1 // SPDX-License-Identifier: GPL-2.0-only
3 * RISC-V SBI CPU idle driver.
5 * Copyright (c) 2021 Western Digital Corporation or its affiliates.
6 * Copyright (c) 2022 Ventana Micro Systems Inc.
9 #define pr_fmt(fmt) "cpuidle-riscv-sbi: " fmt
11 #include <linux/cpuidle.h>
12 #include <linux/cpumask.h>
13 #include <linux/cpu_pm.h>
14 #include <linux/cpu_cooling.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
18 #include <linux/of_device.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>
26 #include <asm/suspend.h>
28 #include "dt_idle_states.h"
29 #include "dt_idle_genpd.h"
31 struct sbi_cpuidle_data {
36 struct sbi_domain_state {
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;
47 static inline void sbi_set_domain_state(u32 state)
49 struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
51 data->available = true;
55 static inline u32 sbi_get_domain_state(void)
57 struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
62 static inline void sbi_clear_domain_state(void)
64 struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
66 data->available = false;
69 static inline bool sbi_is_domain_state_available(void)
71 struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
73 return data->available;
76 static int sbi_suspend_finisher(unsigned long suspend_type,
77 unsigned long resume_addr,
82 ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_SUSPEND,
83 suspend_type, resume_addr, opaque, 0, 0, 0);
85 return (ret.error) ? sbi_err_map_linux_errno(ret.error) : 0;
88 static int sbi_suspend(u32 state)
90 if (state & SBI_HSM_SUSP_NON_RET_BIT)
91 return cpu_suspend(state, sbi_suspend_finisher);
93 return sbi_suspend_finisher(state, 0, 0);
96 static int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
97 struct cpuidle_driver *drv, int idx)
99 u32 *states = __this_cpu_read(sbi_cpuidle_data.states);
101 return CPU_PM_CPU_IDLE_ENTER_PARAM(sbi_suspend, idx, states[idx]);
104 static int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
105 struct cpuidle_driver *drv, int idx,
108 struct sbi_cpuidle_data *data = this_cpu_ptr(&sbi_cpuidle_data);
109 u32 *states = data->states;
110 struct device *pd_dev = data->dev;
114 ret = cpu_pm_enter();
118 /* Do runtime PM to manage a hierarchical CPU toplogy. */
119 rcu_irq_enter_irqson();
121 dev_pm_genpd_suspend(pd_dev);
123 pm_runtime_put_sync_suspend(pd_dev);
124 rcu_irq_exit_irqson();
126 if (sbi_is_domain_state_available())
127 state = sbi_get_domain_state();
131 ret = sbi_suspend(state) ? -1 : idx;
133 rcu_irq_enter_irqson();
135 dev_pm_genpd_resume(pd_dev);
137 pm_runtime_get_sync(pd_dev);
138 rcu_irq_exit_irqson();
142 /* Clear the domain state to start fresh when back from idle. */
143 sbi_clear_domain_state();
147 static int sbi_enter_domain_idle_state(struct cpuidle_device *dev,
148 struct cpuidle_driver *drv, int idx)
150 return __sbi_enter_domain_idle_state(dev, drv, idx, false);
153 static int sbi_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
154 struct cpuidle_driver *drv,
157 return __sbi_enter_domain_idle_state(dev, drv, idx, true);
160 static int sbi_cpuidle_cpuhp_up(unsigned int cpu)
162 struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
165 pm_runtime_get_sync(pd_dev);
170 static int sbi_cpuidle_cpuhp_down(unsigned int cpu)
172 struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
175 pm_runtime_put_sync(pd_dev);
176 /* Clear domain state to start fresh at next online. */
177 sbi_clear_domain_state();
183 static void sbi_idle_init_cpuhp(void)
187 if (!sbi_cpuidle_use_cpuhp)
190 err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
191 "cpuidle/sbi:online",
192 sbi_cpuidle_cpuhp_up,
193 sbi_cpuidle_cpuhp_down);
195 pr_warn("Failed %d while setup cpuhp state\n", err);
198 static const struct of_device_id sbi_cpuidle_state_match[] = {
199 { .compatible = "riscv,idle-state",
200 .data = sbi_cpuidle_enter_state },
204 static bool sbi_suspend_state_is_valid(u32 state)
