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
  31 #include <asm/cputhreads.h>
  32 #include <asm/firmware.h>
  33 #include <asm/reg.h>
  34 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
  35
  36 #define POWERNV_MAX_PSTATES     256
  37 #define PMSR_PSAFE_ENABLE       (1UL << 30)
  38 #define PMSR_SPR_EM_DISABLE     (1UL << 31)
  39 #define PMSR_MAX(x)             ((x >> 32) & 0xFF)
  40 #define PMSR_LP(x)              ((x >> 48) & 0xFF)
  41
  42 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
  43 static bool rebooting, throttled;
  44
  45 /*
  46  * Note: The set of pstates consists of contiguous integers, the
  47  * smallest of which is indicated by powernv_pstate_info.min, the
  48  * largest of which is indicated by powernv_pstate_info.max.
  49  *
  50  * The nominal pstate is the highest non-turbo pstate in this
  51  * platform. This is indicated by powernv_pstate_info.nominal.
  52  */
  53 static struct powernv_pstate_info {
  54         int min;
  55         int max;
  56         int nominal;
  57         int nr_pstates;
  58 } powernv_pstate_info;
  59
  60 /*
  61  * Initialize the freq table based on data obtained
  62  * from the firmware passed via device-tree
  63  */
  64 static int init_powernv_pstates(void)
  65 {
  66         struct device_node *power_mgt;
  67         int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
  68         const __be32 *pstate_ids, *pstate_freqs;
  69         u32 len_ids, len_freqs;
  70
  71         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
  72         if (!power_mgt) {
  73                 pr_warn("power-mgt node not found\n");
  74                 return -ENODEV;
  75         }
  76
  77         if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
  78                 pr_warn("ibm,pstate-min node not found\n");
  79                 return -ENODEV;
  80         }
  81
  82         if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
  83                 pr_warn("ibm,pstate-max node not found\n");
  84                 return -ENODEV;
  85         }
  86
  87         if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
  88                                  &pstate_nominal)) {
  89                 pr_warn("ibm,pstate-nominal not found\n");
  90                 return -ENODEV;
  91         }
  92         pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
  93                 pstate_nominal, pstate_max);
  94
  95         pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
  96         if (!pstate_ids) {
  97                 pr_warn("ibm,pstate-ids not found\n");
  98                 return -ENODEV;
  99         }
 100
 101         pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
 102                                       &len_freqs);
 103         if (!pstate_freqs) {
 104                 pr_warn("ibm,pstate-frequencies-mhz not found\n");
 105                 return -ENODEV;
 106         }
 107
 108         if (len_ids != len_freqs) {
 109                 pr_warn("Entries in ibm,pstate-ids and "
 110                         "ibm,pstate-frequencies-mhz does not match\n");
 111         }
 112
 113         nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
 114         if (!nr_pstates) {
 115                 pr_warn("No PStates found\n");
 116                 return -ENODEV;
 117         }
 118
 119         pr_debug("NR PStates %d\n", nr_pstates);
 120         for (i = 0; i < nr_pstates; i++) {
 121                 u32 id = be32_to_cpu(pstate_ids[i]);
 122                 u32 freq = be32_to_cpu(pstate_freqs[i]);
 123
 124                 pr_debug("PState id %d freq %d MHz\n", id, freq);
 125                 powernv_freqs[i].frequency = freq * 1000; /* kHz */
 126                 powernv_freqs[i].driver_data = id;
 127         }
 128         /* End of list marker entry */
 129         powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
 130
 131         powernv_pstate_info.min = pstate_min;
 132         powernv_pstate_info.max = pstate_max;
 133         powernv_pstate_info.nominal = pstate_nominal;
 134         powernv_pstate_info.nr_pstates = nr_pstates;
 135
 136         return 0;
 137 }
 138
 139 /* Returns the CPU frequency corresponding to the pstate_id. */
 140 static unsigned int pstate_id_to_freq(int pstate_id)
 141 {
 142         int i;
 143
 144         i = powernv_pstate_info.max - pstate_id;
 145         if (i >= powernv_pstate_info.nr_pstates || i < 0) {
 146                 pr_warn("PState id %d outside of PState table, "
 147                         "reporting nominal id %d instead\n",
 148                         pstate_id, powernv_pstate_info.nominal);
 149                 i = powernv_pstate_info.max - powernv_pstate_info.nominal;
 150         }
 151
 152         return powernv_freqs[i].frequency;
 153 }
 154
 155 /*
 156  * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
 157  * the firmware
 158  */
 159 static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
 160                                         char *buf)
 161 {
 162         return sprintf(buf, "%u\n",
 163                 pstate_id_to_freq(powernv_pstate_info.nominal));
 164 }
 165
 166 struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
 167         __ATTR_RO(cpuinfo_nominal_freq);
 168
 169 static struct freq_attr *powernv_cpu_freq_attr[] = {
 170         &cpufreq_freq_attr_scaling_available_freqs,
 171         &cpufreq_freq_attr_cpuinfo_nominal_freq,
 172         NULL,
 173 };
 174
 175 /* Helper routines */
 176
 177 /* Access helpers to power mgt SPR */
 178
 179 static inline unsigned long get_pmspr(unsigned long sprn)
 180 {
 181         switch (sprn) {
 182         case SPRN_PMCR:
 183                 return mfspr(SPRN_PMCR);
 184
 185         case SPRN_PMICR:
 186                 return mfspr(SPRN_PMICR);
 187
 188         case SPRN_PMSR:
 189                 return mfspr(SPRN_PMSR);
 190         }
 191         BUG();
 192 }
 193
 194 static inline void set_pmspr(unsigned long sprn, unsigned long val)
 195 {
 196         switch (sprn) {
 197         case SPRN_PMCR:
 198                 mtspr(SPRN_PMCR, val);
 199                 return;
 200
 201         case SPRN_PMICR:
 202                 mtspr(SPRN_PMICR, val);
 203                 return;
 204         }
 205         BUG();
 206 }
 207
 208 /*
 209  * Use objects of this type to query/update
 210  * pstates on a remote CPU via smp_call_function.
