drivers/cpufreq/powernv-cpufreq.c

   1 /*
   2  * POWERNV cpufreq driver for the IBM POWER processors
   3  *
   4  * (C) Copyright IBM 2014
   5  *
   6  * Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  */
  19
  20 #define pr_fmt(fmt)     "powernv-cpufreq: " fmt
  21
  22 #include <linux/kernel.h>
  23 #include <linux/sysfs.h>
  24 #include <linux/cpumask.h>
  25 #include <linux/module.h>
  26 #include <linux/cpufreq.h>
  27 #include <linux/smp.h>
  28 #include <linux/of.h>
  29 #include <linux/reboot.h>
  30 #include <linux/slab.h>
  31 #include <linux/cpu.h>
  32 #include <trace/events/power.h>
  33
  34 #include <asm/cputhreads.h>
  35 #include <asm/firmware.h>
  36 #include <asm/reg.h>
  37 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
  38 #include <asm/opal.h>
  39
  40 #define POWERNV_MAX_PSTATES     256
  41 #define PMSR_PSAFE_ENABLE       (1UL << 30)
  42 #define PMSR_SPR_EM_DISABLE     (1UL << 31)
  43 #define PMSR_MAX(x)             ((x >> 32) & 0xFF)
  44
  45 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
  46 static bool rebooting, throttled, occ_reset;
  47
  48 static const char * const throttle_reason[] = {
  49         "No throttling",
  50         "Power Cap",
  51         "Processor Over Temperature",
  52         "Power Supply Failure",
  53         "Over Current",
  54         "OCC Reset"
  55 };
  56
  57 enum throttle_reason_type {
  58         NO_THROTTLE = 0,
  59         POWERCAP,
  60         CPU_OVERTEMP,
  61         POWER_SUPPLY_FAILURE,
  62         OVERCURRENT,
  63         OCC_RESET_THROTTLE,
  64         OCC_MAX_REASON
  65 };
  66
  67 static struct chip {
  68         unsigned int id;
  69         bool throttled;
  70         bool restore;
  71         u8 throttle_reason;
  72         cpumask_t mask;
  73         struct work_struct throttle;
  74         int throttle_turbo;
  75         int throttle_sub_turbo;
  76         int reason[OCC_MAX_REASON];
  77 } *chips;
  78
  79 static int nr_chips;
  80 static DEFINE_PER_CPU(struct chip *, chip_info);
  81
  82 /*
  83  * Note: The set of pstates consists of contiguous integers, the
  84  * smallest of which is indicated by powernv_pstate_info.min, the
  85  * largest of which is indicated by powernv_pstate_info.max.
  86  *
  87  * The nominal pstate is the highest non-turbo pstate in this
  88  * platform. This is indicated by powernv_pstate_info.nominal.
  89  */
  90 static struct powernv_pstate_info {
  91         int min;
  92         int max;
  93         int nominal;
  94         int nr_pstates;
  95 } powernv_pstate_info;
  96
  97 /*
  98  * Initialize the freq table based on data obtained
  99  * from the firmware passed via device-tree
 100  */
 101 static int init_powernv_pstates(void)
 102 {
 103         struct device_node *power_mgt;
 104         int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
 105         const __be32 *pstate_ids, *pstate_freqs;
 106         u32 len_ids, len_freqs;
 107
 108         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 109         if (!power_mgt) {
 110                 pr_warn("power-mgt node not found\n");
 111                 return -ENODEV;
 112         }
 113
 114         if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
 115                 pr_warn("ibm,pstate-min node not found\n");
 116                 return -ENODEV;
 117         }
 118
 119         if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
 120                 pr_warn("ibm,pstate-max node not found\n");
 121                 return -ENODEV;
 122         }
 123
 124         if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
 125                                  &pstate_nominal)) {
 126                 pr_warn("ibm,pstate-nominal not found\n");
 127                 return -ENODEV;
 128         }
 129         pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
 130                 pstate_nominal, pstate_max);
 131
