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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
31struct sbi_cpuidle_data {
32 u32 *states;
33 struct device *dev;
34};
35
36struct sbi_domain_state {
37 bool available;
38 u32 state;
39};
40
41static DEFINE_PER_CPU_READ_MOSTLY(struct sbi_cpuidle_data, sbi_cpuidle_data);
42static DEFINE_PER_CPU(struct sbi_domain_state, domain_state);
43static bool sbi_cpuidle_use_osi;
44static bool sbi_cpuidle_use_cpuhp;
45static bool sbi_cpuidle_pd_allow_domain_state;
46
47static 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
55static 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
62static 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
69static 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
76static 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
88static 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
96static __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
109static __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
152static 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
158static 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
165static 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
175static 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
188static 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
203static const struct of_device_id sbi_cpuidle_state_match[] = {
204 { .compatible = "riscv,idle-state",
205 .data = sbi_cpuidle_enter_state },
206 { },
207};
208
209static 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
220static 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
237static 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
263static 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
311fail:
312 of_node_put(cpu_node);
313
314 return ret;
315}
316
317static 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
325static 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;
377deinit:
378 sbi_cpuidle_deinit_cpu(cpu);
379 return ret;
380}
381
382static 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
393static 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
411struct sbi_pd_provider {
412 struct list_head link;
413 struct device_node *node;
414};
415
416static LIST_HEAD(sbi_pd_providers);
417
418static 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
458remove_pd:
459 pm_genpd_remove(pd);
460free_pd_prov:
461 kfree(pd_provider);
462free_pd:
463 dt_idle_pd_free(pd);
464out:
465 pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
466 return ret;
467}
468
469static 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
487static 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_property_present(node, "#power-domain-cells"))
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
521put_node:
522 of_node_put(node);
523remove_pd:
524 sbi_pd_remove();
525 pr_err("failed to create CPU PM domains ret=%d\n", ret);
526no_pd:
527 return ret;
528}
529
530#else
531
532static inline int sbi_genpd_probe(struct device_node *np)
533{
534 return 0;
535}
536
537#endif
538
539static 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_property_present(np, "power-domains") &&
552 of_property_present(np, "power-domain-names")) {
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
586out_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
597static 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
605static 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)) {
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}
634device_initcall(sbi_cpuidle_init);