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/cpuidle.h> 12 #include <linux/cpumask.h> 13 #include <linux/cpu_pm.h> 14 #include <linux/cpu_cooling.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/of.h> 18 #include <linux/of_device.h> 19 #include <linux/slab.h> 20 #include <linux/platform_device.h> 21 #include <linux/pm_domain.h> 22 #include <linux/pm_runtime.h> 23 #include <asm/cpuidle.h> 24 #include <asm/sbi.h> 25 #include <asm/smp.h> 26 #include <asm/suspend.h> 27 28 #include "dt_idle_states.h" 29 #include "dt_idle_genpd.h" 30 31 struct sbi_cpuidle_data { 32 u32 *states; 33 struct device *dev; 34 }; 35 36 struct sbi_domain_state { 37 bool available; 38 u32 state; 39 }; 40 41 static DEFINE_PER_CPU_READ_MOSTLY(struct sbi_cpuidle_data, sbi_cpuidle_data); 42 static DEFINE_PER_CPU(struct sbi_domain_state, domain_state); 43 static bool sbi_cpuidle_use_osi; 44 static bool sbi_cpuidle_use_cpuhp; 45 static bool sbi_cpuidle_pd_allow_domain_state; 46 47 static inline void sbi_set_domain_state(u32 state) 48 { 49 struct sbi_domain_state *data = this_cpu_ptr(&domain_state); 50 51 data->available = true; 52 data->state = state; 53 } 54 55 static inline u32 sbi_get_domain_state(void) 56 { 57 struct sbi_domain_state *data = this_cpu_ptr(&domain_state); 58 59 return data->state; 60 } 61 62 static inline void sbi_clear_domain_state(void) 63 { 64 struct sbi_domain_state *data = this_cpu_ptr(&domain_state); 65 66 data->available = false; 67 } 68 69 static inline bool sbi_is_domain_state_available(void) 70 { 71 struct sbi_domain_state *data = this_cpu_ptr(&domain_state); 72 73 return data->available; 74 } 75 76 static int sbi_suspend_finisher(unsigned long suspend_type, 77 unsigned long resume_addr, 78 unsigned long opaque) 79 { 80 struct sbiret ret; 81 82 ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_SUSPEND, 83 suspend_type, resume_addr, opaque, 0, 0, 0); 84 85 return (ret.error) ? sbi_err_map_linux_errno(ret.error) : 0; 86 } 87 88 static int sbi_suspend(u32 state) 89 { 90 if (state & SBI_HSM_SUSP_NON_RET_BIT) 91 return cpu_suspend(state, sbi_suspend_finisher); 92 else 93 return sbi_suspend_finisher(state, 0, 0); 94 } 95 96 static int sbi_cpuidle_enter_state(struct cpuidle_device *dev, 97 struct cpuidle_driver *drv, int idx) 98 { 99 u32 *states = __this_cpu_read(sbi_cpuidle_data.states); 100 u32 state = states[idx]; 101 102 if (state & SBI_HSM_SUSP_NON_RET_BIT) 103 return CPU_PM_CPU_IDLE_ENTER_PARAM(sbi_suspend, idx, state); 104 else 105 return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(sbi_suspend, 106 idx, state); 107 } 108 109 static int __sbi_enter_domain_idle_state(struct cpuidle_device *dev, 110 struct cpuidle_driver *drv, int idx, 111 bool s2idle) 112 { 113 struct sbi_cpuidle_data *data = this_cpu_ptr(&sbi_cpuidle_data); 114 u32 *states = data->states; 115 struct device *pd_dev = data->dev; 116 u32 state; 117 int ret; 118 119 ret = cpu_pm_enter(); 120 if (ret) 121 return -1; 122 123 /* Do runtime PM to manage a hierarchical CPU toplogy. */ 124 ct_irq_enter_irqson(); 125 if (s2idle) 126 dev_pm_genpd_suspend(pd_dev); 127 else 128 pm_runtime_put_sync_suspend(pd_dev); 129 ct_irq_exit_irqson(); 130 131 if (sbi_is_domain_state_available()) 132 state = sbi_get_domain_state(); 133 else 134 state = states[idx]; 135 136 ret = sbi_suspend(state) ? -1 : idx; 137 138 ct_irq_enter_irqson(); 139 if (s2idle) 140 dev_pm_genpd_resume(pd_dev); 141 else 142 pm_runtime_get_sync(pd_dev); 143 ct_irq_exit_irqson(); 144 145 cpu_pm_exit(); 146 147 /* Clear the domain state to start fresh when back from idle. */ 148 sbi_clear_domain_state(); 149 return ret; 150 } 151 152 static int sbi_enter_domain_idle_state(struct cpuidle_device *dev, 153 struct cpuidle_driver *drv, int idx) 154 { 155 return __sbi_enter_domain_idle_state(dev, drv, idx, false); 156 } 157 158 static int sbi_enter_s2idle_domain_idle_state(struct cpuidle_device *dev, 159 struct cpuidle_driver *drv, 160 int idx) 161 { 162 return __sbi_enter_domain_idle_state(dev, drv, idx, true); 163 } 164 165 static int sbi_cpuidle_cpuhp_up(unsigned int cpu) 166 { 167 struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev); 168 169 if (pd_dev) 170 pm_runtime_get_sync(pd_dev); 171 172 return 0; 173 } 174 175 static int sbi_cpuidle_cpuhp_down(unsigned int cpu) 176 { 177 struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev); 178 179 if (pd_dev) { 180 pm_runtime_put_sync(pd_dev); 181 /* Clear domain state to start fresh at next online. */ 182 sbi_clear_domain_state(); 183 } 184 185 return 0; 186 } 187 188 static void sbi_idle_init_cpuhp(void) 189 { 190 int err; 191 192 if (!sbi_cpuidle_use_cpuhp) 193 return; 194 195 err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING, 196 "cpuidle/sbi:online", 197 sbi_cpuidle_cpuhp_up, 198 sbi_cpuidle_cpuhp_down); 199 if (err) 200 pr_warn("Failed %d while setup cpuhp state\n", err); 201 } 202 203 static const struct of_device_id sbi_cpuidle_state_match[] = { 204 { .compatible = "riscv,idle-state", 205 .data = sbi_cpuidle_enter_state }, 206 { }, 207 }; 208 209 static bool sbi_suspend_state_is_valid(u32 state) 210 { 211 if (state > SBI_HSM_SUSPEND_RET_DEFAULT && 212 state < SBI_HSM_SUSPEND_RET_PLATFORM) 213 return false; 214 if (state > SBI_HSM_SUSPEND_NON_RET_DEFAULT && 215 state < SBI_HSM_SUSPEND_NON_RET_PLATFORM) 216 return false; 217 return true; 218 } 219 220 static int sbi_dt_parse_state_node(struct device_node *np, u32 *state) 221 { 222 int err = of_property_read_u32(np, "riscv,sbi-suspend-param", state); 223 224 if (err) { 225 pr_warn("%pOF missing riscv,sbi-suspend-param property\n", np); 226 return err; 227 } 228 229 if (!sbi_suspend_state_is_valid(*state)) { 230 pr_warn("Invalid SBI suspend state %#x\n", *state); 231 return -EINVAL; 232 } 233 234 return 0; 235 } 236 237 static int sbi_dt_cpu_init_topology(struct cpuidle_driver *drv, 238 struct sbi_cpuidle_data *data, 239 unsigned int state_count, int cpu) 240 { 241 /* Currently limit the hierarchical topology to be used in OSI mode. */ 242 if (!sbi_cpuidle_use_osi) 243 return 0; 244 245 data->dev = dt_idle_attach_cpu(cpu, "sbi"); 246 if (IS_ERR_OR_NULL(data->dev)) 247 return PTR_ERR_OR_ZERO(data->dev); 248 249 /* 250 * Using the deepest state for the CPU to trigger a potential selection 251 * of a shared state for the domain, assumes the domain states are all 252 * deeper states. 