drivers/cpuidle/cpuidle-riscv-sbi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * RISC-V SBI CPU idle driver.
   4  *
   5  * Copyright (c) 2021 Western Digital Corporation or its affiliates.
   6  * Copyright (c) 2022 Ventana Micro Systems Inc.
   7  */
   8
   9 #define pr_fmt(fmt) "cpuidle-riscv-sbi: " fmt
  10
  11 #include <linux/cleanup.h>
  12 #include <linux/cpuhotplug.h>
  13 #include <linux/cpuidle.h>
  14 #include <linux/cpumask.h>
  15 #include <linux/cpu_pm.h>
  16 #include <linux/cpu_cooling.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/slab.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/pm_domain.h>
  23 #include <linux/pm_runtime.h>
  24 #include <asm/cpuidle.h>
  25 #include <asm/sbi.h>
  26 #include <asm/smp.h>
  27 #include <asm/suspend.h>
  28
  29 #include "dt_idle_states.h"
  30 #include "dt_idle_genpd.h"
  31
  32 struct sbi_cpuidle_data {
  33         u32 *states;
  34         struct device *dev;
  35 };
  36
  37 struct sbi_domain_state {
  38         bool available;
  39         u32 state;
  40 };
  41
  42 static DEFINE_PER_CPU_READ_MOSTLY(struct sbi_cpuidle_data, sbi_cpuidle_data);
  43 static DEFINE_PER_CPU(struct sbi_domain_state, domain_state);
  44 static bool sbi_cpuidle_use_osi;
  45 static bool sbi_cpuidle_use_cpuhp;
  46 static bool sbi_cpuidle_pd_allow_domain_state;
  47
  48 static inline void sbi_set_domain_state(u32 state)
  49 {
  50         struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
  51
  52         data->available = true;
  53         data->state = state;
  54 }
  55
  56 static inline u32 sbi_get_domain_state(void)
  57 {
  58         struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
  59
  60         return data->state;
  61 }
  62
  63 static inline void sbi_clear_domain_state(void)
  64 {
  65         struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
  66
  67         data->available = false;
  68 }
  69
  70 static inline bool sbi_is_domain_state_available(void)
  71 {
  72         struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
  73
  74         return data->available;
  75 }
  76
  77 static __cpuidle int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
  78                                              struct cpuidle_driver *drv, int idx)
  79 {
  80         u32 *states = __this_cpu_read(sbi_cpuidle_data.states);
  81         u32 state = states[idx];
  82
  83         if (state & SBI_HSM_SUSP_NON_RET_BIT)
  84                 return CPU_PM_CPU_IDLE_ENTER_PARAM(riscv_sbi_hart_suspend, idx, state);
  85         else
  86                 return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(riscv_sbi_hart_suspend,
  87                                                              idx, state);
  88 }
  89
  90 static __cpuidle int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
  91                                                    struct cpuidle_driver *drv, int idx,
  92                                                    bool s2idle)
  93 {
  94         struct sbi_cpuidle_data *data = this_cpu_ptr(&sbi_cpuidle_data);
  95         u32 *states = data->states;
  96         struct device *pd_dev = data->dev;
  97         u32 state;
  98         int ret;
  99
 100         ret = cpu_pm_enter();
 101         if (ret)
 102                 return -1;
 103
 104         /* Do runtime PM to manage a hierarchical CPU toplogy. */
 105         if (s2idle)
 106                 dev_pm_genpd_suspend(pd_dev);
 107         else
 108                 pm_runtime_put_sync_suspend(pd_dev);
 109
 110         ct_cpuidle_enter();
 111
 112         if (sbi_is_domain_state_available())
 113                 state = sbi_get_domain_state();
 114         else
