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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/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_obj(*pd_provider);
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);