drivers/cpuidle/cpuidle-riscv-sbi.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * RISC-V SBI CPU idle driver.
0004  *
0005  * Copyright (c) 2021 Western Digital Corporation or its affiliates.
0006  * Copyright (c) 2022 Ventana Micro Systems Inc.
0007  */
0008
0009 #define pr_fmt(fmt) "cpuidle-riscv-sbi: " fmt
0010
0011 #include <linux/cpuidle.h>
0012 #include <linux/cpumask.h>
0013 #include <linux/cpu_pm.h>
0014 #include <linux/cpu_cooling.h>
0015 #include <linux/kernel.h>
0016 #include <linux/module.h>
0017 #include <linux/of.h>
0018 #include <linux/of_device.h>
0019 #include <linux/slab.h>
0020 #include <linux/platform_device.h>
0021 #include <linux/pm_domain.h>
0022 #include <linux/pm_runtime.h>
0023 #include <asm/cpuidle.h>
0024 #include <asm/sbi.h>
0025 #include <asm/smp.h>
0026 #include <asm/suspend.h>
0027
0028 #include "dt_idle_states.h"
0029 #include "dt_idle_genpd.h"
0030
0031 struct sbi_cpuidle_data {
0032     u32 *states;
0033     struct device *dev;
0034 };
0035
0036 struct sbi_domain_state {
0037     bool available;
0038     u32 state;
0039 };
0040
0041 static DEFINE_PER_CPU_READ_MOSTLY(struct sbi_cpuidle_data, sbi_cpuidle_data);
0042 static DEFINE_PER_CPU(struct sbi_domain_state, domain_state);
0043 static bool sbi_cpuidle_use_osi;
0044 static bool sbi_cpuidle_use_cpuhp;
0045 static bool sbi_cpuidle_pd_allow_domain_state;
0046
0047 static inline void sbi_set_domain_state(u32 state)
0048 {
0049     struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
0050
0051     data->available = true;
0052     data->state = state;
0053 }
0054
0055 static inline u32 sbi_get_domain_state(void)
0056 {
0057     struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
0058
0059     return data->state;
0060 }
0061
0062 static inline void sbi_clear_domain_state(void)
0063 {
0064     struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
0065
0066     data->available = false;
0067 }
0068
0069 static inline bool sbi_is_domain_state_available(void)
0070 {
0071     struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
0072
0073     return data->available;
0074 }
0075
0076 static int sbi_suspend_finisher(unsigned long suspend_type,
0077                 unsigned long resume_addr,
0078                 unsigned long opaque)
0079 {
0080     struct sbiret ret;
0081
0082     ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_SUSPEND,
0083             suspend_type, resume_addr, opaque, 0, 0, 0);
0084
0085     return (ret.error) ? sbi_err_map_linux_errno(ret.error) : 0;
0086 }
0087
0088 static int sbi_suspend(u32 state)
0089 {
0090     if (state & SBI_HSM_SUSP_NON_RET_BIT)
0091         return cpu_suspend(state, sbi_suspend_finisher);
0092     else
0093         return sbi_suspend_finisher(state, 0, 0);
0094 }
0095
0096 static int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
0097                    struct cpuidle_driver *drv, int idx)
0098 {
0099     u32 *states = __this_cpu_read(sbi_cpuidle_data.states);
0100
0101     return CPU_PM_CPU_IDLE_ENTER_PARAM(sbi_suspend, idx, states[idx]);
0102 }
0103
0104 static int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
0105                       struct cpuidle_driver *drv, int idx,
0106                       bool s2idle)
0107 {
0108     struct sbi_cpuidle_data *data = this_cpu_ptr(&sbi_cpuidle_data);
0109     u32 *states = data->states;
0110     struct device *pd_dev = data->dev;
0111     u32 state;
0112     int ret;
0113
0114     ret = cpu_pm_enter();
0115     if (ret)
0116         return -1;
0117
0118     /* Do runtime PM to manage a hierarchical CPU toplogy. */
0119     ct_irq_enter_irqson();
0120     if (s2idle)
0121         dev_pm_genpd_suspend(pd_dev);
0122     else
0123         pm_runtime_put_sync_suspend(pd_dev);
0124     ct_irq_exit_irqson();
0125