 211  */
 212 struct powernv_smp_call_data {
 213         unsigned int freq;
 214         int pstate_id;
 215 };
 216
 217 /*
 218  * powernv_read_cpu_freq: Reads the current frequency on this CPU.
 219  *
 220  * Called via smp_call_function.
 221  *
 222  * Note: The caller of the smp_call_function should pass an argument of
 223  * the type 'struct powernv_smp_call_data *' along with this function.
 224  *
 225  * The current frequency on this CPU will be returned via
 226  * ((struct powernv_smp_call_data *)arg)->freq;
 227  */
 228 static void powernv_read_cpu_freq(void *arg)
 229 {
 230         unsigned long pmspr_val;
 231         s8 local_pstate_id;
 232         struct powernv_smp_call_data *freq_data = arg;
 233
 234         pmspr_val = get_pmspr(SPRN_PMSR);
 235
 236         /*
 237          * The local pstate id corresponds bits 48..55 in the PMSR.
 238          * Note: Watch out for the sign!
 239          */
 240         local_pstate_id = (pmspr_val >> 48) & 0xFF;
 241         freq_data->pstate_id = local_pstate_id;
 242         freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
 243
 244         pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
 245                 raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
 246                 freq_data->freq);
 247 }
 248
 249 /*
 250  * powernv_cpufreq_get: Returns the CPU frequency as reported by the
 251  * firmware for CPU 'cpu'. This value is reported through the sysfs
 252  * file cpuinfo_cur_freq.
 253  */
 254 static unsigned int powernv_cpufreq_get(unsigned int cpu)
 255 {
 256         struct powernv_smp_call_data freq_data;
 257
 258         smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
 259                         &freq_data, 1);
 260
 261         return freq_data.freq;
 262 }
 263
 264 /*
 265  * set_pstate: Sets the pstate on this CPU.
 266  *
 267  * This is called via an smp_call_function.
 268  *
 269  * The caller must ensure that freq_data is of the type
 270  * (struct powernv_smp_call_data *) and the pstate_id which needs to be set
 271  * on this CPU should be present in freq_data->pstate_id.
 272  */
 273 static void set_pstate(void *freq_data)
 274 {
 275         unsigned long val;
 276         unsigned long pstate_ul =
 277                 ((struct powernv_smp_call_data *) freq_data)->pstate_id;
 278
 279         val = get_pmspr(SPRN_PMCR);
 280         val = val & 0x0000FFFFFFFFFFFFULL;
 281
 282         pstate_ul = pstate_ul & 0xFF;
 283
 284         /* Set both global(bits 56..63) and local(bits 48..55) PStates */
 285         val = val | (pstate_ul << 56) | (pstate_ul << 48);
 286
 287         pr_debug("Setting cpu %d pmcr to %016lX\n",
 288                         raw_smp_processor_id(), val);
 289         set_pmspr(SPRN_PMCR, val);
 290 }
 291
 292 /*
 293  * get_nominal_index: Returns the index corresponding to the nominal
 294  * pstate in the cpufreq table
 295  */
 296 static inline unsigned int get_nominal_index(void)
 297 {
 298         return powernv_pstate_info.max - powernv_pstate_info.nominal;
 299 }
 300
 301 static void powernv_cpufreq_throttle_check(unsigned int cpu)
 302 {
 303         unsigned long pmsr;
 304         int pmsr_pmax, pmsr_lp;
 305
 306         pmsr = get_pmspr(SPRN_PMSR);
 307
 308         /* Check for Pmax Capping */
 309         pmsr_pmax = (s8)PMSR_MAX(pmsr);
 310         if (pmsr_pmax != powernv_pstate_info.max) {
 311                 throttled = true;
 312                 pr_info("CPU %d Pmax is reduced to %d\n", cpu, pmsr_pmax);
 313                 pr_info("Max allowed Pstate is capped\n");
 314         }
 315
 316         /*
 317          * Check for Psafe by reading LocalPstate
 318          * or check if Psafe_mode_active is set in PMSR.