206 if (state > SBI_HSM_SUSPEND_RET_DEFAULT &&
207 state < SBI_HSM_SUSPEND_RET_PLATFORM)
209 if (state > SBI_HSM_SUSPEND_NON_RET_DEFAULT &&
210 state < SBI_HSM_SUSPEND_NON_RET_PLATFORM)
215 static int sbi_dt_parse_state_node(struct device_node *np, u32 *state)
217 int err = of_property_read_u32(np, "riscv,sbi-suspend-param", state);
220 pr_warn("%pOF missing riscv,sbi-suspend-param property\n", np);
224 if (!sbi_suspend_state_is_valid(*state)) {
225 pr_warn("Invalid SBI suspend state %#x\n", *state);
232 static int sbi_dt_cpu_init_topology(struct cpuidle_driver *drv,
233 struct sbi_cpuidle_data *data,
234 unsigned int state_count, int cpu)
236 /* Currently limit the hierarchical topology to be used in OSI mode. */
237 if (!sbi_cpuidle_use_osi)
240 data->dev = dt_idle_attach_cpu(cpu, "sbi");
241 if (IS_ERR_OR_NULL(data->dev))
242 return PTR_ERR_OR_ZERO(data->dev);
245 * Using the deepest state for the CPU to trigger a potential selection
246 * of a shared state for the domain, assumes the domain states are all
249 drv->states[state_count - 1].enter = sbi_enter_domain_idle_state;
250 drv->states[state_count - 1].enter_s2idle =
251 sbi_enter_s2idle_domain_idle_state;
252 sbi_cpuidle_use_cpuhp = true;
257 static int sbi_cpuidle_dt_init_states(struct device *dev,
258 struct cpuidle_driver *drv,
260 unsigned int state_count)
262 struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
263 struct device_node *state_node;
264 struct device_node *cpu_node;
268 cpu_node = of_cpu_device_node_get(cpu);
272 states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL);
278 /* Parse SBI specific details from state DT nodes */
279 for (i = 1; i < state_count; i++) {
280 state_node = of_get_cpu_state_node(cpu_node, i - 1);
284 ret = sbi_dt_parse_state_node(state_node, &states[i]);
285 of_node_put(state_node);
290 pr_debug("sbi-state %#x index %d\n", states[i], i);
292 if (i != state_count) {
297 /* Initialize optional data, used for the hierarchical topology. */
298 ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu);
302 /* Store states in the per-cpu struct. */
303 data->states = states;
306 of_node_put(cpu_node);
311 static void sbi_cpuidle_deinit_cpu(int cpu)
313 struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
315 dt_idle_detach_cpu(data->dev);
316 sbi_cpuidle_use_cpuhp = false;
319 static int sbi_cpuidle_init_cpu(struct device *dev, int cpu)
321 struct cpuidle_driver *drv;
322 unsigned int state_count = 0;
325 drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
329 drv->name = "sbi_cpuidle";
330 drv->owner = THIS_MODULE;
331 drv->cpumask = (struct cpumask *)cpumask_of(cpu);
333 /* RISC-V architectural WFI to be represented as state index 0. */
334 drv->states[0].enter = sbi_cpuidle_enter_state;
335 drv->states[0].exit_latency = 1;
336 drv->states[0].target_residency = 1;
337 drv->states[0].power_usage = UINT_MAX;
338 strcpy(drv->states[0].name, "WFI");
339 strcpy(drv->states[0].desc, "RISC-V WFI");
342 * If no DT idle states are detected (ret == 0) let the driver
343 * initialization fail accordingly since there is no reason to
344 * initialize the idle driver if only wfi is supported, the
345 * default archictectural back-end already executes wfi
348 ret = dt_init_idle_driver(drv, sbi_cpuidle_state_match, 1);
350 pr_debug("HART%ld: failed to parse DT idle states\n",
351 cpuid_to_hartid_map(cpu));
352 return ret ? : -ENODEV;
354 state_count = ret + 1; /* Include WFI state as well */
356 /* Initialize idle states from DT. */
357 ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count);
359 pr_err("HART%ld: failed to init idle states\n",
360 cpuid_to_hartid_map(cpu));
364 ret = cpuidle_register(drv, NULL);
368 cpuidle_cooling_register(drv);
372 sbi_cpuidle_deinit_cpu(cpu);
376 static void sbi_cpuidle_domain_sync_state(struct device *dev)
379 * All devices have now been attached/probed to the PM domain
380 * topology, hence it's fine to allow domain states to be picked.
