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