 115                 state = states[idx];
 116
 117         ret = riscv_sbi_hart_suspend(state) ? -1 : idx;
 118
 119         ct_cpuidle_exit();
 120
 121         if (s2idle)
 122                 dev_pm_genpd_resume(pd_dev);
 123         else
 124                 pm_runtime_get_sync(pd_dev);
 125
 126         cpu_pm_exit();
 127
 128         /* Clear the domain state to start fresh when back from idle. */
 129         sbi_clear_domain_state();
 130         return ret;
 131 }
 132
 133 static int sbi_enter_domain_idle_state(struct cpuidle_device *dev,
 134                                        struct cpuidle_driver *drv, int idx)
 135 {
 136         return __sbi_enter_domain_idle_state(dev, drv, idx, false);
 137 }
 138
 139 static int sbi_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
 140                                               struct cpuidle_driver *drv,
 141                                               int idx)
 142 {
 143         return __sbi_enter_domain_idle_state(dev, drv, idx, true);
 144 }
 145
 146 static int sbi_cpuidle_cpuhp_up(unsigned int cpu)
 147 {
 148         struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
 149
 150         if (pd_dev)
 151                 pm_runtime_get_sync(pd_dev);
 152
 153         return 0;
 154 }
 155
 156 static int sbi_cpuidle_cpuhp_down(unsigned int cpu)
 157 {
 158         struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
 159
 160         if (pd_dev) {
 161                 pm_runtime_put_sync(pd_dev);
 162                 /* Clear domain state to start fresh at next online. */
 163                 sbi_clear_domain_state();
 164         }
 165
 166         return 0;
 167 }
 168
 169 static void sbi_idle_init_cpuhp(void)
 170 {
 171         int err;
 172
 173         if (!sbi_cpuidle_use_cpuhp)
 174                 return;
 175
 176         err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
 177                                         "cpuidle/sbi:online",
 178                                         sbi_cpuidle_cpuhp_up,
 179                                         sbi_cpuidle_cpuhp_down);
 180         if (err)
 181                 pr_warn("Failed %d while setup cpuhp state\n", err);
 182 }
 183
 184 static const struct of_device_id sbi_cpuidle_state_match[] = {
 185         { .compatible = "riscv,idle-state",
 186           .data = sbi_cpuidle_enter_state },
 187         { },
 188 };
 189
 190 static int sbi_dt_parse_state_node(struct device_node *np, u32 *state)
 191 {
 192         int err = of_property_read_u32(np, "riscv,sbi-suspend-param", state);
 193
 194         if (err) {
 195                 pr_warn("%pOF missing riscv,sbi-suspend-param property\n", np);
 196                 return err;
 197         }
 198
 199         if (!riscv_sbi_suspend_state_is_valid(*state)) {
 200                 pr_warn("Invalid SBI suspend state %#x\n", *state);
 201                 return -EINVAL;
 202         }
 203
 204         return 0;
 205 }
 206
 207 static int sbi_dt_cpu_init_topology(struct cpuidle_driver *drv,
 208                                      struct sbi_cpuidle_data *data,
 209                                      unsigned int state_count, int cpu)
 210 {
 211         /* Currently limit the hierarchical topology to be used in OSI mode. */
 212         if (!sbi_cpuidle_use_osi)
 213                 return 0;
 214
 215         data->dev = dt_idle_attach_cpu(cpu, "sbi");
 216         if (IS_ERR_OR_NULL(data->dev))
 217                 return PTR_ERR_OR_ZERO(data->dev);
 218
 219         /*
 220          * Using the deepest state for the CPU to trigger a potential selection
 221          * of a shared state for the domain, assumes the domain states are all
 222          * deeper states.