 132         pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
 133         if (!pstate_ids) {
 134                 pr_warn("ibm,pstate-ids not found\n");
 135                 return -ENODEV;
 136         }
 137
 138         pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
 139                                       &len_freqs);
 140         if (!pstate_freqs) {
 141                 pr_warn("ibm,pstate-frequencies-mhz not found\n");
 142                 return -ENODEV;
 143         }
 144
 145         if (len_ids != len_freqs) {
 146                 pr_warn("Entries in ibm,pstate-ids and "
 147                         "ibm,pstate-frequencies-mhz does not match\n");
 148         }
 149
 150         nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
 151         if (!nr_pstates) {
 152                 pr_warn("No PStates found\n");
 153                 return -ENODEV;
 154         }
 155
 156         pr_debug("NR PStates %d\n", nr_pstates);
 157         for (i = 0; i < nr_pstates; i++) {
 158                 u32 id = be32_to_cpu(pstate_ids[i]);
 159                 u32 freq = be32_to_cpu(pstate_freqs[i]);
 160
 161                 pr_debug("PState id %d freq %d MHz\n", id, freq);
 162                 powernv_freqs[i].frequency = freq * 1000; /* kHz */
 163                 powernv_freqs[i].driver_data = id;
 164         }
 165         /* End of list marker entry */
 166         powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
 167
 168         powernv_pstate_info.min = pstate_min;
 169         powernv_pstate_info.max = pstate_max;
 170         powernv_pstate_info.nominal = pstate_nominal;
 171         powernv_pstate_info.nr_pstates = nr_pstates;
 172
 173         return 0;
 174 }
 175
 176 /* Returns the CPU frequency corresponding to the pstate_id. */
 177 static unsigned int pstate_id_to_freq(int pstate_id)
 178 {
 179         int i;
 180
 181         i = powernv_pstate_info.max - pstate_id;
 182         if (i >= powernv_pstate_info.nr_pstates || i < 0) {
 183                 pr_warn("PState id %d outside of PState table, "
 184                         "reporting nominal id %d instead\n",
 185                         pstate_id, powernv_pstate_info.nominal);
 186                 i = powernv_pstate_info.max - powernv_pstate_info.nominal;
 187         }
 188
 189         return powernv_freqs[i].frequency;
 190 }
 191
 192 /*
 193  * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
 194  * the firmware
 195  */
 196 static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
 197                                         char *buf)
 198 {
 199         return sprintf(buf, "%u\n",
 200                 pstate_id_to_freq(powernv_pstate_info.nominal));
 201 }
 202
 203 struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
 204         __ATTR_RO(cpuinfo_nominal_freq);
 205
 206 static struct freq_attr *powernv_cpu_freq_attr[] = {
 207         &cpufreq_freq_attr_scaling_available_freqs,
 208         &cpufreq_freq_attr_cpuinfo_nominal_freq,
 209         NULL,
 210 };
 211
 212 #define throttle_attr(name, member)                                     \
 213 static ssize_t name##_show(struct cpufreq_policy *policy, char *buf)    \
 214 {                                                                       \
 215         struct chip *chip = per_cpu(chip_info, policy->cpu);            \
 216                                                                         \
 217         return sprintf(buf, "%u\n", chip->member);                      \
 218 }                                                                       \
 219                                                                         \
 220 static struct freq_attr throttle_attr_##name = __ATTR_RO(name)          \
 221
 222 throttle_attr(unthrottle, reason[NO_THROTTLE]);
 223 throttle_attr(powercap, reason[POWERCAP]);
 224 throttle_attr(overtemp, reason[CPU_OVERTEMP]);