253 */ 254 drv->states[state_count - 1].enter = sbi_enter_domain_idle_state; 255 drv->states[state_count - 1].enter_s2idle = 256 sbi_enter_s2idle_domain_idle_state; 257 sbi_cpuidle_use_cpuhp = true; 258 259 return 0; 260 } 261 262 static int sbi_cpuidle_dt_init_states(struct device *dev, 263 struct cpuidle_driver *drv, 264 unsigned int cpu, 265 unsigned int state_count) 266 { 267 struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu); 268 struct device_node *state_node; 269 struct device_node *cpu_node; 270 u32 *states; 271 int i, ret; 272 273 cpu_node = of_cpu_device_node_get(cpu); 274 if (!cpu_node) 275 return -ENODEV; 276 277 states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL); 278 if (!states) { 279 ret = -ENOMEM; 280 goto fail; 281 } 282 283 /* Parse SBI specific details from state DT nodes */ 284 for (i = 1; i < state_count; i++) { 285 state_node = of_get_cpu_state_node(cpu_node, i - 1); 286 if (!state_node) 287 break; 288 289 ret = sbi_dt_parse_state_node(state_node, &states[i]); 290 of_node_put(state_node); 291 292 if (ret) 293 return ret; 294 295 pr_debug("sbi-state %#x index %d\n", states[i], i); 296 } 297 if (i != state_count) { 298 ret = -ENODEV; 299 goto fail; 300 } 301 302 /* Initialize optional data, used for the hierarchical topology. */ 303 ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu); 304 if (ret < 0) 305 return ret; 306 307 /* Store states in the per-cpu struct. */ 308 data->states = states; 309 310 fail: 311 of_node_put(cpu_node); 312 313 return ret; 314 } 315 316 static void sbi_cpuidle_deinit_cpu(int cpu) 317 { 318 struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu); 319 320 dt_idle_detach_cpu(data->dev); 321 sbi_cpuidle_use_cpuhp = false; 322 } 323 324 static int sbi_cpuidle_init_cpu(struct device *dev, int cpu) 325 { 326 struct cpuidle_driver *drv; 327 unsigned int state_count = 0; 328 int ret = 0; 329 330 drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL); 331 if (!drv) 332 return -ENOMEM; 333 334 drv->name = "sbi_cpuidle"; 335 drv->owner = THIS_MODULE; 336 drv->cpumask = (struct cpumask *)cpumask_of(cpu); 337 338 /* RISC-V architectural WFI to be represented as state index 0. */ 339 drv->states[0].enter = sbi_cpuidle_enter_state; 340 drv->states[0].exit_latency = 1; 341 drv->states[0].target_residency = 1; 342 drv->states[0].power_usage = UINT_MAX; 343 strcpy(drv->states[0].name, "WFI"); 344 strcpy(drv->states[0].desc, "RISC-V WFI"); 345 346 /* 347 * If no DT idle states are detected (ret == 0) let the driver 348 * initialization fail accordingly since there is no reason to 349 * initialize the idle driver if only wfi is supported, the 350 * default archictectural back-end already executes wfi 351 * on idle entry. 352 */ 353 ret = dt_init_idle_driver(drv, sbi_cpuidle_state_match, 1); 354 if (ret <= 0) { 355 pr_debug("HART%ld: failed to parse DT idle states\n", 356 cpuid_to_hartid_map(cpu)); 357 return ret ? : -ENODEV; 358 } 359 state_count = ret + 1; /* Include WFI state as well */ 360 361 /* Initialize idle states from DT. */ 362 ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count); 363 if (ret) { 364 pr_err("HART%ld: failed to init idle states\n", 365 cpuid_to_hartid_map(cpu)); 366 return ret; 367 } 368 369 ret = cpuidle_register(drv, NULL); 370 if (ret) 371 goto deinit; 372 373 cpuidle_cooling_register(drv); 374 375 return 0; 376 deinit: 377 sbi_cpuidle_deinit_cpu(cpu); 378 return ret; 379 } 380 381 static void sbi_cpuidle_domain_sync_state(struct device *dev) 382 { 383 /* 384 * All devices have now been attached/probed to the PM domain 385 * topology, hence it's fine to allow domain states to be picked. 