 223          */
 224         drv->states[state_count - 1].flags |= CPUIDLE_FLAG_RCU_IDLE;
 225         drv->states[state_count - 1].enter = sbi_enter_domain_idle_state;
 226         drv->states[state_count - 1].enter_s2idle =
 227                                         sbi_enter_s2idle_domain_idle_state;
 228         sbi_cpuidle_use_cpuhp = true;
 229
 230         return 0;
 231 }
 232
 233 static int sbi_cpuidle_dt_init_states(struct device *dev,
 234                                         struct cpuidle_driver *drv,
 235                                         unsigned int cpu,
 236                                         unsigned int state_count)
 237 {
 238         struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
 239         struct device_node *state_node;
 240         u32 *states;
 241         int i, ret;
 242
 243         struct device_node *cpu_node __free(device_node) = of_cpu_device_node_get(cpu);
 244         if (!cpu_node)
 245                 return -ENODEV;
 246
 247         states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL);
 248         if (!states)
 249                 return -ENOMEM;
 250
 251         /* Parse SBI specific details from state DT nodes */
 252         for (i = 1; i < state_count; i++) {
 253                 state_node = of_get_cpu_state_node(cpu_node, i - 1);
 254                 if (!state_node)
 255                         break;
 256
 257                 ret = sbi_dt_parse_state_node(state_node, &states[i]);
 258                 of_node_put(state_node);
 259
 260                 if (ret)
 261                         return ret;
 262
 263                 pr_debug("sbi-state %#x index %d\n", states[i], i);
 264         }
 265         if (i != state_count)
 266                 return -ENODEV;
 267
 268         /* Initialize optional data, used for the hierarchical topology. */
 269         ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu);
 270         if (ret < 0)
 271                 return ret;
 272
 273         /* Store states in the per-cpu struct. */
 274         data->states = states;
 275
 276         return 0;
 277 }
 278
 279 static void sbi_cpuidle_deinit_cpu(int cpu)
 280 {
 281         struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
 282
 283         dt_idle_detach_cpu(data->dev);
 284         sbi_cpuidle_use_cpuhp = false;
 285 }
 286
 287 static int sbi_cpuidle_init_cpu(struct device *dev, int cpu)
 288 {
 289         struct cpuidle_driver *drv;
 290         unsigned int state_count = 0;
 291         int ret = 0;
 292
 293         drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
 294         if (!drv)
 295                 return -ENOMEM;
 296
 297         drv->name = "sbi_cpuidle";
 298         drv->owner = THIS_MODULE;
 299         drv->cpumask = (struct cpumask *)cpumask_of(cpu);
 300
 301         /* RISC-V architectural WFI to be represented as state index 0. */
 302         drv->states[0].enter = sbi_cpuidle_enter_state;
 303         drv->states[0].exit_latency = 1;
 304         drv->states[0].target_residency = 1;
 305         drv->states[0].power_usage = UINT_MAX;
 306         strcpy(drv->states[0].name, "WFI");
 307         strcpy(drv->states[0].desc, "RISC-V WFI");
 308
 309         /*
 310          * If no DT idle states are detected (ret == 0) let the driver
 311          * initialization fail accordingly since there is no reason to
 312          * initialize the idle driver if only wfi is supported, the
 313          * default archictectural back-end already executes wfi
 314          * on idle entry.
 315          */
 316         ret = dt_init_idle_driver(drv, sbi_cpuidle_state_match, 1);
 317         if (ret <= 0) {
 318                 pr_debug("HART%ld: failed to parse DT idle states\n",
 319                          cpuid_to_hartid_map(cpu));
 320                 return ret ? : -ENODEV;
 321         }
 322         state_count = ret + 1; /* Include WFI state as well */
 323
 324         /* Initialize idle states from DT. */
 325         ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count);
 326         if (ret) {
 327                 pr_err("HART%ld: failed to init idle states\n",
 328                        cpuid_to_hartid_map(cpu));
 329                 return ret;
 330         }
 331
 332         ret = cpuidle_register(drv, NULL);
 333         if (ret)
 334                 goto deinit;
 335
 336         cpuidle_cooling_register(drv);
 337
 338         return 0;
 339 deinit:
 340         sbi_cpuidle_deinit_cpu(cpu);
 341         return ret;
 342 }
 343
 344 static void sbi_cpuidle_domain_sync_state(struct device *dev)
 345 {
 346         /*
 347          * All devices have now been attached/probed to the PM domain
 348          * topology, hence it's fine to allow domain states to be picked.
