drivers/cpufreq/powernv-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * POWERNV cpufreq driver for the IBM POWER processors
   4  *
   5  * (C) Copyright IBM 2014
   6  *
   7  * Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
   8  */
   9
  10 #define pr_fmt(fmt)     "powernv-cpufreq: " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/cpumask.h>
  15 #include <linux/module.h>
  16 #include <linux/cpufreq.h>
  17 #include <linux/smp.h>
  18 #include <linux/of.h>
  19 #include <linux/reboot.h>
  20 #include <linux/slab.h>
  21 #include <linux/cpu.h>
  22 #include <linux/hashtable.h>
  23 #include <trace/events/power.h>
  24
  25 #include <asm/cputhreads.h>
  26 #include <asm/firmware.h>
  27 #include <asm/reg.h>
  28 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
  29 #include <asm/opal.h>
  30 #include <linux/timer.h>
  31
  32 #define POWERNV_MAX_PSTATES_ORDER  8
  33 #define POWERNV_MAX_PSTATES     (1UL << (POWERNV_MAX_PSTATES_ORDER))
  34 #define PMSR_PSAFE_ENABLE       (1UL << 30)
  35 #define PMSR_SPR_EM_DISABLE     (1UL << 31)
  36 #define MAX_PSTATE_SHIFT        32
  37 #define LPSTATE_SHIFT           48
  38 #define GPSTATE_SHIFT           56
  39 #define MAX_NR_CHIPS            32
  40
  41 #define MAX_RAMP_DOWN_TIME                              5120
  42 /*
  43  * On an idle system we want the global pstate to ramp-down from max value to
  44  * min over a span of ~5 secs. Also we want it to initially ramp-down slowly and
  45  * then ramp-down rapidly later on.
  46  *
  47  * This gives a percentage rampdown for time elapsed in milliseconds.
  48  * ramp_down_percentage = ((ms * ms) >> 18)
  49  *                      ~= 3.8 * (sec * sec)
  50  *
  51  * At 0 ms      ramp_down_percent = 0
  52  * At 5120 ms   ramp_down_percent = 100
  53  */
  54 #define ramp_down_percent(time)         ((time * time) >> 18)
  55
  56 /* Interval after which the timer is queued to bring down global pstate */
  57 #define GPSTATE_TIMER_INTERVAL                          2000
  58
  59 /**
  60  * struct global_pstate_info -  Per policy data structure to maintain history of
  61  *                              global pstates
  62  * @highest_lpstate_idx:        The local pstate index from which we are
  63  *                              ramping down
  64  * @elapsed_time:               Time in ms spent in ramping down from
  65  *                              highest_lpstate_idx
  66  * @last_sampled_time:          Time from boot in ms when global pstates were
  67  *                              last set
  68  * @last_lpstate_idx:           Last set value of local pstate and global
  69  * @last_gpstate_idx:           pstate in terms of cpufreq table index
  70  * @timer:                      Is used for ramping down if cpu goes idle for
  71  *                              a long time with global pstate held high
  72  * @gpstate_lock:               A spinlock to maintain synchronization between
  73  *                              routines called by the timer handler and
  74  *                              governer's target_index calls
  75  * @policy:                     Associated CPUFreq policy
  76  */
  77 struct global_pstate_info {
  78         int highest_lpstate_idx;
  79         unsigned int elapsed_time;
  80         unsigned int last_sampled_time;
  81         int last_lpstate_idx;
  82         int last_gpstate_idx;
  83         spinlock_t gpstate_lock;
  84         struct timer_list timer;
  85         struct cpufreq_policy *policy;
  86 };
  87
  88 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
  89
  90 static DEFINE_HASHTABLE(pstate_revmap, POWERNV_MAX_PSTATES_ORDER);
  91 /**
  92  * struct pstate_idx_revmap_data: Entry in the hashmap pstate_revmap
  93  *                                indexed by a function of pstate id.
  94  *
  95  * @pstate_id: pstate id for this entry.
  96  *
  97  * @cpufreq_table_idx: Index into the powernv_freqs
  98  *                     cpufreq_frequency_table for frequency
  99  *                     corresponding to pstate_id.
 100  *
 101  * @hentry: hlist_node that hooks this entry into the pstate_revmap
 102  *          hashtable
 103  */
 104 struct pstate_idx_revmap_data {
 105         u8 pstate_id;
 106         unsigned int cpufreq_table_idx;
 107         struct hlist_node hentry;
 108 };
 109
 110 static bool rebooting, throttled, occ_reset;
 111
 112 static const char * const throttle_reason[] = {
 113         "No throttling",
 114         "Power Cap",
 115         "Processor Over Temperature",
 116         "Power Supply Failure",
 117         "Over Current",
 118         "OCC Reset"
 119 };
 120
 121 enum throttle_reason_type {
 122         NO_THROTTLE = 0,
 123         POWERCAP,
 124         CPU_OVERTEMP,
 125         POWER_SUPPLY_FAILURE,
 126         OVERCURRENT,
 127         OCC_RESET_THROTTLE,
 128         OCC_MAX_REASON
 129 };
 130
 131 static struct chip {
 132         unsigned int id;
 133         bool throttled;
 134         bool restore;
 135         u8 throttle_reason;
 136         cpumask_t mask;
 137         struct work_struct throttle;
 138         int throttle_turbo;
 139         int throttle_sub_turbo;
 140         int reason[OCC_MAX_REASON];
 141 } *chips;
 142
 143 static int nr_chips;
 144 static DEFINE_PER_CPU(struct chip *, chip_info);
 145
 146 /*
 147  * Note:
 148  * The set of pstates consists of contiguous integers.
