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>
22 #include <asm/suspend.h>
24 #include "dt_idle_states.h"
27 * arm64_enter_idle_state - Programs CPU to enter the specified state
33 * Called from the CPUidle framework to program the device to the
34 * specified target state selected by the governor.
36 static int arm64_enter_idle_state(struct cpuidle_device *dev,
37 struct cpuidle_driver *drv, int idx)
49 * Pass idle state index to cpu_suspend which in turn will
50 * call the CPU ops suspend protocol with idle index as a
53 ret = cpu_suspend(idx);
58 return ret ? -1 : idx;
61 static struct cpuidle_driver arm64_idle_driver = {
65 * State at index 0 is standby wfi and considered standard
66 * on all ARM platforms. If in some platforms simple wfi
67 * can't be used as "state 0", DT bindings must be implemented
68 * to work around this issue and allow installing a special
69 * handler for idle state index 0.
72 .enter = arm64_enter_idle_state,
74 .target_residency = 1,
75 .power_usage = UINT_MAX,
76 .flags = CPUIDLE_FLAG_TIME_VALID,
82 static const struct of_device_id arm64_idle_state_match[] __initconst = {
83 { .compatible = "arm,idle-state",
84 .data = arm64_enter_idle_state },
91 * Registers the arm64 specific cpuidle driver with the cpuidle
92 * framework. It relies on core code to parse the idle states
93 * and initialize them using driver data structures accordingly.
95 static int __init arm64_idle_init(void)
98 struct cpuidle_driver *drv = &arm64_idle_driver;
101 * Initialize idle states data, starting at index 1.
102 * This driver is DT only, if no DT idle states are detected (ret == 0)
103 * let the driver initialization fail accordingly since there is no
104 * reason to initialize the idle driver if only wfi is supported.
106 ret = dt_init_idle_driver(drv, arm64_idle_state_match, 1);
109 pr_err("failed to initialize idle states\n");
110 return ret ? : -ENODEV;
114 * Call arch CPU operations in order to initialize
115 * idle states suspend back-end specific data
117 for_each_possible_cpu(cpu) {
118 ret = cpu_init_idle(cpu);
120 pr_err("CPU %d failed to init idle CPU ops\n", cpu);
125 ret = cpuidle_register(drv, NULL);
127 pr_err("failed to register cpuidle driver\n");
133 device_initcall(arm64_idle_init);