 349          */
 350         sbi_cpuidle_pd_allow_domain_state = true;
 351 }
 352
 353 #ifdef CONFIG_DT_IDLE_GENPD
 354
 355 static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)
 356 {
 357         struct genpd_power_state *state = &pd->states[pd->state_idx];
 358         u32 *pd_state;
 359
 360         if (!state->data)
 361                 return 0;
 362
 363         if (!sbi_cpuidle_pd_allow_domain_state)
 364                 return -EBUSY;
 365
 366         /* OSI mode is enabled, set the corresponding domain state. */
 367         pd_state = state->data;
 368         sbi_set_domain_state(*pd_state);
 369
 370         return 0;
 371 }
 372
 373 struct sbi_pd_provider {
 374         struct list_head link;
 375         struct device_node *node;
 376 };
 377
 378 static LIST_HEAD(sbi_pd_providers);
 379
 380 static int sbi_pd_init(struct device_node *np)
 381 {
 382         struct generic_pm_domain *pd;
 383         struct sbi_pd_provider *pd_provider;
 384         struct dev_power_governor *pd_gov;
 385         int ret = -ENOMEM;
 386
 387         pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
 388         if (!pd)
 389                 goto out;
 390
 391         pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
 392         if (!pd_provider)
 393                 goto free_pd;
 394
 395         pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
 396
 397         /* Allow power off when OSI is available. */
 398         if (sbi_cpuidle_use_osi)
 399                 pd->power_off = sbi_cpuidle_pd_power_off;
 400         else
 401                 pd->flags |= GENPD_FLAG_ALWAYS_ON;
 402
 403         /* Use governor for CPU PM domains if it has some states to manage. */
 404         pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;
 405
 406         ret = pm_genpd_init(pd, pd_gov, false);
 407         if (ret)
 408                 goto free_pd_prov;
 409
 410         ret = of_genpd_add_provider_simple(np, pd);
 411         if (ret)
 412                 goto remove_pd;
 413
 414         pd_provider->node = of_node_get(np);
 415         list_add(&pd_provider->link, &sbi_pd_providers);
 416
 417         pr_debug("init PM domain %s\n", pd->name);
 418         return 0;
 419
 420 remove_pd:
 421         pm_genpd_remove(pd);
 422 free_pd_prov:
 423         kfree(pd_provider);
 424 free_pd:
 425         dt_idle_pd_free(pd);
 426 out:
 427         pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
 428         return ret;
 429 }
 430
 431 static void sbi_pd_remove(void)
 432 {
 433         struct sbi_pd_provider *pd_provider, *it;
 434         struct generic_pm_domain *genpd;
 435
 436         list_for_each_entry_safe(pd_provider, it, &sbi_pd_providers, link) {
 437                 of_genpd_del_provider(pd_provider->node);
 438
 439                 genpd = of_genpd_remove_last(pd_provider->node);
 440                 if (!IS_ERR(genpd))
 441                         kfree(genpd);
 442
 443                 of_node_put(pd_provider->node);
 444                 list_del(&pd_provider->link);
 445                 kfree(pd_provider);
 446         }
 447 }
 448
 449 static int sbi_genpd_probe(struct device_node *np)
 450 {
 451         int ret = 0, pd_count = 0;
 452
 453         if (!np)
 454                 return -ENODEV;
 455
 456         /*
 457          * Parse child nodes for the "#power-domain-cells" property and
 458          * initialize a genpd/genpd-of-provider pair when it's found.