0126     if (sbi_is_domain_state_available())
0127         state = sbi_get_domain_state();
0128     else
0129         state = states[idx];
0130
0131     ret = sbi_suspend(state) ? -1 : idx;
0132
0133     ct_irq_enter_irqson();
0134     if (s2idle)
0135         dev_pm_genpd_resume(pd_dev);
0136     else
0137         pm_runtime_get_sync(pd_dev);
0138     ct_irq_exit_irqson();
0139
0140     cpu_pm_exit();
0141
0142     /* Clear the domain state to start fresh when back from idle. */
0143     sbi_clear_domain_state();
0144     return ret;
0145 }
0146
0147 static int sbi_enter_domain_idle_state(struct cpuidle_device *dev,
0148                        struct cpuidle_driver *drv, int idx)
0149 {
0150     return __sbi_enter_domain_idle_state(dev, drv, idx, false);
0151 }
0152
0153 static int sbi_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
0154                           struct cpuidle_driver *drv,
0155                           int idx)
0156 {
0157     return __sbi_enter_domain_idle_state(dev, drv, idx, true);
0158 }
0159
0160 static int sbi_cpuidle_cpuhp_up(unsigned int cpu)
0161 {
0162     struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
0163
0164     if (pd_dev)
0165         pm_runtime_get_sync(pd_dev);
0166
0167     return 0;
0168 }
0169
0170 static int sbi_cpuidle_cpuhp_down(unsigned int cpu)
0171 {
0172     struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
0173
0174     if (pd_dev) {
0175         pm_runtime_put_sync(pd_dev);
0176         /* Clear domain state to start fresh at next online. */
0177         sbi_clear_domain_state();
0178     }
0179
0180     return 0;
0181 }
0182
0183 static void sbi_idle_init_cpuhp(void)
0184 {
0185     int err;
0186
0187     if (!sbi_cpuidle_use_cpuhp)
0188         return;
0189
0190     err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
0191                     "cpuidle/sbi:online",
0192                     sbi_cpuidle_cpuhp_up,
0193                     sbi_cpuidle_cpuhp_down);
0194     if (err)
0195         pr_warn("Failed %d while setup cpuhp state\n", err);
0196 }
0197
0198 static const struct of_device_id sbi_cpuidle_state_match[] = {
0199     { .compatible = "riscv,idle-state",
0200       .data = sbi_cpuidle_enter_state },
0201     { },
0202 };
0203
0204 static bool sbi_suspend_state_is_valid(u32 state)
0205 {
0206     if (state > SBI_HSM_SUSPEND_RET_DEFAULT &&
0207         state < SBI_HSM_SUSPEND_RET_PLATFORM)
0208         return false;
0209     if (state > SBI_HSM_SUSPEND_NON_RET_DEFAULT &&
0210         state < SBI_HSM_SUSPEND_NON_RET_PLATFORM)
0211         return false;
0212     return true;
0213 }
0214
0215 static int sbi_dt_parse_state_node(struct device_node *np, u32 *state)
0216 {
0217     int err = of_property_read_u32(np, "riscv,sbi-suspend-param", state);
0218
0219     if (err) {
0220         pr_warn("%pOF missing riscv,sbi-suspend-param property\n", np);
0221         return err;
0222     }
0223
0224     if (!sbi_suspend_state_is_valid(*state)) {
0225         pr_warn("Invalid SBI suspend state %#x\n", *state);
0226         return -EINVAL;
0227     }
0228
0229     return 0;
0230 }
0231
0232 static int sbi_dt_cpu_init_topology(struct cpuidle_driver *drv,
0233                      struct sbi_cpuidle_data *data,
0234                      unsigned int state_count, int cpu)
0235 {
0236     /* Currently limit the hierarchical topology to be used in OSI mode. */
0237     if (!sbi_cpuidle_use_osi)
0238         return 0;
0239
0240     data->dev = dt_idle_attach_cpu(cpu, "sbi");
0241     if (IS_ERR_OR_NULL(data->dev))
0242         return PTR_ERR_OR_ZERO(data->dev);
0243
0244     /*
0245      * Using the deepest state for the CPU to trigger a potential selection
0246      * of a shared state for the domain, assumes the domain states are all
0247      * deeper states.
