root/drivers/cpuidle/cpuidle-psci.c

DEFINITIONS

1. psci_enter_idle_state
2. psci_dt_parse_state_node
3. psci_dt_cpu_init_idle
4. psci_cpu_init_idle
5. psci_idle_init_cpu
6. psci_idle_init

   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/cpuidle.h>
  12 #include <linux/cpumask.h>
  13 #include <linux/cpu_pm.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/of_device.h>
  18 #include <linux/psci.h>
  19 #include <linux/slab.h>
  20 
  21 #include <asm/cpuidle.h>
  22 
  23 #include "dt_idle_states.h"
  24 
  25 static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
  26 
  27 static int psci_enter_idle_state(struct cpuidle_device *dev,
  28                                 struct cpuidle_driver *drv, int idx)
  29 {
  30         u32 *state = __this_cpu_read(psci_power_state);
  31 
  32         return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter,
  33                                            idx, state[idx - 1]);
  34 }
  35 
  36 static struct cpuidle_driver psci_idle_driver __initdata = {
  37         .name = "psci_idle",
  38         .owner = THIS_MODULE,
  39         /*
  40          * PSCI idle states relies on architectural WFI to
  41          * be represented as state index 0.
  42          */
  43         .states[0] = {
  44                 .enter                  = psci_enter_idle_state,
  45                 .exit_latency           = 1,
  46                 .target_residency       = 1,
  47                 .power_usage            = UINT_MAX,
  48                 .name                   = "WFI",
  49                 .desc                   = "ARM WFI",
  50         }
  51 };
  52 
  53 static const struct of_device_id psci_idle_state_match[] __initconst = {
  54         { .compatible = "arm,idle-state",
  55           .data = psci_enter_idle_state },
  56         { },
  57 };
  58 
  59 static int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
  60 {
  61         int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
  62 
  63         if (err) {
  64                 pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
  65                 return err;
  66         }
  67 
  68         if (!psci_power_state_is_valid(*state)) {
  69                 pr_warn("Invalid PSCI power state %#x\n", *state);
  70                 return -EINVAL;
  71         }
  72 
  73         return 0;
  74 }
  75 
  76 static int __init psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
  77 {
  78         int i, ret = 0, count = 0;
  79         u32 *psci_states;
  80         struct device_node *state_node;
  81 
  82         /* Count idle states */
  83         while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
  84                                               count))) {
  85                 count++;
  86                 of_node_put(state_node);
  87         }
  88 
  89         if (!count)
  90                 return -ENODEV;
  91 
  92         psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
  93         if (!psci_states)
  94                 return -ENOMEM;
  95 
  96         for (i = 0; i < count; i++) {
  97                 state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
  98                 ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
  99                 of_node_put(state_node);
 100 
 101                 if (ret)
 102                         goto free_mem;
 103 
 104                 pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
 105         }
 106 
 107         /* Idle states parsed correctly, initialize per-cpu pointer */
 108         per_cpu(psci_power_state, cpu) = psci_states;
 109         return 0;
 110 
 111 free_mem:
 112         kfree(psci_states);
 113         return ret;
 114 }
 115 
 116 static __init int psci_cpu_init_idle(unsigned int cpu)
 117 {
 118         struct device_node *cpu_node;
 119         int ret;
 120 
 121         /*
 122          * If the PSCI cpu_suspend function hook has not been initialized
 123          * idle states must not be enabled, so bail out
 124          */
 125         if (!psci_ops.cpu_suspend)
 126                 return -EOPNOTSUPP;
 127 
 128         cpu_node = of_cpu_device_node_get(cpu);
 129         if (!cpu_node)
 130                 return -ENODEV;
 131 
 132         ret = psci_dt_cpu_init_idle(cpu_node, cpu);
 133 
 134         of_node_put(cpu_node);
 135 
 136         return ret;
 137 }
 138 
 139 static int __init psci_idle_init_cpu(int cpu)
 140 {
 141         struct cpuidle_driver *drv;
 142         struct device_node *cpu_node;
 143         const char *enable_method;
 144         int ret = 0;
 145 
 146         cpu_node = of_cpu_device_node_get(cpu);
 147         if (!cpu_node)
 148                 return -ENODEV;
 149 
 150         /*
 151          * Check whether the enable-method for the cpu is PSCI, fail
 152          * if it is not.
 153          */
 154         enable_method = of_get_property(cpu_node, "enable-method", NULL);
 155         if (!enable_method || (strcmp(enable_method, "psci")))
 156                 ret = -ENODEV;
 157 
 158         of_node_put(cpu_node);
 159         if (ret)
 160                 return ret;
 161 
 162         drv = kmemdup(&psci_idle_driver, sizeof(*drv), GFP_KERNEL);
 163         if (!drv)
 164                 return -ENOMEM;
 165 
 166         drv->cpumask = (struct cpumask *)cpumask_of(cpu);
 167 
 168         /*
 169          * Initialize idle states data, starting at index 1, since
 170          * by default idle state 0 is the quiescent state reached
 171          * by the cpu by executing the wfi instruction.
 172          *
 173          * If no DT idle states are detected (ret == 0) let the driver
 174          * initialization fail accordingly since there is no reason to
 175          * initialize the idle driver if only wfi is supported, the
 176          * default archictectural back-end already executes wfi
 177          * on idle entry.
 178          */
 179         ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
 180         if (ret <= 0) {
 181                 ret = ret ? : -ENODEV;
 182                 goto out_kfree_drv;
 183         }
 184 
 185         /*
 186          * Initialize PSCI idle states.
 187          */
 188         ret = psci_cpu_init_idle(cpu);
 189         if (ret) {
 190                 pr_err("CPU %d failed to PSCI idle\n", cpu);
 191                 goto out_kfree_drv;
 192         }
 193 
 194         ret = cpuidle_register(drv, NULL);
 195         if (ret)
 196                 goto out_kfree_drv;
 197 
 198         return 0;
 199 
 200 out_kfree_drv:
 201         kfree(drv);
 202         return ret;
 203 }
 204 
 205 /*
 206  * psci_idle_init - Initializes PSCI cpuidle driver
 207  *
 208  * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
 209  * to register cpuidle driver then rollback to cancel all CPUs
 210  * registration.
 211  */
 212 static int __init psci_idle_init(void)
 213 {
 214         int cpu, ret;
 215         struct cpuidle_driver *drv;
 216         struct cpuidle_device *dev;
 217 
 218         for_each_possible_cpu(cpu) {
 219                 ret = psci_idle_init_cpu(cpu);
 220                 if (ret)
 221                         goto out_fail;
 222         }
 223 
 224         return 0;
 225 
 226 out_fail:
 227         while (--cpu >= 0) {
 228                 dev = per_cpu(cpuidle_devices, cpu);
 229                 drv = cpuidle_get_cpu_driver(dev);
 230                 cpuidle_unregister(drv);
 231                 kfree(drv);
 232         }
 233 
 234         return ret;
 235 }
 236 device_initcall(psci_idle_init);