 225 throttle_attr(supply_fault, reason[POWER_SUPPLY_FAILURE]);
 226 throttle_attr(overcurrent, reason[OVERCURRENT]);
 227 throttle_attr(occ_reset, reason[OCC_RESET_THROTTLE]);
 228 throttle_attr(turbo_stat, throttle_turbo);
 229 throttle_attr(sub_turbo_stat, throttle_sub_turbo);
 230
 231 static struct attribute *throttle_attrs[] = {
 232         &throttle_attr_unthrottle.attr,
 233         &throttle_attr_powercap.attr,
 234         &throttle_attr_overtemp.attr,
 235         &throttle_attr_supply_fault.attr,
 236         &throttle_attr_overcurrent.attr,
 237         &throttle_attr_occ_reset.attr,
 238         &throttle_attr_turbo_stat.attr,
 239         &throttle_attr_sub_turbo_stat.attr,
 240         NULL,
 241 };
 242
 243 static const struct attribute_group throttle_attr_grp = {
 244         .name   = "throttle_stats",
 245         .attrs  = throttle_attrs,
 246 };
 247
 248 /* Helper routines */
 249
 250 /* Access helpers to power mgt SPR */
 251
 252 static inline unsigned long get_pmspr(unsigned long sprn)
 253 {
 254         switch (sprn) {
 255         case SPRN_PMCR:
 256                 return mfspr(SPRN_PMCR);
 257
 258         case SPRN_PMICR:
 259                 return mfspr(SPRN_PMICR);
 260
 261         case SPRN_PMSR:
 262                 return mfspr(SPRN_PMSR);
 263         }
 264         BUG();
 265 }
 266
 267 static inline void set_pmspr(unsigned long sprn, unsigned long val)
 268 {
 269         switch (sprn) {
 270         case SPRN_PMCR:
 271                 mtspr(SPRN_PMCR, val);
 272                 return;
 273
 274         case SPRN_PMICR:
 275                 mtspr(SPRN_PMICR, val);
 276                 return;
 277         }
 278         BUG();
 279 }
 280
 281 /*
 282  * Use objects of this type to query/update
 283  * pstates on a remote CPU via smp_call_function.
 284  */
 285 struct powernv_smp_call_data {
 286         unsigned int freq;
 287         int pstate_id;
 288 };
 289
 290 /*
 291  * powernv_read_cpu_freq: Reads the current frequency on this CPU.
 292  *
 293  * Called via smp_call_function.
 294  *
 295  * Note: The caller of the smp_call_function should pass an argument of
 296  * the type 'struct powernv_smp_call_data *' along with this function.
 297  *
 298  * The current frequency on this CPU will be returned via
 299  * ((struct powernv_smp_call_data *)arg)->freq;
 300  */
 301 static void powernv_read_cpu_freq(void *arg)
 302 {
 303         unsigned long pmspr_val;
 304         s8 local_pstate_id;
 305         struct powernv_smp_call_data *freq_data = arg;
 306
 307         pmspr_val = get_pmspr(SPRN_PMSR);
 308
 309         /*
 310          * The local pstate id corresponds bits 48..55 in the PMSR.
 311          * Note: Watch out for the sign!
 312          */
 313         local_pstate_id = (pmspr_val >> 48) & 0xFF;
 314         freq_data->pstate_id = local_pstate_id;
 315         freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
 316
 317         pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
 318                 raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
 319                 freq_data->freq);
 320 }
 321
 322 /*
 323  * powernv_cpufreq_get: Returns the CPU frequency as reported by the
 324  * firmware for CPU 'cpu'. This value is reported through the sysfs
 325  * file cpuinfo_cur_freq.
 326  */
 327 static unsigned int powernv_cpufreq_get(unsigned int cpu)
 328 {
 329         struct powernv_smp_call_data freq_data;
 330
 331         smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
 332                         &freq_data, 1);
 333
 334         return freq_data.freq;
 335 }
 336
 337 /*
 338  * set_pstate: Sets the pstate on this CPU.
 339  *
 340  * This is called via an smp_call_function.
 341  *
 342  * The caller must ensure that freq_data is of the type
 343  * (struct powernv_smp_call_data *) and the pstate_id which needs to be set
 344  * on this CPU should be present in freq_data->pstate_id.
