LXR linux/drivers/cpuidle/cpuidle-psci.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * PSCI CPU idle driver.
   4 *
   5 * Copyright (C) 2019 ARM Ltd.
   6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   7 */
   8
   9#define pr_fmt(fmt) "CPUidle PSCI: " fmt
  10
  11#include <linux/cpuhotplug.h>
  12#include <linux/cpu_cooling.h>
  13#include <linux/cpuidle.h>
  14#include <linux/cpumask.h>
  15#include <linux/cpu_pm.h>
  16#include <linux/kernel.h>
  17#include <linux/module.h>
  18#include <linux/of.h>
  19#include <linux/of_device.h>
  20#include <linux/platform_device.h>
  21#include <linux/psci.h>
  22#include <linux/pm_domain.h>
  23#include <linux/pm_runtime.h>
  24#include <linux/slab.h>
  25#include <linux/string.h>
  26
  27#include <asm/cpuidle.h>
  28
  29#include "cpuidle-psci.h"
  30#include "dt_idle_states.h"
  31
  32struct psci_cpuidle_data {
  33        u32 *psci_states;
  34        struct device *dev;
  35};
  36
  37static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
  38static DEFINE_PER_CPU(u32, domain_state);
  39static bool psci_cpuidle_use_cpuhp;
  40
  41void psci_set_domain_state(u32 state)
  42{
  43        __this_cpu_write(domain_state, state);
  44}
  45
  46static inline u32 psci_get_domain_state(void)
  47{
  48        return __this_cpu_read(domain_state);
  49}
  50
  51static inline int psci_enter_state(int idx, u32 state)
  52{
  53        return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
  54}
  55
  56static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
  57                                          struct cpuidle_driver *drv, int idx,
  58                                          bool s2idle)
  59{
  60        struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
  61        u32 *states = data->psci_states;
  62        struct device *pd_dev = data->dev;
  63        u32 state;
  64        int ret;
  65
  66        ret = cpu_pm_enter();
  67        if (ret)
  68                return -1;
  69
  70        /* Do runtime PM to manage a hierarchical CPU toplogy. */
  71        rcu_irq_enter_irqson();
  72        if (s2idle)
  73                dev_pm_genpd_suspend(pd_dev);
  74        else
  75                pm_runtime_put_sync_suspend(pd_dev);
  76        rcu_irq_exit_irqson();
  77
  78        state = psci_get_domain_state();
  79        if (!state)
  80                state = states[idx];
  81
  82        ret = psci_cpu_suspend_enter(state) ? -1 : idx;
  83
  84        rcu_irq_enter_irqson();
  85        if (s2idle)
  86                dev_pm_genpd_resume(pd_dev);
  87        else
  88                pm_runtime_get_sync(pd_dev);
  89        rcu_irq_exit_irqson();
  90
  91        cpu_pm_exit();
  92
  93        /* Clear the domain state to start fresh when back from idle. */
  94        psci_set_domain_state(0);
  95        return ret;
  96}
  97
  98static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
  99                                        struct cpuidle_driver *drv, int idx)
 100{
 101        return __psci_enter_domain_idle_state(dev, drv, idx, false);
 102}
 103
 104static int psci_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
 105                                               struct cpuidle_driver *drv,
 106                                               int idx)
 107{
 108        return __psci_enter_domain_idle_state(dev, drv, idx, true);
 109}
 110
 111static int psci_idle_cpuhp_up(unsigned int cpu)
 112{
 113        struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
 114
 115        if (pd_dev)
 116                pm_runtime_get_sync(pd_dev);
 117
 118        return 0;
 119}
 120
 121static int psci_idle_cpuhp_down(unsigned int cpu)
 122{
 123        struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
 124
 125        if (pd_dev) {
 126                pm_runtime_put_sync(pd_dev);
 127                /* Clear domain state to start fresh at next online. */
 128                psci_set_domain_state(0);
 129        }
 130
 131        return 0;
 132}
 133
 134static void psci_idle_init_cpuhp(void)
 135{
 136        int err;
 137
 138        if (!psci_cpuidle_use_cpuhp)
 139                return;
 140
 141        err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
 142                                        "cpuidle/psci:online",
 143                                        psci_idle_cpuhp_up,
 144                                        psci_idle_cpuhp_down);
 145        if (err)
 146                pr_warn("Failed %d while setup cpuhp state\n", err);
 147}
 148
 149static int psci_enter_idle_state(struct cpuidle_device *dev,
 150                                struct cpuidle_driver *drv, int idx)
 151{
 152        u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
 153
