drivers/cpuidle/cpuidle-arm.c

   1 /*
   2  * ARM/ARM64 generic CPU idle driver.
   3  *
   4  * Copyright (C) 2014 ARM Ltd.
   5  * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #define pr_fmt(fmt) "CPUidle arm: " fmt
  13
  14 #include <linux/cpuidle.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/cpu_pm.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/slab.h>
  21
  22 #include <asm/cpuidle.h>
  23
  24 #include "dt_idle_states.h"
  25
  26 /*
  27  * arm_enter_idle_state - Programs CPU to enter the specified state
  28  *
  29  * dev: cpuidle device
  30  * drv: cpuidle driver
  31  * idx: state index
  32  *
  33  * Called from the CPUidle framework to program the device to the
  34  * specified target state selected by the governor.
  35  */
  36 static int arm_enter_idle_state(struct cpuidle_device *dev,
  37                                 struct cpuidle_driver *drv, int idx)
  38 {
  39         /*
  40          * Pass idle state index to arm_cpuidle_suspend which in turn
  41          * will call the CPU ops suspend protocol with idle index as a
  42          * parameter.
  43          */
  44         return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);
  45 }
  46
  47 static struct cpuidle_driver arm_idle_driver = {
  48         .name = "arm_idle",
  49         .owner = THIS_MODULE,
  50         /*
  51          * State at index 0 is standby wfi and considered standard
  52          * on all ARM platforms. If in some platforms simple wfi
  53          * can't be used as "state 0", DT bindings must be implemented
  54          * to work around this issue and allow installing a special
  55          * handler for idle state index 0.
  56          */
  57         .states[0] = {
  58                 .enter                  = arm_enter_idle_state,
  59                 .exit_latency           = 1,
  60                 .target_residency       = 1,
  61                 .power_usage            = UINT_MAX,
  62                 .name                   = "WFI",
  63                 .desc                   = "ARM WFI",
  64         }
  65 };
  66
  67 static const struct of_device_id arm_idle_state_match[] __initconst = {
  68         { .compatible = "arm,idle-state",
  69           .data = arm_enter_idle_state },
  70         { },
  71 };
  72
  73 /*
  74  * arm_idle_init
  75  *
  76  * Registers the arm specific cpuidle driver with the cpuidle
  77  * framework. It relies on core code to parse the idle states
  78  * and initialize them using driver data structures accordingly.
  79  */
  80 static int __init arm_idle_init(void)
  81 {
  82         int cpu, ret;
  83         struct cpuidle_driver *drv = &arm_idle_driver;
  84         struct cpuidle_device *dev;
  85
  86         /*
  87          * Initialize idle states data, starting at index 1.
  88          * This driver is DT only, if no DT idle states are detected (ret == 0)
  89          * let the driver initialization fail accordingly since there is no
  90          * reason to initialize the idle driver if only wfi is supported.
  91          */
  92         ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
  93         if (ret <= 0)
  94                 return ret ? : -ENODEV;
  95
  96         ret = cpuidle_register_driver(drv);
  97         if (ret) {
  98                 pr_err("Failed to register cpuidle driver\n");
  99                 return ret;
 100         }
 101
 102         /*
 103          * Call arch CPU operations in order to initialize
 104          * idle states suspend back-end specific data
 105          */
 106         for_each_possible_cpu(cpu) {
 107                 ret = arm_cpuidle_init(cpu);
 108
 109                 /*
 110                  * Skip the cpuidle device initialization if the reported
 111                  * failure is a HW misconfiguration/breakage (-ENXIO).
 112                  */
 113                 if (ret == -ENXIO)
 114                         continue;
 115
 116                 if (ret) {
 117                         pr_err("CPU %d failed to init idle CPU ops\n", cpu);
 118                         goto out_fail;
 119                 }
 120
 121                 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 122                 if (!dev) {
 123                         pr_err("Failed to allocate cpuidle device\n");
 124                         ret = -ENOMEM;
 125                         goto out_fail;
 126                 }
 127                 dev->cpu = cpu;
 128
 129                 ret = cpuidle_register_device(dev);
 130                 if (ret) {
 131                         pr_err("Failed to register cpuidle device for CPU %d\n",
 132                                cpu);
 133                         kfree(dev);
 134                         goto out_fail;
 135                 }
 136         }
 137
 138         return 0;
 139 out_fail:
 140         while (--cpu >= 0) {
 141                 dev = per_cpu(cpuidle_devices, cpu);
 142                 cpuidle_unregister_device(dev);
 143                 kfree(dev);
 144         }
 145
 146         cpuidle_unregister_driver(drv);
 147
 148         return ret;
 149 }
 150 device_initcall(arm_idle_init);