 149  * powernv_pstate_info stores the index of the frequency table for
 150  * max, min and nominal frequencies. It also stores number of
 151  * available frequencies.
 152  *
 153  * powernv_pstate_info.nominal indicates the index to the highest
 154  * non-turbo frequency.
 155  */
 156 static struct powernv_pstate_info {
 157         unsigned int min;
 158         unsigned int max;
 159         unsigned int nominal;
 160         unsigned int nr_pstates;
 161         bool wof_enabled;
 162 } powernv_pstate_info;
 163
 164 static inline u8 extract_pstate(u64 pmsr_val, unsigned int shift)
 165 {
 166         return ((pmsr_val >> shift) & 0xFF);
 167 }
 168
 169 #define extract_local_pstate(x) extract_pstate(x, LPSTATE_SHIFT)
 170 #define extract_global_pstate(x) extract_pstate(x, GPSTATE_SHIFT)
 171 #define extract_max_pstate(x)  extract_pstate(x, MAX_PSTATE_SHIFT)
 172
 173 /* Use following functions for conversions between pstate_id and index */
 174
 175 /*
 176  * idx_to_pstate : Returns the pstate id corresponding to the
 177  *                 frequency in the cpufreq frequency table
 178  *                 powernv_freqs indexed by @i.
 179  *
 180  *                 If @i is out of bound, this will return the pstate
 181  *                 corresponding to the nominal frequency.
 182  */
 183 static inline u8 idx_to_pstate(unsigned int i)
 184 {
 185         if (unlikely(i >= powernv_pstate_info.nr_pstates)) {
 186                 pr_warn_once("idx_to_pstate: index %u is out of bound\n", i);
 187                 return powernv_freqs[powernv_pstate_info.nominal].driver_data;
 188         }
 189
 190         return powernv_freqs[i].driver_data;
 191 }
 192
 193 /*
 194  * pstate_to_idx : Returns the index in the cpufreq frequencytable
 195  *                 powernv_freqs for the frequency whose corresponding
 196  *                 pstate id is @pstate.
 197  *
 198  *                 If no frequency corresponding to @pstate is found,
 199  *                 this will return the index of the nominal
 200  *                 frequency.
 201  */
 202 static unsigned int pstate_to_idx(u8 pstate)
 203 {
 204         unsigned int key = pstate % POWERNV_MAX_PSTATES;
 205         struct pstate_idx_revmap_data *revmap_data;
 206
 207         hash_for_each_possible(pstate_revmap, revmap_data, hentry, key) {
 208                 if (revmap_data->pstate_id == pstate)
 209                         return revmap_data->cpufreq_table_idx;
 210         }
 211
 212         pr_warn_once("pstate_to_idx: pstate 0x%x not found\n", pstate);
 213         return powernv_pstate_info.nominal;
 214 }
 215
 216 static inline void reset_gpstates(struct cpufreq_policy *policy)
 217 {
 218         struct global_pstate_info *gpstates = policy->driver_data;
 219
 220         gpstates->highest_lpstate_idx = 0;
 221         gpstates->elapsed_time = 0;
 222         gpstates->last_sampled_time = 0;
 223         gpstates->last_lpstate_idx = 0;
 224         gpstates->last_gpstate_idx = 0;
 225 }
 226
 227 /*
 228  * Initialize the freq table based on data obtained
 229  * from the firmware passed via device-tree
 230  */
 231 static int init_powernv_pstates(void)
 232 {
 233         struct device_node *power_mgt;
 234         int i, nr_pstates = 0;
 235         const __be32 *pstate_ids, *pstate_freqs;
 236         u32 len_ids, len_freqs;
 237         u32 pstate_min, pstate_max, pstate_nominal;
 238         u32 pstate_turbo, pstate_ultra_turbo;
 239         int rc = -ENODEV;
 240
 241         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 242         if (!power_mgt) {
 243                 pr_warn("power-mgt node not found\n");
 244                 return -ENODEV;
 245         }
 246
 247         if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
 248                 pr_warn("ibm,pstate-min node not found\n");
 249                 goto out;
 250         }
 251
 252         if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
 253                 pr_warn("ibm,pstate-max node not found\n");
 254                 goto out;
 255         }
 256
 257         if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
 258                                  &pstate_nominal)) {
 259                 pr_warn("ibm,pstate-nominal not found\n");
 260                 goto out;
 261         }
 262
 263         if (of_property_read_u32(power_mgt, "ibm,pstate-ultra-turbo",
 264                                  &pstate_ultra_turbo)) {
 265                 powernv_pstate_info.wof_enabled = false;
 266                 goto next;
 267         }
 268
 269         if (of_property_read_u32(power_mgt, "ibm,pstate-turbo",
 270                                  &pstate_turbo)) {
 271                 powernv_pstate_info.wof_enabled = false;
 272                 goto next;
 273         }
 274
 275         if (pstate_turbo == pstate_ultra_turbo)
 276                 powernv_pstate_info.wof_enabled = false;
 277         else
 278                 powernv_pstate_info.wof_enabled = true;
 279
 280 next:
 281         pr_info("cpufreq pstate min 0x%x nominal 0x%x max 0x%x\n", pstate_min,
 282                 pstate_nominal, pstate_max);
 283         pr_info("Workload Optimized Frequency is %s in the platform\n",
 284                 (powernv_pstate_info.wof_enabled) ? "enabled" : "disabled");
 285
 286         pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
 287         if (!pstate_ids) {
 288                 pr_warn("ibm,pstate-ids not found\n");
 289                 goto out;
 290         }
 291
 292         pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
 293                                       &len_freqs);
 294         if (!pstate_freqs) {
 295                 pr_warn("ibm,pstate-frequencies-mhz not found\n");
 296                 goto out;
 297         }
 298
 299         if (len_ids != len_freqs) {
 300                 pr_warn("Entries in ibm,pstate-ids and "
 301                         "ibm,pstate-frequencies-mhz does not match\n");
 302         }
 303
 304         nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
 305         if (!nr_pstates) {
 306                 pr_warn("No PStates found\n");