0248      */
0249     drv->states[state_count - 1].enter = sbi_enter_domain_idle_state;
0250     drv->states[state_count - 1].enter_s2idle =
0251                     sbi_enter_s2idle_domain_idle_state;
0252     sbi_cpuidle_use_cpuhp = true;
0253
0254     return 0;
0255 }
0256
0257 static int sbi_cpuidle_dt_init_states(struct device *dev,
0258                     struct cpuidle_driver *drv,
0259                     unsigned int cpu,
0260                     unsigned int state_count)
0261 {
0262     struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
0263     struct device_node *state_node;
0264     struct device_node *cpu_node;
0265     u32 *states;
0266     int i, ret;
0267
0268     cpu_node = of_cpu_device_node_get(cpu);
0269     if (!cpu_node)
0270         return -ENODEV;
0271
0272     states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL);
0273     if (!states) {
0274         ret = -ENOMEM;
0275         goto fail;
0276     }
0277
0278     /* Parse SBI specific details from state DT nodes */
0279     for (i = 1; i < state_count; i++) {
0280         state_node = of_get_cpu_state_node(cpu_node, i - 1);
0281         if (!state_node)
0282             break;
0283
0284         ret = sbi_dt_parse_state_node(state_node, &states[i]);
0285         of_node_put(state_node);
0286
0287         if (ret)
0288             return ret;
0289
0290         pr_debug("sbi-state %#x index %d\n", states[i], i);
0291     }
0292     if (i != state_count) {
0293         ret = -ENODEV;
0294         goto fail;
0295     }
0296
0297     /* Initialize optional data, used for the hierarchical topology. */
0298     ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu);
0299     if (ret < 0)
0300         return ret;
0301
0302     /* Store states in the per-cpu struct. */
0303     data->states = states;
0304
0305 fail:
0306     of_node_put(cpu_node);
0307
0308     return ret;
0309 }
0310
0311 static void sbi_cpuidle_deinit_cpu(int cpu)
0312 {
0313     struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
0314
0315     dt_idle_detach_cpu(data->dev);
0316     sbi_cpuidle_use_cpuhp = false;
0317 }
0318
0319 static int sbi_cpuidle_init_cpu(struct device *dev, int cpu)
0320 {
0321     struct cpuidle_driver *drv;
0322     unsigned int state_count = 0;
0323     int ret = 0;
0324
0325     drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
0326     if (!drv)
0327         return -ENOMEM;
0328
0329     drv->name = "sbi_cpuidle";
0330     drv->owner = THIS_MODULE;
0331     drv->cpumask = (struct cpumask *)cpumask_of(cpu);
0332
0333     /* RISC-V architectural WFI to be represented as state index 0. */
0334     drv->states[0].enter = sbi_cpuidle_enter_state;
0335     drv->states[0].exit_latency = 1;
0336     drv->states[0].target_residency = 1;
0337     drv->states[0].power_usage = UINT_MAX;
0338     strcpy(drv->states[0].name, "WFI");
0339     strcpy(drv->states[0].desc, "RISC-V WFI");
0340
0341     /*
0342      * If no DT idle states are detected (ret == 0) let the driver
0343      * initialization fail accordingly since there is no reason to
0344      * initialize the idle driver if only wfi is supported, the
0345      * default archictectural back-end already executes wfi
0346      * on idle entry.
0347      */
0348     ret = dt_init_idle_driver(drv, sbi_cpuidle_state_match, 1);
0349     if (ret <= 0) {
0350         pr_debug("HART%ld: failed to parse DT idle states\n",
0351              cpuid_to_hartid_map(cpu));
0352         return ret ? : -ENODEV;
0353     }
0354     state_count = ret + 1; /* Include WFI state as well */
0355
0356     /* Initialize idle states from DT. */
0357     ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count);
0358     if (ret) {
0359         pr_err("HART%ld: failed to init idle states\n",
0360                cpuid_to_hartid_map(cpu));
0361         return ret;
0362     }
0363
0364     ret = cpuidle_register(drv, NULL);
0365     if (ret)
0366         goto deinit;
0367
0368     cpuidle_cooling_register(drv);
0369
0370     return 0;
0371 deinit:
0372     sbi_cpuidle_deinit_cpu(cpu);
0373     return ret;
0374 }
0375
0376 static void sbi_cpuidle_domain_sync_state(struct device *dev)
0377 {
0378     /*
0379      * All devices have now been attached/probed to the PM domain
0380      * topology, hence it's fine to allow domain states to be picked.
