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/cpu_cooling.h> 12 #include <linux/cpuidle.h> 13 #include <linux/cpumask.h> 14 #include <linux/cpu_pm.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/of.h> 18 #include <linux/slab.h> 19 20 #include <asm/cpuidle.h> 21 22 #include "dt_idle_states.h" 23 24 /* 25 * arm_enter_idle_state - Programs CPU to enter the specified state 26 * 27 * dev: cpuidle device 28 * drv: cpuidle driver 29 * idx: state index 30 * 31 * Called from the CPUidle framework to program the device to the 32 * specified target state selected by the governor. 33 */ 34 static int arm_enter_idle_state(struct cpuidle_device *dev, 35 struct cpuidle_driver *drv, int idx) 36 { 37 /* 38 * Pass idle state index to arm_cpuidle_suspend which in turn 39 * will call the CPU ops suspend protocol with idle index as a 40 * parameter. 41 */ 42 return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx); 43 } 44 45 static struct cpuidle_driver arm_idle_driver __initdata = { 46 .name = "arm_idle", 47 .owner = THIS_MODULE, 48 /* 49 * State at index 0 is standby wfi and considered standard 50 * on all ARM platforms. If in some platforms simple wfi 51 * can't be used as "state 0", DT bindings must be implemented 52 * to work around this issue and allow installing a special 53 * handler for idle state index 0. 54 */ 55 .states[0] = { 56 .enter = arm_enter_idle_state, 57 .exit_latency = 1, 58 .target_residency = 1, 59 .power_usage = UINT_MAX, 60 .name = "WFI", 61 .desc = "ARM WFI", 62 } 63 }; 64 65 static const struct of_device_id arm_idle_state_match[] __initconst = { 66 { .compatible = "arm,idle-state", 67 .data = arm_enter_idle_state }, 68 { }, 69 }; 70 71 /* 72 * arm_idle_init_cpu 73 * 74 * Registers the arm specific cpuidle driver with the cpuidle 75 * framework. It relies on core code to parse the idle states 76 * and initialize them using driver data structures accordingly. 77 */ 78 static int __init arm_idle_init_cpu(int cpu) 79 { 80 int ret; 81 struct cpuidle_driver *drv; 82 83 drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL); 84 if (!drv) 85 return -ENOMEM; 86 87 drv->cpumask = (struct cpumask *)cpumask_of(cpu); 88 89 /* 90 * Initialize idle states data, starting at index 1. This 91 * driver is DT only, if no DT idle states are detected (ret 92 * == 0) let the driver initialization fail accordingly since 93 * there is no reason to initialize the idle driver if only 94 * wfi is supported. 95 */ 96 ret = dt_init_idle_driver(drv, arm_idle_state_match, 1); 97 if (ret <= 0) { 98 ret = ret ? : -ENODEV; 99 goto out_kfree_drv; 100 } 101 102 /* 103 * Call arch CPU operations in order to initialize 104 * idle states suspend back-end specific data 105 */ 106 ret = arm_cpuidle_init(cpu); 107 108 /* 109 * Allow the initialization to continue for other CPUs, if the 110 * reported failure is a HW misconfiguration/breakage (-ENXIO). 111 * 112 * Some platforms do not support idle operations 113 * (arm_cpuidle_init() returning -EOPNOTSUPP), we should 114 * not flag this case as an error, it is a valid 115 * configuration. 116 */ 117 if (ret) { 118 if (ret != -EOPNOTSUPP) 119 pr_err("CPU %d failed to init idle CPU ops\n", cpu); 120 ret = ret == -ENXIO ? 0 : ret; 121 goto out_kfree_drv; 122 } 123 124 ret = cpuidle_register(drv, NULL); 125 if (ret) 126 goto out_kfree_drv; 127 128 cpuidle_cooling_register(drv); 129 130 return 0; 131 132 out_kfree_drv: 133 kfree(drv); 134 return ret; 135 } 136 137 /* 138 * arm_idle_init - Initializes arm cpuidle driver 139 * 140 * Initializes arm cpuidle driver for all CPUs, if any CPU fails 141 * to register cpuidle driver then rollback to cancel all CPUs 142 * registeration. 143 */ 144 static int __init arm_idle_init(void) 145 { 146 int cpu, ret; 147 struct cpuidle_driver *drv; 148 struct cpuidle_device *dev; 149 150 for_each_possible_cpu(cpu) { 151 ret = arm_idle_init_cpu(cpu); 152 if (ret) 153 goto out_fail; 154 } 155 156 return 0; 157 158 out_fail: 159 while (--cpu >= 0) { 160 dev = per_cpu(cpuidle_devices, cpu); 161 drv = cpuidle_get_cpu_driver(dev); 162 cpuidle_unregister(drv); 163 kfree(drv); 164 } 165 166 return ret; 167 } 168 device_initcall(arm_idle_init); 169