cpuidle-riscv-sbi.c

  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/string.h>
 22#include <linux/platform_device.h>
 23#include <linux/pm_domain.h>
 24#include <linux/pm_runtime.h>
 25#include <asm/cpuidle.h>
 26#include <asm/sbi.h>
 27#include <asm/smp.h>
 28#include <asm/suspend.h>
 29
 30#include "cpuidle.h"
 31#include "dt_idle_states.h"
 32#include "dt_idle_genpd.h"
 33
 34struct sbi_cpuidle_data {
 35	u32 *states;
 36	struct device *dev;
 37};
 38
 39struct sbi_domain_state {
 40	bool available;
 41	u32 state;
 42};
 43
 44static DEFINE_PER_CPU_READ_MOSTLY(struct sbi_cpuidle_data, sbi_cpuidle_data);
 45static DEFINE_PER_CPU(struct sbi_domain_state, domain_state);
 46static bool sbi_cpuidle_use_osi;
 47static bool sbi_cpuidle_use_cpuhp;
 48
 49static inline void sbi_set_domain_state(u32 state)
 50{
 51	struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
 52
 53	data->available = true;
 54	data->state = state;
 55}
 56
 57static inline u32 sbi_get_domain_state(void)
 58{
 59	struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
 60
 61	return data->state;
 62}
 63
 64static inline void sbi_clear_domain_state(void)
 65{
 66	struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
 67
 68	data->available = false;
 69}
 70
 71static inline bool sbi_is_domain_state_available(void)
 72{
 73	struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
 74
 75	return data->available;
 76}
 77
 78static __cpuidle int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
 79					     struct cpuidle_driver *drv, int idx)
 80{
 81	u32 *states = __this_cpu_read(sbi_cpuidle_data.states);
 82	u32 state = states[idx];
 83
 84	if (state & SBI_HSM_SUSP_NON_RET_BIT)
 85		return CPU_PM_CPU_IDLE_ENTER_PARAM(riscv_sbi_hart_suspend, idx, state);
 86	else
 87		return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(riscv_sbi_hart_suspend,
 88							     idx, state);
 89}
 90
 91static __cpuidle int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
 92						   struct cpuidle_driver *drv, int idx,
 93						   bool s2idle)
 94{
 95	struct sbi_cpuidle_data *data = this_cpu_ptr(&sbi_cpuidle_data);
 96	u32 *states = data->states;
 97	struct device *pd_dev = data->dev;
 98	u32 state;
 99	int ret;
100
101	ret = cpu_pm_enter();
102	if (ret)
103		return -1;
104
105	/* Do runtime PM to manage a hierarchical CPU toplogy. */
106	if (s2idle)
107		dev_pm_genpd_suspend(pd_dev);
108	else
109		pm_runtime_put_sync_suspend(pd_dev);
110
111	ct_cpuidle_enter();
112
113	if (sbi_is_domain_state_available())
114		state = sbi_get_domain_state();
115	else
116		state = states[idx];
117
118	ret = riscv_sbi_hart_suspend(state) ? -1 : idx;
119
120	ct_cpuidle_exit();
121
122	if (s2idle)
123		dev_pm_genpd_resume(pd_dev);
124	else
125		pm_runtime_get_sync(pd_dev);
126
127	cpu_pm_exit();
128
129	/* Clear the domain state to start fresh when back from idle. */
130	sbi_clear_domain_state();
131	return ret;
132}
133
134static int sbi_enter_domain_idle_state(struct cpuidle_device *dev,
135				       struct cpuidle_driver *drv, int idx)
136{
137	return __sbi_enter_domain_idle_state(dev, drv, idx, false);
138}
139
140static int sbi_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
141					      struct cpuidle_driver *drv,
142					      int idx)
143{
144	return __sbi_enter_domain_idle_state(dev, drv, idx, true);
145}
146
147static int sbi_cpuidle_cpuhp_up(unsigned int cpu)
148{
149	struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
150
151	if (pd_dev)
152		pm_runtime_get_sync(pd_dev);
153
154	return 0;
155}
156
157static int sbi_cpuidle_cpuhp_down(unsigned int cpu)
158{
159	struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
160
161	if (pd_dev) {
162		pm_runtime_put_sync(pd_dev);
163		/* Clear domain state to start fresh at next online. */
164		sbi_clear_domain_state();
165	}
166
167	return 0;
168}
169
170static void sbi_idle_init_cpuhp(void)
171{
172	int err;
173
174	if (!sbi_cpuidle_use_cpuhp)
175		return;
176
177	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
178					"cpuidle/sbi:online",
