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