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