 307                 goto out;
 308         }
 309
 310         powernv_pstate_info.nr_pstates = nr_pstates;
 311         pr_debug("NR PStates %d\n", nr_pstates);
 312
 313         for (i = 0; i < nr_pstates; i++) {
 314                 u32 id = be32_to_cpu(pstate_ids[i]);
 315                 u32 freq = be32_to_cpu(pstate_freqs[i]);
 316                 struct pstate_idx_revmap_data *revmap_data;
 317                 unsigned int key;
 318
 319                 pr_debug("PState id %d freq %d MHz\n", id, freq);
 320                 powernv_freqs[i].frequency = freq * 1000; /* kHz */
 321                 powernv_freqs[i].driver_data = id & 0xFF;
 322
 323                 revmap_data = kmalloc(sizeof(*revmap_data), GFP_KERNEL);
 324                 if (!revmap_data) {
 325                         rc = -ENOMEM;
 326                         goto out;
 327                 }
 328
 329                 revmap_data->pstate_id = id & 0xFF;
 330                 revmap_data->cpufreq_table_idx = i;
 331                 key = (revmap_data->pstate_id) % POWERNV_MAX_PSTATES;
 332                 hash_add(pstate_revmap, &revmap_data->hentry, key);
 333
 334                 if (id == pstate_max)
 335                         powernv_pstate_info.max = i;
 336                 if (id == pstate_nominal)
 337                         powernv_pstate_info.nominal = i;
 338                 if (id == pstate_min)
 339                         powernv_pstate_info.min = i;
 340
 341                 if (powernv_pstate_info.wof_enabled && id == pstate_turbo) {
 342                         int j;
 343
 344                         for (j = i - 1; j >= (int)powernv_pstate_info.max; j--)
 345                                 powernv_freqs[j].flags = CPUFREQ_BOOST_FREQ;
 346                 }
 347         }
 348
 349         /* End of list marker entry */
 350         powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
 351
 352         of_node_put(power_mgt);
 353         return 0;
 354 out:
 355         of_node_put(power_mgt);
 356         return rc;
 357 }
 358
 359 /* Returns the CPU frequency corresponding to the pstate_id. */
 360 static unsigned int pstate_id_to_freq(u8 pstate_id)
 361 {
 362         int i;
 363
 364         i = pstate_to_idx(pstate_id);
 365         if (i >= powernv_pstate_info.nr_pstates || i < 0) {
 366                 pr_warn("PState id 0x%x outside of PState table, reporting nominal id 0x%x instead\n",
 367                         pstate_id, idx_to_pstate(powernv_pstate_info.nominal));
 368                 i = powernv_pstate_info.nominal;
 369         }
 370
 371         return powernv_freqs[i].frequency;
 372 }
 373
 374 /*
 375  * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
 376  * the firmware
 377  */
 378 static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
 379                                         char *buf)
 380 {
 381         return sprintf(buf, "%u\n",
 382                 powernv_freqs[powernv_pstate_info.nominal].frequency);
 383 }
 384
 385 static struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
 386         __ATTR_RO(cpuinfo_nominal_freq);
 387
 388 #define SCALING_BOOST_FREQS_ATTR_INDEX          2
 389
 390 static struct freq_attr *powernv_cpu_freq_attr[] = {
 391         &cpufreq_freq_attr_scaling_available_freqs,
 392         &cpufreq_freq_attr_cpuinfo_nominal_freq,
 393         &cpufreq_freq_attr_scaling_boost_freqs,
 394         NULL,
 395 };
 396
 397 #define throttle_attr(name, member)                                     \
 398 static ssize_t name##_show(struct cpufreq_policy *policy, char *buf)    \
 399 {                                                                       \
 400         struct chip *chip = per_cpu(chip_info, policy->cpu);            \
 401                                                                         \
 402         return sprintf(buf, "%u\n", chip->member);                      \
 403 }                                                                       \
 404                                                                         \
 405 static struct freq_attr throttle_attr_##name = __ATTR_RO(name)          \
 406
 407 throttle_attr(unthrottle, reason[NO_THROTTLE]);
 408 throttle_attr(powercap, reason[POWERCAP]);
 409 throttle_attr(overtemp, reason[CPU_OVERTEMP]);
 410 throttle_attr(supply_fault, reason[POWER_SUPPLY_FAILURE]);
 411 throttle_attr(overcurrent, reason[OVERCURRENT]);
 412 throttle_attr(occ_reset, reason[OCC_RESET_THROTTLE]);
 413 throttle_attr(turbo_stat, throttle_turbo);
 414 throttle_attr(sub_turbo_stat, throttle_sub_turbo);
 415
 416 static struct attribute *throttle_attrs[] = {
 417         &throttle_attr_unthrottle.attr,
 418         &throttle_attr_powercap.attr,
 419         &throttle_attr_overtemp.attr,
 420         &throttle_attr_supply_fault.attr,
 421         &throttle_attr_overcurrent.attr,
 422         &throttle_attr_occ_reset.attr,
 423         &throttle_attr_turbo_stat.attr,
 424         &throttle_attr_sub_turbo_stat.attr,
 425         NULL,
 426 };
 427
 428 static const struct attribute_group throttle_attr_grp = {
 429         .name   = "throttle_stats",
 430         .attrs  = throttle_attrs,
 431 };
 432
 433 /* Helper routines */
 434
 435 /* Access helpers to power mgt SPR */
 436
 437 static inline unsigned long get_pmspr(unsigned long sprn)
 438 {
 439         switch (sprn) {
 440         case SPRN_PMCR:
 441                 return mfspr(SPRN_PMCR);
 442
 443         case SPRN_PMICR:
 444                 return mfspr(SPRN_PMICR);
 445
 446         case SPRN_PMSR:
 447                 return mfspr(SPRN_PMSR);
 448         }
 449         BUG();
 450 }
 451
 452 static inline void set_pmspr(unsigned long sprn, unsigned long val)
 453 {
 454         switch (sprn) {
 455         case SPRN_PMCR:
 456                 mtspr(SPRN_PMCR, val);
 457                 return;
 458
 459         case SPRN_PMICR:
 460                 mtspr(SPRN_PMICR, val);
 461                 return;
 462         }
 463         BUG();
 464 }
 465
 466 /*
 467  * Use objects of this type to query/update
 468  * pstates on a remote CPU via smp_call_function.
