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