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
sbi_set_domain_state(u32 state)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
sbi_get_domain_state(void)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
sbi_clear_domain_state(void)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
sbi_is_domain_state_available(void)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
sbi_cpuidle_enter_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)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
__sbi_enter_domain_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx,bool s2idle)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
sbi_enter_domain_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)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
sbi_enter_s2idle_domain_idle_state(struct cpuidle_device * dev,struct cpuidle_driver * drv,int idx)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
sbi_cpuidle_cpuhp_up(unsigned int cpu)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
sbi_cpuidle_cpuhp_down(unsigned int cpu)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
sbi_idle_init_cpuhp(void)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
sbi_dt_parse_state_node(struct device_node * np,u32 * state)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
sbi_dt_cpu_init_topology(struct cpuidle_driver * drv,struct sbi_cpuidle_data * data,unsigned int state_count,int cpu)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
sbi_cpuidle_dt_init_states(struct device * dev,struct cpuidle_driver * drv,unsigned int cpu,unsigned int state_count)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
sbi_cpuidle_deinit_cpu(int cpu)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
sbi_cpuidle_init_cpu(struct device * dev,int cpu)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
sbi_cpuidle_domain_sync_state(struct device * dev)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
sbi_cpuidle_pd_power_off(struct generic_pm_domain * pd)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
sbi_pd_init(struct device_node * np)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
sbi_pd_remove(void)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
sbi_genpd_probe(struct device_node * np)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
sbi_genpd_probe(struct device_node * np)491 static inline int sbi_genpd_probe(struct device_node *np)
492 {
493 return 0;
494 }
495
496 #endif
497
sbi_cpuidle_probe(struct platform_device * pdev)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
sbi_cpuidle_init(void)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