arch/arm64/kernel/topology.c

   1 /*
   2  * arch/arm64/kernel/topology.c
   3  *
   4  * Copyright (C) 2011,2013,2014 Linaro Limited.
   5  *
   6  * Based on the arm32 version written by Vincent Guittot in turn based on
   7  * arch/sh/kernel/topology.c
   8  *
   9  * This file is subject to the terms and conditions of the GNU General Public
  10  * License.  See the file "COPYING" in the main directory of this archive
  11  * for more details.
  12  */
  13
  14 #include <linux/cpu.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/export.h>
  17 #include <linux/init.h>
  18 #include <linux/percpu.h>
  19 #include <linux/node.h>
  20 #include <linux/nodemask.h>
  21 #include <linux/of.h>
  22 #include <linux/sched.h>
  23 #include <linux/slab.h>
  24
  25 #include <asm/cputype.h>
  26 #include <asm/topology.h>
  27 #include <asm/smp_plat.h>
  28
  29
  30 /*
  31  * cpu power table
  32  * This per cpu data structure describes the relative capacity of each core.
  33  * On a heteregenous system, cores don't have the same computation capacity
  34  * and we reflect that difference in the cpu_power field so the scheduler can
  35  * take this difference into account during load balance. A per cpu structure
  36  * is preferred because each CPU updates its own cpu_power field during the
  37  * load balance except for idle cores. One idle core is selected to run the
  38  * rebalance_domains for all idle cores and the cpu_power can be updated
  39  * during this sequence.
  40  */
  41 static DEFINE_PER_CPU(unsigned long, cpu_scale);
  42
  43 unsigned long arch_scale_freq_power(struct sched_domain *sd, int cpu)
  44 {
  45         return per_cpu(cpu_scale, cpu);
  46 }
  47
  48 static void set_power_scale(unsigned int cpu, unsigned long power)
  49 {
  50         per_cpu(cpu_scale, cpu) = power;
  51 }
  52
  53 static int __init get_cpu_for_node(struct device_node *node)
  54 {
  55         struct device_node *cpu_node;
  56         int cpu;
  57
  58         cpu_node = of_parse_phandle(node, "cpu", 0);
  59         if (!cpu_node)
  60                 return -1;
  61
  62         for_each_possible_cpu(cpu) {
  63                 if (of_get_cpu_node(cpu, NULL) == cpu_node) {
  64                         of_node_put(cpu_node);
  65                         return cpu;
  66                 }
  67         }
  68
  69         pr_crit("Unable to find CPU node for %s\n", cpu_node->full_name);
  70
  71         of_node_put(cpu_node);
  72         return -1;
  73 }
  74
  75 static int __init parse_core(struct device_node *core, int cluster_id,
  76                              int core_id)
  77 {
  78         char name[10];
  79         bool leaf = true;
  80         int i = 0;
  81         int cpu;
  82         struct device_node *t;
  83
  84         do {
  85                 snprintf(name, sizeof(name), "thread%d", i);
  86                 t = of_get_child_by_name(core, name);
  87                 if (t) {
  88                         leaf = false;
  89                         cpu = get_cpu_for_node(t);
  90                         if (cpu >= 0) {
  91                                 cpu_topology[cpu].cluster_id = cluster_id;
  92                                 cpu_topology[cpu].core_id = core_id;
  93                                 cpu_topology[cpu].thread_id = i;
  94                         } else {
  95                                 pr_err("%s: Can't get CPU for thread\n",
  96                                        t->full_name);
  97                                 of_node_put(t);
  98                                 return -EINVAL;
  99                         }
 100                         of_node_put(t);
 101                 }
 102                 i++;
 103         } while (t);
 104
 105         cpu = get_cpu_for_node(core);
 106         if (cpu >= 0) {
 107                 if (!leaf) {
 108                         pr_err("%s: Core has both threads and CPU\n",
 109                                core->full_name);
 110                         return -EINVAL;
 111                 }
 112
 113                 cpu_topology[cpu].cluster_id = cluster_id;
 114                 cpu_topology[cpu].core_id = core_id;
 115         } else if (leaf) {
 116                 pr_err("%s: Can't get CPU for leaf core\n", core->full_name);
 117                 return -EINVAL;
 118         }
 119
 120         return 0;
 121 }
 122
 123 static int __init parse_cluster(struct device_node *cluster, int depth)
 124 {
 125         char name[10];
 126         bool leaf = true;
 127         bool has_cores = false;
 128         struct device_node *c;
 129         static int cluster_id __initdata;
 130         int core_id = 0;
 131         int i, ret;
 132
 133         /*
 134          * First check for child clusters; we currently ignore any
 135          * information about the nesting of clusters and present the
 136          * scheduler with a flat list of them.