 459          */
 460         for_each_child_of_node_scoped(np, node) {
 461                 if (!of_property_present(node, "#power-domain-cells"))
 462                         continue;
 463
 464                 ret = sbi_pd_init(node);
 465                 if (ret)
 466                         goto remove_pd;
 467
 468                 pd_count++;
 469         }
 470
 471         /* Bail out if not using the hierarchical CPU topology. */
 472         if (!pd_count)
 473                 goto no_pd;
 474
 475         /* Link genpd masters/subdomains to model the CPU topology. */
 476         ret = dt_idle_pd_init_topology(np);
 477         if (ret)
 478                 goto remove_pd;
 479
 480         return 0;
 481
 482 remove_pd:
 483         sbi_pd_remove();
 484         pr_err("failed to create CPU PM domains ret=%d\n", ret);
 485 no_pd:
 486         return ret;
 487 }
 488
 489 #else
 490
 491 static inline int sbi_genpd_probe(struct device_node *np)
 492 {
 493         return 0;
 494 }
 495
 496 #endif
 497
 498 static int sbi_cpuidle_probe(struct platform_device *pdev)
 499 {
 500         int cpu, ret;
 501         struct cpuidle_driver *drv;
 502         struct cpuidle_device *dev;
 503         struct device_node *np, *pds_node;
 504
 505         /* Detect OSI support based on CPU DT nodes */
 506         sbi_cpuidle_use_osi = true;
 507         for_each_possible_cpu(cpu) {
 508                 np = of_cpu_device_node_get(cpu);
 509                 if (np &&
 510                     of_property_present(np, "power-domains") &&
 511                     of_property_present(np, "power-domain-names")) {
 512                         continue;
 513                 } else {
 514                         sbi_cpuidle_use_osi = false;
 515                         break;
 516                 }
 517         }
 518
 519         /* Populate generic power domains from DT nodes */
 520         pds_node = of_find_node_by_path("/cpus/power-domains");
 521         if (pds_node) {
 522                 ret = sbi_genpd_probe(pds_node);
 523                 of_node_put(pds_node);
 524                 if (ret)
 525                         return ret;
 526         }
 527
 528         /* Initialize CPU idle driver for each CPU */
 529         for_each_possible_cpu(cpu) {
 530                 ret = sbi_cpuidle_init_cpu(&pdev->dev, cpu);
 531                 if (ret) {
 532                         pr_debug("HART%ld: idle driver init failed\n",
 533                                  cpuid_to_hartid_map(cpu));
 534                         goto out_fail;
 535                 }
 536         }
 537
 538         /* Setup CPU hotplut notifiers */
 539         sbi_idle_init_cpuhp();
 540
 541         pr_info("idle driver registered for all CPUs\n");
 542
 543         return 0;
 544
 545 out_fail:
 546         while (--cpu >= 0) {
 547                 dev = per_cpu(cpuidle_devices, cpu);
 548                 drv = cpuidle_get_cpu_driver(dev);
 549                 cpuidle_unregister(drv);
 550                 sbi_cpuidle_deinit_cpu(cpu);
 551         }
 552
 553         return ret;
 554 }
 555
 556 static struct platform_driver sbi_cpuidle_driver = {
 557         .probe = sbi_cpuidle_probe,
 558         .driver = {
 559                 .name = "sbi-cpuidle",
 560                 .sync_state = sbi_cpuidle_domain_sync_state,
 561         },
 562 };
 563
 564 static int __init sbi_cpuidle_init(void)
 565 {
 566         int ret;
 567         struct platform_device *pdev;
 568
 569         if (!riscv_sbi_hsm_is_supported())
 570                 return 0;
 571
 572         ret = platform_driver_register(&sbi_cpuidle_driver);
 573         if (ret)
 574                 return ret;
 575
 576         pdev = platform_device_register_simple("sbi-cpuidle",
 577                                                 -1, NULL, 0);
 578         if (IS_ERR(pdev)) {
 579                 platform_driver_unregister(&sbi_cpuidle_driver);
 580                 return PTR_ERR(pdev);
 581         }
 582
 583         return 0;
 584 }
 585 device_initcall(sbi_cpuidle_init);