 345  */
 346 static void set_pstate(void *freq_data)
 347 {
 348         unsigned long val;
 349         unsigned long pstate_ul =
 350                 ((struct powernv_smp_call_data *) freq_data)->pstate_id;
 351
 352         val = get_pmspr(SPRN_PMCR);
 353         val = val & 0x0000FFFFFFFFFFFFULL;
 354
 355         pstate_ul = pstate_ul & 0xFF;
 356
 357         /* Set both global(bits 56..63) and local(bits 48..55) PStates */
 358         val = val | (pstate_ul << 56) | (pstate_ul << 48);
 359
 360         pr_debug("Setting cpu %d pmcr to %016lX\n",
 361                         raw_smp_processor_id(), val);
 362         set_pmspr(SPRN_PMCR, val);
 363 }
 364
 365 /*
 366  * get_nominal_index: Returns the index corresponding to the nominal
 367  * pstate in the cpufreq table
 368  */
 369 static inline unsigned int get_nominal_index(void)
 370 {
 371         return powernv_pstate_info.max - powernv_pstate_info.nominal;
 372 }
 373
 374 static void powernv_cpufreq_throttle_check(void *data)
 375 {
 376         struct chip *chip;
 377         unsigned int cpu = smp_processor_id();
 378         unsigned long pmsr;
 379         int pmsr_pmax;
 380
 381         pmsr = get_pmspr(SPRN_PMSR);
 382         chip = this_cpu_read(chip_info);
 383
 384         /* Check for Pmax Capping */
 385         pmsr_pmax = (s8)PMSR_MAX(pmsr);
 386         if (pmsr_pmax != powernv_pstate_info.max) {
 387                 if (chip->throttled)
 388                         goto next;
 389                 chip->throttled = true;
 390                 if (pmsr_pmax < powernv_pstate_info.nominal) {
 391                         pr_warn_once("CPU %d on Chip %u has Pmax reduced below nominal frequency (%d < %d)\n",
 392                                      cpu, chip->id, pmsr_pmax,
 393                                      powernv_pstate_info.nominal);
 394                         chip->throttle_sub_turbo++;
 395                 } else {
 396                         chip->throttle_turbo++;
 397                 }
 398                 trace_powernv_throttle(chip->id,
 399                                       throttle_reason[chip->throttle_reason],
 400                                       pmsr_pmax);
 401         } else if (chip->throttled) {
 402                 chip->throttled = false;
 403                 trace_powernv_throttle(chip->id,
 404                                       throttle_reason[chip->throttle_reason],
 405                                       pmsr_pmax);
 406         }
 407
 408         /* Check if Psafe_mode_active is set in PMSR. */
 409 next:
 410         if (pmsr & PMSR_PSAFE_ENABLE) {
 411                 throttled = true;
 412                 pr_info("Pstate set to safe frequency\n");
 413         }
 414
 415         /* Check if SPR_EM_DISABLE is set in PMSR */
 416         if (pmsr & PMSR_SPR_EM_DISABLE) {
 417                 throttled = true;
 418                 pr_info("Frequency Control disabled from OS\n");
 419         }
 420
 421         if (throttled) {
 422                 pr_info("PMSR = %16lx\n", pmsr);
 423                 pr_warn("CPU Frequency could be throttled\n");
 424         }
 425 }
 426
 427 /*
 428  * powernv_cpufreq_target_index: Sets the frequency corresponding to
 429  * the cpufreq table entry indexed by new_index on the cpus in the
 430  * mask policy->cpus
 431  */
 432 static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 433                                         unsigned int new_index)
 434 {
 435         struct powernv_smp_call_data freq_data;
 436
 437         if (unlikely(rebooting) && new_index != get_nominal_index())
 438                 return 0;
 439
 440         if (!throttled)
 441                 powernv_cpufreq_throttle_check(NULL);
 442
 443         freq_data.pstate_id = powernv_freqs[new_index].driver_data;
 444
 445         /*
 446          * Use smp_call_function to send IPI and execute the
 447          * mtspr on target CPU.  We could do that without IPI
 448          * if current CPU is within policy->cpus (core)
 449          */
 450         smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
 451
 452         return 0;
 453 }
 454
 455 static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
 456 {
 457         int base, i;
 458         struct kernfs_node *kn;
 459
 460         base = cpu_first_thread_sibling(policy->cpu);
 461
 462         for (i = 0; i < threads_per_core; i++)
 463                 cpumask_set_cpu(base + i, policy->cpus);
 464