 137          */
 138         i = 0;
 139         do {
 140                 snprintf(name, sizeof(name), "cluster%d", i);
 141                 c = of_get_child_by_name(cluster, name);
 142                 if (c) {
 143                         leaf = false;
 144                         ret = parse_cluster(c, depth + 1);
 145                         of_node_put(c);
 146                         if (ret != 0)
 147                                 return ret;
 148                 }
 149                 i++;
 150         } while (c);
 151
 152         /* Now check for cores */
 153         i = 0;
 154         do {
 155                 snprintf(name, sizeof(name), "core%d", i);
 156                 c = of_get_child_by_name(cluster, name);
 157                 if (c) {
 158                         has_cores = true;
 159
 160                         if (depth == 0) {
 161                                 pr_err("%s: cpu-map children should be clusters\n",
 162                                        c->full_name);
 163                                 of_node_put(c);
 164                                 return -EINVAL;
 165                         }
 166
 167                         if (leaf) {
 168                                 ret = parse_core(c, cluster_id, core_id++);
 169                         } else {
 170                                 pr_err("%s: Non-leaf cluster with core %s\n",
 171                                        cluster->full_name, name);
 172                                 ret = -EINVAL;
 173                         }
 174
 175                         of_node_put(c);
 176                         if (ret != 0)
 177                                 return ret;
 178                 }
 179                 i++;
 180         } while (c);
 181
 182         if (leaf && !has_cores)
 183                 pr_warn("%s: empty cluster\n", cluster->full_name);
 184
 185         if (leaf)
 186                 cluster_id++;
 187
 188         return 0;
 189 }
 190
 191 struct cpu_efficiency {
 192         const char *compatible;
 193         unsigned long efficiency;
 194 };
 195
 196 /*
 197  * Table of relative efficiency of each processors
 198  * The efficiency value must fit in 20bit and the final
 199  * cpu_scale value must be in the range
 200  *   0 < cpu_scale < 3*SCHED_POWER_SCALE/2
 201  * in order to return at most 1 when DIV_ROUND_CLOSEST
 202  * is used to compute the capacity of a CPU.
 203  * Processors that are not defined in the table,
 204  * use the default SCHED_POWER_SCALE value for cpu_scale.
 205  */
 206 static const struct cpu_efficiency table_efficiency[] = {
 207         { "arm,cortex-a57", 3891 },
 208         { "arm,cortex-a53", 2048 },
 209         { NULL, },
 210 };
 211
 212 static unsigned long *__cpu_capacity;
 213 #define cpu_capacity(cpu)       __cpu_capacity[cpu]
 214
 215 static unsigned long middle_capacity = 1;
 216
 217 /*
 218  * Iterate all CPUs' descriptor in DT and compute the efficiency
 219  * (as per table_efficiency). Also calculate a middle efficiency
 220  * as close as possible to  (max{eff_i} - min{eff_i}) / 2
 221  * This is later used to scale the cpu_power field such that an
 222  * 'average' CPU is of middle power. Also see the comments near
 223  * table_efficiency[] and update_cpu_power().
 224  */
 225 static int __init parse_dt_topology(void)
 226 {
 227         struct device_node *cn, *map;
 228         int ret = 0;
 229         int cpu;
 230
 231         cn = of_find_node_by_path("/cpus");
 232         if (!cn) {
 233                 pr_err("No CPU information found in DT\n");
 234                 return 0;
 235         }
 236
 237         /*
 238          * When topology is provided cpu-map is essentially a root
 239          * cluster with restricted subnodes.
