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