0381      */
0382     sbi_cpuidle_pd_allow_domain_state = true;
0383 }
0384
0385 #ifdef CONFIG_DT_IDLE_GENPD
0386
0387 static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)
0388 {
0389     struct genpd_power_state *state = &pd->states[pd->state_idx];
0390     u32 *pd_state;
0391
0392     if (!state->data)
0393         return 0;
0394
0395     if (!sbi_cpuidle_pd_allow_domain_state)
0396         return -EBUSY;
0397
0398     /* OSI mode is enabled, set the corresponding domain state. */
0399     pd_state = state->data;
0400     sbi_set_domain_state(*pd_state);
0401
0402     return 0;
0403 }
0404
0405 struct sbi_pd_provider {
0406     struct list_head link;
0407     struct device_node *node;
0408 };
0409
0410 static LIST_HEAD(sbi_pd_providers);
0411
0412 static int sbi_pd_init(struct device_node *np)
0413 {
0414     struct generic_pm_domain *pd;
0415     struct sbi_pd_provider *pd_provider;
0416     struct dev_power_governor *pd_gov;
0417     int ret = -ENOMEM;
0418
0419     pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
0420     if (!pd)
0421         goto out;
0422
0423     pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
0424     if (!pd_provider)
0425         goto free_pd;
0426
0427     pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
0428
0429     /* Allow power off when OSI is available. */
0430     if (sbi_cpuidle_use_osi)
0431         pd->power_off = sbi_cpuidle_pd_power_off;
0432     else
0433         pd->flags |= GENPD_FLAG_ALWAYS_ON;
0434
0435     /* Use governor for CPU PM domains if it has some states to manage. */
0436     pd_gov = pd->states ? &pm_domain_cpu_gov : NULL;
0437
0438     ret = pm_genpd_init(pd, pd_gov, false);
0439     if (ret)
0440         goto free_pd_prov;
0441
0442     ret = of_genpd_add_provider_simple(np, pd);
0443     if (ret)
0444         goto remove_pd;
0445
0446     pd_provider->node = of_node_get(np);
0447     list_add(&pd_provider->link, &sbi_pd_providers);
0448
0449     pr_debug("init PM domain %s\n", pd->name);
0450     return 0;
0451
0452 remove_pd:
0453     pm_genpd_remove(pd);
0454 free_pd_prov:
0455     kfree(pd_provider);
0456 free_pd:
0457     dt_idle_pd_free(pd);
0458 out:
0459     pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
0460     return ret;
0461 }
0462
0463 static void sbi_pd_remove(void)
0464 {
0465     struct sbi_pd_provider *pd_provider, *it;
0466     struct generic_pm_domain *genpd;
0467
0468     list_for_each_entry_safe(pd_provider, it, &sbi_pd_providers, link) {
0469         of_genpd_del_provider(pd_provider->node);
0470
0471         genpd = of_genpd_remove_last(pd_provider->node);
0472         if (!IS_ERR(genpd))
0473             kfree(genpd);
0474
0475         of_node_put(pd_provider->node);
0476         list_del(&pd_provider->link);
0477         kfree(pd_provider);
0478     }
0479 }
0480
0481 static int sbi_genpd_probe(struct device_node *np)
0482 {
0483     struct device_node *node;
0484     int ret = 0, pd_count = 0;
0485
0486     if (!np)
0487         return -ENODEV;
0488
0489     /*
0490      * Parse child nodes for the "#power-domain-cells" property and
0491      * initialize a genpd/genpd-of-provider pair when it's found.