 465         kn = kernfs_find_and_get(policy->kobj.sd, throttle_attr_grp.name);
 466         if (!kn) {
 467                 int ret;
 468
 469                 ret = sysfs_create_group(&policy->kobj, &throttle_attr_grp);
 470                 if (ret) {
 471                         pr_info("Failed to create throttle stats directory for cpu %d\n",
 472                                 policy->cpu);
 473                         return ret;
 474                 }
 475         } else {
 476                 kernfs_put(kn);
 477         }
 478         return cpufreq_table_validate_and_show(policy, powernv_freqs);
 479 }
 480
 481 static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
 482                                 unsigned long action, void *unused)
 483 {
 484         int cpu;
 485         struct cpufreq_policy cpu_policy;
 486
 487         rebooting = true;
 488         for_each_online_cpu(cpu) {
 489                 cpufreq_get_policy(&cpu_policy, cpu);
 490                 powernv_cpufreq_target_index(&cpu_policy, get_nominal_index());
 491         }
 492
 493         return NOTIFY_DONE;
 494 }
 495
 496 static struct notifier_block powernv_cpufreq_reboot_nb = {
 497         .notifier_call = powernv_cpufreq_reboot_notifier,
 498 };
 499
 500 void powernv_cpufreq_work_fn(struct work_struct *work)
 501 {
 502         struct chip *chip = container_of(work, struct chip, throttle);
 503         unsigned int cpu;
 504         cpumask_t mask;
 505
 506         get_online_cpus();
 507         cpumask_and(&mask, &chip->mask, cpu_online_mask);
 508         smp_call_function_any(&mask,
 509                               powernv_cpufreq_throttle_check, NULL, 0);
 510
 511         if (!chip->restore)
 512                 goto out;
 513
 514         chip->restore = false;
 515         for_each_cpu(cpu, &mask) {
 516                 int index;
 517                 struct cpufreq_policy policy;
 518
 519                 cpufreq_get_policy(&policy, cpu);
 520                 cpufreq_frequency_table_target(&policy, policy.freq_table,
 521                                                policy.cur,
 522                                                CPUFREQ_RELATION_C, &index);
 523                 powernv_cpufreq_target_index(&policy, index);
 524                 cpumask_andnot(&mask, &mask, policy.cpus);
 525         }
 526 out:
 527         put_online_cpus();
 528 }
 529
 530 static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 531                                    unsigned long msg_type, void *_msg)
 532 {
 533         struct opal_msg *msg = _msg;
 534         struct opal_occ_msg omsg;
 535         int i;
 536
 537         if (msg_type != OPAL_MSG_OCC)
 538                 return 0;
 539
 540         omsg.type = be64_to_cpu(msg->params[0]);
 541
 542         switch (omsg.type) {
 543         case OCC_RESET:
 544                 occ_reset = true;
 545                 pr_info("OCC (On Chip Controller - enforces hard thermal/power limits) Resetting\n");
 546                 /*
 547                  * powernv_cpufreq_throttle_check() is called in
 548                  * target() callback which can detect the throttle state
 549                  * for governors like ondemand.
 550                  * But static governors will not call target() often thus
 551                  * report throttling here.
 552                  */
 553                 if (!throttled) {
 554                         throttled = true;
 555                         pr_warn("CPU frequency is throttled for duration\n");
 556                 }
 557
 558                 break;
 559         case OCC_LOAD:
 560                 pr_info("OCC Loading, CPU frequency is throttled until OCC is started\n");
 561                 break;
 562         case OCC_THROTTLE:
 563                 omsg.chip = be64_to_cpu(msg->params[1]);
 564                 omsg.throttle_status = be64_to_cpu(msg->params[2]);
 565
 566                 if (occ_reset) {
 567                         occ_reset = false;
 568                         throttled = false;
 569                         pr_info("OCC Active, CPU frequency is no longer throttled\n");
 570
 571                         for (i = 0; i < nr_chips; i++) {
 572                                 chips[i].restore = true;
 573                                 schedule_work(&chips[i].throttle);
 574                         }
 575
 576                         return 0;
 577                 }
 578
 579                 for (i = 0; i < nr_chips; i++)