386 */ 387 sbi_cpuidle_pd_allow_domain_state = true; 388 } 389 390 #ifdef CONFIG_DT_IDLE_GENPD 391 392 static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd) 393 { 394 struct genpd_power_state *state = &pd->states[pd->state_idx]; 395 u32 *pd_state; 396 397 if (!state->data) 398 return 0; 399 400 if (!sbi_cpuidle_pd_allow_domain_state) 401 return -EBUSY; 402 403 /* OSI mode is enabled, set the corresponding domain state. */ 404 pd_state = state->data; 405 sbi_set_domain_state(*pd_state); 406 407 return 0; 408 } 409 410 struct sbi_pd_provider { 411 struct list_head link; 412 struct device_node *node; 413 }; 414 415 static LIST_HEAD(sbi_pd_providers); 416 417 static int sbi_pd_init(struct device_node *np) 418 { 419 struct generic_pm_domain *pd; 420 struct sbi_pd_provider *pd_provider; 421 struct dev_power_governor *pd_gov; 422 int ret = -ENOMEM; 423 424 pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node); 425 if (!pd) 426 goto out; 427 428 pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL); 429 if (!pd_provider) 430 goto free_pd; 431 432 pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN; 433 434 /* Allow power off when OSI is available. */ 435 if (sbi_cpuidle_use_osi) 436 pd->power_off = sbi_cpuidle_pd_power_off; 437 else 438 pd->flags |= GENPD_FLAG_ALWAYS_ON; 439 440 /* Use governor for CPU PM domains if it has some states to manage. */ 441 pd_gov = pd->states ? &pm_domain_cpu_gov : NULL; 442 443 ret = pm_genpd_init(pd, pd_gov, false); 444 if (ret) 445 goto free_pd_prov; 446 447 ret = of_genpd_add_provider_simple(np, pd); 448 if (ret) 449 goto remove_pd; 450 451 pd_provider->node = of_node_get(np); 452 list_add(&pd_provider->link, &sbi_pd_providers); 453 454 pr_debug("init PM domain %s\n", pd->name); 455 return 0; 456 457 remove_pd: 458 pm_genpd_remove(pd); 459 free_pd_prov: 460 kfree(pd_provider); 461 free_pd: 462 dt_idle_pd_free(pd); 463 out: 464 pr_err("failed to init PM domain ret=%d %pOF\n", ret, np); 465 return ret; 466 } 467 468 static void sbi_pd_remove(void) 469 { 470 struct sbi_pd_provider *pd_provider, *it; 471 struct generic_pm_domain *genpd; 472 473 list_for_each_entry_safe(pd_provider, it, &sbi_pd_providers, link) { 474 of_genpd_del_provider(pd_provider->node); 475 476 genpd = of_genpd_remove_last(pd_provider->node); 477 if (!IS_ERR(genpd)) 478 kfree(genpd); 479 480 of_node_put(pd_provider->node); 481 list_del(&pd_provider->link); 482 kfree(pd_provider); 483 } 484 } 485 486 static int sbi_genpd_probe(struct device_node *np) 487 { 488 struct device_node *node; 489 int ret = 0, pd_count = 0; 490 491 if (!np) 492 return -ENODEV; 493 494 /* 495 * Parse child nodes for the "#power-domain-cells" property and 496 * initialize a genpd/genpd-of-provider pair when it's found. 