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 __cpuidle 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 __cpuidle 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 if (s2idle) 125 dev_pm_genpd_suspend(pd_dev); 126 else 127 pm_runtime_put_sync_suspend(pd_dev); 128 129 ct_cpuidle_enter(); 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_cpuidle_exit(); 139 140 if (s2idle) 141 dev_pm_genpd_resume(pd_dev); 142 else 143 pm_runtime_get_sync(pd_dev); 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].flags |= CPUIDLE_FLAG_RCU_IDLE; 255 drv->states[state_count - 1].enter = sbi_enter_domain_idle_state; 256 drv->states[state_count - 1].enter_s2idle = 257 sbi_enter_s2idle_domain_idle_state; 258 sbi_cpuidle_use_cpuhp = true; 259 260 return 0; 261 } 262 263 static int sbi_cpuidle_dt_init_states(struct device *dev, 264 struct cpuidle_driver *drv, 265 unsigned int cpu, 266 unsigned int state_count) 267 { 268 struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu); 269 struct device_node *state_node; 270 struct device_node *cpu_node; 271 u32 *states; 272 int i, ret; 273 274 cpu_node = of_cpu_device_node_get(cpu); 275 if (!cpu_node) 276 return -ENODEV; 277 278 states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL); 279 if (!states) { 280 ret = -ENOMEM; 281 goto fail; 282 } 283 284 /* Parse SBI specific details from state DT nodes */ 285 for (i = 1; i < state_count; i++) { 286 state_node = of_get_cpu_state_node(cpu_node, i - 1); 287 if (!state_node) 288 break; 289 290 ret = sbi_dt_parse_state_node(state_node, &states[i]); 291 of_node_put(state_node); 292 293 if (ret) 294 return ret; 295 296 pr_debug("sbi-state %#x index %d\n", states[i], i); 297 } 298 if (i != state_count) { 299 ret = -ENODEV; 300 goto fail; 301 } 302 303 /* Initialize optional data, used for the hierarchical topology. */ 304 ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu); 305 if (ret < 0) 306 return ret; 307 308 /* Store states in the per-cpu struct. */ 309 data->states = states; 310 311 fail: 312 of_node_put(cpu_node); 313 314 return ret; 315 } 316 317 static void sbi_cpuidle_deinit_cpu(int cpu) 318 { 319 struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu); 320 321 dt_idle_detach_cpu(data->dev); 322 sbi_cpuidle_use_cpuhp = false; 323 } 324 325 static int sbi_cpuidle_init_cpu(struct device *dev, int cpu) 326 { 327 struct cpuidle_driver *drv; 328 unsigned int state_count = 0; 329 int ret = 0; 330 331 drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL); 332 if (!drv) 333 return -ENOMEM; 334 335 drv->name = "sbi_cpuidle"; 336 drv->owner = THIS_MODULE; 337 drv->cpumask = (struct cpumask *)cpumask_of(cpu); 338 339 /* RISC-V architectural WFI to be represented as state index 0. */ 340 drv->states[0].enter = sbi_cpuidle_enter_state; 341 drv->states[0].exit_latency = 1; 342 drv->states[0].target_residency = 1; 343 drv->states[0].power_usage = UINT_MAX; 344 strcpy(drv->states[0].name, "WFI"); 345 strcpy(drv->states[0].desc, "RISC-V WFI"); 346 347 /* 348 * If no DT idle states are detected (ret == 0) let the driver 349 * initialization fail accordingly since there is no reason to 350 * initialize the idle driver if only wfi is supported, the 351 * default archictectural back-end already executes wfi 352 * on idle entry. 