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 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_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 
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_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 
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)) {
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