 319          */
 320         pmsr_lp = (s8)PMSR_LP(pmsr);
 321         if ((pmsr_lp < powernv_pstate_info.min) ||
 322                                 (pmsr & PMSR_PSAFE_ENABLE)) {
 323                 throttled = true;
 324                 pr_info("Pstate set to safe frequency\n");
 325         }
 326
 327         /* Check if SPR_EM_DISABLE is set in PMSR */
 328         if (pmsr & PMSR_SPR_EM_DISABLE) {
 329                 throttled = true;
 330                 pr_info("Frequency Control disabled from OS\n");
 331         }
 332
 333         if (throttled) {
 334                 pr_info("PMSR = %16lx\n", pmsr);
 335                 pr_crit("CPU Frequency could be throttled\n");
 336         }
 337 }
 338
 339 /*
 340  * powernv_cpufreq_target_index: Sets the frequency corresponding to
 341  * the cpufreq table entry indexed by new_index on the cpus in the
 342  * mask policy->cpus
 343  */
 344 static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 345                                         unsigned int new_index)
 346 {
 347         struct powernv_smp_call_data freq_data;
 348
 349         if (unlikely(rebooting) && new_index != get_nominal_index())
 350                 return 0;
 351
 352         if (!throttled)
 353                 powernv_cpufreq_throttle_check(smp_processor_id());
 354
 355         freq_data.pstate_id = powernv_freqs[new_index].driver_data;
 356
 357         /*
 358          * Use smp_call_function to send IPI and execute the
 359          * mtspr on target CPU.  We could do that without IPI
 360          * if current CPU is within policy->cpus (core)
 361          */
 362         smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
 363
 364         return 0;
 365 }
 366
 367 static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
 368 {
 369         int base, i;
 370
 371         base = cpu_first_thread_sibling(policy->cpu);
 372
 373         for (i = 0; i < threads_per_core; i++)
 374                 cpumask_set_cpu(base + i, policy->cpus);
 375
 376         return cpufreq_table_validate_and_show(policy, powernv_freqs);
 377 }
 378
 379 static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
 380                                 unsigned long action, void *unused)
 381 {
 382         int cpu;
 383         struct cpufreq_policy cpu_policy;
 384
 385         rebooting = true;
 386         for_each_online_cpu(cpu) {
 387                 cpufreq_get_policy(&cpu_policy, cpu);
 388                 powernv_cpufreq_target_index(&cpu_policy, get_nominal_index());
 389         }
 390
 391         return NOTIFY_DONE;
 392 }
 393
 394 static struct notifier_block powernv_cpufreq_reboot_nb = {
 395         .notifier_call = powernv_cpufreq_reboot_notifier,
 396 };
 397
 398 static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
 399 {
 400         struct powernv_smp_call_data freq_data;
 401
 402         freq_data.pstate_id = powernv_pstate_info.min;
 403         smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
 404 }
 405
 406 static struct cpufreq_driver powernv_cpufreq_driver = {
 407         .name           = "powernv-cpufreq",
 408         .flags          = CPUFREQ_CONST_LOOPS,
 409         .init           = powernv_cpufreq_cpu_init,
 410         .verify         = cpufreq_generic_frequency_table_verify,
 411         .target_index   = powernv_cpufreq_target_index,
 412         .get            = powernv_cpufreq_get,
 413         .stop_cpu       = powernv_cpufreq_stop_cpu,
 414         .attr           = powernv_cpu_freq_attr,
 415 };
 416
 417 static int __init powernv_cpufreq_init(void)
 418 {
 419         int rc = 0;
 420
 421         /* Don't probe on pseries (guest) platforms */
 422         if (!firmware_has_feature(FW_FEATURE_OPALv3))
 423                 return -ENODEV;
 424
 425         /* Discover pstates from device tree and init */
 426         rc = init_powernv_pstates();
 427         if (rc) {
 428                 pr_info("powernv-cpufreq disabled. System does not support PState control\n");
 429                 return rc;
 430         }
 431
 432         register_reboot_notifier(&powernv_cpufreq_reboot_nb);
 433         return cpufreq_register_driver(&powernv_cpufreq_driver);
 434 }
 435 module_init(powernv_cpufreq_init);
 436
 437 static void __exit powernv_cpufreq_exit(void)
 438 {
 439         unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
 440         cpufreq_unregister_driver(&powernv_cpufreq_driver);
 441 }
 442 module_exit(powernv_cpufreq_exit);
 443
 444 MODULE_LICENSE("GPL");
 445 MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");