 240          */
 241         map = of_get_child_by_name(cn, "cpu-map");
 242         if (!map)
 243                 goto out;
 244
 245         ret = parse_cluster(map, 0);
 246         if (ret != 0)
 247                 goto out_map;
 248
 249         /*
 250          * Check that all cores are in the topology; the SMP code will
 251          * only mark cores described in the DT as possible.
 252          */
 253         for_each_possible_cpu(cpu) {
 254                 if (cpu_topology[cpu].cluster_id == -1) {
 255                         pr_err("CPU%d: No topology information specified\n",
 256                                cpu);
 257                         ret = -EINVAL;
 258                 }
 259         }
 260
 261 out_map:
 262         of_node_put(map);
 263 out:
 264         of_node_put(cn);
 265         return ret;
 266 }
 267
 268 static void __init parse_dt_cpu_power(void)
 269 {
 270         const struct cpu_efficiency *cpu_eff;
 271         struct device_node *cn;
 272         unsigned long min_capacity = ULONG_MAX;
 273         unsigned long max_capacity = 0;
 274         unsigned long capacity = 0;
 275         int cpu;
 276
 277         __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity),
 278                                  GFP_NOWAIT);
 279
 280         for_each_possible_cpu(cpu) {
 281                 const u32 *rate;
 282                 int len;
 283
 284                 /* Too early to use cpu->of_node */
 285                 cn = of_get_cpu_node(cpu, NULL);
 286                 if (!cn) {
 287                         pr_err("Missing device node for CPU %d\n", cpu);
 288                         continue;
 289                 }
 290
 291                 for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++)
 292                         if (of_device_is_compatible(cn, cpu_eff->compatible))
 293                                 break;
 294
 295                 if (cpu_eff->compatible == NULL) {
 296                         pr_warn("%s: Unknown CPU type\n", cn->full_name);
 297                         continue;
 298                 }
 299
 300                 rate = of_get_property(cn, "clock-frequency", &len);
 301                 if (!rate || len != 4) {
 302                         pr_err("%s: Missing clock-frequency property\n",
 303                                 cn->full_name);
 304                         continue;
 305                 }
 306
 307                 capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency;
 308
 309                 /* Save min capacity of the system */
 310                 if (capacity < min_capacity)
 311                         min_capacity = capacity;
 312
 313                 /* Save max capacity of the system */
 314                 if (capacity > max_capacity)
 315                         max_capacity = capacity;
 316
 317                 cpu_capacity(cpu) = capacity;
 318         }
 319
 320         /* If min and max capacities are equal we bypass the update of the
 321          * cpu_scale because all CPUs have the same capacity. Otherwise, we
 322          * compute a middle_capacity factor that will ensure that the capacity
 323          * of an 'average' CPU of the system will be as close as possible to
 324          * SCHED_POWER_SCALE, which is the default value, but with the
 325          * constraint explained near table_efficiency[].
 326          */
 327         if (min_capacity == max_capacity)
 328                 return;
 329         else if (4 * max_capacity < (3 * (max_capacity + min_capacity)))
 330                 middle_capacity = (min_capacity + max_capacity)
 331                                 >> (SCHED_POWER_SHIFT+1);
 332         else
 333                 middle_capacity = ((max_capacity / 3)
 334                                 >> (SCHED_POWER_SHIFT-1)) + 1;
 335 }
 336
 337 /*
 338  * Look for a customed capacity of a CPU in the cpu_topo_data table during the
 339  * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the
 340  * function returns directly for SMP system.
 341  */
 342 static void update_cpu_power(unsigned int cpu)
 343 {
 344         if (!cpu_capacity(cpu))
 345                 return;
 346
 347         set_power_scale(cpu, cpu_capacity(cpu) / middle_capacity);
 348
 349         pr_info("CPU%u: update cpu_power %lu\n",
 350                 cpu, arch_scale_freq_power(NULL, cpu));
 351 }
 352
 353 /*
 354  * cpu topology table
 355  */
 356 struct cpu_topology cpu_topology[NR_CPUS];
 357 EXPORT_SYMBOL_GPL(cpu_topology);
 358
 359 const struct cpumask *cpu_coregroup_mask(int cpu)
 360 {
 361         return &cpu_topology[cpu].core_sibling;
 362 }
 363
 364 static void update_siblings_masks(unsigned int cpuid)
 365 {
 366         struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
 367         int cpu;
 368
 369         if (cpuid_topo->cluster_id == -1) {
 370                 /*
 371                  * DT does not contain topology information for this cpu.