 469  */
 470 struct powernv_smp_call_data {
 471         unsigned int freq;
 472         u8 pstate_id;
 473         u8 gpstate_id;
 474 };
 475
 476 /*
 477  * powernv_read_cpu_freq: Reads the current frequency on this CPU.
 478  *
 479  * Called via smp_call_function.
 480  *
 481  * Note: The caller of the smp_call_function should pass an argument of
 482  * the type 'struct powernv_smp_call_data *' along with this function.
 483  *
 484  * The current frequency on this CPU will be returned via
 485  * ((struct powernv_smp_call_data *)arg)->freq;
 486  */
 487 static void powernv_read_cpu_freq(void *arg)
 488 {
 489         unsigned long pmspr_val;
 490         struct powernv_smp_call_data *freq_data = arg;
 491
 492         pmspr_val = get_pmspr(SPRN_PMSR);
 493         freq_data->pstate_id = extract_local_pstate(pmspr_val);
 494         freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
 495
 496         pr_debug("cpu %d pmsr %016lX pstate_id 0x%x frequency %d kHz\n",
 497                  raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
 498                  freq_data->freq);
 499 }
 500
 501 /*
 502  * powernv_cpufreq_get: Returns the CPU frequency as reported by the
 503  * firmware for CPU 'cpu'. This value is reported through the sysfs
 504  * file cpuinfo_cur_freq.
 505  */
 506 static unsigned int powernv_cpufreq_get(unsigned int cpu)
 507 {
 508         struct powernv_smp_call_data freq_data;
 509
 510         smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
 511                         &freq_data, 1);
 512
 513         return freq_data.freq;
 514 }
 515
 516 /*
 517  * set_pstate: Sets the pstate on this CPU.
 518  *
 519  * This is called via an smp_call_function.
 520  *
 521  * The caller must ensure that freq_data is of the type
 522  * (struct powernv_smp_call_data *) and the pstate_id which needs to be set
 523  * on this CPU should be present in freq_data->pstate_id.
 524  */
 525 static void set_pstate(void *data)
 526 {
 527         unsigned long val;
 528         struct powernv_smp_call_data *freq_data = data;
 529         unsigned long pstate_ul = freq_data->pstate_id;
 530         unsigned long gpstate_ul = freq_data->gpstate_id;
 531
 532         val = get_pmspr(SPRN_PMCR);
 533         val = val & 0x0000FFFFFFFFFFFFULL;
 534
 535         pstate_ul = pstate_ul & 0xFF;
 536         gpstate_ul = gpstate_ul & 0xFF;
 537
 538         /* Set both global(bits 56..63) and local(bits 48..55) PStates */
 539         val = val | (gpstate_ul << 56) | (pstate_ul << 48);
 540
 541         pr_debug("Setting cpu %d pmcr to %016lX\n",
 542                         raw_smp_processor_id(), val);
 543         set_pmspr(SPRN_PMCR, val);
 544 }
 545
 546 /*
 547  * get_nominal_index: Returns the index corresponding to the nominal
 548  * pstate in the cpufreq table
 549  */
 550 static inline unsigned int get_nominal_index(void)
 551 {
 552         return powernv_pstate_info.nominal;
 553 }
 554
 555 static void powernv_cpufreq_throttle_check(void *data)
 556 {
 557         struct chip *chip;
 558         unsigned int cpu = smp_processor_id();
 559         unsigned long pmsr;
 560         u8 pmsr_pmax;
 561         unsigned int pmsr_pmax_idx;
 562
 563         pmsr = get_pmspr(SPRN_PMSR);
 564         chip = this_cpu_read(chip_info);
 565
 566         /* Check for Pmax Capping */
 567         pmsr_pmax = extract_max_pstate(pmsr);
 568         pmsr_pmax_idx = pstate_to_idx(pmsr_pmax);
 569         if (pmsr_pmax_idx != powernv_pstate_info.max) {
 570                 if (chip->throttled)
 571                         goto next;
 572                 chip->throttled = true;
 573                 if (pmsr_pmax_idx > powernv_pstate_info.nominal) {
 574                         pr_warn_once("CPU %d on Chip %u has Pmax(0x%x) reduced below that of nominal frequency(0x%x)\n",
 575                                      cpu, chip->id, pmsr_pmax,
 576                                      idx_to_pstate(powernv_pstate_info.nominal));
 577                         chip->throttle_sub_turbo++;
 578                 } else {
 579                         chip->throttle_turbo++;
 580                 }
 581                 trace_powernv_throttle(chip->id,
 582                                       throttle_reason[chip->throttle_reason],
 583                                       pmsr_pmax);
 584         } else if (chip->throttled) {
 585                 chip->throttled = false;
 586                 trace_powernv_throttle(chip->id,
 587                                       throttle_reason[chip->throttle_reason],
 588                                       pmsr_pmax);
 589         }
 590
 591         /* Check if Psafe_mode_active is set in PMSR. */
 592 next:
 593         if (pmsr & PMSR_PSAFE_ENABLE) {
 594                 throttled = true;
 595                 pr_info("Pstate set to safe frequency\n");
 596         }
 597
 598         /* Check if SPR_EM_DISABLE is set in PMSR */
 599         if (pmsr & PMSR_SPR_EM_DISABLE) {
 600                 throttled = true;
 601                 pr_info("Frequency Control disabled from OS\n");
 602         }
 603
 604         if (throttled) {
 605                 pr_info("PMSR = %16lx\n", pmsr);
 606                 pr_warn("CPU Frequency could be throttled\n");
 607         }
 608 }
 609
 610 /**
 611  * calc_global_pstate - Calculate global pstate
 612  * @elapsed_time:               Elapsed time in milliseconds
 613  * @local_pstate_idx:           New local pstate
 614  * @highest_lpstate_idx:        pstate from which its ramping down
 615  *
 616  * Finds the appropriate global pstate based on the pstate from which its
 617  * ramping down and the time elapsed in ramping down. It follows a quadratic
 618  * equation which ensures that it reaches ramping down to pmin in 5sec.