 580                         if (chips[i].id == omsg.chip)
 581                                 break;
 582
 583                 if (omsg.throttle_status >= 0 &&
 584                     omsg.throttle_status <= OCC_MAX_THROTTLE_STATUS) {
 585                         chips[i].throttle_reason = omsg.throttle_status;
 586                         chips[i].reason[omsg.throttle_status]++;
 587                 }
 588
 589                 if (!omsg.throttle_status)
 590                         chips[i].restore = true;
 591
 592                 schedule_work(&chips[i].throttle);
 593         }
 594         return 0;
 595 }
 596
 597 static struct notifier_block powernv_cpufreq_opal_nb = {
 598         .notifier_call  = powernv_cpufreq_occ_msg,
 599         .next           = NULL,
 600         .priority       = 0,
 601 };
 602
 603 static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
 604 {
 605         struct powernv_smp_call_data freq_data;
 606
 607         freq_data.pstate_id = powernv_pstate_info.min;
 608         smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
 609 }
 610
 611 static struct cpufreq_driver powernv_cpufreq_driver = {
 612         .name           = "powernv-cpufreq",
 613         .flags          = CPUFREQ_CONST_LOOPS,
 614         .init           = powernv_cpufreq_cpu_init,
 615         .verify         = cpufreq_generic_frequency_table_verify,
 616         .target_index   = powernv_cpufreq_target_index,
 617         .get            = powernv_cpufreq_get,
 618         .stop_cpu       = powernv_cpufreq_stop_cpu,
 619         .attr           = powernv_cpu_freq_attr,
 620 };
 621
 622 static int init_chip_info(void)
 623 {
 624         unsigned int chip[256];
 625         unsigned int cpu, i;
 626         unsigned int prev_chip_id = UINT_MAX;
 627
 628         for_each_possible_cpu(cpu) {
 629                 unsigned int id = cpu_to_chip_id(cpu);
 630
 631                 if (prev_chip_id != id) {
 632                         prev_chip_id = id;
 633                         chip[nr_chips++] = id;
 634                 }
 635         }
 636
 637         chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);
 638         if (!chips)
 639                 return -ENOMEM;
 640
 641         for (i = 0; i < nr_chips; i++) {
 642                 chips[i].id = chip[i];
 643                 cpumask_copy(&chips[i].mask, cpumask_of_node(chip[i]));
 644                 INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);
 645                 for_each_cpu(cpu, &chips[i].mask)
 646                         per_cpu(chip_info, cpu) =  &chips[i];
 647         }
 648
 649         return 0;
 650 }
 651
 652 static inline void clean_chip_info(void)
 653 {
 654         kfree(chips);
 655 }
 656
 657 static inline void unregister_all_notifiers(void)
 658 {
 659         opal_message_notifier_unregister(OPAL_MSG_OCC,
 660                                          &powernv_cpufreq_opal_nb);
 661         unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
 662 }
 663
 664 static int __init powernv_cpufreq_init(void)
 665 {
 666         int rc = 0;
 667
 668         /* Don't probe on pseries (guest) platforms */
 669         if (!firmware_has_feature(FW_FEATURE_OPAL))
 670                 return -ENODEV;
 671
 672         /* Discover pstates from device tree and init */
 673         rc = init_powernv_pstates();
 674         if (rc)
 675                 goto out;
 676
 677         /* Populate chip info */
 678         rc = init_chip_info();
 679         if (rc)
 680                 goto out;
 681
 682         register_reboot_notifier(&powernv_cpufreq_reboot_nb);
 683         opal_message_notifier_register(OPAL_MSG_OCC, &powernv_cpufreq_opal_nb);
 684
 685         rc = cpufreq_register_driver(&powernv_cpufreq_driver);
 686         if (!rc)
 687                 return 0;
 688
 689         pr_info("Failed to register the cpufreq driver (%d)\n", rc);
 690         unregister_all_notifiers();
 691         clean_chip_info();
 692 out:
 693         pr_info("Platform driver disabled. System does not support PState control\n");
 694         return rc;
 695 }
 696 module_init(powernv_cpufreq_init);
 697
 698 static void __exit powernv_cpufreq_exit(void)
 699 {
 700         cpufreq_unregister_driver(&powernv_cpufreq_driver);
 701         unregister_all_notifiers();
 702         clean_chip_info();
 703 }
 704 module_exit(powernv_cpufreq_exit);
 705
 706 MODULE_LICENSE("GPL");
 707 MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");