 154        return psci_enter_state(idx, state[idx]);
 155}
 156
 157static const struct of_device_id psci_idle_state_match[] = {
 158        { .compatible = "arm,idle-state",
 159          .data = psci_enter_idle_state },
 160        { },
 161};
 162
 163int psci_dt_parse_state_node(struct device_node *np, u32 *state)
 164{
 165        int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
 166
 167        if (err) {
 168                pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
 169                return err;
 170        }
 171
 172        if (!psci_power_state_is_valid(*state)) {
 173                pr_warn("Invalid PSCI power state %#x\n", *state);
 174                return -EINVAL;
 175        }
 176
 177        return 0;
 178}
 179
 180static int psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
 181                                     struct psci_cpuidle_data *data,
 182                                     unsigned int state_count, int cpu)
 183{
 184        /* Currently limit the hierarchical topology to be used in OSI mode. */
 185        if (!psci_has_osi_support())
 186                return 0;
 187
 188        data->dev = psci_dt_attach_cpu(cpu);
 189        if (IS_ERR_OR_NULL(data->dev))
 190                return PTR_ERR_OR_ZERO(data->dev);
 191
 192        /*
 193         * Using the deepest state for the CPU to trigger a potential selection
 194         * of a shared state for the domain, assumes the domain states are all
 195         * deeper states.
 196         */
 197        drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
 198        drv->states[state_count - 1].enter_s2idle = psci_enter_s2idle_domain_idle_state;
 199        psci_cpuidle_use_cpuhp = true;
 200
 201        return 0;
 202}
 203
 204static int psci_dt_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
 205                                 struct device_node *cpu_node,
 206                                 unsigned int state_count, int cpu)
 207{
 208        int i, ret = 0;
 209        u32 *psci_states;
 210        struct device_node *state_node;
 211        struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
 212
 213        state_count++; /* Add WFI state too */
 214        psci_states = devm_kcalloc(dev, state_count, sizeof(*psci_states),
 215                                   GFP_KERNEL);
 216        if (!psci_states)
 217                return -ENOMEM;
 218
 219        for (i = 1; i < state_count; i++) {
 220                state_node = of_get_cpu_state_node(cpu_node, i - 1);
 221                if (!state_node)
 222                        break;
 223
 224                ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
 225                of_node_put(state_node);
 226
 227                if (ret)
 228                        return ret;
 229
 230                pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
 231        }
 232
 233        if (i != state_count)
 234                return -ENODEV;
 235
 236        /* Initialize optional data, used for the hierarchical topology. */
 237        ret = psci_dt_cpu_init_topology(drv, data, state_count, cpu);
 238        if (ret < 0)
 239                return ret;
 240
 241        /* Idle states parsed correctly, store them in the per-cpu struct. */
 242        data->psci_states = psci_states;
 243        return 0;
 244}
 245
 246static int psci_cpu_init_idle(struct device *dev, struct cpuidle_driver *drv,
 247                              unsigned int cpu, unsigned int state_count)
 248{
 249        struct device_node *cpu_node;
 250        int ret;
 251
 252        /*
 253         * If the PSCI cpu_suspend function hook has not been initialized
 254         * idle states must not be enabled, so bail out
 255         */
 256        if (!psci_ops.cpu_suspend)
 257                return -EOPNOTSUPP;
 258
 259        cpu_node = of_cpu_device_node_get(cpu);
 260        if (!cpu_node)
 261                return -ENODEV;
 262
 263        ret = psci_dt_cpu_init_idle(dev, drv, cpu_node, state_count, cpu);
 264
 265        of_node_put(cpu_node);
 266
 267        return ret;
 268}
 269
 270static void psci_cpu_deinit_idle(int cpu)
 271{
 272        struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
 273
 274        psci_dt_detach_cpu(data->dev);
 275        psci_cpuidle_use_cpuhp = false;
 276}
 277
 278static int psci_idle_init_cpu(struct device *dev, int cpu)
 279{
 280        struct cpuidle_driver *drv;
 281        struct device_node *cpu_node;
 282        const char *enable_method;
 283        int ret = 0;
 284
 285        cpu_node = of_cpu_device_node_get(cpu);
 286        if (!cpu_node)
 287                return -ENODEV;
 288
 289        /*
 290         * Check whether the enable-method for the cpu is PSCI, fail
 291         * if it is not.