353 */ 354 ret = dt_init_idle_driver(drv, sbi_cpuidle_state_match, 1); 355 if (ret <= 0) { 356 pr_debug("HART%ld: failed to parse DT idle states\n", 357 cpuid_to_hartid_map(cpu)); 358 return ret ? : -ENODEV; 359 } 360 state_count = ret + 1; /* Include WFI state as well */ 361 362 /* Initialize idle states from DT. */ 363 ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count); 364 if (ret) { 365 pr_err("HART%ld: failed to init idle states\n", 366 cpuid_to_hartid_map(cpu)); 367 return ret; 368 } 369 370 ret = cpuidle_register(drv, NULL); 371 if (ret) 372 goto deinit; 373 374 cpuidle_cooling_register(drv); 375 376 return 0; 377 deinit: 378 sbi_cpuidle_deinit_cpu(cpu); 379 return ret; 380 } 381 382 static void sbi_cpuidle_domain_sync_state(struct device *dev) 383 { 384 /* 385 * All devices have now been attached/probed to the PM domain 386 * topology, hence it's fine to allow domain states to be picked. 387 */ 388 sbi_cpuidle_pd_allow_domain_state = true; 389 } 390 391 #ifdef CONFIG_DT_IDLE_GENPD 392 393 static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd) 394 { 395 struct genpd_power_state *state = &pd->states[pd->state_idx]; 396 u32 *pd_state; 397 398 if (!state->data) 399 return 0; 400 401 if (!sbi_cpuidle_pd_allow_domain_state) 402 return -EBUSY; 403 404 /* OSI mode is enabled, set the corresponding domain state. */ 405 pd_state = state->data; 406 sbi_set_domain_state(*pd_state); 407 408 return 0; 409 } 410 411 struct sbi_pd_provider { 412 struct list_head link; 413 struct device_node *node; 414 }; 415 416 static LIST_HEAD(sbi_pd_providers); 417 418 static int sbi_pd_init(struct device_node *np) 419 { 420 struct generic_pm_domain *pd; 421 struct sbi_pd_provider *pd_provider; 422 struct dev_power_governor *pd_gov; 423 int ret = -ENOMEM; 424 425 pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node); 426 if (!pd) 427 goto out; 428 429 pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL); 430 if (!pd_provider) 431 goto free_pd; 432 433 pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN; 434 435 /* Allow power off when OSI is available. */ 436 if (sbi_cpuidle_use_osi) 437 pd->power_off = sbi_cpuidle_pd_power_off; 438 else 439 pd->flags |= GENPD_FLAG_ALWAYS_ON; 440 441 /* Use governor for CPU PM domains if it has some states to manage. */ 442 pd_gov = pd->states ? &pm_domain_cpu_gov : NULL; 443 444 ret = pm_genpd_init(pd, pd_gov, false); 445 if (ret) 446 goto free_pd_prov; 447 448 ret = of_genpd_add_provider_simple(np, pd); 449 if (ret) 450 goto remove_pd; 451 452 pd_provider->node = of_node_get(np); 453 list_add(&pd_provider->link, &sbi_pd_providers); 454 455 pr_debug("init PM domain %s\n", pd->name); 456 return 0; 457 458 remove_pd: 459 pm_genpd_remove(pd); 460 free_pd_prov: 461 kfree(pd_provider); 462 free_pd: 463 dt_idle_pd_free(pd); 464 out: 465 pr_err("failed to init PM domain ret=%d %pOF\n", ret, np); 466 return ret; 467 } 468 469 static void sbi_pd_remove(void) 470 { 471 struct sbi_pd_provider *pd_provider, *it; 472 struct generic_pm_domain *genpd; 473 474 list_for_each_entry_safe(pd_provider, it, &sbi_pd_providers, link) { 475 of_genpd_del_provider(pd_provider->node); 476 477 genpd = of_genpd_remove_last(pd_provider->node); 478 if (!IS_ERR(genpd)) 479 kfree(genpd); 480 481 of_node_put(pd_provider->node); 482 list_del(&pd_provider->link); 483 kfree(pd_provider); 484 } 485 } 486 487 static int sbi_genpd_probe(struct device_node *np) 488 { 489 struct device_node *node; 490 int ret = 0, pd_count = 0; 491 492 if (!np) 493 return -ENODEV; 494 495 /* 496 * Parse child nodes for the "#power-domain-cells" property and 497 * initialize a genpd/genpd-of-provider pair when it's found. 