0492      */
0493     for_each_child_of_node(np, node) {
0494         if (!of_find_property(node, "#power-domain-cells", NULL))
0495             continue;
0496
0497         ret = sbi_pd_init(node);
0498         if (ret)
0499             goto put_node;
0500
0501         pd_count++;
0502     }
0503
0504     /* Bail out if not using the hierarchical CPU topology. */
0505     if (!pd_count)
0506         goto no_pd;
0507
0508     /* Link genpd masters/subdomains to model the CPU topology. */
0509     ret = dt_idle_pd_init_topology(np);
0510     if (ret)
0511         goto remove_pd;
0512
0513     return 0;
0514
0515 put_node:
0516     of_node_put(node);
0517 remove_pd:
0518     sbi_pd_remove();
0519     pr_err("failed to create CPU PM domains ret=%d\n", ret);
0520 no_pd:
0521     return ret;
0522 }
0523
0524 #else
0525
0526 static inline int sbi_genpd_probe(struct device_node *np)
0527 {
0528     return 0;
0529 }
0530
0531 #endif
0532
0533 static int sbi_cpuidle_probe(struct platform_device *pdev)
0534 {
0535     int cpu, ret;
0536     struct cpuidle_driver *drv;
0537     struct cpuidle_device *dev;
0538     struct device_node *np, *pds_node;
0539
0540     /* Detect OSI support based on CPU DT nodes */
0541     sbi_cpuidle_use_osi = true;
0542     for_each_possible_cpu(cpu) {
0543         np = of_cpu_device_node_get(cpu);
0544         if (np &&
0545             of_find_property(np, "power-domains", NULL) &&
0546             of_find_property(np, "power-domain-names", NULL)) {
0547             continue;
0548         } else {
0549             sbi_cpuidle_use_osi = false;
0550             break;
0551         }
0552     }
0553
0554     /* Populate generic power domains from DT nodes */
0555     pds_node = of_find_node_by_path("/cpus/power-domains");
0556     if (pds_node) {
0557         ret = sbi_genpd_probe(pds_node);
0558         of_node_put(pds_node);
0559         if (ret)
0560             return ret;
0561     }
0562
0563     /* Initialize CPU idle driver for each CPU */
0564     for_each_possible_cpu(cpu) {
0565         ret = sbi_cpuidle_init_cpu(&pdev->dev, cpu);
0566         if (ret) {
0567             pr_debug("HART%ld: idle driver init failed\n",
0568                  cpuid_to_hartid_map(cpu));
0569             goto out_fail;
0570         }
0571     }
0572
0573     /* Setup CPU hotplut notifiers */
0574     sbi_idle_init_cpuhp();
0575
0576     pr_info("idle driver registered for all CPUs\n");
0577
0578     return 0;
0579
0580 out_fail:
0581     while (--cpu >= 0) {
0582         dev = per_cpu(cpuidle_devices, cpu);
0583         drv = cpuidle_get_cpu_driver(dev);
0584         cpuidle_unregister(drv);
0585         sbi_cpuidle_deinit_cpu(cpu);
0586     }
0587
0588     return ret;
0589 }
0590
0591 static struct platform_driver sbi_cpuidle_driver = {
0592     .probe = sbi_cpuidle_probe,
0593     .driver = {
0594         .name = "sbi-cpuidle",
0595         .sync_state = sbi_cpuidle_domain_sync_state,
0596     },
0597 };
0598
0599 static int __init sbi_cpuidle_init(void)
0600 {
0601     int ret;
0602     struct platform_device *pdev;
0603
0604     /*
0605      * The SBI HSM suspend function is only available when:
0606      * 1) SBI version is 0.3 or higher
0607      * 2) SBI HSM extension is available
0608      */
0609     if ((sbi_spec_version < sbi_mk_version(0, 3)) ||
0610         sbi_probe_extension(SBI_EXT_HSM) <= 0) {
0611         pr_info("HSM suspend not available\n");
0612         return 0;
0613     }
0614
0615     ret = platform_driver_register(&sbi_cpuidle_driver);
0616     if (ret)
0617         return ret;
0618
0619     pdev = platform_device_register_simple("sbi-cpuidle",
0620                         -1, NULL, 0);
0621     if (IS_ERR(pdev)) {
0622         platform_driver_unregister(&sbi_cpuidle_driver);
0623         return PTR_ERR(pdev);
0624     }
0625
0626     return 0;
0627 }
0628 device_initcall(sbi_cpuidle_init);