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 __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
89static __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(dev: pd_dev);
106 else
107 pm_runtime_put_sync_suspend(dev: 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(dev: pd_dev);
122 else
123 pm_runtime_get_sync(dev: 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
132static 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, s2idle: false);
136}
137
138static 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, s2idle: true);
143}
144
145static 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(dev: pd_dev);
151
152 return 0;
153}
154
155static 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(dev: pd_dev);
161 /* Clear domain state to start fresh at next online. */
162 sbi_clear_domain_state();
163 }
164
165 return 0;
166}
167
168static 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(state: CPUHP_AP_CPU_PM_STARTING,
176 name: "cpuidle/sbi:online",
177 startup: sbi_cpuidle_cpuhp_up,
178 teardown: sbi_cpuidle_cpuhp_down);
179 if (err)
180 pr_warn("Failed %d while setup cpuhp state\n", err);
181}
182
183static const struct of_device_id sbi_cpuidle_state_match[] = {
184 { .compatible = "riscv,idle-state",
185 .data = sbi_cpuidle_enter_state },
186 { },
187};
188
189static int sbi_dt_parse_state_node(struct device_node *np, u32 *state)
190{
191 int err = of_property_read_u32(np, propname: "riscv,sbi-suspend-param", out_value: 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
206static 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, name: "sbi");
215 if (IS_ERR_OR_NULL(ptr: data->dev))
216 return PTR_ERR_OR_ZERO(ptr: 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
232static 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, n: state_count, size: 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, index: i - 1);
256 if (!state_node)
257 break;
258
259 ret = sbi_dt_parse_state_node(np: state_node, state: &states[i]);
260 of_node_put(node: 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
280fail:
281 of_node_put(node: cpu_node);
282
283 return ret;
284}
285
286static 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(dev: data->dev);
291 sbi_cpuidle_use_cpuhp = false;
292}
293
294static 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, size: 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(p: drv->states[0].name, q: "WFI");
314 strcpy(p: drv->states[0].desc, q: "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, matches: sbi_cpuidle_state_match, start_idx: 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;
346deinit:
347 sbi_cpuidle_deinit_cpu(cpu);
348 return ret;
349}
350
351static 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
362static 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
380struct sbi_pd_provider {
381 struct list_head link;
382 struct device_node *node;
383};
384
385static LIST_HEAD(sbi_pd_providers);
386
387static 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
427remove_pd:
428 pm_genpd_remove(pd);
429free_pd_prov:
430 kfree(pd_provider);
431free_pd:
432 dt_idle_pd_free(pd);
433out:
434 pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
435 return ret;
436}
437
438static 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
456static 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
490put_node:
491 of_node_put(node);
492remove_pd:
493 sbi_pd_remove();
494 pr_err("failed to create CPU PM domains ret=%d\n", ret);
495no_pd:
496 return ret;
497}
498
499#else
500
501static inline int sbi_genpd_probe(struct device_node *np)
502{
503 return 0;
504}
505
506#endif
507
508static 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, propname: "power-domains") &&
521 of_property_present(np, propname: "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(path: "/cpus/power-domains");
531 if (pds_node) {
532 ret = sbi_genpd_probe(np: pds_node);
533 of_node_put(node: 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(dev: &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
555out_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
566static 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
574static 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(name: "sbi-cpuidle",
587 id: -1, NULL, num: 0);
588 if (IS_ERR(ptr: pdev)) {
589 platform_driver_unregister(&sbi_cpuidle_driver);
590 return PTR_ERR(ptr: pdev);
591 }
592
593 return 0;
594}
595device_initcall(sbi_cpuidle_init);
596

source code of linux/drivers/cpuidle/cpuidle-riscv-sbi.c