 619  */
 620 static inline int calc_global_pstate(unsigned int elapsed_time,
 621                                      int highest_lpstate_idx,
 622                                      int local_pstate_idx)
 623 {
 624         int index_diff;
 625
 626         /*
 627          * Using ramp_down_percent we get the percentage of rampdown
 628          * that we are expecting to be dropping. Difference between
 629          * highest_lpstate_idx and powernv_pstate_info.min will give a absolute
 630          * number of how many pstates we will drop eventually by the end of
 631          * 5 seconds, then just scale it get the number pstates to be dropped.
 632          */
 633         index_diff =  ((int)ramp_down_percent(elapsed_time) *
 634                         (powernv_pstate_info.min - highest_lpstate_idx)) / 100;
 635
 636         /* Ensure that global pstate is >= to local pstate */
 637         if (highest_lpstate_idx + index_diff >= local_pstate_idx)
 638                 return local_pstate_idx;
 639         else
 640                 return highest_lpstate_idx + index_diff;
 641 }
 642
 643 static inline void  queue_gpstate_timer(struct global_pstate_info *gpstates)
 644 {
 645         unsigned int timer_interval;
 646
 647         /*
 648          * Setting up timer to fire after GPSTATE_TIMER_INTERVAL ms, But
 649          * if it exceeds MAX_RAMP_DOWN_TIME ms for ramp down time.
 650          * Set timer such that it fires exactly at MAX_RAMP_DOWN_TIME
 651          * seconds of ramp down time.
 652          */
 653         if ((gpstates->elapsed_time + GPSTATE_TIMER_INTERVAL)
 654              > MAX_RAMP_DOWN_TIME)
 655                 timer_interval = MAX_RAMP_DOWN_TIME - gpstates->elapsed_time;
 656         else
 657                 timer_interval = GPSTATE_TIMER_INTERVAL;
 658
 659         mod_timer(&gpstates->timer, jiffies + msecs_to_jiffies(timer_interval));
 660 }
 661
 662 /**
 663  * gpstate_timer_handler
 664  *
 665  * @t: Timer context used to fetch global pstate info struct
 666  *
 667  * This handler brings down the global pstate closer to the local pstate
 668  * according quadratic equation. Queues a new timer if it is still not equal
 669  * to local pstate
 670  */
 671 static void gpstate_timer_handler(struct timer_list *t)
 672 {
 673         struct global_pstate_info *gpstates = from_timer(gpstates, t, timer);
 674         struct cpufreq_policy *policy = gpstates->policy;
 675         int gpstate_idx, lpstate_idx;
 676         unsigned long val;
 677         unsigned int time_diff = jiffies_to_msecs(jiffies)
 678                                         - gpstates->last_sampled_time;
 679         struct powernv_smp_call_data freq_data;
 680
 681         if (!spin_trylock(&gpstates->gpstate_lock))
 682                 return;
 683         /*
 684          * If the timer has migrated to the different cpu then bring
 685          * it back to one of the policy->cpus
 686          */
 687         if (!cpumask_test_cpu(raw_smp_processor_id(), policy->cpus)) {
 688                 gpstates->timer.expires = jiffies + msecs_to_jiffies(1);
 689                 add_timer_on(&gpstates->timer, cpumask_first(policy->cpus));
 690                 spin_unlock(&gpstates->gpstate_lock);
 691                 return;
 692         }
 693
 694         /*
 695          * If PMCR was last updated was using fast_swtich then
 696          * We may have wrong in gpstate->last_lpstate_idx
 697          * value. Hence, read from PMCR to get correct data.