 372                  */
 373                 pr_debug("CPU%u: No topology information configured\n", cpuid);
 374                 return;
 375         }
 376
 377         /* update core and thread sibling masks */
 378         for_each_possible_cpu(cpu) {
 379                 cpu_topo = &cpu_topology[cpu];
 380
 381                 if (cpuid_topo->cluster_id != cpu_topo->cluster_id)
 382                         continue;
 383
 384                 cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
 385                 if (cpu != cpuid)
 386                         cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
 387
 388                 if (cpuid_topo->core_id != cpu_topo->core_id)
 389                         continue;
 390
 391                 cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
 392                 if (cpu != cpuid)
 393                         cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
 394         }
 395 }
 396
 397 #ifdef CONFIG_SCHED_HMP
 398
 399 /*
 400  * Retrieve logical cpu index corresponding to a given MPIDR[23:0]
 401  *  - mpidr: MPIDR[23:0] to be used for the look-up
 402  *
 403  * Returns the cpu logical index or -EINVAL on look-up error
 404  */
 405 static inline int get_logical_index(u32 mpidr)
 406 {
 407         int cpu;
 408         for (cpu = 0; cpu < nr_cpu_ids; cpu++)
 409                 if (cpu_logical_map(cpu) == mpidr)
 410                         return cpu;
 411         return -EINVAL;
 412 }
 413
 414 static const char * const little_cores[] = {
 415         "arm,cortex-a53",
 416         NULL,
 417 };
 418
 419 static bool is_little_cpu(struct device_node *cn)
 420 {
 421         const char * const *lc;
 422         for (lc = little_cores; *lc; lc++)
 423                 if (of_device_is_compatible(cn, *lc))
 424                         return true;
 425         return false;
 426 }
 427
 428 void __init arch_get_fast_and_slow_cpus(struct cpumask *fast,
 429                                         struct cpumask *slow)
 430 {
 431         struct device_node *cn = NULL;
 432         int cpu;
 433
 434         cpumask_clear(fast);
 435         cpumask_clear(slow);
 436
 437         /*
 438          * Use the config options if they are given. This helps testing
 439          * HMP scheduling on systems without a big.LITTLE architecture.
 440          */
 441         if (strlen(CONFIG_HMP_FAST_CPU_MASK) && strlen(CONFIG_HMP_SLOW_CPU_MASK)) {
 442                 if (cpulist_parse(CONFIG_HMP_FAST_CPU_MASK, fast))
 443                         WARN(1, "Failed to parse HMP fast cpu mask!\n");
 444                 if (cpulist_parse(CONFIG_HMP_SLOW_CPU_MASK, slow))
 445                         WARN(1, "Failed to parse HMP slow cpu mask!\n");
 446                 return;
 447         }
 448
 449         /*
 450          * Else, parse device tree for little cores.
 451          */
 452         while ((cn = of_find_node_by_type(cn, "cpu"))) {
 453
 454                 const u32 *mpidr;
 455                 int len;
 456
 457                 mpidr = of_get_property(cn, "reg", &len);
 458                 if (!mpidr || len != 8) {
 459                         pr_err("%s missing reg property\n", cn->full_name);
 460                         continue;
 461                 }
 462
 463                 cpu = get_logical_index(be32_to_cpup(mpidr+1));
 464                 if (cpu == -EINVAL) {
 465                         pr_err("couldn't get logical index for mpidr %x\n",
 466                                                         be32_to_cpup(mpidr+1));
 467                         break;
 468                 }
 469
 470                 if (is_little_cpu(cn))
 471                         cpumask_set_cpu(cpu, slow);
 472                 else
 473                         cpumask_set_cpu(cpu, fast);
 474         }
 475
 476         if (!cpumask_empty(fast) && !cpumask_empty(slow))
 477                 return;
 478
 479         /*
 480          * We didn't find both big and little cores so let's call all cores
 481          * fast as this will keep the system running, with all cores being
 482          * treated equal.