179					sbi_cpuidle_cpuhp_up,
180					sbi_cpuidle_cpuhp_down);
181	if (err)
182		pr_warn("Failed %d while setup cpuhp state\n", err);
183}
184
185static const struct of_device_id sbi_cpuidle_state_match[] = {
186	{ .compatible = "riscv,idle-state",
187	  .data = sbi_cpuidle_enter_state },
188	{ },
189};
190
191static int sbi_dt_parse_state_node(struct device_node *np, u32 *state)
192{
193	int err = of_property_read_u32(np, "riscv,sbi-suspend-param", state);
194
195	if (err) {
196		pr_warn("%pOF missing riscv,sbi-suspend-param property\n", np);
197		return err;
198	}
199
200	if (!riscv_sbi_suspend_state_is_valid(*state)) {
201		pr_warn("Invalid SBI suspend state %#x\n", *state);
202		return -EINVAL;
203	}
204
205	return 0;
206}
207
208static int sbi_dt_cpu_init_topology(struct cpuidle_driver *drv,
209				     struct sbi_cpuidle_data *data,
210				     unsigned int state_count, int cpu)
211{
212	/* Currently limit the hierarchical topology to be used in OSI mode. */
213	if (!sbi_cpuidle_use_osi)
214		return 0;
215
216	data->dev = dt_idle_attach_cpu(cpu, "sbi");
217	if (IS_ERR_OR_NULL(data->dev))
218		return PTR_ERR_OR_ZERO(data->dev);
219
220	/*
221	 * Using the deepest state for the CPU to trigger a potential selection
222	 * of a shared state for the domain, assumes the domain states are all
223	 * deeper states.
224	 */
225	drv->states[state_count - 1].flags |= CPUIDLE_FLAG_RCU_IDLE;
226	drv->states[state_count - 1].enter = sbi_enter_domain_idle_state;
227	drv->states[state_count - 1].enter_s2idle =
228					sbi_enter_s2idle_domain_idle_state;
229	sbi_cpuidle_use_cpuhp = true;
230
231	return 0;
232}
233
234static int sbi_cpuidle_dt_init_states(struct device *dev,
235					struct cpuidle_driver *drv,
236					unsigned int cpu,
237					unsigned int state_count)
238{
239	struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
240	struct device_node *state_node;
241	u32 *states;
242	int i, ret;
243
244	struct device_node *cpu_node __free(device_node) = of_cpu_device_node_get(cpu);
245	if (!cpu_node)
246		return -ENODEV;
247
248	states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL);
249	if (!states)
250		return -ENOMEM;
251
252	/* Parse SBI specific details from state DT nodes */
253	for (i = 1; i < state_count; i++) {
254		state_node = of_get_cpu_state_node(cpu_node, i - 1);
255		if (!state_node)
256			break;
257
258		ret = sbi_dt_parse_state_node(state_node, &states[i]);
259		of_node_put(state_node);
260
261		if (ret)
262			return ret;
263
264		pr_debug("sbi-state %#x index %d\n", states[i], i);
265	}
266	if (i != state_count)
267		return -ENODEV;
268
269	/* Initialize optional data, used for the hierarchical topology. */
270	ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu);
271	if (ret < 0)
272		return ret;
273
274	/* Store states in the per-cpu struct. */
275	data->states = states;
276
277	return 0;
278}
279
280static void sbi_cpuidle_deinit_cpu(int cpu)
281{
282	struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
283
284	dt_idle_detach_cpu(data->dev);
285	sbi_cpuidle_use_cpuhp = false;
286}
287
288static int sbi_cpuidle_init_cpu(struct device *dev, int cpu)
289{
290	struct cpuidle_driver *drv;
291	unsigned int state_count = 0;
292	int ret = 0;
293
294	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
295	if (!drv)
296		return -ENOMEM;
297
298	drv->name = "sbi_cpuidle";
299	drv->owner = THIS_MODULE;
300	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
301
302	/* RISC-V architectural WFI to be represented as state index 0. */
303	drv->states[0].enter = sbi_cpuidle_enter_state;
304	drv->states[0].exit_latency = 1;
305	drv->states[0].target_residency = 1;
306	drv->states[0].power_usage = UINT_MAX;
307	strscpy(drv->states[0].name, "WFI");
308	strscpy(drv->states[0].desc, "RISC-V WFI");
309
310	/*
311	 * If no DT idle states are detected (ret == 0) let the driver
312	 * initialization fail accordingly since there is no reason to
313	 * initialize the idle driver if only wfi is supported, the
314	 * default archictectural back-end already executes wfi
315	 * on idle entry.
