2 * ARM64 generic CPU idle driver.
4 * Copyright (C) 2014 ARM Ltd.
5 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
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.
12 #define pr_fmt(fmt) "CPUidle arm64: " fmt
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>
21 #include <asm/cpuidle.h>
23 #include "dt_idle_states.h"
26 * arm64_enter_idle_state - Programs CPU to enter the specified state
32 * Called from the CPUidle framework to program the device to the
33 * specified target state selected by the governor.
35 static int arm64_enter_idle_state(struct cpuidle_device *dev,
36 struct cpuidle_driver *drv, int idx)
48 * Pass idle state index to cpu_suspend which in turn will
49 * call the CPU ops suspend protocol with idle index as a
52 ret = cpu_suspend(idx);
57 return ret ? -1 : idx;
60 static struct cpuidle_driver arm64_idle_driver = {
64 * State at index 0 is standby wfi and considered standard
65 * on all ARM platforms. If in some platforms simple wfi
66 * can't be used as "state 0", DT bindings must be implemented
67 * to work around this issue and allow installing a special
68 * handler for idle state index 0.
71 .enter = arm64_enter_idle_state,
73 .target_residency = 1,
74 .power_usage = UINT_MAX,
80 static const struct of_device_id arm64_idle_state_match[] __initconst = {
81 { .compatible = "arm,idle-state",
82 .data = arm64_enter_idle_state },
89 * Registers the arm64 specific cpuidle driver with the cpuidle
90 * framework. It relies on core code to parse the idle states
91 * and initialize them using driver data structures accordingly.
93 static int __init arm64_idle_init(void)
96 struct cpuidle_driver *drv = &arm64_idle_driver;
99 * Initialize idle states data, starting at index 1.
100 * This driver is DT only, if no DT idle states are detected (ret == 0)
101 * let the driver initialization fail accordingly since there is no
102 * reason to initialize the idle driver if only wfi is supported.
104 ret = dt_init_idle_driver(drv, arm64_idle_state_match, 1);
106 return ret ? : -ENODEV;
109 * Call arch CPU operations in order to initialize
110 * idle states suspend back-end specific data
112 for_each_possible_cpu(cpu) {
113 ret = cpu_init_idle(cpu);
115 pr_err("CPU %d failed to init idle CPU ops\n", cpu);
120 return cpuidle_register(drv, NULL);
122 device_initcall(arm64_idle_init);