498 */ 499 for_each_child_of_node(np, node) { 500 if (!of_find_property(node, "#power-domain-cells", NULL)) 501 continue; 502 503 ret = sbi_pd_init(node); 504 if (ret) 505 goto put_node; 506 507 pd_count++; 508 } 509 510 /* Bail out if not using the hierarchical CPU topology. */ 511 if (!pd_count) 512 goto no_pd; 513 514 /* Link genpd masters/subdomains to model the CPU topology. */ 515 ret = dt_idle_pd_init_topology(np); 516 if (ret) 517 goto remove_pd; 518 519 return 0; 520 521 put_node: 522 of_node_put(node); 523 remove_pd: 524 sbi_pd_remove(); 525 pr_err("failed to create CPU PM domains ret=%d\n", ret); 526 no_pd: 527 return ret; 528 } 529 530 #else 531 532 static inline int sbi_genpd_probe(struct device_node *np) 533 { 534 return 0; 535 } 536 537 #endif 538 539 static int sbi_cpuidle_probe(struct platform_device *pdev) 540 { 541 int cpu, ret; 542 struct cpuidle_driver *drv; 543 struct cpuidle_device *dev; 544 struct device_node *np, *pds_node; 545 546 /* Detect OSI support based on CPU DT nodes */ 547 sbi_cpuidle_use_osi = true; 548 for_each_possible_cpu(cpu) { 549 np = of_cpu_device_node_get(cpu); 550 if (np && 551 of_find_property(np, "power-domains", NULL) && 552 of_find_property(np, "power-domain-names", NULL)) { 553 continue; 554 } else { 555 sbi_cpuidle_use_osi = false; 556 break; 557 } 558 } 559 560 /* Populate generic power domains from DT nodes */ 561 pds_node = of_find_node_by_path("/cpus/power-domains"); 562 if (pds_node) { 563 ret = sbi_genpd_probe(pds_node); 564 of_node_put(pds_node); 565 if (ret) 566 return ret; 567 } 568 569 /* Initialize CPU idle driver for each CPU */ 570 for_each_possible_cpu(cpu) { 571 ret = sbi_cpuidle_init_cpu(&pdev->dev, cpu); 572 if (ret) { 573 pr_debug("HART%ld: idle driver init failed\n", 574 cpuid_to_hartid_map(cpu)); 575 goto out_fail; 576 } 577 } 578 579 /* Setup CPU hotplut notifiers */ 580 sbi_idle_init_cpuhp(); 581 582 pr_info("idle driver registered for all CPUs\n"); 583 584 return 0; 585 586 out_fail: 587 while (--cpu >= 0) { 588 dev = per_cpu(cpuidle_devices, cpu); 589 drv = cpuidle_get_cpu_driver(dev); 590 cpuidle_unregister(drv); 591 sbi_cpuidle_deinit_cpu(cpu); 592 } 593 594 return ret; 595 } 596 597 static struct platform_driver sbi_cpuidle_driver = { 598 .probe = sbi_cpuidle_probe, 599 .driver = { 600 .name = "sbi-cpuidle", 601 .sync_state = sbi_cpuidle_domain_sync_state, 602 }, 603 }; 604 605 static int __init sbi_cpuidle_init(void) 606 { 607 int ret; 608 struct platform_device *pdev; 609 610 /* 611 * The SBI HSM suspend function is only available when: 612 * 1) SBI version is 0.3 or higher 613 * 2) SBI HSM extension is available 614 */ 615 if ((sbi_spec_version < sbi_mk_version(0, 3)) || 616 sbi_probe_extension(SBI_EXT_HSM) <= 0) { 617 pr_info("HSM suspend not available\n"); 618 return 0; 619 } 620 621 ret = platform_driver_register(&sbi_cpuidle_driver); 622 if (ret) 623 return ret; 624 625 pdev = platform_device_register_simple("sbi-cpuidle", 626 -1, NULL, 0); 627 if (IS_ERR(pdev)) { 628 platform_driver_unregister(&sbi_cpuidle_driver); 629 return PTR_ERR(pdev); 630 } 631 632 return 0; 633 } 634 device_initcall(sbi_cpuidle_init); 635