
 284                                 j++) {
 285                         table[k].frequency = VIRT_FREQ(i,
 286                                         freq_table[i][j].frequency);
 287                         pr_debug("%s: index: %d, freq: %d\n", __func__, k,
 288                                         table[k].frequency);
 289                         k++;
 290                 }
 291         }
 292
 293         table[k].driver_data = k;
 294         table[k].frequency = CPUFREQ_TABLE_END;
 295
 296         pr_debug("%s: End, table: %p, count: %d\n", __func__, table, k);
 297
 298         return 0;
 299 }
 300
 301 static void _put_cluster_clk_and_freq_table(struct device *cpu_dev,
 302                                             const struct cpumask *cpumask)
 303 {
 304         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 305
 306         if (!freq_table[cluster])
 307                 return;
 308
 309         clk_put(clk[cluster]);
 310         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 311         if (arm_bL_ops->free_opp_table)
 312                 arm_bL_ops->free_opp_table(cpumask);
 313         dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
 314 }
 315
 316 static void put_cluster_clk_and_freq_table(struct device *cpu_dev,
 317                                            const struct cpumask *cpumask)
 318 {
 319         u32 cluster = cpu_to_cluster(cpu_dev->id);
 320         int i;
 321
 322         if (atomic_dec_return(&cluster_usage[cluster]))
 323                 return;
 324
 325         if (cluster < MAX_CLUSTERS)
 326                 return _put_cluster_clk_and_freq_table(cpu_dev, cpumask);
 327
 328         for_each_present_cpu(i) {
 329                 struct device *cdev = get_cpu_device(i);
 330                 if (!cdev) {
 331                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 332                         return;
 333                 }
 334
 335                 _put_cluster_clk_and_freq_table(cdev, cpumask);
 336         }
 337
 338         /* free virtual table */
 339         kfree(freq_table[cluster]);
 340 }
 341
 342 static int _get_cluster_clk_and_freq_table(struct device *cpu_dev,
 343                                            const struct cpumask *cpumask)
 344 {
 345         u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
 346         int ret;
 347
 348         if (freq_table[cluster])
 349                 return 0;
 350
 351         ret = arm_bL_ops->init_opp_table(cpumask);
 352         if (ret) {
 353                 dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n",
 354                                 __func__, cpu_dev->id, ret);
 355                 goto out;
 356         }
 357
 358         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
 359         if (ret) {
 360                 dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n",
 361                                 __func__, cpu_dev->id, ret);
 362                 goto free_opp_table;
 363         }
 364
 365         clk[cluster] = clk_get(cpu_dev, NULL);
 366         if (!IS_ERR(clk[cluster])) {
 367                 dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p, cluster: %d\n",
 368                                 __func__, clk[cluster], freq_table[cluster],
 369                                 cluster);
 370                 return 0;
 371         }
 372
 373         dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
 374                         __func__, cpu_dev->id, cluster);
 375         ret = PTR_ERR(clk[cluster]);
 376         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 377
 378 free_opp_table:
 379         if (arm_bL_ops->free_opp_table)
 380                 arm_bL_ops->free_opp_table(cpumask);
 381 out:
 382         dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
 383                         cluster);
 384         return ret;
 385 }
 386
 387 static int get_cluster_clk_and_freq_table(struct device *cpu_dev,
 388                                           const struct cpumask *cpumask)
 389 {
 390         u32 cluster = cpu_to_cluster(cpu_dev->id);
 391         int i, ret;
 392
 393         if (atomic_inc_return(&cluster_usage[cluster]) != 1)
 394                 return 0;
 395
 396         if (cluster < MAX_CLUSTERS) {
 397                 ret = _get_cluster_clk_and_freq_table(cpu_dev, cpumask);
 398                 if (ret)
 399                         atomic_dec(&cluster_usage[cluster]);
 400                 return ret;
 401         }
 402
 403         /*
 404          * Get data for all clusters and fill virtual cluster with a merge of
 405          * both
 406          */