 292         */
 293        enable_method = of_get_property(cpu_node, "enable-method", NULL);
 294        if (!enable_method || (strcmp(enable_method, "psci")))
 295                ret = -ENODEV;
 296
 297        of_node_put(cpu_node);
 298        if (ret)
 299                return ret;
 300
 301        drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
 302        if (!drv)
 303                return -ENOMEM;
 304
 305        drv->name = "psci_idle";
 306        drv->owner = THIS_MODULE;
 307        drv->cpumask = (struct cpumask *)cpumask_of(cpu);
 308
 309        /*
 310         * PSCI idle states relies on architectural WFI to be represented as
 311         * state index 0.
 312         */
 313        drv->states[0].enter = psci_enter_idle_state;
 314        drv->states[0].exit_latency = 1;
 315        drv->states[0].target_residency = 1;
 316        drv->states[0].power_usage = UINT_MAX;
 317        strcpy(drv->states[0].name, "WFI");
 318        strcpy(drv->states[0].desc, "ARM WFI");
 319
 320        /*
 321         * If no DT idle states are detected (ret == 0) let the driver
 322         * initialization fail accordingly since there is no reason to
 323         * initialize the idle driver if only wfi is supported, the
 324         * default archictectural back-end already executes wfi
 325         * on idle entry.
 326         */
 327        ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
 328        if (ret <= 0)
 329                return ret ? : -ENODEV;
 330
 331        /*
 332         * Initialize PSCI idle states.
 333         */
 334        ret = psci_cpu_init_idle(dev, drv, cpu, ret);
 335        if (ret) {
 336                pr_err("CPU %d failed to PSCI idle\n", cpu);
 337                return ret;
 338        }
 339
 340        ret = cpuidle_register(drv, NULL);
 341        if (ret)
 342                goto deinit;
 343
 344        cpuidle_cooling_register(drv);
 345
 346        return 0;
 347deinit:
 348        psci_cpu_deinit_idle(cpu);
 349        return ret;
 350}
 351
 352/*
 353 * psci_idle_probe - Initializes PSCI cpuidle driver
 354 *
 355 * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
 356 * to register cpuidle driver then rollback to cancel all CPUs
 357 * registration.
 358 */
 359static int psci_cpuidle_probe(struct platform_device *pdev)
 360{
 361        int cpu, ret;
 362        struct cpuidle_driver *drv;
 363        struct cpuidle_device *dev;
 364
 365        for_each_possible_cpu(cpu) {
 366                ret = psci_idle_init_cpu(&pdev->dev, cpu);
 367                if (ret)
 368                        goto out_fail;
 369        }
 370
 371        psci_idle_init_cpuhp();
 372        return 0;
 373
 374out_fail:
 375        while (--cpu >= 0) {
 376                dev = per_cpu(cpuidle_devices, cpu);
 377                drv = cpuidle_get_cpu_driver(dev);
 378                cpuidle_unregister(drv);
 379                psci_cpu_deinit_idle(cpu);
 380        }
 381
 382        return ret;
 383}
 384
 385static struct platform_driver psci_cpuidle_driver = {
 386        .probe = psci_cpuidle_probe,
 387        .driver = {
 388                .name = "psci-cpuidle",
 389        },
 390};
 391
 392static int __init psci_idle_init(void)
 393{
 394        struct platform_device *pdev;
 395        int ret;
 396
 397        ret = platform_driver_register(&psci_cpuidle_driver);
 398        if (ret)
 399                return ret;
 400
 401        pdev = platform_device_register_simple("psci-cpuidle", -1, NULL, 0);
 402        if (IS_ERR(pdev)) {
 403                platform_driver_unregister(&psci_cpuidle_driver);
 404                return PTR_ERR(pdev);
 405        }
 406
 407        return 0;
 408}
 409device_initcall(psci_idle_init);
 410