 483          */
 484         cpumask_setall(fast);
 485         cpumask_clear(slow);
 486 }
 487
 488 struct cpumask hmp_slow_cpu_mask;
 489
 490 void __init arch_get_hmp_domains(struct list_head *hmp_domains_list)
 491 {
 492         struct cpumask hmp_fast_cpu_mask;
 493         struct hmp_domain *domain;
 494
 495         arch_get_fast_and_slow_cpus(&hmp_fast_cpu_mask, &hmp_slow_cpu_mask);
 496
 497         /*
 498          * Initialize hmp_domains
 499          * Must be ordered with respect to compute capacity.
 500          * Fastest domain at head of list.
 501          */
 502         if(!cpumask_empty(&hmp_slow_cpu_mask)) {
 503                 domain = (struct hmp_domain *)
 504                         kmalloc(sizeof(struct hmp_domain), GFP_KERNEL);
 505                 cpumask_copy(&domain->possible_cpus, &hmp_slow_cpu_mask);
 506                 cpumask_and(&domain->cpus, cpu_online_mask, &domain->possible_cpus);
 507                 list_add(&domain->hmp_domains, hmp_domains_list);
 508         }
 509         domain = (struct hmp_domain *)
 510                 kmalloc(sizeof(struct hmp_domain), GFP_KERNEL);
 511         cpumask_copy(&domain->possible_cpus, &hmp_fast_cpu_mask);
 512         cpumask_and(&domain->cpus, cpu_online_mask, &domain->possible_cpus);
 513         list_add(&domain->hmp_domains, hmp_domains_list);
 514 }
 515 #endif /* CONFIG_SCHED_HMP */
 516
 517 /*
 518  * cluster_to_logical_mask - return cpu logical mask of CPUs in a cluster
 519  * @socket_id:          cluster HW identifier
 520  * @cluster_mask:       the cpumask location to be initialized, modified by the
 521  *                      function only if return value == 0
 522  *
 523  * Return:
 524  *
 525  * 0 on success
 526  * -EINVAL if cluster_mask is NULL or there is no record matching socket_id
 527  */
 528 int cluster_to_logical_mask(unsigned int socket_id, cpumask_t *cluster_mask)
 529 {
 530         int cpu;
 531
 532         if (!cluster_mask)
 533                 return -EINVAL;
 534
 535         for_each_online_cpu(cpu) {
 536                 if (socket_id == topology_physical_package_id(cpu)) {
 537                         cpumask_copy(cluster_mask, topology_core_cpumask(cpu));
 538                         return 0;
 539                 }
 540         }
 541
 542         return -EINVAL;
 543 }
 544
 545 void store_cpu_topology(unsigned int cpuid)
 546 {
 547         update_siblings_masks(cpuid);
 548         update_cpu_power(cpuid);
 549 }
 550
 551 static void __init reset_cpu_topology(void)
 552 {
 553         unsigned int cpu;
 554
 555         for_each_possible_cpu(cpu) {
 556                 struct cpu_topology *cpu_topo = &cpu_topology[cpu];
 557
 558                 cpu_topo->thread_id = -1;
 559                 cpu_topo->core_id = 0;
 560                 cpu_topo->cluster_id = -1;
 561
 562                 cpumask_clear(&cpu_topo->core_sibling);
 563                 cpumask_set_cpu(cpu, &cpu_topo->core_sibling);
 564                 cpumask_clear(&cpu_topo->thread_sibling);
 565                 cpumask_set_cpu(cpu, &cpu_topo->thread_sibling);
 566         }
 567 }
 568
 569 static void __init reset_cpu_power(void)
 570 {
 571         unsigned int cpu;
 572
 573         for_each_possible_cpu(cpu)
 574                 set_power_scale(cpu, SCHED_POWER_SCALE);
 575 }
 576
 577 void __init init_cpu_topology(void)
 578 {
 579         reset_cpu_topology();
 580
 581         /*
 582          * Discard anything that was parsed if we hit an error so we
 583          * don't use partial information.
 584          */
 585         if (parse_dt_topology())
 586                 reset_cpu_topology();
 587
 588         reset_cpu_power();
 589         parse_dt_cpu_power();
 590 }