316	 */
317	ret = dt_init_idle_driver(drv, sbi_cpuidle_state_match, 1);
318	if (ret <= 0) {
319		pr_debug("HART%ld: failed to parse DT idle states\n",
320			 cpuid_to_hartid_map(cpu));
321		return ret ? : -ENODEV;
322	}
323	state_count = ret + 1; /* Include WFI state as well */
324
325	/* Initialize idle states from DT. */
326	ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count);
327	if (ret) {
328		pr_err("HART%ld: failed to init idle states\n",
329		       cpuid_to_hartid_map(cpu));
330		return ret;
331	}
332
333	if (cpuidle_disabled())
334		return 0;
335
336	ret = cpuidle_register(drv, NULL);
337	if (ret)
338		goto deinit;
339
340	cpuidle_cooling_register(drv);
341
342	return 0;
343deinit:
344	sbi_cpuidle_deinit_cpu(cpu);
345	return ret;
346}
347
348#ifdef CONFIG_DT_IDLE_GENPD
349
350static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)
351{
352	struct genpd_power_state *state = &pd->states[pd->state_idx];
353	u32 *pd_state;
354
355	if (!state->data)
356		return 0;
357
358	/* OSI mode is enabled, set the corresponding domain state. */
359	pd_state = state->data;
360	sbi_set_domain_state(*pd_state);
361
362	return 0;
363}
364
365struct sbi_pd_provider {
366	struct list_head link;
367	struct device_node *node;
368};
369
370static LIST_HEAD(sbi_pd_providers);
371
372static int sbi_pd_init(struct device_node *np)
373{
374	struct generic_pm_domain *pd;
375	struct sbi_pd_provider *pd_provider;
376	struct dev_power_governor *pd_gov;
377	int ret = -ENOMEM;
378
379	pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
380	if (!pd)
381		goto out;
382
383	pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
384	if (!pd_provider)
385		goto free_pd;
386
387	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
388
389	/* Allow power off when OSI is available. */
390	if (sbi_cpuidle_use_osi)
391		pd->power_off = sbi_cpuidle_pd_power_off;
392	else
393		pd->flags |= GENPD_FLAG_ALWAYS_ON;
394
395	/* Use governor for CPU PM domains if it has some states to manage. */
396	pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;
397
398	ret = pm_genpd_init(pd, pd_gov, false);
399	if (ret)
400		goto free_pd_prov;
401
402	ret = of_genpd_add_provider_simple(np, pd);
403	if (ret)
404		goto remove_pd;
405
406	pd_provider->node = of_node_get(np);
407	list_add(&pd_provider->link, &sbi_pd_providers);
408
409	pr_debug("init PM domain %s\n", pd->name);
410	return 0;
411
412remove_pd:
413	pm_genpd_remove(pd);
414free_pd_prov:
415	kfree(pd_provider);
416free_pd:
417	dt_idle_pd_free(pd);
418out:
419	pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
420	return ret;
421}
422
423static void sbi_pd_remove(void)
424{
425	struct sbi_pd_provider *pd_provider, *it;
426	struct generic_pm_domain *genpd;
427
428	list_for_each_entry_safe(pd_provider, it, &sbi_pd_providers, link) {
429		of_genpd_del_provider(pd_provider->node);
430
431		genpd = of_genpd_remove_last(pd_provider->node);
432		if (!IS_ERR(genpd))
433			kfree(genpd);
434
435		of_node_put(pd_provider->node);
436		list_del(&pd_provider->link);
437		kfree(pd_provider);
438	}
439}
440
441static int sbi_genpd_probe(struct device_node *np)
442{
443	int ret = 0, pd_count = 0;
444
445	if (!np)
446		return -ENODEV;
447
448	/*
449	 * Parse child nodes for the "#power-domain-cells" property and
450	 * initialize a genpd/genpd-of-provider pair when it's found.