 407         for_each_present_cpu(i) {
 408                 struct device *cdev = get_cpu_device(i);
 409                 if (!cdev) {
 410                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 411                         return -ENODEV;
 412                 }
 413
 414                 ret = _get_cluster_clk_and_freq_table(cdev, cpumask);
 415                 if (ret)
 416                         goto put_clusters;
 417         }
 418
 419         ret = merge_cluster_tables();
 420         if (ret)
 421                 goto put_clusters;
 422
 423         /* Assuming 2 cluster, set clk_big_min and clk_little_max */
 424         clk_big_min = get_table_min(freq_table[0]);
 425         clk_little_max = VIRT_FREQ(1, get_table_max(freq_table[1]));
 426
 427         pr_debug("%s: cluster: %d, clk_big_min: %d, clk_little_max: %d\n",
 428                         __func__, cluster, clk_big_min, clk_little_max);
 429
 430         return 0;
 431
 432 put_clusters:
 433         for_each_present_cpu(i) {
 434                 struct device *cdev = get_cpu_device(i);
 435                 if (!cdev) {
 436                         pr_err("%s: failed to get cpu%d device\n", __func__, i);
 437                         return -ENODEV;
 438                 }
 439
 440                 _put_cluster_clk_and_freq_table(cdev, cpumask);
 441         }
 442
 443         atomic_dec(&cluster_usage[cluster]);
 444
 445         return ret;
 446 }
 447
 448 /* Per-CPU initialization */
 449 static int bL_cpufreq_init(struct cpufreq_policy *policy)
 450 {
 451         u32 cur_cluster = cpu_to_cluster(policy->cpu);
 452         struct device *cpu_dev;
 453         int ret;
 454
 455         cpu_dev = get_cpu_device(policy->cpu);
 456         if (!cpu_dev) {
 457                 pr_err("%s: failed to get cpu%d device\n", __func__,
 458                                 policy->cpu);
 459                 return -ENODEV;
 460         }
 461
 462         if (cur_cluster < MAX_CLUSTERS) {
 463                 int cpu;
 464
 465                 cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
 466
 467                 for_each_cpu(cpu, policy->cpus)
 468                         per_cpu(physical_cluster, cpu) = cur_cluster;
 469         } else {
 470                 /* Assumption: during init, we are always running on A15 */
 471                 per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;
 472         }
 473
 474         ret = get_cluster_clk_and_freq_table(cpu_dev, policy->cpus);
 475         if (ret)
 476                 return ret;
 477
 478         ret = cpufreq_table_validate_and_show(policy, freq_table[cur_cluster]);
 479         if (ret) {
 480                 dev_err(cpu_dev, "CPU %d, cluster: %d invalid freq table\n",
 481                         policy->cpu, cur_cluster);
 482                 put_cluster_clk_and_freq_table(cpu_dev, policy->cpus);
 483                 return ret;
 484         }
 485
 486         if (arm_bL_ops->get_transition_latency)
 487                 policy->cpuinfo.transition_latency =
 488                         arm_bL_ops->get_transition_latency(cpu_dev);
 489         else
 490                 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 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         struct device *cpu_dev = get_cpu_device(policy->cpu);
 525         int cur_cluster = cpu_to_cluster(policy->cpu);
 526         struct device_node *np;
 527
 528         /* Do not register a cpu_cooling device if we are in IKS mode */
 529         if (cur_cluster >= MAX_CLUSTERS)
 530                 return;
 531
 532         np = of_node_get(cpu_dev->of_node);
 533         if (WARN_ON(!np))
 534                 return;
 535
 536         if (of_find_property(np, "#cooling-cells", NULL)) {
 537                 u32 power_coefficient = 0;
 538
 539                 of_property_read_u32(np, "dynamic-power-coefficient",
 540                                      &power_coefficient);
 541
 542                 cdev[cur_cluster] = of_cpufreq_power_cooling_register(np,
 543                                 policy->related_cpus, power_coefficient, NULL);
 544                 if (IS_ERR(cdev[cur_cluster])) {
 545                         dev_err(cpu_dev,
 546                                 "running cpufreq without cooling device: %ld\n",
 547                                 PTR_ERR(cdev[cur_cluster]));
 548                         cdev[cur_cluster] = NULL;
 549                 }
 550         }
 551         of_node_put(np);
 552 }
 553
 554 static struct cpufreq_driver bL_cpufreq_driver = {
 555         .name                   = "arm-big-little",
