1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ARM/ARM64 generic CPU idle driver. 4 * 5 * Copyright (C) 2014 ARM Ltd. 6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> 7 */ 8 9 #define pr_fmt(fmt) "CPUidle arm: " 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/slab.h> 18 19 #include <asm/cpuidle.h> 20 21 #include "dt_idle_states.h" 22 23 /* 24 * arm_enter_idle_state - Programs CPU to enter the specified state 25 * 26 * dev: cpuidle device 27 * drv: cpuidle driver 28 * idx: state index 29 * 30 * Called from the CPUidle framework to program the device to the 31 * specified target state selected by the governor. 32 */ 33 static int arm_enter_idle_state(struct cpuidle_device *dev, 34 struct cpuidle_driver *drv, int idx) 35 { 36 /* 37 * Pass idle state index to arm_cpuidle_suspend which in turn 38 * will call the CPU ops suspend protocol with idle index as a 39 * parameter. 40 */ 41 return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx); 42 } 43 44 static struct cpuidle_driver arm_idle_driver __initdata = { 45 .name = "arm_idle", 46 .owner = THIS_MODULE, 47 /* 48 * State at index 0 is standby wfi and considered standard 49 * on all ARM platforms. If in some platforms simple wfi 50 * can't be used as "state 0", DT bindings must be implemented 51 * to work around this issue and allow installing a special 52 * handler for idle state index 0. 53 */ 54 .states[0] = { 55 .enter = arm_enter_idle_state, 56 .exit_latency = 1, 57 .target_residency = 1, 58 .power_usage = UINT_MAX, 59 .name = "WFI", 60 .desc = "ARM WFI", 61 } 62 }; 63 64 static const struct of_device_id arm_idle_state_match[] __initconst = { 65 { .compatible = "arm,idle-state", 66 .data = arm_enter_idle_state }, 67 { }, 68 }; 69 70 /* 71 * arm_idle_init_cpu 72 * 73 * Registers the arm specific cpuidle driver with the cpuidle 74 * framework. It relies on core code to parse the idle states 75 * and initialize them using driver data structures accordingly. 76 */ 77 static int __init arm_idle_init_cpu(int cpu) 78 { 79 int ret; 80 struct cpuidle_driver *drv; 81 82 drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL); 83 if (!drv) 84 return -ENOMEM; 85 86 drv->cpumask = (struct cpumask *)cpumask_of(cpu); 87 88 /* 89 * Initialize idle states data, starting at index 1. This 90 * driver is DT only, if no DT idle states are detected (ret 91 * == 0) let the driver initialization fail accordingly since 92 * there is no reason to initialize the idle driver if only 93 * wfi is supported. 94 */ 95 ret = dt_init_idle_driver(drv, arm_idle_state_match, 1); 96 if (ret <= 0) { 97 ret = ret ? : -ENODEV; 98 goto out_kfree_drv; 99 } 100 101 /* 102 * Call arch CPU operations in order to initialize 103 * idle states suspend back-end specific data 104 */ 105 ret = arm_cpuidle_init(cpu); 106 107 /* 108 * Allow the initialization to continue for other CPUs, if the 109 * reported failure is a HW misconfiguration/breakage (-ENXIO). 110 * 111 * Some platforms do not support idle operations 112 * (arm_cpuidle_init() returning -EOPNOTSUPP), we should 113 * not flag this case as an error, it is a valid 114 * configuration. 115 */ 116 if (ret) { 117 if (ret != -EOPNOTSUPP) 118 pr_err("CPU %d failed to init idle CPU ops\n", cpu); 119 ret = ret == -ENXIO ? 0 : ret; 120 goto out_kfree_drv; 121 } 122 123 ret = cpuidle_register(drv, NULL); 124 if (ret) 125 goto out_kfree_drv; 126 127 return 0; 128 129 out_kfree_drv: 130 kfree(drv); 131 return ret; 132 } 133 134 /* 135 * arm_idle_init - Initializes arm cpuidle driver 136 * 137 * Initializes arm cpuidle driver for all CPUs, if any CPU fails 138 * to register cpuidle driver then rollback to cancel all CPUs 139 * registeration. 140 */ 141 static int __init arm_idle_init(void) 142 { 143 int cpu, ret; 144 struct cpuidle_driver *drv; 145 struct cpuidle_device *dev; 146 147 for_each_possible_cpu(cpu) { 148 ret = arm_idle_init_cpu(cpu); 149 if (ret) 150 goto out_fail; 151 } 152 153 return 0; 154 155 out_fail: 156 while (--cpu >= 0) { 157 dev = per_cpu(cpuidle_devices, cpu); 158 drv = cpuidle_get_cpu_driver(dev); 159 cpuidle_unregister(drv); 160 kfree(drv); 161 } 162 163 return ret; 164 } 165 device_initcall(arm_idle_init); 166