451	 */
452	for_each_child_of_node_scoped(np, node) {
453		if (!of_property_present(node, "#power-domain-cells"))
454			continue;
455
456		ret = sbi_pd_init(node);
457		if (ret)
458			goto remove_pd;
459
460		pd_count++;
461	}
462
463	/* Bail out if not using the hierarchical CPU topology. */
464	if (!pd_count)
465		goto no_pd;
466
467	/* Link genpd masters/subdomains to model the CPU topology. */
468	ret = dt_idle_pd_init_topology(np);
469	if (ret)
470		goto remove_pd;
471
472	return 0;
473
474remove_pd:
475	sbi_pd_remove();
476	pr_err("failed to create CPU PM domains ret=%d\n", ret);
477no_pd:
478	return ret;
479}
480
481#else
482
483static inline int sbi_genpd_probe(struct device_node *np)
484{
485	return 0;
486}
487
488#endif
489
490static int sbi_cpuidle_probe(struct platform_device *pdev)
491{
492	int cpu, ret;
493	struct cpuidle_driver *drv;
494	struct cpuidle_device *dev;
495	struct device_node *pds_node;
496
497	/* Detect OSI support based on CPU DT nodes */
498	sbi_cpuidle_use_osi = true;
499	for_each_possible_cpu(cpu) {
500		struct device_node *np __free(device_node) = of_cpu_device_node_get(cpu);
501		if (np &&
502		    of_property_present(np, "power-domains") &&
503		    of_property_present(np, "power-domain-names")) {
504			continue;
505		} else {
506			sbi_cpuidle_use_osi = false;
507			break;
508		}
509	}
510
511	/* Populate generic power domains from DT nodes */
512	pds_node = of_find_node_by_path("/cpus/power-domains");
513	if (pds_node) {
514		ret = sbi_genpd_probe(pds_node);
515		of_node_put(pds_node);
516		if (ret)
517			return ret;
518	}
519
520	/* Initialize CPU idle driver for each present CPU */
521	for_each_present_cpu(cpu) {
522		ret = sbi_cpuidle_init_cpu(&pdev->dev, cpu);
523		if (ret) {
524			pr_debug("HART%ld: idle driver init failed\n",
525				 cpuid_to_hartid_map(cpu));
526			goto out_fail;
527		}
528	}
529
530	/* Setup CPU hotplut notifiers */
531	sbi_idle_init_cpuhp();
532
533	if (cpuidle_disabled())
534		pr_info("cpuidle is disabled\n");
535	else
536		pr_info("idle driver registered for all CPUs\n");
537
538	return 0;
539
540out_fail:
541	while (--cpu >= 0) {
542		dev = per_cpu(cpuidle_devices, cpu);
543		drv = cpuidle_get_cpu_driver(dev);
544		cpuidle_unregister(drv);
545		sbi_cpuidle_deinit_cpu(cpu);
546	}
547
548	return ret;
549}
550
551static struct platform_driver sbi_cpuidle_driver = {
552	.probe = sbi_cpuidle_probe,
553	.driver = {
554		.name = "sbi-cpuidle",
555	},
556};
557
558static int __init sbi_cpuidle_init(void)
559{
560	int ret;
561	struct platform_device *pdev;
562
563	if (!riscv_sbi_hsm_is_supported())
564		return 0;
565
566	ret = platform_driver_register(&sbi_cpuidle_driver);
567	if (ret)
568		return ret;
569
570	pdev = platform_device_register_simple("sbi-cpuidle",
571						-1, NULL, 0);
572	if (IS_ERR(pdev)) {
573		platform_driver_unregister(&sbi_cpuidle_driver);
574		return PTR_ERR(pdev);
575	}
576
577	return 0;
578}
579arch_initcall(sbi_cpuidle_init);