 698          */
 699         val = get_pmspr(SPRN_PMCR);
 700         freq_data.gpstate_id = extract_global_pstate(val);
 701         freq_data.pstate_id = extract_local_pstate(val);
 702         if (freq_data.gpstate_id  == freq_data.pstate_id) {
 703                 reset_gpstates(policy);
 704                 spin_unlock(&gpstates->gpstate_lock);
 705                 return;
 706         }
 707
 708         gpstates->last_sampled_time += time_diff;
 709         gpstates->elapsed_time += time_diff;
 710
 711         if (gpstates->elapsed_time > MAX_RAMP_DOWN_TIME) {
 712                 gpstate_idx = pstate_to_idx(freq_data.pstate_id);
 713                 lpstate_idx = gpstate_idx;
 714                 reset_gpstates(policy);
 715                 gpstates->highest_lpstate_idx = gpstate_idx;
 716         } else {
 717                 lpstate_idx = pstate_to_idx(freq_data.pstate_id);
 718                 gpstate_idx = calc_global_pstate(gpstates->elapsed_time,
 719                                                  gpstates->highest_lpstate_idx,
 720                                                  lpstate_idx);
 721         }
 722         freq_data.gpstate_id = idx_to_pstate(gpstate_idx);
 723         gpstates->last_gpstate_idx = gpstate_idx;
 724         gpstates->last_lpstate_idx = lpstate_idx;
 725         /*
 726          * If local pstate is equal to global pstate, rampdown is over
 727          * So timer is not required to be queued.
 728          */
 729         if (gpstate_idx != gpstates->last_lpstate_idx)
 730                 queue_gpstate_timer(gpstates);
 731
 732         set_pstate(&freq_data);
 733         spin_unlock(&gpstates->gpstate_lock);
 734 }
 735
 736 /*
 737  * powernv_cpufreq_target_index: Sets the frequency corresponding to
 738  * the cpufreq table entry indexed by new_index on the cpus in the
 739  * mask policy->cpus
 740  */
 741 static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 742                                         unsigned int new_index)
 743 {
 744         struct powernv_smp_call_data freq_data;
 745         unsigned int cur_msec, gpstate_idx;
 746         struct global_pstate_info *gpstates = policy->driver_data;
 747
 748         if (unlikely(rebooting) && new_index != get_nominal_index())
 749                 return 0;
 750
 751         if (!throttled) {
 752                 /* we don't want to be preempted while
 753                  * checking if the CPU frequency has been throttled
 754                  */
 755                 preempt_disable();
 756                 powernv_cpufreq_throttle_check(NULL);
 757                 preempt_enable();
 758         }
 759
 760         cur_msec = jiffies_to_msecs(get_jiffies_64());
 761
 762         freq_data.pstate_id = idx_to_pstate(new_index);
 763         if (!gpstates) {
 764                 freq_data.gpstate_id = freq_data.pstate_id;
 765                 goto no_gpstate;
 766         }
 767
 768         spin_lock(&gpstates->gpstate_lock);
 769
 770         if (!gpstates->last_sampled_time) {
 771                 gpstate_idx = new_index;
 772                 gpstates->highest_lpstate_idx = new_index;
 773                 goto gpstates_done;
 774         }
 775
 776         if (gpstates->last_gpstate_idx < new_index) {
 777                 gpstates->elapsed_time += cur_msec -
 778                                                  gpstates->last_sampled_time;
 779
 780                 /*
 781                  * If its has been ramping down for more than MAX_RAMP_DOWN_TIME
 782                  * we should be resetting all global pstate related data. Set it
 783                  * equal to local pstate to start fresh.
 784                  */
 785                 if (gpstates->elapsed_time > MAX_RAMP_DOWN_TIME) {
 786                         reset_gpstates(policy);
 787                         gpstates->highest_lpstate_idx = new_index;
 788                         gpstate_idx = new_index;
 789                 } else {
 790                 /* Elaspsed_time is less than 5 seconds, continue to rampdown */
 791                         gpstate_idx = calc_global_pstate(gpstates->elapsed_time,
 792                                                          gpstates->highest_lpstate_idx,
 793                                                          new_index);
 794                 }
 795         } else {
 796                 reset_gpstates(policy);
 797                 gpstates->highest_lpstate_idx = new_index;
 798                 gpstate_idx = new_index;
 799         }
 800
 801         /*
 802          * If local pstate is equal to global pstate, rampdown is over
 803          * So timer is not required to be queued.
 804          */
 805         if (gpstate_idx != new_index)
 806                 queue_gpstate_timer(gpstates);
 807         else
 808                 del_timer_sync(&gpstates->timer);
 809
 810 gpstates_done:
 811         freq_data.gpstate_id = idx_to_pstate(gpstate_idx);
 812         gpstates->last_sampled_time = cur_msec;
 813         gpstates->last_gpstate_idx = gpstate_idx;
 814         gpstates->last_lpstate_idx = new_index;
 815
 816         spin_unlock(&gpstates->gpstate_lock);
 817
 818 no_gpstate:
 819         /*
 820          * Use smp_call_function to send IPI and execute the
 821          * mtspr on target CPU.  We could do that without IPI
 822          * if current CPU is within policy->cpus (core)
 823          */
 824         smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
 825         return 0;
 826 }
 827
 828 static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
 829 {
 830         int base, i;
 831         struct kernfs_node *kn;
 832         struct global_pstate_info *gpstates;
 833
 834         base = cpu_first_thread_sibling(policy->cpu);
 835
 836         for (i = 0; i < threads_per_core; i++)
 837                 cpumask_set_cpu(base + i, policy->cpus);
 838
 839         kn = kernfs_find_and_get(policy->kobj.sd, throttle_attr_grp.name);
 840         if (!kn) {
