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); 586