382 sbi_cpuidle_pd_allow_domain_state = true;
385 #ifdef CONFIG_DT_IDLE_GENPD
387 static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)
389 struct genpd_power_state *state = &pd->states[pd->state_idx];
395 if (!sbi_cpuidle_pd_allow_domain_state)
398 /* OSI mode is enabled, set the corresponding domain state. */
399 pd_state = state->data;
400 sbi_set_domain_state(*pd_state);
405 struct sbi_pd_provider {
406 struct list_head link;
407 struct device_node *node;
410 static LIST_HEAD(sbi_pd_providers);
412 static int sbi_pd_init(struct device_node *np)
414 struct generic_pm_domain *pd;
415 struct sbi_pd_provider *pd_provider;
416 struct dev_power_governor *pd_gov;
419 pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
423 pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
427 pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
429 /* Allow power off when OSI is available. */
430 if (sbi_cpuidle_use_osi)
431 pd->power_off = sbi_cpuidle_pd_power_off;
433 pd->flags |= GENPD_FLAG_ALWAYS_ON;
435 /* Use governor for CPU PM domains if it has some states to manage. */
436 pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;
438 ret = pm_genpd_init(pd, pd_gov, false);
442 ret = of_genpd_add_provider_simple(np, pd);
446 pd_provider->node = of_node_get(np);
447 list_add(&pd_provider->link, &sbi_pd_providers);
449 pr_debug("init PM domain %s\n", pd->name);
459 pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
463 static void sbi_pd_remove(void)
465 struct sbi_pd_provider *pd_provider, *it;
466 struct generic_pm_domain *genpd;
468 list_for_each_entry_safe(pd_provider, it, &sbi_pd_providers, link) {
469 of_genpd_del_provider(pd_provider->node);
471 genpd = of_genpd_remove_last(pd_provider->node);
475 of_node_put(pd_provider->node);
476 list_del(&pd_provider->link);
481 static int sbi_genpd_probe(struct device_node *np)
483 struct device_node *node;
484 int ret = 0, pd_count = 0;
490 * Parse child nodes for the "#power-domain-cells" property and
491 * initialize a genpd/genpd-of-provider pair when it's found.
493 for_each_child_of_node(np, node) {
494 if (!of_find_property(node, "#power-domain-cells", NULL))
497 ret = sbi_pd_init(node);
504 /* Bail out if not using the hierarchical CPU topology. */
508 /* Link genpd masters/subdomains to model the CPU topology. */
509 ret = dt_idle_pd_init_topology(np);
519 pr_err("failed to create CPU PM domains ret=%d\n", ret);
526 static inline int sbi_genpd_probe(struct device_node *np)
533 static int sbi_cpuidle_probe(struct platform_device *pdev)
536 struct cpuidle_driver *drv;
537 struct cpuidle_device *dev;
538 struct device_node *np, *pds_node;
540 /* Detect OSI support based on CPU DT nodes */
541 sbi_cpuidle_use_osi = true;
542 for_each_possible_cpu(cpu) {
543 np = of_cpu_device_node_get(cpu);
545 of_find_property(np, "power-domains", NULL) &&
546 of_find_property(np, "power-domain-names", NULL)) {
549 sbi_cpuidle_use_osi = false;
554 /* Populate generic power domains from DT nodes */
555 pds_node = of_find_node_by_path("/cpus/power-domains");
557 ret = sbi_genpd_probe(pds_node);
558 of_node_put(pds_node);
563 /* Initialize CPU idle driver for each CPU */
564 for_each_possible_cpu(cpu) {
565 ret = sbi_cpuidle_init_cpu(&pdev->dev, cpu);
567 pr_debug("HART%ld: idle driver init failed\n",
568 cpuid_to_hartid_map(cpu));
573 /* Setup CPU hotplut notifiers */
574 sbi_idle_init_cpuhp();
576 pr_info("idle driver registered for all CPUs\n");
582 dev = per_cpu(cpuidle_devices, cpu);
583 drv = cpuidle_get_cpu_driver(dev);
584 cpuidle_unregister(drv);
585 sbi_cpuidle_deinit_cpu(cpu);
591 static struct platform_driver sbi_cpuidle_driver = {
592 .probe = sbi_cpuidle_probe,
594 .name = "sbi-cpuidle",
595 .sync_state = sbi_cpuidle_domain_sync_state,
599 static int __init sbi_cpuidle_init(void)
602 struct platform_device *pdev;
605 * The SBI HSM suspend function is only available when:
606 * 1) SBI version is 0.3 or higher
607 * 2) SBI HSM extension is available
609 if ((sbi_spec_version < sbi_mk_version(0, 3)) ||
610 sbi_probe_extension(SBI_EXT_HSM) <= 0) {
611 pr_info("HSM suspend not available\n");
615 ret = platform_driver_register(&sbi_cpuidle_driver);
619 pdev = platform_device_register_simple("sbi-cpuidle",
622 platform_driver_unregister(&sbi_cpuidle_driver);
623 return PTR_ERR(pdev);
628 device_initcall(sbi_cpuidle_init);