 841                 int ret;
 842
 843                 ret = sysfs_create_group(&policy->kobj, &throttle_attr_grp);
 844                 if (ret) {
 845                         pr_info("Failed to create throttle stats directory for cpu %d\n",
 846                                 policy->cpu);
 847                         return ret;
 848                 }
 849         } else {
 850                 kernfs_put(kn);
 851         }
 852
 853         policy->freq_table = powernv_freqs;
 854         policy->fast_switch_possible = true;
 855
 856         if (pvr_version_is(PVR_POWER9))
 857                 return 0;
 858
 859         /* Initialise Gpstate ramp-down timer only on POWER8 */
 860         gpstates =  kzalloc(sizeof(*gpstates), GFP_KERNEL);
 861         if (!gpstates)
 862                 return -ENOMEM;
 863
 864         policy->driver_data = gpstates;
 865
 866         /* initialize timer */
 867         gpstates->policy = policy;
 868         timer_setup(&gpstates->timer, gpstate_timer_handler,
 869                     TIMER_PINNED | TIMER_DEFERRABLE);
 870         gpstates->timer.expires = jiffies +
 871                                 msecs_to_jiffies(GPSTATE_TIMER_INTERVAL);
 872         spin_lock_init(&gpstates->gpstate_lock);
 873
 874         return 0;
 875 }
 876
 877 static int powernv_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 878 {
 879         struct powernv_smp_call_data freq_data;
 880         struct global_pstate_info *gpstates = policy->driver_data;
 881
 882         freq_data.pstate_id = idx_to_pstate(powernv_pstate_info.min);
 883         freq_data.gpstate_id = idx_to_pstate(powernv_pstate_info.min);
 884         smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
 885         if (gpstates)
 886                 del_timer_sync(&gpstates->timer);
 887
 888         kfree(policy->driver_data);
 889
 890         return 0;
 891 }
 892
 893 static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
 894                                 unsigned long action, void *unused)
 895 {
 896         int cpu;
 897         struct cpufreq_policy *cpu_policy;
 898
 899         rebooting = true;
 900         for_each_online_cpu(cpu) {
 901                 cpu_policy = cpufreq_cpu_get(cpu);
 902                 if (!cpu_policy)
 903                         continue;
 904                 powernv_cpufreq_target_index(cpu_policy, get_nominal_index());
 905                 cpufreq_cpu_put(cpu_policy);
 906         }
 907
 908         return NOTIFY_DONE;
 909 }
 910
 911 static struct notifier_block powernv_cpufreq_reboot_nb = {
 912         .notifier_call = powernv_cpufreq_reboot_notifier,
 913 };
 914
 915 static void powernv_cpufreq_work_fn(struct work_struct *work)
 916 {
 917         struct chip *chip = container_of(work, struct chip, throttle);
 918         struct cpufreq_policy *policy;
 919         unsigned int cpu;
 920         cpumask_t mask;
 921
 922         cpus_read_lock();
 923         cpumask_and(&mask, &chip->mask, cpu_online_mask);
 924         smp_call_function_any(&mask,
 925                               powernv_cpufreq_throttle_check, NULL, 0);
 926
 927         if (!chip->restore)
 928                 goto out;
 929
 930         chip->restore = false;
 931         for_each_cpu(cpu, &mask) {
 932                 int index;
 933
 934                 policy = cpufreq_cpu_get(cpu);
 935                 if (!policy)
 936                         continue;
 937                 index = cpufreq_table_find_index_c(policy, policy->cur, false);
 938                 powernv_cpufreq_target_index(policy, index);
 939                 cpumask_andnot(&mask, &mask, policy->cpus);
 940                 cpufreq_cpu_put(policy);
 941         }
 942 out:
 943         cpus_read_unlock();
 944 }
 945
 946 static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 947                                    unsigned long msg_type, void *_msg)
 948 {
 949         struct opal_msg *msg = _msg;
 950         struct opal_occ_msg omsg;
 951         int i;
 952
 953         if (msg_type != OPAL_MSG_OCC)
 954                 return 0;
 955
 956         omsg.type = be64_to_cpu(msg->params[0]);
 957
 958         switch (omsg.type) {
 959         case OCC_RESET:
 960                 occ_reset = true;
 961                 pr_info("OCC (On Chip Controller - enforces hard thermal/power limits) Resetting\n");
 962                 /*
 963                  * powernv_cpufreq_throttle_check() is called in
 964                  * target() callback which can detect the throttle state
 965                  * for governors like ondemand.
 966                  * But static governors will not call target() often thus
 967                  * report throttling here.
 968                  */
 969                 if (!throttled) {
 970                         throttled = true;
 971                         pr_warn("CPU frequency is throttled for duration\n");
 972                 }
 973
 974                 break;
 975         case OCC_LOAD:
 976                 pr_info("OCC Loading, CPU frequency is throttled until OCC is started\n");
 977                 break;
 978         case OCC_THROTTLE:
 979                 omsg.chip = be64_to_cpu(msg->params[1]);
 980                 omsg.throttle_status = be64_to_cpu(msg->params[2]);
 981
 982                 if (occ_reset) {
 983                         occ_reset = false;
 984                         throttled = false;
 985                         pr_info("OCC Active, CPU frequency is no longer throttled\n");
 986
 987                         for (i = 0; i < nr_chips; i++) {
 988                                 chips[i].restore = true;
 989                                 schedule_work(&chips[i].throttle);
 990                         }
 991
 992                         return 0;
 993                 }
 994
 995                 for (i = 0; i < nr_chips; i++)
 996                         if (chips[i].id == omsg.chip)
 997                                 break;
 998
 999                 if (omsg.throttle_status >= 0 &&
