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
default_enter_idle(struct cpuidle_device * dev,struct cpuidle_driver * drv,int index)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
haltpoll_cpu_online(unsigned int cpu)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
haltpoll_cpu_offline(unsigned int cpu)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
haltpoll_uninit(void)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
haltpoll_init(void)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
haltpoll_exit(void)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