 556         .flags                  = CPUFREQ_STICKY |
 557                                         CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 558                                         CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 559         .verify                 = cpufreq_generic_frequency_table_verify,
 560         .target_index           = bL_cpufreq_set_target,
 561         .get                    = bL_cpufreq_get_rate,
 562         .init                   = bL_cpufreq_init,
 563         .exit                   = bL_cpufreq_exit,
 564         .ready                  = bL_cpufreq_ready,
 565         .attr                   = cpufreq_generic_attr,
 566 };
 567
 568 #ifdef CONFIG_BL_SWITCHER
 569 static int bL_cpufreq_switcher_notifier(struct notifier_block *nfb,
 570                                         unsigned long action, void *_arg)
 571 {
 572         pr_debug("%s: action: %ld\n", __func__, action);
 573
 574         switch (action) {
 575         case BL_NOTIFY_PRE_ENABLE:
 576         case BL_NOTIFY_PRE_DISABLE:
 577                 cpufreq_unregister_driver(&bL_cpufreq_driver);
 578                 break;
 579
 580         case BL_NOTIFY_POST_ENABLE:
 581                 set_switching_enabled(true);
 582                 cpufreq_register_driver(&bL_cpufreq_driver);
 583                 break;
 584
 585         case BL_NOTIFY_POST_DISABLE:
 586                 set_switching_enabled(false);
 587                 cpufreq_register_driver(&bL_cpufreq_driver);
 588                 break;
 589
 590         default:
 591                 return NOTIFY_DONE;
 592         }
 593
 594         return NOTIFY_OK;
 595 }
 596
 597 static struct notifier_block bL_switcher_notifier = {
 598         .notifier_call = bL_cpufreq_switcher_notifier,
 599 };
 600
 601 static int __bLs_register_notifier(void)
 602 {
 603         return bL_switcher_register_notifier(&bL_switcher_notifier);
 604 }
 605
 606 static int __bLs_unregister_notifier(void)
 607 {
 608         return bL_switcher_unregister_notifier(&bL_switcher_notifier);
 609 }
 610 #else
 611 static int __bLs_register_notifier(void) { return 0; }
 612 static int __bLs_unregister_notifier(void) { return 0; }
 613 #endif
 614
 615 int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
 616 {
 617         int ret, i;
 618
 619         if (arm_bL_ops) {
 620                 pr_debug("%s: Already registered: %s, exiting\n", __func__,
 621                                 arm_bL_ops->name);
 622                 return -EBUSY;
 623         }
 624
 625         if (!ops || !strlen(ops->name) || !ops->init_opp_table) {
 626                 pr_err("%s: Invalid arm_bL_ops, exiting\n", __func__);
 627                 return -ENODEV;
 628         }
 629
 630         arm_bL_ops = ops;
 631
 632         set_switching_enabled(bL_switcher_get_enabled());
 633
 634         for (i = 0; i < MAX_CLUSTERS; i++)
 635                 mutex_init(&cluster_lock[i]);
 636
 637         ret = cpufreq_register_driver(&bL_cpufreq_driver);
 638         if (ret) {
 639                 pr_info("%s: Failed registering platform driver: %s, err: %d\n",
 640                                 __func__, ops->name, ret);
 641                 arm_bL_ops = NULL;
 642         } else {
 643                 ret = __bLs_register_notifier();
 644                 if (ret) {
 645                         cpufreq_unregister_driver(&bL_cpufreq_driver);
 646                         arm_bL_ops = NULL;
 647                 } else {
 648                         pr_info("%s: Registered platform driver: %s\n",
 649                                         __func__, ops->name);
 650                 }
 651         }
 652
 653         bL_switcher_put_enabled();
 654         return ret;
 655 }
 656 EXPORT_SYMBOL_GPL(bL_cpufreq_register);
 657
 658 void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops)
 659 {
 660         if (arm_bL_ops != ops) {
 661                 pr_err("%s: Registered with: %s, can't unregister, exiting\n",
 662                                 __func__, arm_bL_ops->name);
 663                 return;
 664         }
 665
 666         bL_switcher_get_enabled();
 667         __bLs_unregister_notifier();
 668         cpufreq_unregister_driver(&bL_cpufreq_driver);
 669         bL_switcher_put_enabled();
 670         pr_info("%s: Un-registered platform driver: %s\n", __func__,
 671                         arm_bL_ops->name);
 672         arm_bL_ops = NULL;
 673 }
 674 EXPORT_SYMBOL_GPL(bL_cpufreq_unregister);
 675
 676 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
 677 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver");
 678 MODULE_LICENSE("GPL v2");