1000                     omsg.throttle_status <= OCC_MAX_THROTTLE_STATUS) {
1001                         chips[i].throttle_reason = omsg.throttle_status;
1002                         chips[i].reason[omsg.throttle_status]++;
1003                 }
1004
1005                 if (!omsg.throttle_status)
1006                         chips[i].restore = true;
1007
1008                 schedule_work(&chips[i].throttle);
1009         }
1010         return 0;
1011 }
1012
1013 static struct notifier_block powernv_cpufreq_opal_nb = {
1014         .notifier_call  = powernv_cpufreq_occ_msg,
1015         .next           = NULL,
1016         .priority       = 0,
1017 };
1018
1019 static unsigned int powernv_fast_switch(struct cpufreq_policy *policy,
1020                                         unsigned int target_freq)
1021 {
1022         int index;
1023         struct powernv_smp_call_data freq_data;
1024
1025         index = cpufreq_table_find_index_dl(policy, target_freq, false);
1026         freq_data.pstate_id = powernv_freqs[index].driver_data;
1027         freq_data.gpstate_id = powernv_freqs[index].driver_data;
1028         set_pstate(&freq_data);
1029
1030         return powernv_freqs[index].frequency;
1031 }
1032
1033 static struct cpufreq_driver powernv_cpufreq_driver = {
1034         .name           = "powernv-cpufreq",
1035         .flags          = CPUFREQ_CONST_LOOPS,
1036         .init           = powernv_cpufreq_cpu_init,
1037         .exit           = powernv_cpufreq_cpu_exit,
1038         .verify         = cpufreq_generic_frequency_table_verify,
1039         .target_index   = powernv_cpufreq_target_index,
1040         .fast_switch    = powernv_fast_switch,
1041         .get            = powernv_cpufreq_get,
1042         .attr           = powernv_cpu_freq_attr,
1043 };
1044
1045 static int init_chip_info(void)
1046 {
1047         unsigned int *chip;
1048         unsigned int cpu, i;
1049         unsigned int prev_chip_id = UINT_MAX;
1050         cpumask_t *chip_cpu_mask;
1051         int ret = 0;
1052
1053         chip = kcalloc(num_possible_cpus(), sizeof(*chip), GFP_KERNEL);
1054         if (!chip)
1055                 return -ENOMEM;
1056
1057         /* Allocate a chip cpu mask large enough to fit mask for all chips */
1058         chip_cpu_mask = kcalloc(MAX_NR_CHIPS, sizeof(cpumask_t), GFP_KERNEL);
1059         if (!chip_cpu_mask) {
1060                 ret = -ENOMEM;
1061                 goto free_and_return;
1062         }
1063
1064         for_each_possible_cpu(cpu) {
1065                 unsigned int id = cpu_to_chip_id(cpu);
1066
1067                 if (prev_chip_id != id) {
1068                         prev_chip_id = id;
1069                         chip[nr_chips++] = id;
1070                 }
1071                 cpumask_set_cpu(cpu, &chip_cpu_mask[nr_chips-1]);
1072         }
1073
1074         chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);
1075         if (!chips) {
1076                 ret = -ENOMEM;
1077                 goto out_free_chip_cpu_mask;
1078         }
1079
1080         for (i = 0; i < nr_chips; i++) {
1081                 chips[i].id = chip[i];
1082                 cpumask_copy(&chips[i].mask, &chip_cpu_mask[i]);
1083                 INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);
1084                 for_each_cpu(cpu, &chips[i].mask)
1085                         per_cpu(chip_info, cpu) =  &chips[i];
1086         }
1087
1088 out_free_chip_cpu_mask:
1089         kfree(chip_cpu_mask);
1090 free_and_return:
1091         kfree(chip);
1092         return ret;
1093 }
1094
1095 static inline void clean_chip_info(void)
1096 {
1097         int i;
1098
1099         /* flush any pending work items */
1100         if (chips)
1101                 for (i = 0; i < nr_chips; i++)
1102                         cancel_work_sync(&chips[i].throttle);
1103         kfree(chips);
1104 }
1105
1106 static inline void unregister_all_notifiers(void)
1107 {
1108         opal_message_notifier_unregister(OPAL_MSG_OCC,
1109                                          &powernv_cpufreq_opal_nb);
1110         unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
1111 }
1112
1113 static int __init powernv_cpufreq_init(void)
1114 {
1115         int rc = 0;
1116
1117         /* Don't probe on pseries (guest) platforms */
1118         if (!firmware_has_feature(FW_FEATURE_OPAL))
1119                 return -ENODEV;
1120
1121         /* Discover pstates from device tree and init */
1122         rc = init_powernv_pstates();
1123         if (rc)
1124                 goto out;
1125
1126         /* Populate chip info */
1127         rc = init_chip_info();
1128         if (rc)
1129                 goto out;
1130
1131         if (powernv_pstate_info.wof_enabled)
1132                 powernv_cpufreq_driver.boost_enabled = true;
1133         else
1134                 powernv_cpu_freq_attr[SCALING_BOOST_FREQS_ATTR_INDEX] = NULL;
1135
1136         rc = cpufreq_register_driver(&powernv_cpufreq_driver);
1137         if (rc) {
1138                 pr_info("Failed to register the cpufreq driver (%d)\n", rc);
1139                 goto cleanup;
1140         }
1141
1142         if (powernv_pstate_info.wof_enabled)
1143                 cpufreq_enable_boost_support();
1144
1145         register_reboot_notifier(&powernv_cpufreq_reboot_nb);
1146         opal_message_notifier_register(OPAL_MSG_OCC, &powernv_cpufreq_opal_nb);
1147
1148         return 0;
1149 cleanup:
1150         clean_chip_info();
1151 out:
1152         pr_info("Platform driver disabled. System does not support PState control\n");
1153         return rc;
1154 }
1155 module_init(powernv_cpufreq_init);
1156
1157 static void __exit powernv_cpufreq_exit(void)
1158 {
1159         cpufreq_unregister_driver(&powernv_cpufreq_driver);
1160         unregister_all_notifiers();
1161         clean_chip_info();
1162 }
1163 module_exit(powernv_cpufreq_exit);
1164
1165 MODULE_LICENSE("GPL");
1166 MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");