497 */ 498 for_each_child_of_node(np, node) { 499 if (!of_find_property(node, "#power-domain-cells", NULL)) 500 continue; 501 502 ret = sbi_pd_init(node); 503 if (ret) 504 goto put_node; 505 506 pd_count++; 507 } 508 509 /* Bail out if not using the hierarchical CPU topology. */ 510 if (!pd_count) 511 goto no_pd; 512 513 /* Link genpd masters/subdomains to model the CPU topology. */ 514 ret = dt_idle_pd_init_topology(np); 515 if (ret) 516 goto remove_pd; 517 518 return 0; 519 520 put_node: 521 of_node_put(node); 522 remove_pd: 523 sbi_pd_remove(); 524 pr_err("failed to create CPU PM domains ret=%d\n", ret); 525 no_pd: 526 return ret; 527 } 528 529 #else 530 531 static inline int sbi_genpd_probe(struct device_node *np) 532 { 533 return 0; 534 } 535 536 #endif 537 538 static int sbi_cpuidle_probe(struct platform_device *pdev) 539 { 540 int cpu, ret; 541 struct cpuidle_driver *drv; 542 struct cpuidle_device *dev; 543 struct device_node *np, *pds_node; 544 545 /* Detect OSI support based on CPU DT nodes */ 546 sbi_cpuidle_use_osi = true; 547 for_each_possible_cpu(cpu) { 548 np = of_cpu_device_node_get(cpu); 549 if (np && 550 of_find_property(np, "power-domains", NULL) && 551 of_find_property(np, "power-domain-names", NULL)) { 552 continue; 553 } else { 554 sbi_cpuidle_use_osi = false; 555 break; 556 } 557 } 558 559 /* Populate generic power domains from DT nodes */ 560 pds_node = of_find_node_by_path("/cpus/power-domains"); 561 if (pds_node) { 562 ret = sbi_genpd_probe(pds_node); 563 of_node_put(pds_node); 564 if (ret) 565 return ret; 566 } 567 568 /* Initialize CPU idle driver for each CPU */ 569 for_each_possible_cpu(cpu) { 570 ret = sbi_cpuidle_init_cpu(&pdev->dev, cpu); 571 if (ret) { 572 pr_debug("HART%ld: idle driver init failed\n", 573 cpuid_to_hartid_map(cpu)); 574 goto out_fail; 575 } 576 } 577 578 /* Setup CPU hotplut notifiers */ 579 sbi_idle_init_cpuhp(); 580 581 pr_info("idle driver registered for all CPUs\n"); 582 583 return 0; 584 585 out_fail: 586 while (--cpu >= 0) { 587 dev = per_cpu(cpuidle_devices, cpu); 588 drv = cpuidle_get_cpu_driver(dev); 589 cpuidle_unregister(drv); 590 sbi_cpuidle_deinit_cpu(cpu); 591 } 592 593 return ret; 594 } 595 596 static struct platform_driver sbi_cpuidle_driver = { 597 .probe = sbi_cpuidle_probe, 598 .driver = { 599 .name = "sbi-cpuidle", 600 .sync_state = sbi_cpuidle_domain_sync_state, 601 }, 602 }; 603 604 static int __init sbi_cpuidle_init(void) 605 { 606 int ret; 607 struct platform_device *pdev; 608 609 /* 610 * The SBI HSM suspend function is only available when: 611 * 1) SBI version is 0.3 or higher 612 * 2) SBI HSM extension is available 613 */ 614 if ((sbi_spec_version < sbi_mk_version(0, 3)) || 615 sbi_probe_extension(SBI_EXT_HSM) <= 0) { 616 pr_info("HSM suspend not available\n"); 617 return 0; 618 } 619 620 ret = platform_driver_register(&sbi_cpuidle_driver); 621 if (ret) 622 return ret; 623 624 pdev = platform_device_register_simple("sbi-cpuidle", 625 -1, NULL, 0); 626 if (IS_ERR(pdev)) { 627 platform_driver_unregister(&sbi_cpuidle_driver); 628 return PTR_ERR(pdev); 629 } 630 631 return 0; 632 } 633 device_initcall(sbi_cpuidle_init); 634