1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * cpuidle driver for haltpoll governor. 4 * 5 * Copyright 2019 Red Hat, Inc. and/or its affiliates. 6 * 7 * This work is licensed under the terms of the GNU GPL, version 2. See 8 * the COPYING file in the top-level directory. 9 * 10 * Authors: Marcelo Tosatti <mtosatti@redhat.com> 11 */ 12 13 #include <linux/init.h> 14 #include <linux/cpu.h> 15 #include <linux/cpuidle.h> 16 #include <linux/module.h> 17 #include <linux/sched/idle.h> 18 #include <linux/kvm_para.h> 19 #include <linux/cpuidle_haltpoll.h> 20 21 static struct cpuidle_device __percpu *haltpoll_cpuidle_devices; 22 static enum cpuhp_state haltpoll_hp_state; 23 24 static int default_enter_idle(struct cpuidle_device *dev, 25 struct cpuidle_driver *drv, int index) 26 { 27 if (current_clr_polling_and_test()) { 28 local_irq_enable(); 29 return index; 30 } 31 default_idle(); 32 return index; 33 } 34 35 static struct cpuidle_driver haltpoll_driver = { 36 .name = "haltpoll", 37 .governor = "haltpoll", 38 .states = { 39 { /* entry 0 is for polling */ }, 40 { 41 .enter = default_enter_idle, 42 .exit_latency = 1, 43 .target_residency = 1, 44 .power_usage = -1, 45 .name = "haltpoll idle", 46 .desc = "default architecture idle", 47 }, 48 }, 49 .safe_state_index = 0, 50 .state_count = 2, 51 }; 52 53 static int haltpoll_cpu_online(unsigned int cpu) 54 { 55 struct cpuidle_device *dev; 56 57 dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu); 58 if (!dev->registered) { 59 dev->cpu = cpu; 60 if (cpuidle_register_device(dev)) { 61 pr_notice("cpuidle_register_device %d failed!\n", cpu); 62 return -EIO; 63 } 64 arch_haltpoll_enable(cpu); 65 } 66 67 return 0; 68 } 69 70 static int haltpoll_cpu_offline(unsigned int cpu) 71 { 72 struct cpuidle_device *dev; 73 74 dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu); 75 if (dev->registered) { 76 arch_haltpoll_disable(cpu); 77 cpuidle_unregister_device(dev); 78 } 79 80 return 0; 81 } 82 83 static void haltpoll_uninit(void) 84 { 85 if (haltpoll_hp_state) 86 cpuhp_remove_state(haltpoll_hp_state); 87 cpuidle_unregister_driver(&haltpoll_driver); 88 89 free_percpu(haltpoll_cpuidle_devices); 90 haltpoll_cpuidle_devices = NULL; 91 } 92 93 static int __init haltpoll_init(void) 94 { 95 int ret; 96 struct cpuidle_driver *drv = &haltpoll_driver; 97 98 /* Do not load haltpoll if idle= is passed */ 99 if (boot_option_idle_override != IDLE_NO_OVERRIDE) 100 return -ENODEV; 101 102 cpuidle_poll_state_init(drv); 103 104 if (!kvm_para_available() || 105 !kvm_para_has_hint(KVM_HINTS_REALTIME)) 106 return -ENODEV; 107 108 ret = cpuidle_register_driver(drv); 109 if (ret < 0) 110 return ret; 111 112 haltpoll_cpuidle_devices = alloc_percpu(struct cpuidle_device); 113 if (haltpoll_cpuidle_devices == NULL) { 114 cpuidle_unregister_driver(drv); 115 return -ENOMEM; 116 } 117 118 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "cpuidle/haltpoll:online", 119 haltpoll_cpu_online, haltpoll_cpu_offline); 120 if (ret < 0) { 121 haltpoll_uninit(); 122 } else { 123 haltpoll_hp_state = ret; 124 ret = 0; 125 } 126 127 return ret; 128 } 129 130 static void __exit haltpoll_exit(void) 131 { 132 haltpoll_uninit(); 133 } 134 135 module_init(haltpoll_init); 136 module_exit(haltpoll_exit); 137 MODULE_LICENSE("GPL"); 138 MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>"); 139